Note: Descriptions are shown in the official language in which they were submitted.
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BACKGROUND OF THE INVENTION
Field of the Invention:
'rhe invention concerns a drive arrangement consisting of an
electric rotating or traveling field machine of variable angular or linear
speed energized from an A. C. or D. C. source by rectifier.
Description of the Prior Art:
Among the numerous electric motor drives with variable speed
there are instances of use requiring three phase motors with the simplest
possible rotor construction. To this class belong asynchronous machines
with squirrel cage rotors and homopolar synchronous machines, the speed
of which is adjustable or controllable by the frequency and voltage regulation
of a transverter. The energizing of such three phase drives with variable
frequency and voltage through rectifiers with D. C. interstage or through
direct transverters is known.
The operation of asynchronous machines entails a high cost (a)
for self commutating rectifiers with a D. C. current or voltage interstage
because of the double energy transformation in the converter and inverter
as well as the energy storage in the intermediate filter and (b) for direct
transverters because of the need for antiparallel rectifiers in every winding
lead. Beslde the highe~t frequency attainable presently by mean of
_z_
~'"
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high power direct transverters is limited.
Homopolar synchronous machines, furthermore, require an
excitation winding in addition to the three phase stator winding.
SUMMARY OF TlIE INVENTION
The problem faced by the invention is that of reducing the cost
of the said rectifiers feeding rotating field and traveling field machines.
An additional problem for the invention is, in connection with electric
traveling field machines intended for driving magnetic suspension vehicles,
to combine in a single winding the ordinarily separate windings for
traction in synchronous machines and the excitation winding for the
guiding and support magnets. This single winding is to be fed from a
common rectifier control permitting the two functions of propelling and
of guiding or supporting the vehicle to be controlled independently of one
another over wide ranges.
As the solution of the first mentioned problem, it is provided
according to the invention that the windings of the electrical machine are
fed by a rectifier producing three D. C. biased A. C. currents forming
a three phase system. ~he stator winding of the machine is a multi-
layer one so constructed $hat each of the two winding strands or conductor
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rods laid in a slot carries a D. C. biased A, C. current with the D. C.
components of the currents flowing in opposite directions and the ampere-
turns produced by the D. C. current components of the two winding strands
or conductor rods in every slot cancelling each other out but with the A. C.
components cooperating to produce a rotating or traveling field.
It is understandable that such a machine, because of the non-
torque-producing D. C. currents, must be poorer in efficiency as well
as in output than an electrical machine of conventional construction and
must therefore be larger for the same output.
~his extra cost will be made up for, however, because the
cost of the transverter driving the electrical machine can be cut to almost
half that of the conventional transverter. Before describing the structure
of the transverters, made with known components, the various embodiments
of the electrical machines conforming with the invention will be described.
~he electrical machine for the drive arrangement according to
the invention can be constructed as an asynchronous as well as homopolar
synchronous machine.
In a first embodiment of the form of an asynchronous rotating
field machine, the stator winding is so constructed that the ampere turns
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produced by the D. C. current components cancel in the coil end of each
pushing side.
In a first variant of this embodiment, the stator winding is a
two layer winding. ~his winding can be a three phase winding short
pitched by one zone. Here the circulations of the top and bottom layers
of a coil are different or belong to different sections.
In a second variant, the stator (primary) winding is three layered
with each phase connected to a layer (plane).
In a further development of this embodiment, the coils of each
phase are arranged concentrically in one another and the face connections
lie in the same plane (layer) as the coil segment lying in the iron. By
means of this configuration, off-setting of the coils can be avoided with a
further reduction in cost.
In a second embodiment of the electrical machine in accordance
with the invention in the form of a homopolar synchronous machine, the
coils of the primary winding are each short pitched around a third of a
pole pitch so that the D. C. current components in the winding always add
in the coil ends of the machine to produce a constant circulation in one
direction on one pushing side and in the other on the other side which
constitutes the excitation ampere turns by which the machine's armature is
magnetized.
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In a further embodiment of the invention intended to solve
the second problem, the electrical machine is built, in the above-
mentioned arrangement, as an asynchronous traveling field machine
for propelling a magnetic suspension vehicle. ~he winding is laid in
slots running perpendicularly to the length of the machine in the middle
leg of a yoke with a U, E or V shaped cross section so that the D. C.
current components of the winding currents are in the same direction in
the coil end producing a constant coil and flux and a steady flux through
the iron which exerts a supporting force on the secondary part of the travel-
ing field machine.
If a one sided asynchronous linear motor having a secondary
part without a closed magnetic circuit is driven, then, with suitable
dimensioning, there is possible an electrodynamic suspension of the
vehicle because of electrodynamic repulsion between the primary and
secondary parts as long as the frequency of the currents induced in the
secondary part is sufficiently high. For stable tractive operation, this
electrodynamic suspension requires a regulated rectifier output unit. rhis
already exists in the form of the energizing rectifiers in the new arrange-
ment so that the cost for the drive arrangement described is reduced in
comparison with other solutions.
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By another feature of the invention, the winding can be made a two
layered lap or wave winding with pitch shortened by one third the pole
pitch.
In a further embodiment of the invention, the asynchronous
traveling field machine has a multiple wave winding as a full pitch
two layer winding of doubled zone width.
In a further embodiment of the invention, the winding is a
three layer form with coils of different widths arranged concentrically
with the coils of one phase always lying in the same plane and the portions
of the slots not occupied by conductors being made into cooling ducts.
~he coil groups in the middle are made full pitched. ~he advantage of
this configuration is narrower coil ends and the simpler fabrication of
the coils.
In accordance with a further characteristic of the invention, there
is located opposite the yoke, E shaped in cross section, of the traveling
field machine a magnetic short circuiter, a conducting plate and a
support rail with an air gap between the yoke and the magnetic short cir-
cuiter, conducting plate and support rail.
~he width of the conducting plate is substantially equal to the
distance between the inner edges of the two outer legs. ~he width of the
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support rail is substantially equal to the distance between the outer edges
of the two outer legs. ~he width of the magnetic short circuiter is about
that of the middle leg.
In a one-sided configuration of an asynchronous linear motor
with secondary part and magnetic short circuiter there is effective along
with the electrodynamic repulsion forces a greater electromagnetic attrac-
tive force which contributes, to some extent at least, to supporting the
vehicle. Stable support and guidance of the vehicle requires regulation
of the electromagnetic attraction which can be effected with the help of the
present rectifiers.
In the forms of the invention proposed herein, in addition to
the savings on the rectifier in the configuration, savings are permitted
both on the support winding and on the control elements for energizing the
support and guiding magnets.
There are known to arise in one sided traveling field machines,
in addition to the force components in the direction of travel, force
` components perpendicular to them which in asynchronous machines the
secondary part of which has a magnetic short circuiter, act as attractive
forces between the secondary and primary parts.
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With decreasing separation (air gaps) these attractive forces
decrease. The air gap must therefore always be held constant by
suitable rr.eans, for example, by mechanical or electromagnetic control.
In a paper by H. Kemper printed in the ETZ-A 1953, pps. 10-15, under
the title "Railroad Cars with Electromagnetic Suspension", there are
described cars driven by traveling field machines which support and
guide the car by means of separate support and guiding magnets or even by
additional support windings on the machine.
In contrast to the known configurations, the arrangement of the
invention produces a reduction in cost which is achieved on the one hand
by sparing the support winding and on the other by the sparing of a separate
support current control element. By merging the control elements for
armature three phase current and D. C. support current, or support and
excitation D. C. current, into an undulatory current control element there
is obtained a further simplication when, as in the arrangement of the
invention, the D. C. current component is greater than the amplitude of the
A. C. current component since here the cost of the rectifier may be sub-
stantially reduced.
Systems suited for electromagnetic position control require,
in order to achieve sufficiently fast changes in magnetic flux, a large
enough over-excitation voltage. With a separate excitation arrangement,
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the cost of the rectifier for the support magnet circuit is thereby determined.
In the combined, undulatory current fed drive and support
desi gn, the reserve voltage necessary for overexcitation is present at no
extra cost, since the transverter producing the traveling field can also
cause a fast enough flux change for the steady field.
In a further embodiment of the solution of the second part of the
prop~ ed problem, the electrical machine, in the above mentioned arrange-
ment is constructed as a synchronous, homopolar, traveling field machine
with a primary part and a reaction bar opposite it and provided as the
drive of a magnetic suspension vehicle. For this the winding is so con-
structed that the D. C. current components of the winding currents flow in
the same direction in the coil end producing a coil and circulation which
forces a steady flux through the iron which serves as excitation for the
machine. ~he force exerted by the magnetic field of the steady circulation
is, in addition, used for support of the suspension vehicle. ~he mentioned
steady circulation acts therefore as excitation circulation which produces
through the magnetic conductivity variations of the reaction bar a modulated
excitation traveling field and the mentioned additional force for support of
the suspension vehicle.
In a ordance with a further characteristic oS the invention, the
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winding of the synchronous traveling field machine is constructed as
a full pitch two layer winding of double zone width.
In a further embodiment of the invention, the homopolar,
synchronous, traveling field machine has a full pitch three layer winding
of double zone width in the middle. ~he advantage of this configuration
is, as in the aforementioned winding for an asynchronous traveling field
machine, a reduced width of the coil ends and simpler fabrication of the
coils.
According to another characteristic of the inventio,n, the homo-
polor, synchronous, traveling field machine has two armatures, one
on each side of the reaction bars, each with its separate winding and con-
nected through a U shaped magnetic yoke. By separate control of the
D. C. current components of the currents in the two windings, surer guid-
ing of the reaction rail in the middle of the gap between the two armatures
is possible.
; In another embodiment of the invention, the primary part of the
electrical traveling field machine has an E shaped cross section with the
winding slots cut in the top of the middle leg at right angles to the length
of the machine. In this arrangement with an E shaped cross section,
ao of the prir.~ar art, by control of the excitation and therefore the
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attractive force between the primary part and yoke on one side and reaction
bar on the other, constant distance of the latter can be achieved and the
drive arrangement supports the vehicle.
In a further embodiment of the invention, the primary part of the
electrical traveling field machine has a U shaped cross section with slots
in the top sides of both outer legs substantially perpendicular to the length
of the machine. In the slots are laid two separate windings. In this con-
figuration, an additional leakage barrier can be located between the two
winding legs.
In this arrangement an additional possibility of controlling the
vehicle position is provided by separate regulation of the D. C. current
components of the currents flowing in the two armatures.
In a further embodiment of the invention, the primary part has
a V shaped cross section with the faces of the reaction rail opposite the
legs of the primary part perpendicular to the length of the machine. ~he
surfaces of the V shaped legs next to these faces have about the same slope
and the winding slots in the legs have a uniform depth. ~he slope angle
of the faces of the V shaped legs and the opposed faces of the reaction rails
is determined the ratio of the required guiding and supporting forces.
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1037~L10
In all the configurations described above, the structure of the
primary part, or the leg of it carrying the winding, can be in the form of
a series of lamination stacks of the width of a tooth and the winding can
be laid in the gaps between the teeth. In the above described arrangement,
it does not matter whether the reaction rail or the primary structure
is stationary or attached to the vehicle.
I'he energizing of the three winding coils of the above described
asynchronous or synchronous rotating field machines or the asynchronous
or homopolar synchronous traveling field types can be effected in each
case in conformity with the invention with a unidirectional rectifier control
unit.
In a special configuration, the energizing rectifier arrangement
consists of three controlled three phase rectifiers in a center point connect-
ion, and an additional controlled three phase rectifier with reversed con-
ducting direction connected between the neutral point of the star connected
drive motor and the terminals of the secondary windings, also star connected ,
of the rectifier.
In a further embodiment of the invention, two electrical machines
are connected to the terminals of the star connected output of the rectifier
transformer, each by way of three three phase rectifiers with opp~site con-
ducting directions, these machines being star connected with a common
ne utral.
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In another embodiment of the invention, the rectifier for each
winding coil is a unidirectional rectifier control unit.
In a special configuration of the invention, the rectifier for
each winding coil is a 3n pulsed rectifier bridge circuit fed by a separate
winding of a rectifier transformer, n being an integer.
In a further embodiment, the rectifier for each winding coil
is a separate 3n pulsed rectifier with its like phase inputs connected
in parallel. I'he outputs of each rectifier are connected to the two ends
of one of the winding coils, the latter being electrically isolated from
one another. ~he like phase inputs of the rectifier are connected to a
three phase line.
~he control of the three phase rectifiers is appropriately
effected in such a way that the D. C. current component of the winding cur-
rent is greater than the amplitude of the A. C. component.
BRIEF DESCRIP~IC)N OF ~HE DRAWINGS
A more complete appreciation of the invention and many of the
attendant advantages thereof will be readily obtained as the same becomes
better understood by reference to the following detailed description when
considered in connection with the accompanying drawings, wherein:
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FIGURE 1 is a winding diagram for a conventional rotating
field machine with full pitched two layer winding,
.FIGURE 2 is a winding diagram for an asynchronous rotating
field machine according to the invention with two layer winding,
FIGURE 3 is a winding diagram for an asynchronous rotating
field machine according to the invention with three layer winding,
FIGURE 4 is a winding diagram for a homopolar synchronous
machine in accordance with the invention,
FIGURE 5 is a diagram of a two layer winding for an asynchron-
ous or homopolar synchronous traveling field machine,
FIGUR.E 6 is the diagram for a three layer winding of an asyn-
chronous or homopolar synchronous traveling field machine,
FIGURE 7 is a diagram of the distribution of the steady circulation
in an asynchronous traveling field machine,
FIGURE 8 is a diagram for the distribution of the steady circulatio:
over the length of a synchronous traveling field machine,
FIGURE 9 is an asynchronous traveling field machine according
to the invention in cross section,
FIGURE 10 is a synchronous homopolar traveling field machine
with U formed primary part and two windings in cross section,
FIGURE 11 is a cross section of a synchronous homopolar travel-
ing field machine with E shaped cross section in the primary part,
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FIGUR.E 12 is a section through a traveling field machine
with U shaped primary part and leakage barrier with two separate
windings per leg,
FIGURE 13 is the same type of traveling field machine but with
S a primary part of V shaped cross section,
FIGURE 14 is a traveling field machine in which the legs with
the windings are divided into separate lamination stacks,
FIGUR.E 15 is a block diagram for the arrangement conforming
with the invention,
FIGURE 16 is a rectifier arrangement for energizing the arrange-
ment of the invention with three controlled three phase rectifiers in center
point connection,
FIGURE 17 is a rectifier arrangement for energizing the traveling
field machines with two controlled three phase rectifiers each of which
energizes a traveling field machine, with the star connected machines having
a common neutral,
: FIGURE 18 is a schematic of a transverter conforming with
the invention with a unidirectional rectifier control element,
FIGURE 19 is a schematic of a transverter with a rectifier
bridge circuit having separate transformer windings for each leg of the bridg
and
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FIGURE 20 is a transverter circuit with common inputs to
the rectifier bridges.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMEN~S
In the drawings, the winding layers in a two layer configuration
are denoted by a, b, and in a three layer configuration by c, d, e.
The winding coils are deno ted by u-u, v-v and w-w. Further, 3 denotes
a zone width, 4 a double pole pitch, 5 the part of the coils passing be-
tween the lamination stacks and 6 the face connectors. The arrows in
the face connections show the directions of the D. C. current components
flowing through them.
In the conventional winding shown in Figure 1, the coil width
equals the pole pitch.
In the two layer winding of an arrangement conforming with the
invention shown in Figure 2, the coil width is short pitched by a third
amounting therefore to two thirds the pole pitch. As appears from Figure
2, the D. CO current component in one layer of the winding in the slot
flows in one direction, and that in the other in the opposite direction so
that the D. C. magneti~ation within the iron core cancels out. The same
holds true for the coil ends in which the D. C. currents flow in different
direction~. -17-
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Part A of the figures shows the distribution of the winding turns
in zone 3. Part B of the figures shows the corresponding winding schematic
with each coil group in zone 3 being represented by only one coil. ~he
coil sides 1 from the top layer a and the sides 2 fo~m the bottom layer b.
In the three layer winding for an asynchronous rotating field
machine shown in Figure 3, as in the winding arrangement of Figure 2,
the coils have the same width. Since each coil lies in a single plane,
there are substantial simplifications in the coil end resulting in lower
material and labor costs. However, this winding requires greater
slot depth than the arrangement of Figure 2 since the slots are filled
only to two thirds of their depth. I'he unused spaces in the slots can
be used as cooling channels so that better cooling is achieved and heavier
loading of the machine is permissible.
The two layer winding for a homopolar synchronous rotating or
traveling field machine or even for an asynchrnous traveling field machine
shown in Figures 4 and 5 cancels out the D. C. magnetization inside the
iron only. The D. C. current components in the coil ends all have the
same direction and produce the ampere turns required for the excitation
field as well as the necessary force for supporting the vehicle.
The same is true also for the three layer winding shown in
1~;17110
Figure 6 with c~ils of different widths arranged concentrically inside
one another and made full pitched with double zone width on the average.
Here, as already mentioned, there are special advantages in the structure
of the coil end.
In the cross sections of linear motors shown in Figures 9 to 14,
the lamination stacks receiving the winding are denoted by 21, the
reaction bars by 22, the winding by 23 and the yoke by 25.
In the drawings of Figures 10 and 11 for synchronous homopolar
traveling field machines, an additional support winding 24 is shown in dashed
lines and must be provided in prior art machines. In the traveling field
machines of the invention, this winding 24 is not required. Further ref-
erence symbols will be explained in the description of the individual figures.
In the section of an asynchronous linear machine conforming
with the invention as shown in Figure 9, the primary part is E shaped
in cross section and consists of a U shaped yoke 25 plus a middle leg
34, in the slots of which, running across the length of the primary part,
the winding, a three layer one in the example, is laid. The secondary
part is located across the airgap 28 from the yol~e 25. It consists of the
support bar 29, the magnetic short circuiter 30 and a conducting plate 31.
The steady flux passes through the yoke 25, the air gap 28 and the support
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bars 29 across the direction of travel. The flux of the magnetic traveling
field runs either in the plane in the travel direction or across the direction
of travel like the steady flux. In this latter case the yoke 25 and support
bar 29 are laminated.
The circuit connections required for multiple wave windings are
denoted by 32 and, like the windings, lie in the three layers c, d, e outside
the yoke 25. In this arrangement part of the D. C. flux penetrates the
yoke 25 as leakage flux of the active region denoted by 5. Magnetic satur-
ation of the active part does not occur, howeverJ because of the low in-
duction of the traveling field.
This asynchronous drive arrangement, which serves simultan-
eously for controlled electromagnetic support and/or guidance, posses,
for example, a multiple wave winding such as a full pitch two layer winding
with double zone width as in Figure 1 or such as a three layer winding with
like shaped coil groups which are full pitch on the average in Figure 2.
These windings have a circulation acting in the same direction at both
coil ends 6. By independen t control of the D. C. current components
of the winding currents, it is then possible to control or regulate the
forces necessary for electrical suspension separately from the tractive
2 0 forces .
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It should also be pointed out that in the boundary regions, and
thus in the beginning and end regions of the windings shown in Figures
1 to 6, not every coil conductor carrying a D. C. current faces another
with oppositely flowing D. C. current so that the D. C. circulation in the slot
region does not completely cancel out.
In Figure 7, is plotted the D. C. current distribution A= and
the steady circulation _ over the length of an asynchronous linear motor
in the direction of motion. This additional steady circulation can be taken
care of by suitable compensation coils which are provided at the ends of
the machine for windings of asynchronous linear motors. This can be
effected, for example, by a coil group of V conductors in the arrangement
of Figure 3, full pitched with around two zone widths.
In Figure 8, the D. C. current distribution A= and the steady
circulation ;F= are likewise plotted over the length of the machine for a
homopolar synchronous traveling field machine. In the traveling field
machines of the synchronous homopolar configuration shown in Figures
10 to 14, there is produced, as appears from Figure 8, a steady circulation
~_ running the length of the machine as a result of the D. C. current
slot circulation of the beginning and end regions of the winding and the
D. C. coil end circulation. This acts as excitation circulation and, by the
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fluctuations in magnetic susceptibility of the reaction rail 22, produces
a modulated traveling excitation field.
Examples of embodiments of linear homopolar traveling field
machines are shown in Figures 10 to 14.
In the examples in Figures 10 and 11, only about a pole pitch
long region of higher magnetic conductance of the reaction rails 22 is
shown. The gaps between the illustrated parts of the reaction rail are
filled with a nonmagnetic material, not shown, in the drawi ng, which
mechanically bonds the two regions of the reaction rail 22. The sections
in the drawings of Figures 8 and 9 only show the region of higher magnetic
conductance .
In Figure 10, is shown an exan ple of a homopolar synchronous
traveling field machine conforming with the invention with two arma$ures
21 arranged one on each side of the reaction rail 22 and connected by
a magnetic yoke 25. The attractive forces acting between the reaction
rail 22 and armatures 21 in such an arrangement balance out only in a
completely symmetric condition. By independnent control of the D. C.
current components of the two armature currents, reliable guidance of
the reaction rail 22 halfway between the two armatures is possible.
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Figure 11 shows a drive with armature 21 located on one side
of reaction rail 22, the magnetic return path of which is through a yoke
25. In this E shaped unilateral arrangement, by regulation of the
excitation according to the invention and therefore the attractive
force between armature and yoke on one hand and reaction rail on the
other, separation can be maintained constant while at the same time the
vehicle is supported.
A further configuration of the homopolar synchronous motor
of the invention is shown in Figure 12. Here there are two armatures 21
connected by a yoke 25 to produced a U shaped arrangement which is
excited by the steady fields of the coil ends 6, the magnetic circuit of
which is closed through air gaps and reaction rail 22. In this U shaped
arrangement, according to the invention, the force of attraction to the
reaction rail 22 can be regulated for support of the vehicle.
If the arrangement of Figure 12 is completed with a leakage
barrier 33, then, by independent regulation of the excitation of both
armatures 21, there is an additional capability for controlling the vehicle
position.
A further embodiment of the homopolar synchronous motor of
the inventim i he V Rhaped arrangement of the two armatures 21 shown
--23 -
10;17~10
in Figure 13 which enables the supporting and guiding of a vehicle. The
slope angle ~ of the pole faces of the armatures 21 and the pole faces
of the reaction rail 22 is determined by the ratio of the required guidance
and support forces.
In all these arrangements it makes no difference as far as
the invention is concerned whether the reaction rail 22 or the armature
arrangement is stationary or attached to the vehicle.
In Figure 14isan E shaped unilateral arrangement of an
armature 21 with yoke 25 of a homopolar synchronousmachine in which the
active part 5 or armature 21 with the yoke 25 is divided up into a series
of separate lamination stacks 26 of the width of a tooth between which the
winding is placed. This division into individual lamination stacks is
also possible with the other described homopolar machines of Figures 7
and 8 as well as the asynchronous machine of Figure 4. It offers advantages
in fabrication in the production of linear machines.
Figure 15 shows an embodiment of the connection of the drive
with a special direct trans verter, e. g., a unidirectional rectifier control
unit. The controller 7 furnishes the signal fl for the output frequency of
the direct transverter and I for the amplitude of the A. C. current to the
, three phase 9 ewave generator 3 which produces the desired values iu,
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iv and iw corresponding to the three phase system. Block 9 computes
from I the desired D. C. current I= to be superimposed. These desired
current values are combined at the summing points 10 and control the
three current regulators 11 of the three unidirectional rectifier control
B units~ of the special direct transverter which is connected to the three phase
line of frequency fO, not shown here, and which energizes the three wind-
ings 13 of the rotating field machine or traveling field machine, the wind-
ings of which are connected according to one of the Figures 2 to 6.
Examples of configurations of rectifier installations for energizing
the above described rotating field or traveling field machines are shown
in Figures 16 to 20.
The example in Figure 16 consists of three controlled three
phase rectifiers 15 with center point connection to which the star
connected electrical machine 13 is connected. The neutral point of the
electrical machine 13 is connected by way of an additional controlled
three phase rectifier 17 with reversed conducting direction to the likewise
star connected secondary part of the rectifier transformer. The three
phase rectifier is controlled in such a way that the D. C. current compon-
ent of the current in the windings is greater than amplitude of the A. C.
component.
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In the switching arrangement of the exarnple of Figure 17, two
traveling field machines 13 are star connected with a common neutral
point. Each of the machines is fed by three controlled three phase recti-
fiers with opposite conduction directions and in central point connection
with both being driven by the same secondary windings 14 of a rectifier
transformer. Instead of the two, possibly mechanically coupled,
electrical traveling field machines, use may be made of the two windings
of synchronous homopolar traveling field machines as shown in Figures
5 - 7 and 8. In this way, the D, C. current component of the winding
currents is prevented from flowing in the secondary winding 14 of the
rectifier transformer. This is the reason the thyristors of the two recti-
fier bridges are reversed in conducting directions.
In the energizing connection shown in Figure 18 for an electrical
machine in accordance with the invention, there are three three pulsed
unidirectional rectifier control units each of which has a thyristor group
15 fed by a transformer winding 14, The outputs of the three thyristor
control units energize three machine windings 13.
The rectifier arrangement of Figure 19 has three three phase rec-
tifier bridges each of which is driven by a special three phase winding of
the rectifier transformer. ~he outputs of the three three phase rectifier
~371~Q
bridges 17 drive the winding ends u, x, v, y, w, z of the three windings
13 of the rotating field or traveling field machine.
In the connection shown in Figure 20, the three three phase
rectifier bridges 17 are connected independently of one another. This
S enables tying together their three phase input terminals R, S, ~ and
connecting these points either to the line 19 or to a transformer, in
case the line voltage is different from the desired energizing voltage.
The windings 13 of the rotating field or traveling field machine are not
connected together in this circuit and so exhibit six terminals u, x,
v, y, w, z. ~he ends of each winding are therefore connected to the
outputs of one three phase rectifier bridge.
Other rectifier circuits, with the same action as the above-
described ones,may obviously be applied equally well to these drive
arrangements.
Obviously, numerous modifications and variations of the present
invention are possible in light of the above teachings. It is therefore to
be understood that within the scope of the appended claims, the invention
may be practiced otherwise than as specifically described herein.
