Note: Descriptions are shown in the official language in which they were submitted.
CA 02409377 2006-04-26
1
MAGNETIC CONTROLLED CURRENT OR VOLTAGE REGULATOR AND TRANSFORMER
The present invention relates to a magnetically influenced device, in
particular but
not exclusively, a magnetically influenced current or voltage regulator and a
magnetically influenced converter for controlled connection and disconnection
together with distribution of electrical energy.
The invention, which is a continuation of the known transductor technology, is
suitable as a voltage connector, current regulator or voltage converter in
several
areas of the field of power electronics. The transformative or inductive
connection
between the control winding and the main winding can be approximately 0 and
the
inductance in the main winding can be regulated through the current in the
control
winding, and furthermore the magnetic connection between a primary winding and
a
secondary winding in a transformer configuration can be regulated through the
current in the control winding.
In the field of rectification, for example, the present invention can be
employed in
connection with regulation of the high-voltage input in large rectifiers,
where the
advantage will be full exploitation of a diode rectifier over the entire
voltage range.
For asynchronous motors, the use of the invention may be envisaged in
connection
with the soft start of high-voltage motors. The invention is also suitable for
use in the
field of power distribution in connection with voltage regulation of power
lines, and
may be used for continuously controlled compensation of reactive power in the
network.
Even though it should not be considered limiting for the use of the device, it
may,
e.g., form part of a frequency converter for converting input frequency to
randomly
selected output frequency, for example intended for operation of an
asynchronous
motor, where the frequency converter's input side has a three-phase supply
which
by means of its phase conductors feeds the input to at least one transformer
intended for each of the converter's three-phase outputs, and where the
outputs of
such a transformer are connected via respective, selectively controllable
voltage
connectors, or via additional transformer-coupled voltage connectors, in order
to
form one of the said three-phase outputs.
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2
A second application of the device is as a direct converter of DC voltage to
AC
voltage whereby the AC voltage's frequency is continuously adjustable.
The use of this type of frequency converter in a subsea context, especially at
great
depths, will be where the use is required of high-capacity pumps with variable
speeds. Pumping in a subsea system will typically be performed from the
underwater site to a location above water (boosting) and with water injection
from
the underwater site down into the reservoir.
Variable speed engine controls are normally based on two principles; a) direct
electronic frequency-regulated converters, and b) AC-DC-AC converters with
pulse-
width modulation, and with extended use of semiconductors such as thyristors
and
IGBTs. The latter represents the technology widely used in industrial
applications
and for use on board locomotives, etc.
Speed control has recently been introduced for motors in underwater
environments.
The main challenge has been the packing and operation of such systems. In this
context, operation refers to service, maintenance, etc. Complex electronic
systems
generally have to operate in controlled environments with regard to
temperature and
pressure. Marine-based versions of such systems have to be encapsulated in
containers filled with nitrogen maintaining a pressure of 1 atm. On account of
heat
generation as a result of heat loss in the electronics, a substantial amount
of heat
may be generated, thus resulting in the need for forced air cooling. This is
usually
solved by the use of fans. The fans introduce a component which dramatically
reduces the working life of the system and represents a highly unsuitable
solution.
The sensitivity of the electronics and the electronic power semiconductors is
high
and requires protective circuits. This complicates the system and forces up
the
costs.
At great depths (over 300 meters) a protective container for such a system
will be
extremely heavy, representing a fairly significant proportion of the total
weight of the
system. In addition, maintenance of a system more often
than not will require the entire frequency converter to be raised, since even
simpler
maintenance is difficult to perform with a remotely operated vehicle (ROV).
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Thus it has been a co-ordinate object of the device according to the present
invention to offer the possibility of providing a frequency converter which is
suitable
for underwater pumping operations, particularly with the focus on operational
reliability, stability and minimum maintenance requirements. The operational
requirement will be approximately 25 years at 3000 m depth.
The standard frequency converters which are based on semiconductor technology
convert alternating current (AC) power with a given frequency to alternating
current
power in the other selected frequency without any intermediate DC connection.
The
conversion is carried out by forming a connection between given input and
output
terminals during controlled time intervals. An output voltage wave with an
output
frequency FO is generated by sequentially connecting selected segments of the
voltage waves on the AC input source with the input frequency Fl to the
terminals.
Such frequency converters exist in the form of the standard symmetrical
cycloconverter circuits for supplying power from a three- phase network to a
three-
phase motor. The standard cycloconverter module consists of a dual converter
in
each motor phase. Thus the normal method is to employ three identical,
essentially
independent dual converters which provide a three-phase output.
Amongst other known types of frequency converters is a symmetrical 12-pulse
centre cycloconverter consisting of three identical 4-quadrant 12-pulse centre
converters, with one for each output phase. All three converters share common
secondary windings on the input transformer. The neutral conductor can be
omitted
for a balanced 3-phase loaded Y-coupled motor.
Another known frequency converter based on semiconductor technology is the so-
called symmetrical 12-pulse bridge circuit which has three identical 4-
quadrant 12-
pulse bridge converters with one for each output phase. The input terminals on
each
of the six individual 6-pulse converters are fed from separate secondary
windings on
the input transformer. It should be noted that it is not permitted to use the
same
secondary winding for more than one converter. This is due to the fact that
each 12-
pulse converter in itself requires two completely insulated transformer
secondary
windings.
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It has therefore been a secondary object of the invention to avoid primarily
semiconductor components in the frequency converter which has to be located at
great depths and for this purpose the use has therefore been proposed
according to
the invention of the new magnetic converter technology based on an entirely
untraditional concept.
Thus a first embodiment of the invention comprises a magnetically influenced
current or voltage regulator, which comprises: a body which is composed of a
magnetisable material and provides a closed, magnetic circuit, at least one
first
electrical conductor wound round the body along at least a part of the closed
circuit
for at least one turn which forms a first main winding, at least one second
electrical
conductor wound around the body along at least a part of the closed circuit to
at
least one turn which forms a second main winding or control winding, where the
winding axis for the turn or turns in the main winding is at right angles to
the winding
axis for the turn or turns in the control winding. The object of this is to
provide
orthogonal magnetic fields in the body and thereby control the behaviour of
the
magnetisable material relative to the field in the main winding by means of
the field
in the control winding. In an advantageous version of this first embodiment,
the axis
for the turn(s) in the main winding is parallel to or coincident with the
body's
longitudinal direction, while the turn(s) in the control winding extend
substantially
along the magnetisable body and the axis for the control winding is therefore
at right
angles to the body's longitudinal direction. A second possible variant of the
first
embodiment consists in the axis for the turn(s) in the control winding being
parallel
to or coincident with the body's longitudinal direction, while the turn(s) in
the main
winding extend substantially along the magnetisable body and the axis for the
main
winding is therefore at right angles to the body's longitudinal direction.
This first embodiment of the device can be adapted for use as a transformer by
being equipped with a third electrical conductor wound around the body along
at
least a part of the closed circuit for at least one turn, forming a third main
winding,
the winding axis for the turn or turns in the third main winding coinciding
with or
being parallel to the winding axis for the turn or turns in the first main
winding, thus
providing a transformer effect between the first and the third main windings
when at
least one of them is excited. A second possibility for adapting the first
embodiment
of the invention for use as a transformer is to equip it with a third
electrical conductor
wound around the body along at least a part of the closed circuit for at least
one
CA 02409377 2006-04-18
turn, forming a third main winding, the winding axis for the turn or turns in
the third
main winding being coincident with or parallel to the winding axis for the
turn or turns
in the control winding, thus providing a transformer effect between the third
main
winding and the control winding when at least one of them is excited.
5
A second embodiment of the invention comprises a magnetically influenced
current
or voltage regulator, comprising a first body and a second body, each of which
is
composed of a magnetisable material which provides a closed, magnetic circuit,
the
said bodies being juxtaposed, at least one first electrical conductor wound
along at
least a part of the closed circuit for at least one turn which forms a first
main
winding, at least one second electrical conductor wound around at least a part
of the
first and/or second body for at least one turn which forms a second main
winding or
control winding, where the winding axis for the turn or turns in the main
winding is at
right angles to the winding axis for the turn or turns in the control winding.
The object
of this is to provide orthogonal magnetic fields in the body and thereby
control the
behaviour of the magnetisable material relative to the field in the main
winding by
means of the field in the control winding. The main and control windings may
of
course be interchanged, thus providing a magnetically influenced current or
voltage
regulator, characterized in that it comprises at least one first electrical
conductor
wound round at least a part of the first and/or the second body for at least
one turn
which forms a first main winding, at least one second electrical conductor
wound
along at least a part of the closed circuit for at least one turn which forms
a second
main winding or control winding, where the winding axis for the turn or turns
in the
main winding is at right angles to the winding axis for the turn or turns in
the control
winding with the object of providing orthogonal magnetic fields in the body
and
thereby controlling the behaviour of the magnetisable material relative to the
field in
the main winding by means of the field in the control winding.
A preferred variant of this second embodiment comprises first and second
magnetic
field connectors which together with the bodies form the closed magnetic
circuit.
This second embodiment of the device can also be adapted for use as a
transformer
by equipping it with a third electrical conductor wound for one turn which
forms a
third main winding, the winding axis for the turn or turns in the third main
winding
being coincident with or parallel to the winding axis A2 for the turn or turns
in the first
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main winding or in the control winding, thus providing a transformer effect
between
the third main winding and the first main winding or the control winding when
at least
one of this is excited.
In an advantageous version of this second embodiment of the invention, the
first and
the second body are tubular, thus enabling the first conductor or the second
conductor to extend through the first and the second body. In this version the
magnetic field connectors comprise apertures for the conductors. In a more
advantageous version of the invention, each magnetic field connector comprises
a
gap to facilitate the insertion of the first or the second conductor. In an
even more
advantageous embodiment the device is equipped with an insulating film placed
between the end surfaces of the tubes and the magnetic field connectors with
the
object of insulating the connecting surfaces from each other in order to
prevent
induced eddy currents from being produced in the connecting surfaces by short-
circuiting of the layer of film. For a core made of ferrite or compressed
powder, an
insulation film will not be necessary. Furthermore, it is particularly
advantageous that
each tube in this second embodiment comprises two or more core parts and that
in
addition an insulating layer is provided between the core parts. The tubes in
this
second embodiment of the invention, moreover, may have circular, square,
rectangular, triangular or hexagonal cross sections.
A third embodiment of the invention relates to a magnetically influenced
current or
voltage regulator, comprising a first, external tubular body and a second,
internal
tubular body, each of which is composed of a magnetisable material and
provides a
closed, magnetic circuit, the said bodies being concentric relative to each
other and
thus having a common axis, at least one first electrical conductor wound round
the
tubular bodies for at least one turn which forms a first main winding, at
least one
second electrical conductor provided in the space between the bodies and wound
around the bodies' common axis for at least one turn which forms a second main
winding or control winding, where the winding axis for the turn or turns in
the main
winding is at right angles to the winding axis for the turn or turns in the
control
winding. The object again is to provide orthogonal magnetic fields in the
bodies and
thereby control the behaviour of the magnetisable material relative to the
field in the
main winding by means of the field in the control winding. The main winding
and the
control winding will also be interchangeable in this third embodiment of the
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7
invention, thus providing a magnetically influenced current or voltage
regulator,
where at least one first electrical conductor is provided in the space between
the
bodies and wound round the bodies' common axis for at least one turn which
forms
a first main winding, at least one second electrical conductor is wound around
the
tubular bodies for at least one turn which forms a second main winding or
control
winding, and the winding axis for the turn or turns in the main winding is at
right
angles to the winding axis for the tum or turns in the control winding.
A variant of this third embodiment of the invention comprises first and second
magnetic field connectors which together with the bodies form the closed
magnetic
circuit.
This third embodiment of the device can also be adapted for use as a
transformer by
equipping the device with a third electrical conductor wound for at least one
turn
which forms a third main winding. In this case too the winding axis for the
turn or
turns in the third main winding may either be coincident with or parallel to
the
winding axis for the turn or turns in the first main winding, thus providing a
transformer effect between the first and the third main windings when at least
one of
this is excited, or the winding axis for the turn or turns in the third main
winding may
be coincident with or parallel to the winding axis for the turn or turns in
the control
winding, thus providing a transformer effect between the third main winding
and the
control winding when at least one of this is excited.
A fourth embodiment of the invention relates to a magnetically influenced
current or
voltage regulator which, in the same manner as in the third embodiment of the
invention, comprises a first, external tubular body and a second, internal
tubular
body, each of which is composed of a magnetisable material and forms a closed,
magnetic circuit or internal core. The device also comprises an additional
tubular
body which provides an external core mounted on the outside of the first,
external
tubular body, where the bodies are concentric relative to each other and thus
have a
common axis, at least one first electrical conductor wound round the tubular
bodies for at least one turn which forms a first main winding, at least one
second
electrical conductor provided in the space between the first and the second
body
and wound around the bodies' common axis for at least one turn which forms a
second main winding or control winding, where the winding axis for the turn or
turns
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in the main winding is at right angles to the winding axis for the turn or
turns in the
control winding. The object again is to provide orthogonal magnetic fields in
the
body and thereby control the behaviour of the magnetisable material relative
to the
field in the main winding by means of the field in the control winding. In the
same
way as in the second embodiment of the invention, the main winding and the
control
winding may be interchangeable, thus providing a device where at least one
first
electrical conductor is provided in the space between the first and the second
bodies
and wound round the bodies' common axis for at least one turn which forms a
second main winding or control winding, at least one second electrical
conductor is
wound around the tubular bodies for at least one turn which forms a second
main
winding or control winding.
A variant of this fourth embodiment of the invention comprises first and
second
magnetic field connectors which together with the bodies form the closed
magnetic
circuit.
This fourth embodiment of the device can also be adapted for use as a
transformer
by equipping it with a third electrical conductor wound around the external
core for
one turn which forms a third main winding. In this case too there will be two
alternatives: one where the winding axis for the turn or turns in the third
main
winding is coincident with or parallel to the winding axis for the turn or
turns in the
first main winding, thus providing a transformer effect between the first and
the third
main windings when at least one of this is excited, and one where the winding
axis
for the turn or turns in the third main winding is coincident with or parallel
to the
winding axis for the turn or turns in the control winding, thus providing a
transformer
effect between the third main winding and the control winding when at least
one of
this is excited.
It is, of course, possible to implement this fourth embodiment of the
invention in
such a manner that the two tubular bodies which form the internal core are
mounted
on the outside of the tubular body forming the external core, thus providing
an
internal core with one tubular body and an external core with two tubular
bodies.
In a variant of this fourth embodiment of the invention, the device is
characterized in
that the external core consists of several annular parts, and that the first
and/or the
third main winding forms individual windings around each annular part. A
second
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possibility is that the control winding and/or the third main winding form
individual
windings around each annular part.
The fourth embodiment will be the one which will be preferred in principle.
The device according to the invention will have many interesting applications,
of
which we shall mention only a few. These are: a) as a component in a frequency
converter for converting input frequency to randomly selected output frequency
preferably intended for operation of an asynchronous motor, in a
cycloconverter
connection, b) as a connector in a frequency converter for converting input
frequency to randomly selected output frequency and intended for operation of
an
asynchronous motor, for addition of parts of the phase voltage generated from
a 6 or
12-pulse transformer to each motor phase, c) as a DC to AC converter which
converts DC voltage/current to an AC voltage/current of randomly selected
output
frequency, d) as in c) but where three such variable inductance voltage
converters
are interconnected in order to generate a three-phase voltage with randomly
selected out-put frequency which is connected to the said asynchronous
machine,
e) for converting AC voltage to DC voltage within the processing industry,
where the
device is used as a reluctance- controlled variable transformer where the
output
voltage is proportional to the reluctance change in a core which is
magnetically
connected in parallel or in series to an external or internal core with a
separate
secondary winding, and where three or more such reluctance- controlled
transformers are connected to the known three-phase rectifier connections for
6 or
12- pulse rectifier connections for diode output stage, f) for use in a
rectifier for
converting AC voltage to DC voltage for use in the processing industry, where
the
device forms voltage connectors which are used as variable inductances in
series
with primary windings on known transformer connectors, and where three or more
such transformers are connected to three-phase rectifier connectors for 6 or
12-
pulse rectifier connectors for diode output stage, g) for AC/DC or DC/AC
converters
for use in the field of switched power supply, for reduction of the size of
the
magnetic voltage converter, where the device forms a reluctance-controlled
variable
transformer where the output voltage is proportional to the reluctance change
in a
core which is magnetically connected in parallel or in series to an external
or internal
core with a separate secondary winding, for example by filters in which
inductance is
included being formed with a variable inductance, h) as a component in a
CA 02409377 2006-04-26
controllable voltage compensator in the high voltage distribution network,
where the
device forms a linear variable inductance, i) as a component in a controllable
reactive power compensator (VAR compensator), where the device creates linear
variable inductance in connection with known filter circuits in which at least
one
5 condenser also forms an element, the device in the form of a reluctance-
controlled
transformer being employed as an element in a compensator connection where
capacitance or inductance are automatically connected and adjusted to the
extent
required to compensate for the reactive power, j) in a system for reluctance-
controlled direct conversion of an AC voltage to a DC voltage, k) in a system
for
10 reluctancecontrolled direct conversion of a DC voltage to an AC voltage.
The voltage connector is without movable parts for absorbing electrical
voltage
between a generator and a load. The function of the connector is to be able to
control the voltage between the generator and the load from 0-100% by means of
a
small control current. A second function could be as a pure voltage switch or
as a
current regulator. A further function could be forming and converting of a
voltage
curve.
The new technology according to the invention will be able to be used for
upgrading
existing diode rectifiers where there is a need for regulation. In connection
with 12-
pulse or 24-pulse rectifier systems, it will be possible to balance voltages
in the
system in a simple manner while having controllable diode rectification from 0-
100%.
The current or voltage regulator according to the invention can be implemented
in
the form of a magnetic connector substantially without movable parts, and it
will be
able to be used for connecting and thereby transferring electrical energy
between a
generator and a load. The function of the magnetic connector is to be capable
of
closing and opening an electrical circuit.
The connector will therefore act in a different way to a transductor where the
transformer principle is employed in order to saturate the core. The present
connector controls the working voltage by bringing the main core with a main
winding in and out of saturation by means of a control winding. The connector
has
no noticeable transformative or inductive connection between the control
winding
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11
and the main winding (in contrast to a transductor), i.e. no noticeable common
flux is
produced for the control winding and the main winding.
This new magnetically controlled connector technology will be capable of
replacing
semiconductors such as GTO's in high-powered applications, and MosFet or IGBT
in other applications, except that it will be limited to applications which
can withstand
stray currents which are produced by the main winding's magnetisation no-load
current. As mentioned in the introduction, the new converter will be suitable
for
realising a frequency converter which converts alternating current power with
a
given frequency to alternating current power which has a different selected
output
frequency. No intermediate DC connection will be necessary in this case.
As mentioned at the beginning, the device according to the invention is
capable of
being employed in connection with frequency converters, such as those based on
the cycloconverter principle, but also frequency converters based on 12-pulse
bridge
converters, or by direct conversion of DC voltage to AC voltage of variable
frequency.
The principle of the device according to the invention, where a variable
reluctance is
employed in a magnetisable body or main core, is based on the fact that
magnetisation current in a main winding, which is wound round a main core, is
limited by the flux resistance according to Faraday's Law. The flux which has
to be
established in order to generate counter-induced voltage is dependent on the
flux
resistance in the magnetic core. The magnitude of the magnetisation current is
determined by the amount of flux which has to be established in order to
balance
applied voltage.
The flux resistance in a coil where the core is air is of the order of 1.000-
900.000
times greater than for a winding which is wound round a core of ferromagnetic
material. In the case of low flux resistance (iron core) little current is
required to
establish a flux which is necessary to generate a
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12
bucking voltage to the applied voltage, according to Faraday's Law. In the
case of high
flux resistance (air core) a large current is required in order to establish
the flux necessary
to generate the same induced bucking voltage.
By controlling the flux resistance, the magnetisation current or the load
current in the
circuit can be controlled. In order to control the flux resistance, according
to the invention
a saturation of the main core is employed by means of a control flux which is
orthogonal
relative to the flux generated by the main winding. As already mentioned, the
above-
mentioned principle forms the basis of the invention, which relates to a
magnetically
influenced current or voltage regulator (connector) and a magnetically
influenced
converter device.
It will be appreciated that both the connector and the converter can be
produced by
means of suitable production equipment for toroidal cores. From the technical
point of
view, the converter can be produced by magnetic material such as
electroplating being
wound up in suitably designed cylindrical cores or used for higher frequencies
with
compressed powder or ferrite. It is, of course, also advantageous to produce
ferrite cores
or compressed powder cores according to the dictates of the application.
More specifically, in accordance with the present invention as broadly
claimed, there is
provided a magnetically influenced device, comprising a body that comprises a
closed
magnetic circuit. The magnetic circuit comprises an anisotropic magnetisable
material, at
least one first electrical conductor wound around the body along at least a
part of the
closed circuit for at least one turn which forms a first main winding, and at
least one
second electrical conductor wound around the body along at least a part of the
closed
circuit for at least one turn which forms a control winding. A winding axis
for the turn in the
main winding is at right angles to a winding axis for the turn in the control
winding,
orthogonal magnetic fields are generated in the body when the first main
winding and the
control winding are excited, and a characteristic of the anisotropic
magnetisable material
relative to a field in the main winding is controlled by means of a field in
the control
winding.
Also according with the present invention, there is provided a magnetically
influenced
device comprising a first body and a second body that are juxtaposed and that
comprise
each a magnetic circuit that comprises an anisotropic magnetisable material,
at least one
CA 02409377 2006-04-18
12a
first electrical conductor wound along at least a part of the magnetic circuit
for at least one
turn to form a first main winding, and at least one second electrical
conductor wound
around at least a part of at least one of the first body and the second body
for at least one
turn to form a control winding. A winding axis for the turn in the main
winding is at right
angles to a winding axis for the turn in the control winding. Orthogonal
magnetic fields are
generated in at least one of the first body and the second body when the first
main winding
and the control winding are excited. A characteristic of the anisotropic
magnetisable
material relative to a field in the main winding is controlled by means of a
field in the control
winding.
Yet the present invention provides for a magnetically influenced device that
comprises a
first body and a second body that comprise each an anisotropic magnetisable
material, a
first magnetic field connector, a second magnetic field connector, a closed
magnetic circuit
formed by a combination of the first and second magnetic field connectors and
the first and
second bodies, at least one first electrical conductor wound around at least a
part of at
least one of the first body and the second body for at least one turn to form
a first main
winding, and at least one second electrical conductor wound along at least a
part of the
closed circuit for at least one turn to form a control winding. The first and
second bodies are
juxtaposed. A winding axis for the turn in the main winding is at right angles
to a winding
axis for the turn in the control winding. Orthogonal magnetic fields are
generated in at least
one of the first body and the second body when the first main winding and the
control
winding are excited. A characteristic of the anisotropic magnetisable material
relative to a
field in the main winding is controlled by means of a field in the control
winding.
Still according to the present invention, there is provided a magnetically
influenced device
that comprises a first external tubular body and a second internal tubular
body located
concentric to each other around a common axis with each body comprising an
anisotropic
magnetisable material that provides a magnetic circuit, at least one first
electrical conductor
wound round the tubular bodies for at least one turn to form a first main
winding, and at
least one second electrical conductor provided in a gap between the tubular
bodies and
wound around the common axis for at least one turn to form a control winding.
A winding
axis for the turn in the main winding is at right angles to a winding axis for
the turn in the
control winding. Orthogonal magnetic fields are generated in the body when the
first main
winding and the control winding are excited. A characteristic of the
anisotropic
magnetisable material relative to a field in the main winding is controlled by
means of a
CA 02409377 2006-04-18
12b
field in the control winding.
The present invention also provides for a magnetically influenced device that
comprises a
first external tubular body and a second internal tubular body located
concentric to each
other around a common axis with each body comprising an anisotropic
magnetisable
material, a first magnetic field connector, a second magnetic field connector,
a closed
magnetic circuit formed by the tubular bodies and the first and second
connectors, at least
one first electrical conductor provided in a gap between the tubular bodies,
the first
electrical conductor wound around the common axis for at least one turn to
form a first
main winding, and at least one second electrical conductor wound round the
tubular bodies
for at least one turn to form a control winding. A winding axis for the turn
in the main
winding is at right angles to a winding axis for the turn in the control
winding. Orthogonal
magnetic fields are generated in at least one of the first body and the second
body when
the first main winding and the control winding are excited. A characteristic
of the
anisotropic magnetisable material relative to a field in the main winding is
controlled by
means of a field in the control winding.
Furthermore, it is provided with the present invention a magnetically
influenced device that
comprises a first external tubular body comprising an anisotropic magnetisable
material, a
second internal tubular body comprising the anisotropic magnetisable material,
an
additional tubular body which provides an external core which is mounted
outside of and
concentric with the first external tubular body along a common axis, at least
one first
electrical conductor wound round the tubular bodies for at least one turn to
form a first main
winding, and at least one second electrical conductor mounted in a gap between
the first
and the second bodies and wound around the common axis for at least one turn
to form a
control winding. The tubular bodies each provide a closed magnetic circuit. A
winding axis
for the turn in the main winding is at right angles to a winding axis for the
turn in the control
winding. Orthogonal magnetic fields are generated in at least one of the first
body and the
second body when the first main winding and the control winding are excited. A
characteristic of the anisotropic magnetisable material relative to the field
in the main
winding is controlled by means of a field in the control winding.
Moreover, the present invention provides for a magnetically influenced device
that
comprises a first external tubular body comprising an anisotropic magnetisable
material, a
second internal tubular body comprising the anisotropic magnetisable material,
an
additional tubular body which provides an external core mounted outside of and
concentric
CA 02409377 2006-04-18
12c
with the first external tubular body along a common axis, at least one first
electrical
conductor wound around the tubular bodies for at least one turn to form a
first main
winding, and at least one second electrical conductor mounted in a gap between
the first
and the second bodies and wound round the common axis for at least one turn to
form a
control winding. The tubular bodies each provide a closed magnetic circuit. A
winding axis
for the turn in the main winding is at right angles to a winding axis for the
turn in the control
winding. Orthogonal magnetic fields are generated in at least one of the first
body and the
second body when the first main winding and the control winding are excited. A
characteristic of the anisotropic magnetisable material relative to a field in
the main winding
is controlled by means of a field in the control winding.
The present invention also provides for a controllable magnetic structure that
comprises an
anisotropic magnetic body comprising a closed magnetic circuit, a main winding
wound
around a portion of the anisotropic magnetic body defining a first axis, and a
control
winding in conjunction with the portion of the anisotropic magnetic body. The
control
winding wound about a second axis orthogonal to the first axis. A main field
is generated by
the main winding in the closed magnetic circuit in a high permeability
direction when the
main winding is energized. A control field, orthogonal to the main field, is
generated by the
control winding in the closed magnetic circuit in a low permeability direction
when the
control winding is energized. The main field is controllable by the control
field.
Finally, the present invention provides for a method of employing a second
field to control a
first field in a closed magnetic circuit. The closed magnetic circuit
comprises an anisotropic
magnetic material. The method comprises the steps of generating the first
field in the
closed magnetic circuit in a high permeability direction, generating the
second field,
orthogonal to the first field, in the closed magnetic circuit in a low
permeability direction, and
adjusting the second field to control the first field.
The foregoing and other objects, advantages and features of the present
invention will
become more apparent upon reading the following non restrictive description of
illustrative
embodiments thereof, given by way of example only with reference to the
accompanying
drawings.
The invention will now be described in greater detail with reference to the
attached
drawings, in which:
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12d
Figs. 1 and 2 illustrate the basic principle of the invention and a first
embodiment thereof.
Fig. 3 is a schematic illustration of an embodiment of the device according to
the invention.
Fig. 4 illustrates the areas of the different magnetic fluxes which form part
of the device
according to the invention.
Fig. 5 illustrates a first equivalent circuit for the device according to the
invention.
Fig. 6 is a simpiified block diagram of the device according to the invention.
Fig. 7 is a diagram for flux versus current.
Figs. 8 and 9 illustrate magnetisation curves and domains for the magnetic
material in the
device according to the invention. Fig. 10 illustrates flux densities for the
main and control
windings.
Fig. 11 illustrates a second embodiment of the invention.
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13
Fig. 12 illustrates the same second embodiment of the invention.
Figs. 13 and 14 illustrate the second embodiment in section.
Figs. 15-18 illustrate different embodiments of the magnetic field connectors
in the said second embodiment of the invention.
Figs. 19-32 illustrate different embodiments of the tubular bodies in the
second embodiment of the invention.
Figs. 33-38 illustrate different aspects of the magnetic field connectors for
use in the second embodiment of the invention.
Fig. 39 illustrates an assembled device according to the second embodiment
of the invention.
Figs. 40 and 41 are a section and a view of a third embodiment of the
invention.
Figs. 42, 43 and 44 illustrate special embodiments of magnetic field
connectors for use in the third embodiment of the invention.
Fig. 45 illustrates the third embodiment of the invention adapted for use as a
transformer.
Figs. 46 and 47 are a section and a view of a fourth embodiment of the
invention for use as a reluctance-controlled, flux-connected transformer.
Figs. 48 and 49 illustrate the fourth embodiment of the invention adapted to
suit a powder-based magnetic material, and tliereby without magnetic field
connectors.
Figs. 50 and 51 are sections along lines VI-VI and V-V in figure 48.
Figs. 52 and 53 illustrate a core adapted to suit a powder-based magnetic
material, and thereby without magnetic field connectors.
Fig. 54 is an "X-ray picture" of a variant of the fourth embodiment of the
invention.
Fig. 55 illustrates a second variant of the device according to the invention
together with the principle behind a possibility for transformer connection.
Fig. 56 illustrates a proposal for an electro-technical schematic symbol for
the voltage connector according to the invention.
Fig. 57 illustrates a proposal for a block schematic symbol for the voltage
connector.
Fig. 58 illustrates a magnetic circuit where the control winding and control
flux are not included.
In figs. 59 and 60 there are proposals for electro-technical schematic symbols
for the voltage converter according to the invention.
Fig. 61 illustrates the use of the invention in an alternating current
circuit.
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14
Fig. 62 illustrates the use of the invention in a three-phase system.
Fig. 63 illustrates a use as a variable choke in DC-DC converters.
Fig. 64 illustrates a use as a variable choke in a filter together with
condensers.
Fig. 65 illustrates a simplified reluctance model for the device according to
the invention
and a simplified electrical equivalent diagram for the connector according to
the
invention.
Fig. 66 illustrates the connection for a magnetic switch.
Fig. 67 illustrates examples of a three- phase use of the invention.
Fig. 68 illustrates the device employed as a switch.
Fig. 69 illustrates a circuit comprising 6 devices according to the invention.
Fig. 70 illustrates the use of the device according to the invention as a DCAC
converter.
Fig. 71 illustrates a use of the device according to the invention as an AC-DC
converter.
Fig. 71 a is a graph showing, as a function of time, the voltages R(t), S(t)
and T(t) of
Figure 71.
The invention will now be explained in principle in connection with figs. 1 a
and lb.
In the entire description, the arrows associated with magnetic field and flux
will
substantially indicate the directions thereof within the magnetic material.
The arrows
are drawn on the outside for the sake of clarity.
Figure 1 a illustrates a device comprising a body 1 of a magnetisable material
which
forms a closed magnetic circuit. This magnetisable body or core 1 may be
annular or of
another suitable shape. Round the body 1 is wound a first main winding 2, and
the
direction of the magnetic field H1 (corresponding to the direction of the flux
density 131)
which will be created when the main winding is excited will follow the
magnetic circuit.
The main winding 2 corresponds to a winding in an ordinary transformer. In an
embodiment the device includes a second main winding 3 which in the same way
as
the main winding 2 is wound round the magnetisable body 1 and which will
thereby
provide a magnetic field which extends substantially along the body 1 (i. e.
parallel to
H1, B1). The device finally includes a third main winding 4 which in a
preferred
embodiment of the invention extends internally along the magnetic body 1. The
magnetic field H2 (and thus the magnetic flux density B2) which is created
when the
third main winding 4 is excited will have a direction which is at right angles
to the
direction of the fields in the first and
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the second main winding (direction of H1, B1). The invention may also
include a fourth main winding 5 which is wound round a leg of the body 1.
When the fourth main winding 5 is excited, it will produce a magnetic field
with a direction which is at right angles both to the field in the first (H1),
the
5 second and the third main winding (H2) (figure 3). This will naturally
require
the use of a closed magnetic circuit for the field which is created by the
fourth main winding. This circuit is not illustrated in the figure, since the
figure is only intended to illustrate the relative positions of the windings.
In the topologies which are considered to be preferred in the present
10 description, however, it is the case that the turns in the main winding
follow
the field direction from the control field and the turns in the control
winding
follow the field direction to the main field.
Figures 1 b-1 g illustrate the definition of the axes and the direction of the
different windings and the magnetic body. With regard to the windings, we
15 shall call the axis the perpendicular to the surface which is restricted by
each
turn. The main winding 2 will have an axis A2, the main winding 3 an axis
A3 and the control winding 4 an axis A4.
With regard to the magnetisable body, the longitudinal direction will vary
with respect to the shape. If the body is elongated, the longitudinal
direction
Al will correspond to the body's longitudinal axis. If the magnetic body is
square as illustrated in figure la, a longitudinal direction Al can be defined
for each leg of the square. Where the body is tubular, the longitudinal
direction A1 will be the tube's axis, and for an annular body the longitudinal
direction A 1 will follow the ring's circumference.
The invention is based on the possibility of altering the characteristics of
the
magnetisable body 1 in relation to a first magnetic field by altering a second
magnetic field which is at right angles to the first. Thus, for example, the
field H1 can be defined as the working field and control the body's 1
characteristics (and thereby the behaviour of the working field H1) by means
of the field H2 (hereinafter called control field H2). This will now be
explained in more detail.
The magnetisation current in an electrical conductor which is enclosed by a
ferromagnetic material is limited by the reluctance according to Faraday's
Law. The flux which has to be established in order to generate
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16
counterinduced voltage depends on the reluctance in the magnetic material
enclosing the conductor.
The extent of the magnetisation current is determined by the amount of flux
which has to be established in order to balance applied voltage.
In general the following steady-state equation applies for sinusoidal voltage:
1) Flux:
E = applied voltage
1 w = angular frequency
~ -j E
N.co N = number of turns for winding
where the flux (D through the magnetic material is determined by the voltage
E. The current required in order to establish necessary flux is determined by:
2) Current
I=(D =Rn' (D I N
N Rm
3) Reluctance (flux resistance)
lj = length of flux path
Ij r = relative permeability
Rm=
o . r . Aj o = permeability in vacuum
Aj = cross-sectional area of the flux path
Where there is low reluctance (iron enclosure), according to expression 2)
above, little current will be required in order to establish the necessary
flux,
and supplied voltage will overlay the connector. In the case of high
reluctance (air) on the other hand, a large current will be required in order
to
establish the necessary flux. In this case the current will then be limited by
the voltage over the load and the voltage induced in the connector. The
difference between reluctance in air and reluctance in magnetic material may
be of the order of 1.000 - 900.000.
The magnetic induction or flux density in a magnetic material is determined
by the material's relative permeability and the magnetic field intensity. The
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magnetic field intensity is generated by the current in a winding arranged
round or through the material.
For the systems which have to be evaluated the following applies:
The field intensity
H = field intensity
f H.ds = I. N s = the integration path
I = current in winding
N = number of windings
Flux density or induction:
(3 = o = r H H= magnetic field intensity
The ratio between magnetic induction and field intensity is non-linear, with
the result that when the field intensity increases above a certain limit, the
flux density will not increase and on account of a saturation phenomenon
which is due to the fact that the magnetic domains in a ferromagnetic
material are in a state of saturation. Thus it is desirable to provide a
control
field H2 which is perpendicular to a working field H1 in the magnetic
material in order to control the saturation in the magnetisable material,
while
avoiding magnetic connection between the two fields and thereby avoiding
transformative or inductive connection. Transformative connection means a
connection where two windings "share" a field, with the result that a change
in the field from one winding will lead to a change in the field in the other
winding.
One will avoid increasing H to saturation as by a transformative connection
where the fluxes will have a common path and will be added together. If the
fluxes are orthogonal they will not be added together. For example, by
providing the magnetic material as a tube where the main winding or the
winding which carries the working current is located inside the tube and is
wound in the tube's longitudinal direction, and where the control winding or
the winding which carries the control current is wound round the
circumference of the tube, the desired effect is achieved. Depending on the
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18'
tube dimensions, a small area for the control flux and a large area for the
working flux are thereby also achieved.
In the said embodiment, the working flux will travel in the direction along
the tube's circumference and have a closed magnetic circuit. The control flux
on the other hand will travel in the tube's longitudinal direction and will
have
to be connected in a closed magnetic circuit, either by two tubes being placed
in parallel and a magnetic material connecting the control flux between the
two tubes, or by a first tube being placed around a second tube, with the
result that the control winding is located between the two tubes, and the end
surfaces of the tubes are magnetically interconnected, thereby obtaining a
closed path for the control flux. These solutions will be described in greater
detail later.
The parts which provide magnetic connection between the tubes or the core
parts will hereinafter be called magnetic field connectors or magnetic field
couplings.
The total flux in the material is given by
4) (D =B =Aj
The flux density B is composed of the vector sum of B 1 and B2 (fig. 4d). B 1
is generated by the current 11 in the first main winding 2, and B 1 has a
direction tangentially to the conductors in the main winding 2. The main
winding 2 has N1 turns and is wound round the magnetisable body 1. B2 is
generated by the current 12 in the control winding 4 with N2 number of turns
and where the control winding 4 is wound round the body 1. B2 will have a
direction tangentially to the conductors in the control winding 4.
Since the windings 2 and 4 are placed at 90 to each other, B1 and B2 will be
orthogonally located. In the magnetisable body 1, B 1 will be oriented
transversally and B2 longitudinally. In this connection we refer particularly
to what is illustrated in figs. 1-4.
5)B=B,+Ba
It is considered an advantage that the relative permeability is higher in the
working field's (Hl) direction than in the control field's (H2) direction,
i.e.
the magnetic material in the magnetisable body 1 is anisotropic, but of course
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this should not be considered limiting with regard to the scope of the
invention.
The vector sum of the fields H1 and H2 will determine the total field in the
body 1, and thus the body's 1 condition with regard to saturation, and will be
determining for the magnetisation current and the voltage which is divided
between a load connected to the main winding 2 and the connector. Since the
sources for B 1 and B2 will be located orthogonally to each other, none of the
fields will be able to be decomposed into the other. This means that B 1
cannot be a function of B2 and vice versa. However, B, which is the vector
sum of B 1 and B2 will be influenced by the extent of each of them.
B2 is the vector which is generated by the control current. The cross-
sectional surface A2 for the B2 vector will be the transversal surface of the
magnetic body 1, cf. figure 4c. This may be a small surface limited by the
thickness of the magnetisable body 1, given by the surface sector between the
internal and external diameters of the body 1, in the case of an annular body.
The cross-sectional surface Al (see figures 4a, b) for the B 1 field on the
other hand is given by the length of the magnetic core and the rating of
applied voltage. This surface will be able to be 5-10 times larger than the
surface of the control flux density B2, without this being considered limiting
for the invention.
When B2 is at saturation level, a change in B 1 will not result in a change in
B. This makes it possible to control which level on B 1 gives saturation of
the
material, and thereby control the reluctance for B.
The inductance for the control winding 4 (with N2 turns) will be able to be
rated at a small value suitable for pulsed control of the regulator, i.e.
enabling a rapid reaction (of the order of milliseconds) to be provided.
6)
N2= Number of turns for control winding
A2 A2 = Area of control flux density B2
Ls = N22 =,uY_~.Q, =,uo 12 12 = Length of flux path for control flux
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A silnplified mathematical description will now be given of the invention and
its applications, based on Maxwell's equations.
For simple calculations of magnetic fields in electrical power technology,
Maxwell's equations are used in integral form.
5 In a device of the type which will be analysed here (and to some extent also
in the invention), the magnetic field has low frequency.
The displacement current can thus be neglected compared with the current
density.
Maxwell's equation
10 crrrl ( K) = J+~ D 7)
is simplified to
curl (R) J 8)
The integral form is found in Toke's theorem:
15 J(H)dl = I 9)
presents a solution for the system in fig. 4, where the main winding 2
establishes the H 1 field. The calculations are performed here with
concentrated windings in order to be able to focus on the principle and not an
exact calculation.
20 The integration path coincides with the field direction and an average
field
length 11 is chosen in the magnetisable body 1. The solution of the integral
equation then becomes:
H111=N1=I1 11)
This is also known as the magnetomotive force MMK.
F1 = N1 = Il 12)
The control winding 4 will establish a corresponding MMK generated by the
current 12:
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21
H2=I2=N2=I2 13)
F2 = N2 = 12 14)
The magnetisation of the material under the influence of the H field which is
generated from the source windings 2 and 4 is expressed by the flux density
B. For the main winding 2:
B, = ,uo = ,C17 1 = H. 15)
For the control winding 4:
B2 = ,ua = ,ur2 = H2 16)
The permeability in the transversal direction is of the order of 1 to 2
decades
less than for the longitudinal direction. The permeability for vacuum is:
,uo=4=TC=10-'=H 17)
m
The capacity to conduct magnetic fields in iron is given by Pr, and the
magnitude of p is from 1000 to 100.000 for iron and for the new Metglas
materials up to 900.000.
By combining equations 11) and 15), for the main winding 2 we get:
=I,
Bl = pt, ' pr ' N, l 18)
1
The flux in the magnetisable body 1 from the main winding 2 is given by
equation:
(D,=~Bi=nds 19)
Assuming the flux is constant over the core cross section:
N'I' A'
(D,=B,=A1=po'pr l 20)
~
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Here we recognise the expression for the flux resistance Rm or the reluctance
as given under 3):
(D' 21)
Rml
Rm, = l' 22)
,uo - ,ur Ai
In the same way we find flux and reluctance for the control winding 4:
-N2 IZ 23)
Z Rm2
Rm2 = 1z 24)
po - pr2 A 2
The invention is based on the physical fact that the differential of the
magnetic field intensity which has its source in the current in a conductor is
expressed by curl to the H field. Curl to H says something about the
differential or the field change of the H field across the field direction of
H.
In our case we have calculated the field on the basis that the surface
perpendicular of the differential field loop has the same direction as the
current. This means that the fields from the current-carrying conductors
forming the windings which are perpendicular to each other are also
orthogonal. The fact that the fields are perpendicular to each other is
important in relation to the orientation of the domains in the material.
Before examining this more closely, let us introduce self-inductance which
will play a major role in the application of the new magnetically controlled
power components.
According to Maxwell's equations, a time-varying magnetic field will induce
a time-varying electrical field, expressed by
~E.dl = ~t(~B = nds) 25)
The left side of the integral is an expression of the potential equation in
integral form. The source of the field variation may be the voltage from a
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23
generator and we can express Faraday's Law when the winding has N turns
and all flux passes through all the turns, see fig. 5:
e=N=A.; .dtB=N'dt~= d ~, 26)
dt
2,, (Wb) gives an expression of the number of flux turns and is the sum of the
flux through each turn in the winding. If one envisages the generator G in
fig.
5 being disconnected after the field is established, the source of the field
variation will be the current in the circuit and from circuit technology we
have, see fig. 5a:
e=L=~t 27)
From equation 21 we have:
(D =k=I 28)
When L is constant, the combination of equations 26 and 27 gives:
= L 29)
dt dt
The solution of 29 is:
A =L=i+C 30)
From 28 we derive that C is 0 and:
L = A 31)
i
This is an expression of self-inductance for the winding N (or in our case the
main winding 2). The self-inductance is equal to the ratio between the flux
turns established by the current in the winding (the coil) and the current in
the winding (the coil).
The self-inductance in the winding is approximately linear as long as the
magnetisable body or the core are not in saturation. However, we shall
change the self-inductance through changes in'the permeability in the
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material of the magnetisable body by changing the domain magnetisation in
the transversal direction by the control field (i.e. by the field H2 which is
established by the control winding 4).
From equation 21) combined with 31) we obtain:
L = N 32)
RTn
The alternating current resistance or the reactance in an electrical circuit
with
self-inductance is given by
XL = jwL 33)
By magnetising the domains in the magnetisable body in the transversal
direction, the reluctance of the longitudinal direction will be changed. We
shall not go into details here in the description of what happens to the
domains during different field influences. Here we have considered ordinary
commercial electroplate with a silicon content of approximately 3%, and in
this description we shall not offer an explanation of the phenomenon in
relation to the Metglas materials, but this, of course, should not be
considered limiting for the invention, since the magnetic materials with
amorphous structure will be able to play an important role in some
applications of the invention.
In a transformer we employ closed cores with high permeability where
energy is stored in magnetic leakage fields and a small amount in the core,
but the stored energy does not form a direct part in the transformation of
energy, with the result that no energy conversion takes place in the sense of
what occurs in an electromechanical system where electrical energy is
converted to mechanical energy, but energy is transformed via magnetic flux
through the transformer. In an inductance coil or choke with an air gap, the
reluctance in the air gap is dominant compared to the reluctance in the core,
with approximately all the energy being stored in the air gap.
In the device according to the invention a "virtual" air gap is generated
through saturation phenomena in the domains. In this case the energy storage
will take place in a distributed air gap comprising the whole core. We
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consider the actual magnetic energy storage system to be free for losses, and
any losses will thus be represented by external components.
The energy description which we use will be based on the principle of
conservation of energy.
5 The first law of thermodynamics applied to the loss-free electromagnetic
system above gives, see fig. 6:
dWelin = dWfld 34)
where dWelin = differential electrical energy supply
dWfld = differential change in magnetically stored energy
10 From equation 26) we have
e=d~
dt
Now our inductance is variable through the orthogonal field or the control
field H2, and equation 31) inserted in 26) gives:
e=d(dt Z)=L - dt dt
+l 35)
The effect within the system is
p=i=e--i=~t~, 36)
Thus we have
dW,,,;,, = i = dll 37)
For a system with a core where the reluctance can be varied and which only
has a main winding, equation 35) inserted in equation 37) will give
dW,;,,=i=d(L=i)=i=(L=di+i=dl) 38)
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In the device according to the invention L will be varied as a function of pr,
the relative permeability in the magnetisable body or the core 1, which in
turn is a function of 12, the control current in the control winding 4.
When L is constant, i.e. when 12 is constant, we can disregard the section i x
dL since dL is equal to 0, and thus the magnetic field energy will be given
by:
W~,, L i z 39)
2
When L is varied by means of 12, the field energy will be altered as a result
of the altered value of L, and thereby the current I will also be altered
since it
is associated with the field value through the flux turns X. Since i and X are
variable and functions of each other, while being non-linear functions, we
shall not go into the solution here since it will involve mathematics which
exceed the bounds of the description of the invention.
However, we can draw the conclusion that the field energy and the energy
distribution will be controllable via r and influence how energy stored in
the field is increased and decreased. When the field energy is decreased, the
surplus portion will be returned to the generator. Or if we have an extra
winding (e.g. winding 3, figure 1) in the same winding window as the first
main winding 2 and with the same winding axis as it has, this will provide a
transformative transfer of energy from the first winding 2 to the second main
winding 3.
This is illustrated in fig. 7 where an alteration of k results in an
alteration of
the energy in the field Wflt which originally is Wflt(ko, io). A variation is
envisaged here which is so small that i is approximately constant during the
alteration of k. In the same way an alteration of i will give an alteration of
X.
When we look at our variable inductance, therefore, we can say the
following:
The substance of what takes place is illustrated in fig. 8 and fig. 9.
Fig. 8 illustrates the magnetisation curves for the entire material of the
magnetisable body 1 and the domain change under the influence of the H1
field from the main winding 2.
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Fig. 9 illustrates the magnetisation curves for the entire material of the
magnetisable body 1 and the domain change under the influence of the H2
field in the direction from the control winding 4.
Figs. 10a and 10b illustrate the flux densities B1 (where the field H1 is
established by the working current), and B2 (corresponding to the control
current). The ellipse illustrates the saturation limit for the B fields, i.e.
when
the B field reaches the limit, this will cause the material of the
magnetisable
body 1 to reach saturation. The form of the ellipse's axes will be given by
the
field length and the permeability of the two fields B 1(H1) and B2 (H2) in
the core material of the magnetisable body 1.
By having the axes in figure 10 express the MMK distribution or the H field
distribution, a picture can be seen of the magnetomotive force from the two
currents Il and 12.
We now refer back to figures 8 and 9. By means of a partial magnetisation of
the domains by the control field B2 (H2), an additional field B1 (H1) from
the main winding 2 will be added vectorially to the control field B2 (H2),
further magnetising the domains, with the result that the inductance of the
main winding 2 will start from the basis given by the state of the domains
under the influence of the control field B2 (H2).
The domain magnetisation, the inductance L and the alternating current
resistance XL will thereby be varied linearly as a function of the control
field
B2.
We shall now describe the various embodiments of the device according to
the invention, with reference to the remaining figures.
Figure I 1 is a schematic illustration of a second embodiment of the
invention.
Figure 12 illustrates the same embodiment of a magnetically influenced
connector according to the invention, where fig. 12a illustrates the assembled
connector and fig. 12b illustrates the connector viewed from the end.
Figure 13 illustrates a section along line II in figure 12b.
As illustrated in the figures the magnetisable body 1 is composed of inter
alia
two parallel tubes 6 and 7 made of magnetisable material. An electrically
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insulated conductor 8 (figs. 12a, 13) is passed continuously in a path through
the first tube 6 and the second tube 7 N number of times, where N= 1, ... r,
forming the first main winding 2, with the conductor 8 extending in the
opposite direction through the two tubes 6 and 7, as is clearly illustrated in
fig. 13. Even though the conductor 8 is only shown extending through the
first tube 6 and the second tube 7 twice, it should be self-explanatory that
it
is possible for the conductor 8 to extend through respective tubes either only
once or possibly several times (as indicated by the fact that the winding
number N can vary from 0 to r), thus creating a magnetic field H1 in the
parallel tubes 6 and 7 when the conductor is excited. A combined control and
magnetisation winding 4, 4', composed of the conductor 9, is wound round
the first tube and the second tube (6 and 7 respectively) in such a manner
that
the direction of the field H2 (B2) which is created in the said tubes when the
winding 4 is excited will be oppositely directed, as indicated by the arrows
for the field B2 (H2) in figure 11. The magnetic field connectors 10, 11 are
mounted at the ends of the respective pipes 6, 7 in order to interconnect the
tubes fieldwise in a loop. The conductor 8 will be able to carry a load
current
11 (fig. 12a). The tubes' 6, 7 length and diameter will be determined on the
basis of the power and voltage which have to be connected. The number of
turns Nl on the main winding 2 will be determined by the reverse blocking
ability for voltage and the cross-sectional area of the extent of the working
flux ~2. The number of turns N2 on the control winding 4 is determined by
the fields required for saturation of the magnetisable body 1, which
comprises the tubes 6, 7 and the magnetic field connectors 10, 11.
Figure 14 illustrates a special design of the main winding 2 in the device
according to the invention. In reality, the solution in fig. 14 differs from
that
illustrated in figs. 12 and 13 only by the fact that instead of a single
insulated
conductor 8 which is passed through the pipes 6 and 7, two separate
oppositely directed conductors, so-called primary conductors 8 and
secondary conductors 8' are employed, in order thereby to achieve a voltage
converter function for the magnetically influenced device according to the
invention. This will now be explained in more detail. The design is basically
similar to that illustrated in figs. 11, 12 and 13. The magnetisable body 1
comprises two parallel tubes 6 and 7. An electrically insulated primary
conductor 8 is passed continuously in a path through the first tube 6 and the
second tube 7 N1 number of times, where Nl = 1, ... r, with the primary
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conductor 8 extending in the opposite direction through the two tubes 6 and
7. An electrically insulated secondary conductor 8' is passed continuously in
a path through the first tube 6 and the second tube 7 Nl' number of times,
where N1' = 1, ... r, with the secondary conductor 8' extending in the
opposite
direction relative to the primary conductor 8 through the two tubes 6 and 7.
At least one combined control and magnetisation winding 4 and 4' is wound
round the first tube 6 and the second tube 7 respectively, with the result
that
the field direction created on the said tube is oppositely directed. As for
the
embodiment according to figs. 11, 12. and 13, magnetic field connectors 10,
11 are mounted on the end of respective tubes (6, 7) in order to interconnect
the tubes 6 and 7 fieldwise in a loop, thereby forming the magnetisable body
1. Even though for the sake of simplicity the primary conductor 8 and the
secondary conductor 8' are illustrated in the drawings with only one pass
through the tubes 6 and 7, it will be immediately apparent that both the
primary conductor 8 and the secondary conductor 8' will be able to be passed
through the tubes 6 and 7 Nl and N1' number of times respectively. The
tubes' 6 and 7 length and diameter will be determined on the basis of the
power and voltage which have to be converted. For a transformer with a
conversion ratio (N1:N1') equal to 10:1, in practice ten conductors will be
used as primary conductors 8 and only one secondary conductor 8'.
An embodiment of magnetic field connectors 10 and/or 11 is illustrated in
figure 15. A magnetic field connector 10, 11 is illustrated, composed of a
magnetically conducting material, wherein two preferably circular apertures
12 for the conductor 8 in the main winding 2 (see, e.g. fig. 13) are machined
out of the magnetic material in the connectors 10, 11. Moreover, there is
provided a gap 13 which interrupts the magnetic field path of the conductor
8. End surface 14 is the connecting surface for the magnetic field H2 from
the control winding 4 consisting of conductors 9 and 9' (fig. 13).
Fig. 16 illustrates a thin insulating film 15 which will be placed between the
end surface on tubes 6 and 7 and the magnetic field connector 10, 11 in a
preferred embodiment of the invention.
Figures 17 and 18 illustrate other alternative embodiments of the magnetic
field connectors 10, 11.
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Figures 19-32 illustrate various embodiments of a core 16 which in the
embodiment illustrated in figures 12, 13 and 14 forms the main part of the
tubes 6 and 7 which preferably together with the magnetic field connectors
10 and 11 form the magnetisable body 1.
5 Fig. 19 illustrates a cylindrical core part 16 which is divided lengthwise
as
illustrated and where there are placed one or more layers 17 of an insulating
material between the two core halves 16', 16".
Fig. 20 illustrates a rectangular core part 16 and fig. 21 illustrates an
embodiment of this core part 16 where it is divided in two with partial
10 sections in the lateral surface. In the embodiment illustrated in fig. 21,
one or
more layers of an insulating material 17 are provided between the core halves
16, 16'. A further variant is illustrated in figure 22 where the partial
section
is placed in each corner.
Figs. 23, 24 and 25 illustrate a rectangular shape. Figures 26, 27 and 28
15 illustrate the same for a triangular shape. Figs. 29 and 30 illustrate an
oval
variant, and finally figures 31 and 32 illustrate a hexagonal shape. In figure
31 the hexagonal shape is composed of 6 equal surfaces 18 and in fig. 30 the
hexagon consists of two parts 16' and 16". Reference numeral 17 refers to a
thin insulating film.
20 Figures 33 and 34 illustrate a magnetic field connector 10, 11 which can be
used as a control field connector between the rectangular and square main
cores 16 (illustrated in figures 20-21 and 23-25 respectively). This magnetic
field connector comprises three parts 10', 10" and 19.
Fig. 34 illustrates an embodiment of the core part or main core 16 where the
25 end surface 14 or the connecting surface for the control flux is at right
angles
to the axis of the core part 16.
Fig. 35 illustrates a second embodiment of the core part 16 where the
connecting surface 14 for the control flux is at an angle oc to the axis of
the
core part 16.
30 Figures 36-38 illustrate various designs of the magnetic field connector
10,
11, which are based on the fact that the connecting surfaces 14' of the
magnetic field connector 10, 11 are at the same angle as the end surfaces 14
to the core part 16.
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Fig. 36 illustrates a magnetic field connector 10, 11 in which different hole
shapes 12 are indicated for the main winding 2 on the basis of the shape of
the core part 16 (round, triangular, etc.).
In fig. 37 the magnetic connector 10, 11 is flat. It is adapted for use with
core
parts 16 with right-angled end surfaces 14.
In fig. 38 an angle a' is indicated to the magnetic field connector 10, 11,
which is adapted to the angle a to the core part (figure 35), thus causing the
end surface 14 and the connecting surface 14' to coincide.
In fig. 39 a an embodiment of the invention is illustrated with an assembly of
magnetic field connectors 10, 11 and core parts 16. Figure 39b illustrates the
same embodiment viewed from the side.
Even though only individual combinations of magnetic field connectors and
core parts are described in order to illustrate the invention, it will be
obvious
to a person skilled in the art that other combinations are entirely possible
and
will thus fall within the scope of the invention.
It will also be possible to switch the positions of the control winding and
the
main winding.
Figures 40 and 41 are a sectional illustration and view respectively of a
third
embodiment of a magnetically influenced voltage connector device. The
device comprises (see figure 40b) a magnetisable body 1 comprising an
external tube 20 and an internal tube 21 (or core parts 16, 16') which are
concentric and made of a magnetisable material with a gap 22 between the
external tube's 20 inner wall and the internal tube's 21 outer wall. Magnetic
field connectors 10, 11 between the tubes 20 and 21 are mounted at
respective ends thereof (fig. 40a). A spacer 23 (fig. 40a) is placed in the
gap
22, thus keeping the tubes 20, 21 concentric. A combined control and
magnetisation winding 4 composed of conductors 9 is wound round the
internal tube 21 and is located in the said gap 22. The winding axis A2 for
the control winding therefore coincides with the axis A1 of the tubes 20 and
21. An electrical current-carrying or main winding 2 composed of the current
conductor 8 is passed through the internal tube 21 and along the outside of
the external tube 20 N1 number of times, where N1 = 1, ... r. With the
combined control and magnetisation winding 4 in co-operation with the main
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winding 2 or the said current-carrying conductor 8, an easily constructed but
efficient magnetically influenced voltage connector is obtained. This
embodiment of the device may also be modified in such a manner that the
tubes 20, 21 do not have a circular cross section, but a cross section which
is
square, rectangular, triangular, etc.
It is also possible to wind the main winding round the internal tube 21, in
which case the axis A2 of the main winding will coincide with the axis Al of
the tubes, while the control winding is wound about the tubes on the inside of
21 and the outside of 20.
Figs. 42-44 illustrate various embodiments of the magnetic field connector
10, 11 which are specially adapted to the latter design of the invention, i.e.
as
described in connection with figures 40 and 41.
Figure 42a illustrates in section and figure 42b in a view from above a
magnetic field connector 10, 11 with connecting surfaces 14' at an angle
relative to the axis of the tubes 20, 21 (the core parts 16) and it is obvious
that the internal 21 and external 20 tubes should also be at the same angle to
the connecting surfaces 14.
Figures 43 and 44 illustrate other variants of the magnetic field connector
10,
11, where the connecting surfaces 14' of the control field H2 (B2) are
perpendicular to the main axis of the core parts 16 (tubes 20, 21).
Figure 43 illustrates a hollow semi-toroidal magnetic field connector 10, 11
with a hollow semi-circular cross section, while figure 44 illustrates a
toroidal magnetic field connector with a rectangular cross section.
A variant of the device illustrated in figures 40 and 41 is illustrated in
fig.
45, where figure 45a illustrates the device from the side while 45b
illustrates
it from above. The only difference from the voltage connector in figs. 40-41
is that a second main winding 3 is wound in the same course as the main
winding 2. By this means an easily constructed, but efficient magnetically
influenced voltage converter is obtained.
Figures 46 and 47 are a section and a view illustrating a fourth embodiment
of the voltage connector with concentric tubes.
Figures 46 and 47 illustrate the voltage connector which acts as a voltage
converter with joined cores. An internal reluctance-controlled core 24 is
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located within an external core 25 round which is wound a main winding 2.
The reluctance-controlled internal core 24 has the same construction as
mentioned previously under the description of figs. 40 and 41, but the only
difference is that there is no main winding 2 round the core 24. It has only a
control winding 4 which is located in the gap 22 between the inner 21 and
outer parts forming the internal reluctance-controlled core 24, with the
result
that only core 24 is magnetically reluctance-controlled under the influence of
a control field H2 (B2) from current in the control winding 4.
The main winding 2 in figs. 46 and 47 is a winding which encloses both core
24 and core 25.
The mode of operation of the reluctance-controlled voltage connector or
converter according to the invention and described in connection with figures
46 and 47 will now be described.
We shall also refer to figure 55 which illustrates the principle of the
connection, figure 65 with a simplified equivalent diagram for the reluctance
model where Rmk is the variable reluctance which controls the flux between
the windings 2 and 3, and figure 65b which illustrates an equivalent
electrical
circuit for the connection where Lk is the variable inductance.
An alternating voltage V 1 over winding 2 will establish a magnetisation
current 11 in winding 2. This is generated by the flux ~ 1+~ 1' in the cores
24
and 25 which requires to be established in order to provide the bucking
voltage which according to Faraday's Law is generated in 2. When there is no
control current in the reluctance-controlled core 24, the flux will be divided
between the cores 24 and 25 based on the reluctance in the respective cores
24 and 25.
In order to bring energy through from one winding to the other, the internal
reluctance-controlled core 24 has to be supplied with control current 12.
By supplying control current 12 in the positive half-period of the alternating
voltage V 1 in 2, we shall obtain a half-period voltage over 2. Since the
energy is transferred by flux displacement between the reluctance-controlled
core 24 and the external (secondary) core 25, the reluctance-controlled core
24 will essentially be influenced by the control current 12 during the period
when it is controlled in saturation, while the working flux will travel in the
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secondary external core 25 and interact with the primary winding 2 during
the energy transfer.
When the reluctance-controlled core 24 is brought out of saturation by
resetting the control flux B2 (H2) which is orthogonal to the working flux B 1
(H1), the flux from the primary side will again be divided between the cores
24 and 25, and a load connected to the secondary winding 3 will only see a
low reluctance and thereby high inductance and little connection between
primary (VI) and secondary (V3) voltage. A voltage will be generated over
the secondary winding 3, but on account of the magnitude of Lk compared to
the magnetisation impedance Lm, most of the voltage (Vl) from the primary
winding 2 will overlay Lk. The flux from the primary winding 2 will
essentially go where there is the least reluctance and where the flux path is
shortest (fig. 65b).
It may also be envisaged that the external core 25 could be made
controllable, in addition to having a fourth main winding wound round the
internal controllable core 24. This is to enable the voltage between the cores
24 and 25 to be controlled as required.
Fig. 48 describes a further variant of the fourth embodiment of a
magnetically influenced voltage connector or voltage converter according to
the invention, where the magnetisable body 1 is so designed that the control
flux B2 (H2) is connected directly without a separate magnetic field
connector through the main core 16.
Fig. 48 illustrates a voltage connector in the form of a toroid viewed from
the
side. The voltage connector comprises two core parts 16 and 16', a main
winding 2 and a control winding 4.
Fig. 49 illustrates a voltage connector according to the invention equipped
with an extra main winding 3 which offers the possibility of converting the
voltage.
Fig. 50 illustrates the device in figure 48 in section along line VI-VI in
figure
48 and figure 51 illustrates a section along line V-V. In figure 50 a circular
aperture 12 is illustrated for placing the control winding 4.
Figure 51 illustrates an additional aperture 26 for passing through wiring.
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Figures 52 and 53 illustrate the structure of a core 16 without windings and
where the core 16 is so designed that there is no need for an extra magnetic
field connector for the control field. The core 16 has two core parts 16, 16'
and an aperture 12 for a control winding 4. This design is intended for use
5 where the magnetic material is sintered or compressed powder-moulded
material. In this case it will be possible to insert closed magnetic field
paths
in the topology, with the result that what were previously separate connectors
which were required for foil-wound cores form part of the actual core and are
a productive part of the structure. The core, which forms the closed magnetic
10 circuit without separate magnetic field connectors and which is illustrated
in
these figures 52 and 53, will be able to be used in all the embodiments of the
invention even though the figures illustrate a body 1 adapted for the first
embodiment of the invention (illustrated inter alia in figures 1 and 2).
Figure 54 illustrates a magnetically influenced voltage converter device,
15 where the device has an internal control core 24 consisting of an external
tube 20 and an internal tube 21 which are concentric and made of a
magnetisable material with a gap 22 between the external tube's 20 inner wall
and the internal tube's 21 outer wall. Spacers 23 are mounted in the gap
between the external tube's 20 inner wall and the internal tube's 21 outer
20 wall. Magnetic field connectors 10, 11 are mounted between the tubes 20 and
21 at respective ends thereof. A combined control and magnetisation winding
4 is wound round the internal tube 21 and is located in the said gap 22. The
device further consists of an external secondary core 25 with windings
comprising a plurality of ring core coils 25', 25", 25"' etc. placed on the
25 outside of the control core 24. Each ring core coil 25', 25", 25"' etc.
consists
of a ring of a magnetisable material wound round by a respective second
main winding or secondary winding 3, only one of which is illustrated for the
sake of clarity. A first main winding or primary winding 2 is passed through
the internal tube 21 in the control core 24 and along the outside of the
30 external cores 25 N1 number of times, where Nl = 1, ... r.
It is also possible to envisage the secondary core device being located within
the control core 24, in which case the primary winding 2 will have to be
passed through the ring cores 25 and along the outside of the control core 24.
Figure 55 is a schematic illustration of a second embodiment of the
35 magnetically influenced voltage regulator according to the invention with a
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first reluctance-controlled core 24 and a second core 25, each of which is
composed of a magnetisable material and designed in the form of a closed,
magnetic circuit, the said cores being juxtaposed. At least one first
electrical
conductor 8 is wound on to a main winding 2 about both the first and the
second core's cross-sectional profile along at least a part of the said closed
circuit. At least one second electrical conductor 9 is mounted as a winding 4
in the reluctance-controlled core 24 in a form which essentially corresponds
to the closed circuit. In addition, at least one third electrical conductor 27
is
wound round the second core's 25 cross-sectional profile along at least a part
of the closed circuit. The field direction from the first conductor's 8
winding
2 and the second conductor's 9 winding is orthogonal. By means of this
solution, the first conductor 8 and the third conductor 27 form a primary
winding 2 and a secondary winding 3 respectively.
Figure 56 illustrates a proposal for an electro-technical schematic symbol for
the voltage connector according to the invention. Fig. 57 illustrates a
proposal for a block schematic symbol for the voltage connector.
Figure 58 illustrates a magnetic circuit where the control winding 4 and
control flux B2 (H2) are not included.
In figs. 59 and 60 there is a proposal for an electro-technical schematic
symbol for the voltage converter where the reluctance in the control core 24
shifts magnetic flux between a core with fixed reluctance 25 and a second
core with variable reluctance 24 (see for example figure 55).
There is, of course, no restriction to having two cores with variable
reluctance. The fact that we can shift flux between two cores within the same
winding will be employed in order to make a magnetic switch which can
switch a voltage off and on independently of the course of magnetisation in
the main core. This means that we have a switch which has the same function
as a GTO, except that we can choose whatever switching time we wish.
The device according to the invention will be able to be used in many
different connections and examples will now be given of applications in
which it will be particularly suitable.
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Figure 61 illustrates the use of the invention in an alternating current
circuit
in order to control the voltage over a load RL, which may be a light source, a
heat source or other load.
Figure 62 illustrates the use of the invention in a three-phase system where
such a voltage connector in each phase, connected to a diode bridge, is used
for a linear regulation of the output voltage from the diode bridge.
Figure 63 illustrates a use as a variable choke in DC-DC converters.
Figure 64 illustrates a use as a variable choke in a filter together with
condensers. Here we have only illustrated a series and a parallel filter (64a
and 64b respectively), but it is implicit that the variable inductance can be
used in a number of filter topologies.
A further application of the invention is that described inter alia in
connection with figures 14 and 45, where proposals for schematic symbols
were given in figure 59. In this application, the voltage connector has a
function as a voltage converter where a secondary winding is added. An
application as a voltage regulator is also illustrated here, where the
magnetisation current in the transformer connection and the leakage
reactance are controllable via the control winding 4. The special feature of
this system is that the transformer equations will apply, while at the same
time the magnetisation current can be controlled by changing gr. In this case,
therefore, the characteristic of the transformer can be regulated to a certain
extent. If there is a DC excitation of one winding 2, it will be possible to
obtain transformed energy through the transformer by varying r and thereby
the flux in the reluctance-controlled core instead of varying the excitation.
Thus it is possible in principle to generate an AC voltage from a DC voltage
by means of the fact that an alteration of the magnetisation current from the
DC generator into this system will be able to be transformed to a winding on
the secondary side.
Another application of the invention is illustrated in figures 46 and 47,
where
a variable reluctance as control core is surrounded or enclosed by one or
more separate cores with separate windings, as well as figure 55 wllere a
first
reluctance-controlled core and a second core are designed as closed magnetic
circuits and are juxtaposed. We also refer to figure 65 which illustrates an
equivalent electrical circuit.
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Figure 55 illustrates how the fluxes in the invention travel in the cores. We
wish to emphasise that the flux in the control core is connected to the flux
in
the working core via the windings enclosing both cores. In this system
transformation of electrical energy will be able to be controlled by flux
being
connected to and disconnected from a control core and a working core. Since
the fluxes between the cores are interconnected through Faraday's induction
law, the functional dependence of the equations for the primary side and the
equations for the secondary side will be controlled by the connection
between the fluxes. In a linear application we will be able to control a
transformation of voltages and currents between a primary winding and a
secondary winding linearly by altering the reluctance in the control core,
thus
permitting us to introduce here the term reluctance-controlled transformer.
For a switched embodiment we will be able to introduce the term reluctance-
controlled switch.
The flux connection between the primary or first main winding 2 and the
secondary winding or second main winding 3 will now be explained.
Winding 2 which now encloses both the reluctance-controlled control core 24
and the main core 25 will establish flux in both cores. The self-inductance LI
to 2 tells how much flux, or how many flux turns are produced in the cores
when a current is passed in Il in 2. The mutual inductance between the
primary winding 2 and the secondary winding 3 indicates how many of the
flux turns established by 2 and 11 are turned about 2 and about the secondary
winding 3.
We may, of course, also envisage the main core 25 being reluctance-
controlled, but for the sake of simplicity we shall refer here to a system
with
a main core 25 where the reluctance is constant, and a control core 24 where
the reluctance is variable.
The flux lines will follow the path which gives the highest permeance (where
the permeability is highest), i.e. with the least reluctance.
In figs. 55 and 65 we have not taken into consideration the leakage fields in
the main windings 2 and 3. Fig. 55 illustrates a simplified model of the
transformer where the primary 2 and secondary 3 windings are each wound
around a transformer leg, while in practice they will preferably be wound on
the same transformer leg, and in our case, for example, the outer ring core
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which is the main core 25 will be wound around the secondary winding 3
distributed along the entire core 25. Similarly, the primary winding 2 will be
wound around the main core 25 and the control core 24 which may be located
concentrically and within the main core.
Figure 65 illustrates a simplified reluctance model for the device according
to the invention.
Fig. 65b illustrates a simplified electrical equivalent diagram for the
connector according to the invention, where the reluctances are replaced by
inductances.
A current in 2 generates flux in the cores 24 and 25:
(D = (Dk + (D1 40)
where:
(Dp = total flux established by the current in 2.
(Dk = the total flux travelling through the control core 24.
(Dl = part of the total flux travelling through the main core 25.
Since the leakage flux in main core 24 and control core 25 are disregarded,
(D1=-(D2 41)
In a way (Dk may be regarded as a controlled leakage flux.
On the basis of fig. 65 we can formulate the highly simplified electrical
equivalent diagram for the magnetic circuit illustrated in fig. 65b.
Figure 65b therefore illustrates the principle of the reluctance-controlled
connector, where the inductance Lk absorbs the voltage from the primary
side.
2
L~=Rl 42)
urk
This inductance is controlled through the variable reluctance in the control
core 24, with the result that the connection or the voltage division for a
sinusoidal steady-state voltage applied to the primary winding will be,
approximately equal to the ratio between the inductance in the respective
cores as illustrated in equation 43.
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e2 Lm
e, Lk + Lm 43)
When the control core 24 is in saturation, Lk is very small compared to Lm
and the voltage division will be according to the ratio between the number of
turns N1/N3. When the control core is in the off state, Lk will be large and
to
5 the same extent will block voltage transformation to the secondary side.
The magnetisation of the cores relative to applied voltage and frequency is so
rated that the main core 25 and the control core 24 can each separately
absorb the entire time voltage integral without going into saturation. In our
model the area of iron on the control and working cores is equal without this
10 being considered as limiting for the invention.
Since the control core 24 is not in saturation on account of the main winding
2, we shall be able to reset the control core 24 independently of the working
flux B 1(H1), thereby achieving the object by means of the invention of
realising a magnetic switch. If necessary the main core 25 may be reset after
15 an on pulse or a half on period by the necessary MMF being returned in the
second half-period only in order to compensate for any distortions in the
magnetisation current.
In a switched application, when the switch is off, i.e. when the flux on the
primary winding 2 is distributed between the control core 24 and the working
20 core 25, the flux connection between the primary 2 and the secondary 3
winding will be slight and very little energy transfer takes place between
primary 2 and secondary 3 winding.
When the switch is on, i.e. when the reluctance in the control core 24 is very
low ( r = 10-50) and approaching the reluctance of an air coil, we will have a
25 very good flux connection between primary 2 and secondary 3 winding and
transfer of energy.
An important application of the invention will thus be as a frequency
converter with reluctance-controlled switches and a DC-AC or AC-DC
converter by employing the reluctance-controlled switch in traditional
30 frequency converter connections and rectifier connections.
A frequency converter variant may be envisaged realised by adding bits of
sinus voltages from each phase in a three-phase system, each connected to a
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separate reluctance-controlled core which in turn is connected to one or more
adding cores which are magnetically connected to the reluctance-controlled
cores through a common winding through the adding cores and the
reluctance-controlled cores. Parts of sinus voltages can then be connected
from the reluctance-controlled cores into the adding core and a voltage with a
different frequency is generated.
A DC-AC converter may be realised by connecting a DC voltage to the main
winding enclosing the working core, where this time the working core is also
wound round a secondary winding where we can obtain a sinus voltage by
changing the flux connection between working core and control core
sinusoidally.
Fig. 66 illustrates the connection for a magnetic switch. This may, of course,
also act as an adjustable transformer.
Figures 67 and 67a illustrate an example of a three-phase design. All the
other three-phase rectifier connectors are, of course, also feasible. By means
of connection to a diode bridge or individual diodes to the respective outlets
in a 12-pulse connector, an adjustable rectifier is obtained.
In the application as an adjustable transformer, it must be emphasised that
the size of the reluctance-controlled core is determined by the range of
adjustment which is required for the transformer, (0-100% or 80-110%) for
the voltage.
Figure 67b illustrates the use of the device according to the invention as a
connector in a frequency converter for converting input frequency to
randomly selected output frequency and intended for operation of an
asynchronous motor, for adding parts of the phase voltage generated from a 6
or 12-pulse transformer to each motor phase (figure 67b).
Fig. 68 illustrates the device used as a switch in a UFC (unrestricted
frequency changer with forced commutation).
Fig. 69 illustrates a circuit comprising 6 devices 28-33 according to the
invention. The devices 28-33 are employed as frequency converters where
the period of the voltages generated is composed of parts of the fundamental
frequency. This works by "letting through" only the positive half-periods or
parts of the half-periods of a sinus voltage in order to make the positive new
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half-period in the new sinus voltage, and subsequently the negative half-
periods or parts of the negative half-periods in order thereby to make the
negative half-periods in the new sinus voltage. In this way a sinus voltage is
generated with a frequency from 10% to 100% of the fundamental frequency.
This converter also acts as a soft start since the voltage on the output is
regulated via the reluctance control of the connection between the primary
and the secondary winding.
In fig. 69, if the first half-period is allowed through connector no. 28 (main
winding 2), the current through the secondary winding (main winding 3) in
the same connector will commutate to the secondary winding (main winding
3) in connector no. 29, and on from 29 to 28, etc.
Fig. 70 illustrates the use of the device according to the invention as a DC
to
AC converter. Here the main winding 2 in the connector is excited by a DC
voltage U 1 which establishes a field H 1(B 1) both in the control core 24 and
in the main core 25 (these are not shown in the figure). The number of turns
N1, N2, N3 and the area of iron are designed in such a manner that none of
the cores are in saturation in steady state. In the event of a control signal
(i.e.
excitation of the control winding 4) into the control core 24, the flux B2
(H2)
therein will be transferred to the main core 25 and a change in the flux B 1
(Hl) in this core 25 will induce a voltage in the secondary winding (main
winding 3). By having a sinusoidal control current 12, a sinusoidal voltage
will be able to be generated on the secondary side (main winding 3), with the
same frequency as the control voltage U1.
Figure 70b illustrates the use of the invention as a converter with a change
of
reluctance.
Figure 71 illustrates a use of the device according to the invention as an AC-
DC converter. The same control principle is used here as that explained
above in the description of a frequency converter in fig. 69. Figure 71b
illustrates a diagram of the time of the device's input and output voltage.
As mentioned previously, the voltage connector according to the invention is
substantially without movable parts for the absorption of electrical voltage
between a generator and a load. The function of the connector is to be able to
control the voltage between the generator and the load from 0-100% by
means of a small control current. A second function will be purely as a
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43
voltage switch. A further function could be forming and transforming of a
voltage curve.
The new technology according to the invention will be capable of being used
for upgrading existing diode rectifiers, where there is a need for regulation.
In connection with 12-pulse or 24-pulse rectifier systems, it will be possible
to balance voltages in the system in a simple manner while having
controllable rectification from 0-100%.
With regard to the magnetic materials involved in the invention, these will be
chosen on the basis of a cost/benefit function. The costs will be linked to
several parameters such as availability on the market, produceability for the
various solutions selected, and price. The benefit functions are based on
which electro-technical function the material requires to have, including
material type and magnetic properties. Magnetic properties considered to be
important include hysteresis loss, saturation flux level, permeability,
magnetisation capacity in the two main directions of the material and
magnetostriction. The electrical units frequency, voltage and power to the
energy sources and users involved in the invention will be determining for
the choice of material. Suitable materials include the following:
a) Iron - silicon steel: produced as a strip of a thickness approximately
0.lmm-0.3mm and width from 10mm to 1100mm and rolled up into coils.
Perhaps the most preferred for large cores on account of price and already
developed production technology. For use at low frequencies.
b) Iron - nickel alloys (permalloys) and/or iron - cobalt alloys (permendur)
produced as a strip rolled up into coils. These are alloys with special
magnetic properties with subgroups where very special properties have
been cultivated.
c) Amorphous alloys, Metglas: produced as a strip of a thickness of
approximately 20 m - 50 in, width from 4mm to 200mm and rolled up
into coils. Very high permeability, very low loss, can be made with almost
0 magnetostriction. Exists in a countless number of variants, iron-based,
cobalt-based, etc. Fantastic properties but high price.
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d) Soft ferrites: Sintered in special forms developed for the converter
industry. Used at high frequencies due to small loss. Low flux density.
Low loss. Restrictions on physically realisable size.
e) Compressed powder cores: Compressed iron powder alloy in special
shapes developed for special applications. Low permeability, maximum
approximately 400-600 to-day. Low loss, but high flux density. Can be
produced in very complicated shapes.
All sintered and press-moulded cores can implement the topologies which are
relevant in connection with the invention without the need for special
magnetic field connectors, since the actual shape is made in such a way that
closed magnetic field paths are obtained for the relevant fields.
If cores are made based on rolled sheet metal, they will have to be
supplemented by one or more magnetic field connectors.
