CA2096244A1 - Skewing of pole laminations of a switched reluctance machine to reduce acoustic noise - Google Patents
Skewing of pole laminations of a switched reluctance machine to reduce acoustic noiseInfo
- Publication number
- CA2096244A1 CA2096244A1 CA 2096244 CA2096244A CA2096244A1 CA 2096244 A1 CA2096244 A1 CA 2096244A1 CA 2096244 CA2096244 CA 2096244 CA 2096244 A CA2096244 A CA 2096244A CA 2096244 A1 CA2096244 A1 CA 2096244A1
- Authority
- CA
- Canada
- Prior art keywords
- stator
- rotor
- poles
- laminations
- pair
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/24—Rotor cores with salient poles ; Variable reluctance rotors
- H02K1/246—Variable reluctance rotors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/12—Stationary parts of the magnetic circuit
- H02K1/14—Stator cores with salient poles
- H02K1/146—Stator cores with salient poles consisting of a generally annular yoke with salient poles
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K1/00—Details of the magnetic circuit
- H02K1/06—Details of the magnetic circuit characterised by the shape, form or construction
- H02K1/22—Rotating parts of the magnetic circuit
- H02K1/24—Rotor cores with salient poles ; Variable reluctance rotors
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K19/00—Synchronous motors or generators
- H02K19/02—Synchronous motors
- H02K19/10—Synchronous motors for multi-phase current
- H02K19/103—Motors having windings on the stator and a variable reluctance soft-iron rotor without windings
-
- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02K—DYNAMO-ELECTRIC MACHINES
- H02K2201/00—Specific aspects not provided for in the other groups of this subclass relating to the magnetic circuits
- H02K2201/06—Magnetic cores, or permanent magnets characterised by their skew
Abstract
The laminations (40, 50) respectively comprising the rotor and stator poles (116a, 116b, 118a, 118b, 120a, 120b, 124a, 124b) of a switched reluctance machine (SRM) (114) are skewed as they are stacked during machine assembly in order to reduce the tendency of the SRM (114) to flatten and thereby assume an oval shape during machine operation. As a result, the acoustic noise generated by the SRM (114) during machine operation is substantially reduced.
Description
~' 93~07~71 P~r/~IS~2/0~6~,~
209~2~
P~ELUCTANCE MA~HINE TO REDU~E ACOUSTIC NOISE
Field of the invention -~
The present invention relates ~enerally ~o switched reluc~ance S machines and, more par~icularly, to ~h~ skewing of ro~or and stator laminations in order to reduce acous~ic noise generated by the machine.
Backaround of the InvçntiQn A switched reluctance machine (SRM) is a brushless, synchronous maehine having salien~ rotor and stator poles. There is a concentrated 10 winding on each of the stator poles, but no windings or permanent magnets on the rotor. Each pair of diametrically opposite st~or pole windings is connected in series or in parallel to form an indep~ndent rnachine phase winding o~the multiphase SRM. Ideally, the flux entering the rotor frorn one s~ator pole balances the flux leaving ~he rotor from the 15 di~metri~ally opposite stator pole, so that ~here is no mutual magnetic couplin~ among ~he phases.
Torque is produced by swi~ching current in each phase windin~ in a predetermined sequcnce that is synchronized wi~h angular position of the rotor. In this way, a ma~natic force of attractl~n resul~s between the 20 rotor poles and the stator poles that are approachin~ each o~her. The current is switched off in each phase before thc rotor poles n~arest the ~-stator poles of tha~ phase rota~e past the aiigned position; otherwise, the magn~tic forcz of attraction would produce a nega~ive, or brakiny, torque. In a SMF~, torque direction is independent of current Jirection.
~5 Therefore, in contrast to most other brushless machines which require WO 93/0767I PCI/US92/0~
209~2~
P~ELUCTANCE MA~HINE TO REDU~E ACOUSTIC NOISE
Field of the invention -~
The present invention relates ~enerally ~o switched reluc~ance S machines and, more par~icularly, to ~h~ skewing of ro~or and stator laminations in order to reduce acous~ic noise generated by the machine.
Backaround of the InvçntiQn A switched reluctance machine (SRM) is a brushless, synchronous maehine having salien~ rotor and stator poles. There is a concentrated 10 winding on each of the stator poles, but no windings or permanent magnets on the rotor. Each pair of diametrically opposite st~or pole windings is connected in series or in parallel to form an indep~ndent rnachine phase winding o~the multiphase SRM. Ideally, the flux entering the rotor frorn one s~ator pole balances the flux leaving ~he rotor from the 15 di~metri~ally opposite stator pole, so that ~here is no mutual magnetic couplin~ among ~he phases.
Torque is produced by swi~ching current in each phase windin~ in a predetermined sequcnce that is synchronized wi~h angular position of the rotor. In this way, a ma~natic force of attractl~n resul~s between the 20 rotor poles and the stator poles that are approachin~ each o~her. The current is switched off in each phase before thc rotor poles n~arest the ~-stator poles of tha~ phase rota~e past the aiigned position; otherwise, the magn~tic forcz of attraction would produce a nega~ive, or brakiny, torque. In a SMF~, torque direction is independent of current Jirection.
~5 Therefore, in contrast to most other brushless machines which require WO 93/0767I PCI/US92/0~
2~962~
bldirectional phase currents, a SMR power inverter can be configured to enable curren~ flow in only one direction through a phase ~1 winding. Such an inverter generaliy employs one or more switching devices, such as transistors or thyristors, in series with each machine phase winding. Exemplary SRM conve~ers are illustrated in commonly assigned U.S. Patent No. 4,684,867, issued to T.J.E. Miller on August 4, 1987, which is hereby incorporated by reference.
A SRM operates by switching ~he machine phase currents on and off in synchronism with rotor position. That is, by properly positioning lO the firing puls~s relative to rotor an~le, forward or reverse operation and motoring or generating operation ean be obtained. Usually, the desired phase current commutation is achieved by feeding back the rotor posi~ion signal to a oontroiler from a shaft angle transducer, e.~., an encoder or a resolver.
15Despits its advantages as a simple and efficient machine useful in adjustable speed drives, a SRM is typieally noisy. In large part, this is due to the "ovaling" of the stator dwin~ machine operation. "OYaling"
refers ~o the tendency of the stator to fiat~en and ~hereby assume an oval shape during mactline operation, resulting from the electromagnetic ~;
20 attraction between the rotor poles of ~he machine and the diametrically-opposed stator poles of each energized phase. Therefore, an objec~ of the presen~ inv~ntion is to reduce th~ "ovalin~" eff~ct of an SRM stator ;
as it rotates, th~reby r~ducing the acoustic noise generated during SRM
operatlon.
! -2~~m~t~l~ ' - - The laminations respectively comprising the rotor and stator polee of a SRM are skewed as ~hey are staeked during machine assembly. As a resuit, the electromagnetic force of attraction between the rotor poles WO ~3~0~671 PCr/U~92tO86h~
20962~4 and th~ stator poles of ~ach en~r~ d phas~ is sprea~ out, thereby ~` reducin~ the t~ndency of the SRM to assume an oval shape duringmachine operation. In this way, the acoustic noise ~enerated by ~he SRM during machine operation is ubstantially reduced.
Brief De~riDti~n of the Drawinqs The features and advanta~es of the present invention will become apparent from the following detailed description of the invention when read with the accompanying drawin~s in which:
Figure 1 is a cross sec~ional view of a typical SRM rotor and stator confi~uration; and :
Fi~ure 2 is a cross sectional view of a rotor and stator of a SRM, the rotor and stator each having skewed laminations in accordance with the present invention.
~' ~
Detailed Des~riQtion of th~ lnyen~loQ
Figure 1 is a cross sectional view of a sta~or 1Q and a ro~or 12 of a typical switched reluctance machine (SRM) 14. P~otor 12 of SRM 14 is rotatable in ei~her a forward or reverse direction within stationary sta~or 10. Ro~or 12 has two pairs of diametrically opposi~e rotor poles 1Ga-16b and 18a^18b. Stator 10 has thre~ pairs of diarretrically opposite stator pol~s 20a-20b, 22a-22b and 24a-24b. For purposes of iilus~ration, s~ator poie coil windings 2Ba and 26b ars shown as bain~
wound only about ~ator poles 20a and 20b, resp~ctivel~; however, i~ is ~o be unders~ood ~hat s~ator pol~ coil windings would yener~ be wound about each pair of opposin~ stator poles. The stator pole coil windings ~5 on each pair of opposin~ or companion stator pole pairs are connec~ed in sefies or parallel to form a motor phase winding. A~ shown in Figure 1, the current I in each phase produces a magnetic flux linkage by .
, ': ' ' , :
, . ~
': - ' ' ' ''' ' ' . :
WO 93/~671 PCI/VS9~/08668 2~962~
generating flux In the directions indica~ed by arrows ~8 and 30. For xample, as shown, windings 26a and 26b are conneete~ in seri~s so tha~
~he current I flows in the direction indieated. Durin~ SRM operation, the electromagnetic force of at~raction between the rotor poles and the 5 stator poles of each energized phase causes the ~tator "ovaling"
phenomena described hereinabove, resultin~ in noisy SRM operation.
Figure 2 illustrates a SRM 114 according to the present invention having skewed rotor laminations 40 comprising rotor poles 11 6a, 11 6b, 118a and 118b, and further having skewed s~ator laminations 50 comprising stator poles 120a, 120b, 122a, 122b, 124a and 124b. In particular, the laminations of each stator poles and each rotor pole are -arranged in a fan-like manner so as to spread ou~ each respective pole.
As a result, the electrom3gnetic forces of attrac~ion between the rotor poies and the stator poles of each energized phase are spread over a lS larger pole are, thereby avoiding the tendeney of ~he s~ator to flatten per the "ovaling" phenomena. Moreover, the skewing of the rotor and stator laminations f urther provides mechanical reinforcement of the rotor-stator configuration, also tendin~ to avoid ~ovalinga. By thus avoiding "ovalingN, acoustic noise ~enerated by the SR \A is substantially reduced .
~0 In an alternative embodiment, only ~h~ stator pole lamination~ are skewed to reducs acoustic noise.
Although SRM 114 is shown ir) Fiyur~ 2 as having thre0-phases with six stator polcs and four rotor poles, it is to ba understood that the princlpl0s of ~he present inverl~ion apply ~o a SF~M havin~ any number of 25 phases and also to any suitable combination of stator and ro~or poles.
While ~he preferred embodimen~s of the present inven~ion have been shown and described hereir~, i~ will be obvious that such embodiments are provided by way ot example only. Numerous variations, changes and - ' ~
W~ ~3/07~71 P~/US92/086S8 ~ j i i` ;' 5 2~1~62~
substitutions will occur to thosa of skill in the art without depalting from the invention herein. Accordin~ly, it is intended ~hat ~he invention be limited only by the spirit and scope of the appended claims.
, .' . '':
, ............ . , . :
' , , ~' , ~;...
I
~ .
bldirectional phase currents, a SMR power inverter can be configured to enable curren~ flow in only one direction through a phase ~1 winding. Such an inverter generaliy employs one or more switching devices, such as transistors or thyristors, in series with each machine phase winding. Exemplary SRM conve~ers are illustrated in commonly assigned U.S. Patent No. 4,684,867, issued to T.J.E. Miller on August 4, 1987, which is hereby incorporated by reference.
A SRM operates by switching ~he machine phase currents on and off in synchronism with rotor position. That is, by properly positioning lO the firing puls~s relative to rotor an~le, forward or reverse operation and motoring or generating operation ean be obtained. Usually, the desired phase current commutation is achieved by feeding back the rotor posi~ion signal to a oontroiler from a shaft angle transducer, e.~., an encoder or a resolver.
15Despits its advantages as a simple and efficient machine useful in adjustable speed drives, a SRM is typieally noisy. In large part, this is due to the "ovaling" of the stator dwin~ machine operation. "OYaling"
refers ~o the tendency of the stator to fiat~en and ~hereby assume an oval shape during mactline operation, resulting from the electromagnetic ~;
20 attraction between the rotor poles of ~he machine and the diametrically-opposed stator poles of each energized phase. Therefore, an objec~ of the presen~ inv~ntion is to reduce th~ "ovalin~" eff~ct of an SRM stator ;
as it rotates, th~reby r~ducing the acoustic noise generated during SRM
operatlon.
! -2~~m~t~l~ ' - - The laminations respectively comprising the rotor and stator polee of a SRM are skewed as ~hey are staeked during machine assembly. As a resuit, the electromagnetic force of attraction between the rotor poles WO ~3~0~671 PCr/U~92tO86h~
20962~4 and th~ stator poles of ~ach en~r~ d phas~ is sprea~ out, thereby ~` reducin~ the t~ndency of the SRM to assume an oval shape duringmachine operation. In this way, the acoustic noise ~enerated by ~he SRM during machine operation is ubstantially reduced.
Brief De~riDti~n of the Drawinqs The features and advanta~es of the present invention will become apparent from the following detailed description of the invention when read with the accompanying drawin~s in which:
Figure 1 is a cross sec~ional view of a typical SRM rotor and stator confi~uration; and :
Fi~ure 2 is a cross sectional view of a rotor and stator of a SRM, the rotor and stator each having skewed laminations in accordance with the present invention.
~' ~
Detailed Des~riQtion of th~ lnyen~loQ
Figure 1 is a cross sectional view of a sta~or 1Q and a ro~or 12 of a typical switched reluctance machine (SRM) 14. P~otor 12 of SRM 14 is rotatable in ei~her a forward or reverse direction within stationary sta~or 10. Ro~or 12 has two pairs of diametrically opposi~e rotor poles 1Ga-16b and 18a^18b. Stator 10 has thre~ pairs of diarretrically opposite stator pol~s 20a-20b, 22a-22b and 24a-24b. For purposes of iilus~ration, s~ator poie coil windings 2Ba and 26b ars shown as bain~
wound only about ~ator poles 20a and 20b, resp~ctivel~; however, i~ is ~o be unders~ood ~hat s~ator pol~ coil windings would yener~ be wound about each pair of opposin~ stator poles. The stator pole coil windings ~5 on each pair of opposin~ or companion stator pole pairs are connec~ed in sefies or parallel to form a motor phase winding. A~ shown in Figure 1, the current I in each phase produces a magnetic flux linkage by .
, ': ' ' , :
, . ~
': - ' ' ' ''' ' ' . :
WO 93/~671 PCI/VS9~/08668 2~962~
generating flux In the directions indica~ed by arrows ~8 and 30. For xample, as shown, windings 26a and 26b are conneete~ in seri~s so tha~
~he current I flows in the direction indieated. Durin~ SRM operation, the electromagnetic force of at~raction between the rotor poles and the 5 stator poles of each energized phase causes the ~tator "ovaling"
phenomena described hereinabove, resultin~ in noisy SRM operation.
Figure 2 illustrates a SRM 114 according to the present invention having skewed rotor laminations 40 comprising rotor poles 11 6a, 11 6b, 118a and 118b, and further having skewed s~ator laminations 50 comprising stator poles 120a, 120b, 122a, 122b, 124a and 124b. In particular, the laminations of each stator poles and each rotor pole are -arranged in a fan-like manner so as to spread ou~ each respective pole.
As a result, the electrom3gnetic forces of attrac~ion between the rotor poies and the stator poles of each energized phase are spread over a lS larger pole are, thereby avoiding the tendeney of ~he s~ator to flatten per the "ovaling" phenomena. Moreover, the skewing of the rotor and stator laminations f urther provides mechanical reinforcement of the rotor-stator configuration, also tendin~ to avoid ~ovalinga. By thus avoiding "ovalingN, acoustic noise ~enerated by the SR \A is substantially reduced .
~0 In an alternative embodiment, only ~h~ stator pole lamination~ are skewed to reducs acoustic noise.
Although SRM 114 is shown ir) Fiyur~ 2 as having thre0-phases with six stator polcs and four rotor poles, it is to ba understood that the princlpl0s of ~he present inverl~ion apply ~o a SF~M havin~ any number of 25 phases and also to any suitable combination of stator and ro~or poles.
While ~he preferred embodimen~s of the present inven~ion have been shown and described hereir~, i~ will be obvious that such embodiments are provided by way ot example only. Numerous variations, changes and - ' ~
W~ ~3/07~71 P~/US92/086S8 ~ j i i` ;' 5 2~1~62~
substitutions will occur to thosa of skill in the art without depalting from the invention herein. Accordin~ly, it is intended ~hat ~he invention be limited only by the spirit and scope of the appended claims.
, .' . '':
, ............ . , . :
' , , ~' , ~;...
I
~ .
Claims (4)
1. A switched reluctance machine, comprising:
a stator having at least one pair of opposing stator poles, each of said stator poles comprising a plurality of stator laminations, said stator laminations of each of said stator poles being skewed in a fan-like manner in order to minimize acoustic noise generated during operation of said switched reluctance machine;
a stator pole winding wound about each of said stator poles, the stator pole windings of each pair of opposing stator poles being electrically connected together; and a rotor positioned for rotation within said stator, said rotor having at least one pair of opposing rotor poles, each of said rotor poles comprising a plurality of rotor laminations, said rotor laminations of each of said rotor poles being skewed in a fan-like manner.
a stator having at least one pair of opposing stator poles, each of said stator poles comprising a plurality of stator laminations, said stator laminations of each of said stator poles being skewed in a fan-like manner in order to minimize acoustic noise generated during operation of said switched reluctance machine;
a stator pole winding wound about each of said stator poles, the stator pole windings of each pair of opposing stator poles being electrically connected together; and a rotor positioned for rotation within said stator, said rotor having at least one pair of opposing rotor poles, each of said rotor poles comprising a plurality of rotor laminations, said rotor laminations of each of said rotor poles being skewed in a fan-like manner.
2. A switched reluctance machine, comprising:
a stator having at least one pair of opposing stator poles, each of said stator poles comprising a plurality of stator laminations, said stator laminations of each of said stator poles being skewed in a fan-like manner in order to minimize acoustic noise generated during operation of said switched reluctance machine;
a stator pole winding wound about each of said stator poles, the stator pole windings of each pair of opposing stator poles being electrically connected together; and a rotor positioned for rotation within said stator, said rotor having at least one pair of opposing rotor poles, each of said rotor poles comprising a plurality of rotor laminations.
a stator having at least one pair of opposing stator poles, each of said stator poles comprising a plurality of stator laminations, said stator laminations of each of said stator poles being skewed in a fan-like manner in order to minimize acoustic noise generated during operation of said switched reluctance machine;
a stator pole winding wound about each of said stator poles, the stator pole windings of each pair of opposing stator poles being electrically connected together; and a rotor positioned for rotation within said stator, said rotor having at least one pair of opposing rotor poles, each of said rotor poles comprising a plurality of rotor laminations.
3. A method for constructing a switched reluctance machine, comprising:
providing a plurality of substantially identical rotor laminations, each having at least one pair of opposing rotor poles;
stacking and arranging said rotor laminations so that the corresponding rotor poles of said laminations are skewed in a fan-like manner;
providing a plurality of substantially identical stator laminations, each having at least one pair of opposing stator poles;
stacking and arranging said stator laminations so that the corresponding stator poles of said laminations are skewed in a fan-like manner;
winding a stator coil winding about each of said stator poles;
electrically connecting the coil windings about each pair of opposing stator poles together; and situating said rotor for rotation within said stator.
providing a plurality of substantially identical rotor laminations, each having at least one pair of opposing rotor poles;
stacking and arranging said rotor laminations so that the corresponding rotor poles of said laminations are skewed in a fan-like manner;
providing a plurality of substantially identical stator laminations, each having at least one pair of opposing stator poles;
stacking and arranging said stator laminations so that the corresponding stator poles of said laminations are skewed in a fan-like manner;
winding a stator coil winding about each of said stator poles;
electrically connecting the coil windings about each pair of opposing stator poles together; and situating said rotor for rotation within said stator.
4. A method for constructing a switched reluctance machine, comprising:
providing a plurality of substantially identical rotor laminations, each having at least one pair of opposing rotor poles;
stacking and arranging said rotor laminations so that the corresponding rotor poles of said laminations are aligned;
providing a plurality of substantially identical stator laminations, each having at least one pair of opposing stator poles;
stacking and arranging said stator laminations so that the corresponding stator poles of said laminations are skewed in a fan-like manner in order to minimize acoustic noise generated during operation of said switched reluctance machine;
winding a stator coil winding about each of said stator poles;
electrically connecting the coil windings about each pair of opposing stator poles together; and situating said rotor for rotation within said stator.
providing a plurality of substantially identical rotor laminations, each having at least one pair of opposing rotor poles;
stacking and arranging said rotor laminations so that the corresponding rotor poles of said laminations are aligned;
providing a plurality of substantially identical stator laminations, each having at least one pair of opposing stator poles;
stacking and arranging said stator laminations so that the corresponding stator poles of said laminations are skewed in a fan-like manner in order to minimize acoustic noise generated during operation of said switched reluctance machine;
winding a stator coil winding about each of said stator poles;
electrically connecting the coil windings about each pair of opposing stator poles together; and situating said rotor for rotation within said stator.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US77382291A | 1991-10-09 | 1991-10-09 | |
| US773,822 | 1991-10-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2096244A1 true CA2096244A1 (en) | 1993-04-10 |
Family
ID=25099419
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2096244 Abandoned CA2096244A1 (en) | 1991-10-09 | 1992-10-09 | Skewing of pole laminations of a switched reluctance machine to reduce acoustic noise |
Country Status (5)
| Country | Link |
|---|---|
| EP (1) | EP0560972A1 (en) |
| AU (1) | AU658946B2 (en) |
| CA (1) | CA2096244A1 (en) |
| NZ (1) | NZ244664A (en) |
| WO (1) | WO1993007671A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6700272B1 (en) | 1997-09-30 | 2004-03-02 | Emf 97 Elektro-Maschinen-Vertrieb-Magnettechnik- Und Forschungs Gmbh | Reluctance motor with gearless step-down without electronic control of rotating field |
| DE19743380C1 (en) * | 1997-09-30 | 1999-03-25 | Emf 97 Gmbh | Energy conversion reluctance motor |
| FR2809240A1 (en) * | 2000-05-17 | 2001-11-23 | Minarro Bernot Ind Diffusion C | Homo-polar electrical machine and fabrication method, uses stampings from a flat metallic sheet, shaped teeth to support conductors |
| FR3029026B1 (en) * | 2014-11-20 | 2018-01-19 | Valeo Systemes De Controle Moteur | ELECTRIC MACHINE HAVING HELICOIDAL TEETH FOR APPLICATION IN A MOTOR VEHICLE |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB215433A (en) * | 1923-02-07 | 1924-05-07 | Matthew William Walbank Mackie | Improvements in dynamos and motors |
| US1835505A (en) * | 1930-10-09 | 1931-12-08 | L S Brach Mfg Corp | Synchronous clock motor |
| US4260926A (en) * | 1979-03-16 | 1981-04-07 | Societe Elpalux | Variable reluctance electric motor with progressively saturable poles |
| JPS57180339A (en) * | 1981-04-29 | 1982-11-06 | Mitsubishi Electric Corp | Field core for rotary electric machine |
| DE3578867D1 (en) * | 1984-10-19 | 1990-08-30 | Kollmorgen Corp | VARIABLE RELUCTIVE MACHINE WITH VARIABLE SPEED. |
-
1992
- 1992-10-08 NZ NZ24466492A patent/NZ244664A/en unknown
- 1992-10-09 AU AU28628/92A patent/AU658946B2/en not_active Ceased
- 1992-10-09 CA CA 2096244 patent/CA2096244A1/en not_active Abandoned
- 1992-10-09 WO PCT/US1992/008668 patent/WO1993007671A1/en not_active Application Discontinuation
- 1992-10-09 EP EP19920921815 patent/EP0560972A1/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| AU658946B2 (en) | 1995-05-04 |
| WO1993007671A1 (en) | 1993-04-15 |
| AU2862892A (en) | 1993-05-03 |
| EP0560972A1 (en) | 1993-09-22 |
| NZ244664A (en) | 1995-04-27 |
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Legal Events
| Date | Code | Title | Description |
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| FZDE | Dead |