CA1251255A - Brushless asynchronous alternating current machine controllable by secondary excitation - Google Patents
Brushless asynchronous alternating current machine controllable by secondary excitationInfo
- Publication number
- CA1251255A CA1251255A CA000501924A CA501924A CA1251255A CA 1251255 A CA1251255 A CA 1251255A CA 000501924 A CA000501924 A CA 000501924A CA 501924 A CA501924 A CA 501924A CA 1251255 A CA1251255 A CA 1251255A
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- Prior art keywords
- pole
- windings
- winding
- unitary
- phase stator
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K17/00—Asynchronous induction motors; Asynchronous induction generators
- H02K17/02—Asynchronous induction motors
- H02K17/30—Structural association of asynchronous induction motors with auxiliary electric devices influencing the characteristics of the motor or controlling the motor, e.g. with impedances or switches
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K17/00—Asynchronous induction motors; Asynchronous induction generators
- H02K17/02—Asynchronous induction motors
- H02K17/22—Asynchronous induction motors having rotors with windings connected to slip-rings
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Windings For Motors And Generators (AREA)
- Synchronous Machinery (AREA)
- Induction Machinery (AREA)
Abstract
Abstract:
A brushless induction motor comprises an eight pole three-phase stator winding, a four pole three-phase stator winding overlapping the eight pole three-phase stator winding, and a rotor winding facing and coaxial with the eight pole and four pole three-phase stator windings and formed of six unitary windings. The six unit windings are uniformly arranged with respect to the eight pole and four pole three-phase stator windings. Each unitary winding includes a coil having six turns. The first end terminals of the coils of six unitary windings are connected to a first end ring and the other end terminals thereof are connected to a second end ring. The rotating speed of the brushless induction motor is controlled by regulating an exciting current frequency applied to the four pole three-phase stator winding.
A brushless induction motor comprises an eight pole three-phase stator winding, a four pole three-phase stator winding overlapping the eight pole three-phase stator winding, and a rotor winding facing and coaxial with the eight pole and four pole three-phase stator windings and formed of six unitary windings. The six unit windings are uniformly arranged with respect to the eight pole and four pole three-phase stator windings. Each unitary winding includes a coil having six turns. The first end terminals of the coils of six unitary windings are connected to a first end ring and the other end terminals thereof are connected to a second end ring. The rotating speed of the brushless induction motor is controlled by regulating an exciting current frequency applied to the four pole three-phase stator winding.
Description
l~S12~i~
Brushless asynchronous alternatin~ current machine ___________ ____________________ ___________ _ co tr_llabl _by_sec_ndary _ xcit_tion The present invention relates to an asynchronous alternating current machine, such as an induction motor or an induction generator, without slip rings and brushes (hereinafter called brushless), which is controlled by secondary excitation and, in particular, relates to a brushless induction motor whose speed of rotation is controlled by secondary excitation and which is suitable for driving a pump or a fan.
The present invention is an improvement to the induction motor disclosed in our copending U.S. Patent Application Serial No. 634,538 filed July 26, 1984, for "Squirrel-Cage Induction Motor" assi~ned to the assignee of the present invention, now U.S. Patent 4,562,397 issued December 31, 1985.
The squirrel-cage induction motor reference above comprises two types of three-phase stator windings having different numbers of poles and rotor conductor bars, the number of which is selected to be the same as the average number of poles of the two types of three-phase stator windings. ~ecause of the specific number of rotor conductor bars, the rotating magnetic field caused by currents flowing through these bars includes a substantial lZS12S5 amount of two rotating magnetic field component.s that respectively correspond to two rotating magnetic field components that are respectively caused by the two types of three-phase stator windings with different numbers of poles. Accordingly, the speed of rotation of the squirrel-cage induction motor is controlled by regulating the exciting current or frequency applied to one of the two types of three-phase stator windings, the rotating magnetic fields of which are coupled with the corresponding rotating magnetic field component caused by the currents flowing through the rotor conductor bars without using slip rings and brushes. However, since the number of rotor conductor bars is limited, the winding factor of the rotor conductor bars is reduced, which corresponds to the strength of the lS magnetic coupling between the rotor conductor bars and each of the two types of three-phase stator windings, and further since the rotating magnetic field caused by the rotor conductor bar current includes a large amount of rotating magnetic field co~ponents that do not couple with the rotating magnetic field components generated by the two types of three-phase stator windings, because the direction of current flowing throught the rotor conductor bars is unconditionally determined by the immediate vari-ation of the rotating magnetic field caused by the three-phase stator windings. Accordingly the power factor of the motor is limited.
One object of the present invention is to provide a brushless asynchronous alternating current machine controllable by secondary excitation, having a high rotor winding ~actor.
Another objec~ of the present invention is to provide such a machine having improved rotating magnetic field waveforms caused by the rotor winding currents. A further object of the present invention is to provide such a machine having a high ,vower factor.
SS
To this end, the invention consists of a brushless asynchronous alternating current machine controllable by secondary excitation comprising: a first three-phase stator winding having a first number of poles; a second three-phase stator winding having a second number of poles different from said first number of poles and overlapping said first three-phase stator winding; and a rotor winding facing and coaxial with said first and second three-phase stator windings, and being formed of a plurality of unitary windings, the number of which corresponds to the average pole number of said first and second three-phase stator windings, said unitary windings being uniformly arranged with respect to said first and second three-phase stator windings, each unitary winding including a coil having at least one turn and both ends of the coils of the respective unitary windings being electrically interconnected.
The invention also provides a brushless asynchronous alternating current machine controllable by secondary excitation comprising: an eight pole three-phase stator winding; a four pole three-phase stator winding overlapping said eight pole three-phase stator winding; and a rotor winding facing and coaxial with said eight pole and four pole three-phase stator windings and being formed of six unitary windings, the six unitary windings being uniformly arranged with respect to said eight pole and four pole three-phase stator windings, each unitary winding including a coil having at least three turns, first end terminals of the coils of the six unitary windings being connected to a first end ring and the other end terminals thereof being connected to a second end ring.
In the drawings:
Fig. 1 ~shows a schematic wiring diagram of stator and rotor windings of a machine embodying the present invention. The rotor winding is illustrated developed.
~2Si255 Figs. 2(a), 2(b), 2(c) and 2(d) are diagrams explaining the operating principles of the present invention.
Figs. 3(a) and 3(b) are graphs of relative amplitude of magnetic field components classified according to the number of poles, included in the rotating magnetic field generated by the rotor winding currents of the present invention.
Fig. 4 shows developed another embodiment of rotor winding according to the present invention.
Fig. 5 shows a schematic circuit diagram of a machine control system including a machine embodying the present invention.
Referring to Fig. 1, an asynchronous alternating current machine 10 includes eight and four pole, three-phase stator windings 22 and 24 and a rotor winding 32.
The eight pole, three-phase stator winding 22 and the four pole three-phase stator winding 24 are schematically illustrated. The rotor winding 32 is illustrated in development, and comprises six unitary windings 34 that are disposed in slots formed uniformly around the circumferential surface of the rotor 30. The number of unitary windings 34 is selected to be six and to have the average pole number of the two stator windings, i.e. four and eight. Each unitary winding 34 consists of three turn coils and thus has six coil sides. One end of each unitary winding 34 is connected to a first end ring 36 and the other end thereof is connected to a second end ring 38.
The coil side pitch ~b of each unitary winding 34 is one and the coil pitch or coil crossover pitch ~c thereof is three. The pitch between adjacent unitary windings ~b is also three in the present embodiment. Since the number of unitary windings 34 is six, ~b x 6 = 2~ The coil sides illustrated in solid lines of the respective unitary windings 34 are disposed in the upper part of the respective slots and the coil sides illustrated in dotted lZ~lZS5 lines of the respective unitary windings 34 are disposed in the lower part of the respective slots.
The operating principle of this machine is explained with reference to Figs. 2(a), 2(b), 2(c), 2(d) and 3.
When alternating current with a predetermined frequency is applied to the four pole three-phase stator winding 24, a four pole rotating magnetic field ~214 as shown in Fig.
Brushless asynchronous alternatin~ current machine ___________ ____________________ ___________ _ co tr_llabl _by_sec_ndary _ xcit_tion The present invention relates to an asynchronous alternating current machine, such as an induction motor or an induction generator, without slip rings and brushes (hereinafter called brushless), which is controlled by secondary excitation and, in particular, relates to a brushless induction motor whose speed of rotation is controlled by secondary excitation and which is suitable for driving a pump or a fan.
The present invention is an improvement to the induction motor disclosed in our copending U.S. Patent Application Serial No. 634,538 filed July 26, 1984, for "Squirrel-Cage Induction Motor" assi~ned to the assignee of the present invention, now U.S. Patent 4,562,397 issued December 31, 1985.
The squirrel-cage induction motor reference above comprises two types of three-phase stator windings having different numbers of poles and rotor conductor bars, the number of which is selected to be the same as the average number of poles of the two types of three-phase stator windings. ~ecause of the specific number of rotor conductor bars, the rotating magnetic field caused by currents flowing through these bars includes a substantial lZS12S5 amount of two rotating magnetic field component.s that respectively correspond to two rotating magnetic field components that are respectively caused by the two types of three-phase stator windings with different numbers of poles. Accordingly, the speed of rotation of the squirrel-cage induction motor is controlled by regulating the exciting current or frequency applied to one of the two types of three-phase stator windings, the rotating magnetic fields of which are coupled with the corresponding rotating magnetic field component caused by the currents flowing through the rotor conductor bars without using slip rings and brushes. However, since the number of rotor conductor bars is limited, the winding factor of the rotor conductor bars is reduced, which corresponds to the strength of the lS magnetic coupling between the rotor conductor bars and each of the two types of three-phase stator windings, and further since the rotating magnetic field caused by the rotor conductor bar current includes a large amount of rotating magnetic field co~ponents that do not couple with the rotating magnetic field components generated by the two types of three-phase stator windings, because the direction of current flowing throught the rotor conductor bars is unconditionally determined by the immediate vari-ation of the rotating magnetic field caused by the three-phase stator windings. Accordingly the power factor of the motor is limited.
One object of the present invention is to provide a brushless asynchronous alternating current machine controllable by secondary excitation, having a high rotor winding ~actor.
Another objec~ of the present invention is to provide such a machine having improved rotating magnetic field waveforms caused by the rotor winding currents. A further object of the present invention is to provide such a machine having a high ,vower factor.
SS
To this end, the invention consists of a brushless asynchronous alternating current machine controllable by secondary excitation comprising: a first three-phase stator winding having a first number of poles; a second three-phase stator winding having a second number of poles different from said first number of poles and overlapping said first three-phase stator winding; and a rotor winding facing and coaxial with said first and second three-phase stator windings, and being formed of a plurality of unitary windings, the number of which corresponds to the average pole number of said first and second three-phase stator windings, said unitary windings being uniformly arranged with respect to said first and second three-phase stator windings, each unitary winding including a coil having at least one turn and both ends of the coils of the respective unitary windings being electrically interconnected.
The invention also provides a brushless asynchronous alternating current machine controllable by secondary excitation comprising: an eight pole three-phase stator winding; a four pole three-phase stator winding overlapping said eight pole three-phase stator winding; and a rotor winding facing and coaxial with said eight pole and four pole three-phase stator windings and being formed of six unitary windings, the six unitary windings being uniformly arranged with respect to said eight pole and four pole three-phase stator windings, each unitary winding including a coil having at least three turns, first end terminals of the coils of the six unitary windings being connected to a first end ring and the other end terminals thereof being connected to a second end ring.
In the drawings:
Fig. 1 ~shows a schematic wiring diagram of stator and rotor windings of a machine embodying the present invention. The rotor winding is illustrated developed.
~2Si255 Figs. 2(a), 2(b), 2(c) and 2(d) are diagrams explaining the operating principles of the present invention.
Figs. 3(a) and 3(b) are graphs of relative amplitude of magnetic field components classified according to the number of poles, included in the rotating magnetic field generated by the rotor winding currents of the present invention.
Fig. 4 shows developed another embodiment of rotor winding according to the present invention.
Fig. 5 shows a schematic circuit diagram of a machine control system including a machine embodying the present invention.
Referring to Fig. 1, an asynchronous alternating current machine 10 includes eight and four pole, three-phase stator windings 22 and 24 and a rotor winding 32.
The eight pole, three-phase stator winding 22 and the four pole three-phase stator winding 24 are schematically illustrated. The rotor winding 32 is illustrated in development, and comprises six unitary windings 34 that are disposed in slots formed uniformly around the circumferential surface of the rotor 30. The number of unitary windings 34 is selected to be six and to have the average pole number of the two stator windings, i.e. four and eight. Each unitary winding 34 consists of three turn coils and thus has six coil sides. One end of each unitary winding 34 is connected to a first end ring 36 and the other end thereof is connected to a second end ring 38.
The coil side pitch ~b of each unitary winding 34 is one and the coil pitch or coil crossover pitch ~c thereof is three. The pitch between adjacent unitary windings ~b is also three in the present embodiment. Since the number of unitary windings 34 is six, ~b x 6 = 2~ The coil sides illustrated in solid lines of the respective unitary windings 34 are disposed in the upper part of the respective slots and the coil sides illustrated in dotted lZ~lZS5 lines of the respective unitary windings 34 are disposed in the lower part of the respective slots.
The operating principle of this machine is explained with reference to Figs. 2(a), 2(b), 2(c), 2(d) and 3.
When alternating current with a predetermined frequency is applied to the four pole three-phase stator winding 24, a four pole rotating magnetic field ~214 as shown in Fig.
2(a) is qenerated. The arrow in Fig. 2(a) indicates the rotating direction of the field component. Due to the movement of the four pole rotating magnetic field component ~214, an electromotive force is induced in the rotor winding 32 with the six unitary windings 34, and thus current as shown in Fig. 2(b) flows through the respective unit windings 34 as indicated by arrows. As a result of the current flow indicated in Fig. 2(b), a magnetomotive force is induced in the rotor winding, and thus a moving magnetic field as shown in Fig. 2(c) is generated. The development into a Fourier series of this moving magnetic field is illustrated in Fig. 2(d), and includes a large amount of an eight pole rotating magnetic field component ~228 that is included and which couples, meets or co-operates with the eight pole three-phase stator winding 22, as well as a large amount of a four pole rotating magnetic field component ~224 which couples with the four pole three-phase stator winding 24. As can be seen from Figs.
2(a) and 2(d), the directions of rotation of the field component ~228 and field components ~214 and ~224 are opposite to each other, the stator winding 24 being connected to an alternating current source in a negative phase sequence with respect to the phase sequence thereof for the stator winding 22. A small amount of the rotating magnetic field components, other than these four and eight pole components, are included in the moving magnetic field shown in Fig. 2(c). However, they have been s)mitted from Fig. 2(d) because the amount thereof is negligibly small.
~2~Z5S
Fig. 3(a) illustrates the relative amplitudes of the respective magnetic field components classified by the numbers of poles included in the moving magnetic field generated by the rotor winding currents, when only the four pole stator winding 24 is excited, as explained in connection with Figs. 2(a) to (d). In Figs. 3(a) and 3(b), the relative amplitude 1.0 is the amplitude of the original moving magnetic field before developing into a Fourier series, as for example shown in Fig. 2(c)~ As indicated previously in connection with Figs. 2(a) to (d), the rotating magnetic field components other than the four and eight pole components are negligibly small.
Fig. 3(b) illustrates the relative amplitudes of respective magnetic field components classified by n~mbers of poles in a moving magnetic field generated by the rotor winding currents, when only the eight pole stator winding 22 is excited. As is apparent from Fig. 3(b), a large amount of the four pole rotating magnetic field component that couples with the four pole stator winding 24 is included in the moving magnetic field, as well as a large amount of an eight pole rotating magnetic field component.
Another embodiment of the present invention will be explained in Fig. 4. To avoid complicating the drawing, only a developed rotor winding diagram is illustrated in Fig. 4. The rotor of this embodiment is provided with thirty-six slots. The corresponding stator (not shown) is provided with fifty-four slots and with an eight pole, three-phase stator winding with a coil pitch of five and a four pole, three-phase stator winding with a coil pitch of eleven. The four pole, three-phase stator winding is arranged in overlapping relation with the eight pole three-phase stator winding. The rotor winding 32 includes six unitary windings 34, the number of which corresponds to the average pole number of the two stator windings, i.e. 8 and 4. Each unitary winding 34 includes six turn coils and ~ZSlZ~i~
thus has twelve coil sides. One end of each unitary winding 34 is connected to a first end ring 36 and the other end is connected to a second end ring 38. The coil side pitch of the unit winding 34 is one and the coil pitch thereof is five. The pitch between adjacent unitary wind-ings is six. The coil sides illustrated in solid lines of the respective unitary winding 34 are disposed in the upper part of the respectlve slots and the coil sides illustrated in dotted lines of the respective unitary windings 34 are disposed in the lower part of the respective slots.
The speed control of the machine 10 will be explained with reference to Fig. 5, and represents a static or thyristor Scherbius system. The rotor 30 is connected to a rotatable load 46 through a shaft 42 and a coupling 48.
The eight pole stator winding 22 is connected to first output terminals of a three-phase circuit breaker 56, the input terminals of which are connected to a three-phase power source 50 with a predetermined frequency fl. The four pole stator winding 24 is connected to the circuit breaker 56 through a frequency converter 52 and a trans-former 54. The winding 24 is connected to the converter 52 in a negative phase sequence with respect to that of the winding 22. The stator winding 22 is arranged in overlapping relation with the stator winding 24. The speed of the rotor 30 is controlled by regulating the frequency f2 fed to the four pole winding 24 through the converter 52.
As explained above, the current flowing through the rotor winding 32 induces a large amplitude of eight pole and four pole rotating magnetic field components that are coupled respectively with the eight pole stator winding 22 and the four pole stator winding 24. ~hen at least one of the stator windings 22 and 24 is excited, the rotor winding 32 (including six unitary windings 34) functions as if there were a four pole three-phase rotor winding and an eight pole three-phase rotor winding. Accordingly, assuming that the alternating current frequency applied to the eight pole winding 22 is fl and that applied to the four pole winding 24 is f2, and the actual rotating speed of the machine is nr, the synchronous speed nsl of the eight pole three-phase part of the machine is expressed, as:
nsl= 120fl ......... ,.,,,,.,,,~1) nr=nsl(1-sl) ......................................... .......... ~) wherein sl is the slip of the eight pole part of the machine at a speed nr.
The synchronous speed ns2 of the four pole three-phase part of the machine is expressed as:
120slfl ........................... .....r ... i 3 ) ns2=
nr=ns2(1-s2) ............................ .......... ( wherein s2 is the slip-of the four pole part of the machine at a speed nr.
From equations (2) and (4), nsl(1-sl)-ns2(1-s2) ............................... (5) Substituting nsl and ns2 of equations (1) and (3) into equation (5), (l-sl) = ~ s2) . -----(6) (1- 1) sl (1- 2) 1-sl+sl-sls2 1-sls2 4 ~+4 8+4 ~;~51255 Substituting nsl of equation (1) in equation (2), (l-sl) ................................................. (8) nr=
Substituting equation (7) in equation (8), nr= 1 ~ sls2) ......... (9) 8+4 Since, f2=s1s2fl .......... (10) ,. sls2= - .......... (11) When substituting equation (11) in equation (9), 120~1 f2 120 ~ )= (fl-f2) 8+4 fl 8+4 ............................................. .(12) Accordingly, the speed of the machine is controlled by regulating the applied frequency f2 to the four pole three-phase stator winding 24.
In t~e above preferred embodiment, the first set of end terminals of the respective unit windings are connected to the first end ring and the other set of end terminals are connected to the second end ring. However, both sets oE end terminals of the respective unit windings can be connected to a common end ring.
In the above preferred embodiment, only the combination of a four pole, three-phase ,stator winding, an eight pole, three-phase stator winding, and a rotor winding having six unitary windings is disclosed. However any other combin-ation is possible provided that the following conditions are satisfied.
lZS1255 (1) the number of poles of the two three phase stator windings is different.
(2 the number of the unitary windings of the rotor winding is an integral number and is the average of the numbers of poles of the two stator windings.
Further, the coil side pitch Rb, the coil pitch Rc, and number of coil turns of each unitary winding and the pitch between adjacent unitary windings ~b, which primari~y depend on the number of rotor slots, are adjustable, so as to increase the winding factor of the rotor winding and to improve the waveform of the rotating magnetic field generated by the rotor winding currents.
2(a) and 2(d), the directions of rotation of the field component ~228 and field components ~214 and ~224 are opposite to each other, the stator winding 24 being connected to an alternating current source in a negative phase sequence with respect to the phase sequence thereof for the stator winding 22. A small amount of the rotating magnetic field components, other than these four and eight pole components, are included in the moving magnetic field shown in Fig. 2(c). However, they have been s)mitted from Fig. 2(d) because the amount thereof is negligibly small.
~2~Z5S
Fig. 3(a) illustrates the relative amplitudes of the respective magnetic field components classified by the numbers of poles included in the moving magnetic field generated by the rotor winding currents, when only the four pole stator winding 24 is excited, as explained in connection with Figs. 2(a) to (d). In Figs. 3(a) and 3(b), the relative amplitude 1.0 is the amplitude of the original moving magnetic field before developing into a Fourier series, as for example shown in Fig. 2(c)~ As indicated previously in connection with Figs. 2(a) to (d), the rotating magnetic field components other than the four and eight pole components are negligibly small.
Fig. 3(b) illustrates the relative amplitudes of respective magnetic field components classified by n~mbers of poles in a moving magnetic field generated by the rotor winding currents, when only the eight pole stator winding 22 is excited. As is apparent from Fig. 3(b), a large amount of the four pole rotating magnetic field component that couples with the four pole stator winding 24 is included in the moving magnetic field, as well as a large amount of an eight pole rotating magnetic field component.
Another embodiment of the present invention will be explained in Fig. 4. To avoid complicating the drawing, only a developed rotor winding diagram is illustrated in Fig. 4. The rotor of this embodiment is provided with thirty-six slots. The corresponding stator (not shown) is provided with fifty-four slots and with an eight pole, three-phase stator winding with a coil pitch of five and a four pole, three-phase stator winding with a coil pitch of eleven. The four pole, three-phase stator winding is arranged in overlapping relation with the eight pole three-phase stator winding. The rotor winding 32 includes six unitary windings 34, the number of which corresponds to the average pole number of the two stator windings, i.e. 8 and 4. Each unitary winding 34 includes six turn coils and ~ZSlZ~i~
thus has twelve coil sides. One end of each unitary winding 34 is connected to a first end ring 36 and the other end is connected to a second end ring 38. The coil side pitch of the unit winding 34 is one and the coil pitch thereof is five. The pitch between adjacent unitary wind-ings is six. The coil sides illustrated in solid lines of the respective unitary winding 34 are disposed in the upper part of the respectlve slots and the coil sides illustrated in dotted lines of the respective unitary windings 34 are disposed in the lower part of the respective slots.
The speed control of the machine 10 will be explained with reference to Fig. 5, and represents a static or thyristor Scherbius system. The rotor 30 is connected to a rotatable load 46 through a shaft 42 and a coupling 48.
The eight pole stator winding 22 is connected to first output terminals of a three-phase circuit breaker 56, the input terminals of which are connected to a three-phase power source 50 with a predetermined frequency fl. The four pole stator winding 24 is connected to the circuit breaker 56 through a frequency converter 52 and a trans-former 54. The winding 24 is connected to the converter 52 in a negative phase sequence with respect to that of the winding 22. The stator winding 22 is arranged in overlapping relation with the stator winding 24. The speed of the rotor 30 is controlled by regulating the frequency f2 fed to the four pole winding 24 through the converter 52.
As explained above, the current flowing through the rotor winding 32 induces a large amplitude of eight pole and four pole rotating magnetic field components that are coupled respectively with the eight pole stator winding 22 and the four pole stator winding 24. ~hen at least one of the stator windings 22 and 24 is excited, the rotor winding 32 (including six unitary windings 34) functions as if there were a four pole three-phase rotor winding and an eight pole three-phase rotor winding. Accordingly, assuming that the alternating current frequency applied to the eight pole winding 22 is fl and that applied to the four pole winding 24 is f2, and the actual rotating speed of the machine is nr, the synchronous speed nsl of the eight pole three-phase part of the machine is expressed, as:
nsl= 120fl ......... ,.,,,,.,,,~1) nr=nsl(1-sl) ......................................... .......... ~) wherein sl is the slip of the eight pole part of the machine at a speed nr.
The synchronous speed ns2 of the four pole three-phase part of the machine is expressed as:
120slfl ........................... .....r ... i 3 ) ns2=
nr=ns2(1-s2) ............................ .......... ( wherein s2 is the slip-of the four pole part of the machine at a speed nr.
From equations (2) and (4), nsl(1-sl)-ns2(1-s2) ............................... (5) Substituting nsl and ns2 of equations (1) and (3) into equation (5), (l-sl) = ~ s2) . -----(6) (1- 1) sl (1- 2) 1-sl+sl-sls2 1-sls2 4 ~+4 8+4 ~;~51255 Substituting nsl of equation (1) in equation (2), (l-sl) ................................................. (8) nr=
Substituting equation (7) in equation (8), nr= 1 ~ sls2) ......... (9) 8+4 Since, f2=s1s2fl .......... (10) ,. sls2= - .......... (11) When substituting equation (11) in equation (9), 120~1 f2 120 ~ )= (fl-f2) 8+4 fl 8+4 ............................................. .(12) Accordingly, the speed of the machine is controlled by regulating the applied frequency f2 to the four pole three-phase stator winding 24.
In t~e above preferred embodiment, the first set of end terminals of the respective unit windings are connected to the first end ring and the other set of end terminals are connected to the second end ring. However, both sets oE end terminals of the respective unit windings can be connected to a common end ring.
In the above preferred embodiment, only the combination of a four pole, three-phase ,stator winding, an eight pole, three-phase stator winding, and a rotor winding having six unitary windings is disclosed. However any other combin-ation is possible provided that the following conditions are satisfied.
lZS1255 (1) the number of poles of the two three phase stator windings is different.
(2 the number of the unitary windings of the rotor winding is an integral number and is the average of the numbers of poles of the two stator windings.
Further, the coil side pitch Rb, the coil pitch Rc, and number of coil turns of each unitary winding and the pitch between adjacent unitary windings ~b, which primari~y depend on the number of rotor slots, are adjustable, so as to increase the winding factor of the rotor winding and to improve the waveform of the rotating magnetic field generated by the rotor winding currents.
Claims (5)
1. A brushless asynchronous alternating current machine controllable by secondary excitation comprising:
a first three-phase stator winding having a first number of poles;
a second three-phase stator winding having a second number of poles different from said first number of poles and overlapping said first three-phase stator winding; and a rotor winding facing and coaxial with said first and second three-phase stator windings, and being formed of a plurality of unitary windings, the number of which corres-ponds to the average pole number of said first and second three-phase stator windings, said unitary windings being uniformly arranged with respect to said first and second three-phase stator windings, each unitary winding including a coil having at least one turn and both ends of the coils of the respective unitary windings being electrically interconnected.
a first three-phase stator winding having a first number of poles;
a second three-phase stator winding having a second number of poles different from said first number of poles and overlapping said first three-phase stator winding; and a rotor winding facing and coaxial with said first and second three-phase stator windings, and being formed of a plurality of unitary windings, the number of which corres-ponds to the average pole number of said first and second three-phase stator windings, said unitary windings being uniformly arranged with respect to said first and second three-phase stator windings, each unitary winding including a coil having at least one turn and both ends of the coils of the respective unitary windings being electrically interconnected.
2. A brushless asynchronous alternating current machine according to claim 1, wherein first end terminals of the coils of the respective unitary windings are connected to a first end ring and the other end terminals thereof are connected to a second end ring.
3. A brushless asynchronous alternating current machine according to claim 1, wherein both end terminals of the coils of the respective unitary windings are connected to a common end ring.
4. A brushless asynchronous alternating current machine according to claim 1, wherein each unitary winding includes a coil having more than three turns.
5. A brushless asynchronous alternating current machine controllable by secondary excitation comprising:
an eight pole three-phase stator winding;
a four pole three-phase stator winding overlapping said eight pole three-phase stator winding; and a rotor winding facing and coaxial with said eight pole and four pole three-phase stator windings and being formed of six unitary windings, the six unitary windings being uniformly arranged with respect to said eight pole and four pole three-phase stator windings, each unitary winding including a coil having at least three turns, first end terminals of the coils of the six unitary windings being connected to a first end ring and the other end terminals thereof being connected to a second end ring.
an eight pole three-phase stator winding;
a four pole three-phase stator winding overlapping said eight pole three-phase stator winding; and a rotor winding facing and coaxial with said eight pole and four pole three-phase stator windings and being formed of six unitary windings, the six unitary windings being uniformly arranged with respect to said eight pole and four pole three-phase stator windings, each unitary winding including a coil having at least three turns, first end terminals of the coils of the six unitary windings being connected to a first end ring and the other end terminals thereof being connected to a second end ring.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP60-26275 | 1985-02-15 | ||
| JP2627585A JPS61189156A (en) | 1985-02-15 | 1985-02-15 | Induction rotary electric machine |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1251255A true CA1251255A (en) | 1989-03-14 |
Family
ID=12188731
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000501924A Expired CA1251255A (en) | 1985-02-15 | 1986-02-14 | Brushless asynchronous alternating current machine controllable by secondary excitation |
Country Status (2)
| Country | Link |
|---|---|
| JP (1) | JPS61189156A (en) |
| CA (1) | CA1251255A (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE9201761L (en) * | 1991-06-17 | 1992-12-18 | Elektronik Regelautomatik | PROCEDURE MOVE SPEED CONTROL OF INDUCTION ENGINES |
| EP1557933A3 (en) * | 1994-01-06 | 2009-10-07 | Hyun Laboratory Co., Ltd. | Electrical apparatus |
| AU9751601A (en) * | 1994-01-06 | 2002-02-21 | Hyun Laboratory Co., Ltd. | Power generator |
-
1985
- 1985-02-15 JP JP2627585A patent/JPS61189156A/en active Pending
-
1986
- 1986-02-14 CA CA000501924A patent/CA1251255A/en not_active Expired
Also Published As
| Publication number | Publication date |
|---|---|
| JPS61189156A (en) | 1986-08-22 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |