Note: Descriptions are shown in the official language in which they were submitted.
1 The p:resellt :i.nv~nt:i.on relcltec; to a rotatiny
electric machine according to the gener:ic clause of -the rna:in
claim.
A rotating electr:ic machine of the type mentioned
hereinbe~ore is known :Erom its use as synchronous rotary
current generator. In the case of.such a synchronous rotary
current generator the stator has provided thereon three
stator windings.disposed on a circle round the a~is and off-
set by 120 with respect to one another. The rotor, which
is adapted to be rotated about the axis and which is disposed
opposite the stator, has provided thereon a direct-current
winding. The direct current flowing through said rotor
winding generates a constant magnetic field rotating with the
rotor. Due to the time-dependent change in the magnetic
1.5 -flu~ flowing through the stator w.indings a voltage is
induced in the stator windings. When a connection to a rotary
current load or to a rotary current mains supply is esta
blished, a rotary current flows through the stator windi.ngs
so that the load or the mains supply is supplied with active
power~ In view of the fact that the rotor rotates, the
exciting current must be supplied to the rotor winding via
sliding contacts. Such a rotating electric machine shows
the disadvantage that, due to the high electrical and
mechanical loads occurring, the sliding contacts will be
worn~out after a short period o~f time so that said sliding
contacts are constantl~ in need of maintenance.
The present invention is based on the task of pro-
viding a rotating electric machine of the type mentioned
3~
1 hereinbefore, which can be opercl-ted w.ithou-t any use of
sl:iding contacts and which, consequently, avoids the
above-men-tioned disadvantayes of the known struc-tural design.
This task is solved by providing a rotating
electric machine of -the above-mentioned -type which comprises
a rotating electric machine comprising a stator and a
rotor disposed opposite said stator and rotatable about an
axis, and further comprising a number N of stator windings
disposed on said stator on a circle round the axis at uniform
distarlces from one another, characterized in that the rotor
has provided thereon a number N of rotor windings disposed
on a circle round the axis at uniform distances from one
another and used for exciting a magnetic field, said nwnber
N of rotor windings corresponding to said number N of stator
windings, that a second rotor is connected to said first
rotor and rotates at the speed of rotation of said fi.rst
rotor about the axis thereof, that said second rotor has
provided thereon a number N of rotor windings disposed on a
circle round the axis at uniform di.stances from one
another, said number N of rotor windin~s.corresponding to
said number N of stator windings, that when the rotor
windings of each rotor are referred to by a series of
reference numbers n = 1,2, ... N, the first rotor winding of
the first rotor is connected to the first rotor winding of
~5 the second rotor and that, as far as the other rotor windings
are concerned, the nth rotor winding of the first rotor is
connected to the [N + 2 - n]th rotor winding of the second
,1 rotor 90 -that tlle xotary :Ei.elcls at the two roLors have
opposite directions oE rotation w,i.th recJard to said rotors,
that a second stator is provided for the second rotor, and
that said second s-tator has prov.idecl thereon a number N of
stator windings disposed on a circle round the axis at unl-
form distances from one another, said number N of stator
windings of said second stator corresponding to said number
N of stator windings of said first stator.
Among other advantages, the rotating electric
machine according to the invention shows the followiny
~dvantages
The machine can be excited by supplyiny rotary
current to the windings 1~, 15, 16 of the second stator 13.
The machine can also be excited by supplying direct
, ; 15 -current to one of the windings 14, 15, 16 of the stator 13.
When used as a ~enerator, the machine can have it
output frequency influenced, since said output frequency
consists of the negative rotational frequency of the rotary
field applied to the second stator 13 and of twiae the
rotational frequency of the rotor.
When the machine is used as a motor, the speed of
rotation of the rotors 5, 9 can be adjusted due to the fact
that it is half the sum of the speeds of rotation of the
rotational speed of the rotary field applied to the first
stator 1 and of the rotary field applied to the second
stator 13.
The construction of this machine does not require
any special components so that the machine can be produced
1 by emp:loy:incJ the p:roduct:i.on m~ns of any Eactory corl-
structing e:l.ectric machlnes.
.~n advantageous development oE the rotatincJ
elec-tric machi.ne according to the invention for use as a
generator is disclosed in claim 2. Adapting the frequency
and the phase position of the rotary voltage i.nduced in the
windings 2, 3, 4 of the first stator 1 to predetermined
nominal values is one of the fundamental problems in the
field of generator technology. Such an adaptation is par-
ticularly necessary in cases in ~hich a generator has to
supply power to a mains which is already supplied with
power by other generators. Normally, complicated mechanical
control means are provided for controlling these quantities,
said control means influencing the speed and the phase
; 15 position of the rotor. In the case of the rotating electric
machine according to the invention for.use as a generator,
as indicated in claim 2, this problem ;.s solved in a simple
manner by the feature that the frequency and the phase
position of the rotary current, which is suppl:ied to the
windings 14/ 15, 16 of the stator 13, are controlled in such
a way that, in spite of changes in the speed of rotation of
the rotors 5, 9, a constant phase and frequency of the
rotary voltage induced in the windings 2, 3, 4 of the first
stator 1 is maintained.
A further development of the rotating electric
machine according to the invention for use as a generator is
disclosed in claim 3. By means of the controlled system
indicated in said claim it is achieved that the amplitude of
3~6
1 -the ro-tary voltacJe ind~lced in the windln~s 2, 3, ~ of the
first sta-tor 1 xe~mains constant i.n a load-independent manner
wi.thin the power ranye of the generator.
A further advantageous developmen-t of the ro-tating
electric machine according to the invention for use as a
motor is disclosed in claim ~. Normally, ln the case of
synchronous motors the difficulty occurs that a starting
motor is re~uired for starting these machines, since
latching.or synchronizing of the motor speed is only possible
when the motor rotates at approximately the same rotational
speed as the rotary magnetic field generated by the rotary
c~l.rrent flowing in the windings 2, 3, 4 of the first stator
1. The structural design oE a motor disclosed in claim ~
eliminates the necessity of provi.diny a sta.rting motor as
- 15 - well as the problem of synchronous latch;.ng of the motor.
In view of the fact that the rotational speed .results from
half the sum of the rotational spee~s of the rotary fields
generated by the currents in the windings 6, 7, 8; 14, 15, 16
of the stators 1, 13, the starting operation can e.g. simply
be effected by employiny the measure that, at first, the
`field at the second stator 13 rotates at the same, but
oppositely directed rotational speed as the field at the
first stator 1. In response.to a slow change in the
rotational speed of the field at the second stator 13 the
rotor 5, 9 starts to rotate. This, too, is a possible way
of adjusting any desired speed of.rotation of the rotors 5,
9, in spite of the synchronous mode of operation.
1 One eml)ocl:iment of the rotal,irl~J e:l,ectric mach:ine
according -to the ,invention wi:Ll he clescribed herelnaE-ter
on the basis o~ the drawing, in which:
Fig. 1 is a schematic representation of the ~Jinding
arrangement, and
Fig. 2 is a schematic representation of a speed-
and amplitude-controlled rotary current generator provided
with the wi,nding arrangement shown in Fig. 1.
The special case (N = 3) shown in the figures will
be the most commom form of application, since this is the
conventional three-phase rotary current system. A first
stator 1 has provided thereon three stator windings 2, 3, 4
disposed on a circle round an axis and oEEset by 120 with
respec-t to one another~ A rotor 5, which is adapted to be
! 15 rotated ahout the axis, is disposed opposite the stator.
Said rotor has provided thereon three rotor windings 6, 7,
8 which are disposed on a circle round the axis thereof and
offset by 120 with respect to one another and which are used
for exciting a magnetic Eield. A second rotor 9 is ~ixedly
connected to said first rotor 5 and rotates at the speed of
rotation of said first rotor 5 about the axis thereof. The
connection between the two rotors 5, 9 can be effected by an
axis by means of which the rotors 5, 9 are supported. The
second rotor 9 has provided thereon three rotor windings 10,
11, 12 disposed on a circle round the axis and off set by
120 with respect to one another. The first rotor winding
6 of the first rotor 5 is connected to the first rotor
winding 10 of the second rotor 9. The second rotor winding 7
1 o:E the :E:i.rst rotox 5 :is connected to t.he th:ird rotor windiny
12 oE the seconcl roto:r 9. The thi.r(l ro-tor winding ~ of -the
Eirs-t ro-to.r 5 is connecteA to -the second rotor winding 11
of the second rotor 9. A second stator 13 is disposed
opposite the second rotor 9. Said second stator 13 has
provlded thereon three stator windings 14, 15, 16 disposed
on a circle round the axis and offset by 120 wi-th
r~spect to one another.
Fig. 2 shows the ahove described rotating eleccric
machine when used as a generator. The speed of rotation of
the rotors 5, 9 is determined by a measuring means. The
measuring means consists of a circulating permanent magnet
22 and of a stationary induction coil. A control means 18
controls the frequenc~ and phase of an exciting current
- generator 21. It is thus achieved that, when the speed of
rotation and the rotary phase of the rotors 5, 9 deviate from
th~ir nominal speed of rotation and nominal phase, the speed
of rotation and the rotary phase o~ an input rotary field,
: which is generated by an exciting rotar~ current flowing
in the stator winding 1~, 15, 16 of the second stator
13,is readjusted such that the frequency and phase position
of the rotary voltage induced in the w;.ndings 2, 3, ~ of the
first stator 1 main-tains predetermined nominal values. In
the case of low power levels the exciting current generator
may be designed as a solid-state circuit. In the case of
higher power levels the exciting current generator could
consist of an additional generator, as shown in Fig~ 2,
which precedes this generator, said preceding generator being
~3~L~
1 :in turn Eed by a sol:id-stclte e~clt:incJ current generator.
A second measuring Ifleans 19 taps v:ia an :incluctive coupling
-the voltage amplitude of the rotary vo:ltaye :induced in -the
~indi~gs 2, 3, 4 oE the first stator 1. A second control
means 20 contro:Ls the ampll-tude of the exciting current,
which flows through the stator windings 14, 15, 16 of the
second sta-tor 13, such that the amplitude of the rotary
voltage induced in the windings 2, 3, 4 of the first stator
1 remains constant in a load-independent manner within the
power range of the generator. In the case of an increase
in the load, i.e. when the amplitude of the rotary voltage
appli~d to the wind:ings 2, 3, 4 of the first stator 1
decreases, the measuring means 19 will measure the voltage
drop and impart this information to the control means 20
which, in turn, will increase the amplitude of the e~citing
rotary curren-t supplied to the windings 14, 15, 16 of the
stator 13. It is a matter of course that not even such a
controlled system will be capable of increasing the power
range of a generator, bu-t the only thing which can be achieved
~o is a constant output voltage of the generator even in
the case of varying loads, as long as the maximum load on
the generator is not exceeded. The control means 20 for
controlling the amplitude can also be designed as a solid-
state circuit, as long as the exciting current required has
only small or medium values. In view of the fact that in
the case of high power requirements a cascade connection
of the generators is necessary not least for purposes of
frequenc~ control, it will also in this case be possible to
3~
1 cleskJ~ he respective~ f:i.rst excit:i.nCJ generator as a
solid-sta-te circuit.
The invention is not limited to the three-phase
rotary current system. The rotating electric mach:ine accord-
ing to the invention can be used in N~phase :rotary currentsystems in an equally advantayeous manner. And it is also
possible to supply only a single winding 14, 15, 16 of the
second stator 13 with a direct current serving to excite
the rotary current generator or the rotary current motor.
In this case the other two windings of th~ second stator 13
will be superfluous. It is also possible to u.se the windings
14, 15, 16 simultaneously as a measuring means 17 for
measuring the speed of rotation of the rotors 5, 9. When the
the rotor is driven hy a synchronous motor, the electric
- 15 -machine according to the invention can also be used Eor
trans~ittiny power frorn a first :rotary current mains supply
h~ving a first frequency to a second rotary current mains
supply having a second :Erequency.
