CN103081318A - Fault tolerant flux switching machine - Google Patents

Abstract

A stator for a flux switching permanent magnet machine has multiple pole pieces with windings around each pole piece. Each pole piece and the windings associated with each pole piece are physically separated from the other pole pieces and the associated windings by a separator. The purpose of the separator is to induce for each pole piece a higher self inductance profile than the mutual inductance profile for the other pole pieces. The separator substantially isolates the adjacent poles pieces electrically from each other, and may be of ferromagnetic material.

Description

Fault-tolerant flux switch motor

The present invention relates to a kind of magneto, especially but do not relate to uniquely a kind of topological structure be used to improving the flux switch permanent magnet motor fault tolerance.

Flux switch permanent magnet motor is known in electric motors.Generally speaking, these motors are comprised of a simple brushless rotor that is arranged in the stator, wherein, have magnet and coil in the stator.A kind of known flux switch permanent magnet motor (FSPM) see for example Fig. 1.This motor is conducive to high power/torque density and efficient.In addition, for producing, simple rotor structure is firm and cheap.

But the type of flux switch motor shown in Figure 1 is fault-intolerant.For example, the short circuit meeting often causes motor fault in the rotor coil.Especially, the fault of motor resistance will cause motor to exceed burning of tolerance range and assembly.High mutual inductance between each pole piece coil generally is approximately 50% of self-induction between the phase place of this problem.Lack fault-tolerant ability and can limit this motor in some key areas, such as the application in space flight and national defence field.This misgivings also are prevalent in hybrid power/electric motor car industry, and in these fields, the high electric current that the driving frequency converter brings can destroy expensive engine.

The permanent magnet surface motor (PMSM) of some particular design allows fault-tolerant.But utilize to keep to overlap magnet is limited on the position, for producing, keeps the cover price high, can reduce the resistance to overturning of equipment, and bring the rising of excess loss.In addition, they do not have the corresponding so much advantage of FSPM.

An object of the present invention is to alleviate or overcome at least some the problems referred to above.

According to a first aspect of the invention, for flux switch permanent magnet motor provides a kind of stator, described stator has a plurality of pole pieces, center on coil around each pole piece, wherein, each pole piece and the corresponding coil of each pole piece are blocked component physical with other pole piece and their corresponding coils and separate, to realize the being in a ratio of coefficient of mutual inductance that other pole piece brings, for each pole piece brings higher coefficient of self-inductance.

According to a further aspect in the invention, a kind of flux switch permanent magnet motor is provided, comprise and turn the stator that son, contains a plurality of pole pieces always, each pole piece is centered on by coil, and a ferromagnetism barrier component and each pole piece and corresponding coil thereof adjoin, wherein, the ferromagnetism barrier component is set is for each pole piece and other pole piece physical isolation, thus, than the coefficient of mutual inductance of bringing for other pole piece, can bring high coefficient of self-inductance for each electrode.

For each above-mentioned aspect of the present invention, the stator general layout is the improvement that the fault-tolerant ability of flux switch motor is brought.

Another aspect, this aspect provides a kind of linear motor that includes stator, or the relevant flux switch permanent magnet motor of the above-mentioned any aspect of the present invention.

Other advantage of the present invention, aspect and feature are according to additional claim and be apparent with reference to the description of only carrying out as a kind of embodiment that gives an example and accompanying drawing next, wherein:

Fig. 1 is a kind of flux switch permanent magnet motor (FSPM) topological structure example in the prior art;

Fig. 2 is the example of a kind of FSPM of preferred embodiment according to the present invention;

Fig. 2 a is the zoomed-in view of Fig. 2 isolated part;

Fig. 3 is the split ratio of FSPM shown among Fig. 2 and the relation curve of average torque;

Fig. 4 is the relative rotor magnetic pole arc of FSPM shown among Fig. 2 and the relation curve of average torque;

Fig. 5 is the thick relation curve with average torque and relative torque pulsation of the relative magnetic of FSPM shown among Fig. 2;

Fig. 6 is the wire casing isolated part thickness of FSPM shown among Fig. 2 and the relation curve of induction and average torque;

Fig. 7 is the relation curve of slit and induction coefficient and average torque between the adjacent teeth pin of FSPM shown among Fig. 2;

Fig. 8 is the example of a kind of fault-tolerant PMSM, compares with it, and the preferred embodiment of the present invention is detected;

Fig. 9 is the reaction electromotive force correlation curve of the PMSM of the shown FSPM of Fig. 2 and Fig. 8;

Figure 10 is the torque of PMSM of the shown FSPM of Fig. 2 and Fig. 8 and the curve of cogging torque;

Figure 11 is mutual inductance and the self-induction curve of the PMSM of the shown FSPM of Fig. 2 and Fig. 8;

Figure 12 is the torque correlation curve under the passage of the PMSM of the shown FSPM of Fig. 2 and Fig. 8 opens circuit;

Figure 13 is the torque correlation curve under the passage short circuit of the shown FSPM of Fig. 2;

Figure 14 is the torque correlation curve under the passage short circuit of PMSM of Fig. 8;

Figure 15 is the more preferred embodiment of FSPM in accordance with a preferred embodiment of the present invention; And

Figure 16 is the further preferred embodiment of FSPM in accordance with a preferred embodiment of the present invention.

At first with reference to Fig. 1, a kind of of FSPM of the prior art is described at 10 indications for example, comprises the stator 12 with outward flange 11 and inward flange 13, and be installed in the stator 12, be positioned at the rotor 14 on the shelf 16.

Stator 12 has six radial pole pieces of arranging 22.Radial arranging of permanent magnet 18(is arranged) in each pole piece 22.Run through is coil (do not indicate, but be positioned at the position of 20 indications) around each pole piece 22.The structure, quantity and the density that center on the coil 20 of each pole piece 22 can change according to designing requirement.Similarly, the quantity of pole piece 22 and corresponding permanent magnet 18 can change.

Rotor 14 is simple brushless design, has 7 teeth 24.Than the quantity of pole piece 22, the quantity of tooth 24 can change according to design alternative.Usually pole piece 22 is different with the quantity of tooth 24, so that efficient to be provided, such as the mode by the reduction cogging torque.

Example as can be seen, magnet 18 and coil 20 are the part of stator 12.Pole piece 22 extends to the inward flange 13 of stator 12, but provides space 23 between the pole piece 22 that is installed in inward flange 13 places of stator.In the embodiment of a demonstration, space 23 is defined to be substantial arcuation along stator 12 inward flanges 13, and for example, the length that has the basically width with pole piece 22 is identical.

Stator flux line and the mutual inductance line of flux are pointed out by mark 26 and 28 respectively.The flux that described stator flux line 26 shows between the pole piece 22 is high.In Fig. 1, the mutual inductance line of flux 28 is marked by dotted line, with for referencial use.For example can see, the route of the mutual inductance line of flux along the outward flange of stator 11 between two pole pieces 22.Cause so high-caliber mutual inductance and therefore fault-tolerant step-down; Short circuit in the pole piece 22 will increase flux, may make flux surpass estimated value.

Fig. 2 shown a kind of preferred embodiment according to the present invention FSPM for example, it is designed to improve the fault-tolerant ability of FSPM.In this embodiment, FSPM is three phase electric machine.Fig. 2 a is the pole piece of the shown FSPM of Fig. 2 and the zoomed-in view of barrier component.

In Fig. 1, motor 10 contains a stator 12 with six pole pieces, and with the rotor 14 of seven teeth 24.But according to the preferred embodiment of the present invention, stator 12 comprises a barrier component 30 between each pole piece 22.Described barrier component 30 is used for each pole piece 22 and other pole piece 22 physical isolation.Described barrier component 30 not with pole piece 22 physical contacts that are positioned at stator 12 inward flanges 13 places.Be equivalent to, between barrier component 30 and the pole piece 22 in the vicinity at stator 12 inward flanges 13 places, provide a gap 23.The clear and definite demonstration in Fig. 2 a of space 23 between pole piece 22 and the barrier component 30.This space is obviously less than the space 23 between the pole piece 22 among the embodiment of Fig. 1.

In this preferred embodiment, barrier component 30 be shaped as the radiated entends arm, extend to the inward flange 13 of stator 12 from the outward flange 14 of stator 12.Example as can be seen, barrier component 30 is installed in the space 23 between the pole piece embodiment illustrated in fig. 1 22, and, between the stator adjacent part at inward flange 13 places, stay space 23.Little space has determined the self-induction of coil, and the size in space can be adjusted according to determined final fault-tolerant ability.

In order to keep identical coil region, the design (wherein, coil 20 is generally copper) that shows such as FSPM among Fig. 1, the width that the introduction of barrier component 30 is accompanied by the tooth 24 of rotor 14 in Fig. 2 preferred embodiment reduces, and this allows motor to keep identical torque output.

The stator structure that shows among Fig. 2 has the magnetic that is different from the stator of FSPM among Fig. 1 and electrically.Especially, having produced different flux paths, mainly is the self-induction (line of flux of single pole piece is shown at 32 places as the dotted line of overstriking, so that reference) around each independent pole piece 22.

Example is as directed, and the line of flux 32 of pole piece 22 forms a ring below pole piece 22, and along the outward flange of stator 11, the tooth 24 that passes rotor 22 enters isolated part 30, turns back to departure place pole piece 22.Have minimum flux 32 between the different pole pieces 22, thus, phase winding, keep very low around the mutual inductance of each coiling of pole piece 22.Therefore, barrier component 30 should be considered to pole piece 22 and other pole piece 22 are isolated simultaneously physically with on the electromagnetism, therefore, if the first pole piece 22 makes a mistake, flux path 32 is guaranteed described mistake for self-supporting, thus, and on the almost not impact of other pole piece, guarantee that motor 10 can not exceed load current value, and can when short circuit occurs, detrimentally not affect other phase winding.

In a preferred embodiment, barrier component 30 has ferromagnetic material, for example iron to make, to increase the electromagnetism isolation of pole piece 22.

Fig. 3 to Fig. 7 has shown the related experiment data of the design of the FSPM that Fig. 2 shows.The motor that is used for drawing described experimental data has 75mm fixed outer diameter and 100mm axial length, and is optimized the induction coefficient that obtains 1pu, be equivalent to 3.19mH.Motor 10 as shown in Figure 2, be described sextupole sheet stator and seven tooth rotors, but, those skilled in the art can be understood that, scope as described herein, relevant with the specific embodiment that is described with reference to figure 2, and, in the situation that do not break away from the fault-tolerant stator structure of the present invention or FSPM arranges this fault-tolerant stator structure content, described scope can change.

Fig. 3 has shown the relation curve of the average torque of split ratio and generation.Split ratio is defined as the ratio between stator hole diameter (defined such as inward flange 13) and the stator outside diameters (defined such as outward flange 11), example as can be seen, average torque has maximum between 0.5 and 0.6.

Fig. 4 has shown the relation curve of relative pole arc and average torque.Pole arc is measured with radian relatively, and data clearly can be found out at about 0.9 to 1.2 radian to reach breakdown torque by experiment.

From experimental data, split ratio reaches breakdown torque at 0.55 scope, pole arc at about 1 radian.

Fig. 5 has shown the data of the relative magnetic of definite optimization thick (ratio of magnet width and rotor radius).Fig. 5 a shown for the thick average torque of relative magnetic, and Fig. 5 b has shown for the thick torque pulsation relative percentage of relative magnetic.

From Fig. 5 a, clearly breakdown torque occurs in the thick place of 0.6 to 1.25 relative magnetic, and peak value is approximately 1.0.

Fig. 5 b has shown that torque pulsation approximately is held constant at 0.75 and then begins to be rapidly increased near 1.0.The high torque (HT) pulsation is unwelcome, it was noted that in full motor can't provide constant output.

From Fig. 5 a and Fig. 5 b, clearly higher relative magnetic is thick is undesirable, because it can bring high torque pulse.Also find, the torque output of the optimization under the pull up torque pulse, thick at magnetic is to be implemented in 0.8 scope.

Fig. 6 has shown the data that are used for optimizing barrier component thickness, and for fault-tolerant motor, it is desirable having alap coefficient of mutual inductance, not affecting torque simultaneously.

Fig. 6 a has shown: barrier component thickness for mutual inductance and coefficient of self-inductance relation curve, Fig. 6 b shown barrier component thickness for the torque of generation.

From Fig. 6 a, clearly, barrier component is thicker, and coefficient of mutual inductance is lower, keeps constant and coefficient of self-inductance is about.Obviously can find out, even very thin barrier component (such as 0.5mm), coefficient of mutual inductance is approximately 30% than in coefficient of self-inductance relatively, compares down, is designed to 50% among Fig. 1.Be in the 2.5mm situation at barrier component thickness, coefficient of mutual inductance is than in coefficient of self-inductance＜10% relatively.

Fig. 6 b has shown thickness approximately to the 2.5mm situation, and it is constant that average torque approximately keeps, thickness greater than the 2.5mm situation under, obvious torque having occurred increases.From Fig. 6 a and 6b data, the barrier component thickness that can find out optimization is 2.5mm.

Fig. 7 has shown the prioritization scheme in " space between adjacent sheaves ".The relation that has shown induction coefficient and space among Fig. 7 a has shown the relation in torque and space among Fig. 7 b.Space 23 is as shown in Fig. 2 a.

From above-mentioned data, clearly, high coefficient of self-inductance is brought in little space between the adjacent teeth, but is low average torque, and by above-mentioned data, the space aperture of optimization is 0.8 degree (deg).

Experimental data draws, can when following test result, obtain the maximal efficiency of the motor of 75mm diameter and 100mm axial length: split ratio 0.55, the rotor magnetic pole arc is 1 relatively, magnetic is thick relatively is 0.8, barrier component thickness is 2.5mm, and the space aperture is 0.8 degree.

For the effect of testing of electric motors and its fault freedom, test according to the electrode of foregoing preparation, and relatively in order to obtain 12 teeth groove that breakdown torque density is optimized, the PMSM of 14 pole pieces.

PMSM describes in Fig. 8 again.For example appreciable in Fig. 8, described magnet is arranged on the pole piece below.This is known in order to fault-tolerant structure, but needs are expensive and reservation that be difficult to produce is embedded with the maintenance magnet in position.

Fig. 9 is the contrast of prior art PMSM reaction electromotive force among FSPM of the present invention and Fig. 9 b among Fig. 9 a.

The reaction electromotive force of two kinds of motor generations is similar.FSPM has obviously higher maximum output.The output of two kinds of motors is all close to sinusoidal shape, and is suitable for the BLAC operation.

Figure 10 be FSPM(Figure 10 a) and PMSM(Figure 10 b) torque and the contrast of cogging torque.

Two kinds of motors all demonstrate low-down cogging torque, compare with FSPM, and PMSM has produced larger torque value, although PMSM only contains the copper-base sheet, and the mixture that FSPM contains between copper and the magnet obtains higher torque with prediction.

Figure 11 be FSPM(Figure 11 a) and PMSM(Figure 11 b) contrast of self-induction and coefficient of mutual inductance.

The good results are evident provides for the magnetic isolation that provides by ferromagnetic barrier component among the FSPM, and than the design of PMSM, the coefficient of mutual inductance of gained is very low, and in the design of PMSM, coefficient of mutual inductance probably is half of coefficient of self-inductance.

PMSM has shown almost negligible coefficient of mutual inductance, therefore provide extraordinary magnetic isolation alternate, two kinds of motors all have the high coefficient of self-inductance close to 1pu, and in the situation that short circuit, do not have a kind of motor meeting off-rating, therefore make it have fault-tolerant ability.

Two kinds of motors all can be used as two independently three-phase passage operations.Each passage provides an independently three phase converter.In the situation that detect a certain mistake that opens circuit mutually in the passage, whole passage is disconnected by its converter, remains healthy passage required torque will be provided.To be almost double to the high assessed value of healthy channel current.

Similarly, in the situation of the turn-to-turn short circuit that detects certain passage, the whole three-phase terminal of this passage will be short-circuited by its converter.This helps to reduce the false current of short circuit circle and make mistake " symmetry ".In this case, because the passage of short circuit, remaining healthy passage must be over-evaluated, and adds dynamic torque with torque before fault is provided.

When only a passage was in normal operation, in fact this passage acted on the linear machine that is equivalent to " end magnetic field effect ".This end effect can minimize, and reduces the mutual coupling between the adjacent two-phase.Thisly be coupling in two passages in conjunction with pointing out and occuring.

Figure 12 has shown FSPM(Figure 12 a) and PMSM(Figure 12 b) the torque contrast of the channel errors that opens circuit.

Torque waveform in passage situation that opens circuit is shown as a second harmonic low frequency pulsating.This pulsation stems from the above-mentioned end magnetic field effect at two passage binding site places.This low frequency pulsating is more remarkable in FSPM, but in the PMSM motor, almost can ignore, because alternate mutual coupling is very low in the single layer coil technology.

Figure 13 has shown FSPM(Figure 13 A) and PMSM(Figure 13 B) (the figure subscript a) and the electric current (figure subscript b) that produces for torque under passage short-circuit conditions.

Example as can be seen, the response of two kinds of motors is similar.For two kinds of motors, short circuit current is very approaching, but is lower than rated value (Figure 13 Ab and Figure 13 Bb).These electric currents are safe, and can not be motor overheating.Therefore, in the situation that short circuit, FSPM and PMSM all can avoid burn-down of electric motor.Especially, FSPM and PMSM all demonstrate almost stably electric current (Figure 13 Ab and Figure 13 Bb) and acceptable torque pulsation (Figure 13 Aa and Figure 13 Ba).

Described experimental data shows, provides barrier component 30 to mean magnetic isolation and allows FSPM to have fault-tolerant ability, and the Data Comparison of Fig. 9 to Figure 13 of FSPM shows, the isolating erroneous and performance of motor can be compared with known PMSM.

Figure 14 has shown the further embodiment according to the fault-tolerant FSPM of the preferred embodiment of the present invention, has as above the feature with reference to the described fault-tolerant FSPM of Fig. 2, but wherein, motor is a three phase electric machine, with 14 rotor tooths and 12 pole pieces.This motor is the expansion of foregoing principle of the present invention.

Figure 15 is the further embodiment of fault-tolerant FSPM 40, has a stator 42, " rotor " 44, magnet 46, isolated part 48 and pole piece 50.This embodiment is linear machine, and wherein, " rotor " 44 moves in the direction of arrow that accompanying drawing provides.Stator 42, rotor 44, magnet 46 and isolated part 48 functions as mentioned above, wherein, a series of isolated parts 48 are used for physical isolation and magnetic isolation pole piece 50.

For those skilled in the art, clearly, above-mentioned principle can be used to any flux switch motor, and with physics and electricity particle pole piece, by allowing the electric isolation of pole piece, this structure allows the high coefficient of self-inductance of pole piece and low coefficient of mutual inductance.

Therefore, should be understood that, isolated part 30 can be considered to pole piece 22 and other pole piece 22 are carried out isolation on physics and the electromagnetism simultaneously, therefore, in a single day make a mistake on the first pole piece 22, flux path 32 guarantees that described mistake is own substantially, therefore, on the almost not impact of other pole piece 22, guaranteed motor 10 in the situation that the short circuit generation can off-rating.

Claims (24)

1. stator that is used for flux switch permanent magnet motor, described stator contains a plurality of pole pieces, center on each pole piece coil is arranged, it is characterized in that, each pole piece and corresponding coil thereof are by an isolated part and other pole pieces and corresponding coil physical isolation thereof, than the coefficient of mutual inductance of bringing for other pole piece, for each pole piece brings higher coefficient of self-inductance.

2. stator according to claim 1 is characterized in that, the coefficient of mutual inductance of described pole piece is lower than 30% of coefficient of self-inductance.

3. stator according to claim 1 and 2 is characterized in that, described isolated part is fully with adjacent pole piece each other physics and electrical isolation.

4. the described stator of any one in 3 according to claim 1 is characterized in that, described isolated part is fully with adjacent pole piece each other physics and electromagnetic isolation.

5. the described stator of any one in 4 according to claim 1 is characterized in that not having physical connection between described pole piece and the isolated part.

6. stator according to claim 5 is provided with the space between isolated part and adjacent pole piece.

7. the described stator of any one in 6 according to claim 1 is characterized in that, described isolated part is ferromagnetism.

8. the described stator of any one in 7 according to claim 1 is characterized in that, described stator is annular.

9. stator according to claim 8 is characterized in that, the split ratio of described stator between 0.5 and 0.65 in the scope, more preferably 0.55.

10. according to claim 8 or 9 described stators, it is characterized in that, relatively the rotor magnetic pole arc in 0.9 and 1.2 radian scopes, 1 radian more preferably.

11. the described stator of any one in 10 is characterized in that according to claim 8, magnetic is thick between 0.6 and 1.25 in the scope relatively, more preferably 0.8.

12. the described stator of any one in 11 is characterized in that according to claim 8, the space aperture in 0.7 and 0.9 degree scope, 0.8 degree more preferably.

13. according to the described stator of above-mentioned any one claim, it is characterized in that, described stator is annular, has the axial length of the overall diameter of about 75mm, about 10mm and the isolated part thickness of about 2.5mm.

14. according to the described stator of above-mentioned any one claim, it is characterized in that, described stator is designed to linear machine.

15. a fault-tolerant magnetic flux switching permanent magnetism motor comprises according to claim 1 the stator of any one claim in 14.

16. a flux switch permanent magnet motor comprises turning son always; One stator, stator contain a plurality of pole pieces, center on coil on each pole piece; And the ferromagnetic isolation parts adjacent with each pole piece and corresponding coil thereof, it is characterized in that, described ferromagnetic isolation parts are used for each pole piece and other pole piece physical isolation, therefore, in situation that the coefficient of mutual inductance of bringing for other pole piece is compared, for each pole piece brings high coefficient of self-inductance.

17. motor according to claim 16 is characterized in that, described stator is annular.

18. according to claim 16 or 17 described motors, it is characterized in that, described rotor contains 7 teeth, and described stator contains 6 pole pieces.

19. according to claim 13 or 14 described motors, it is characterized in that, described rotor contains 14 teeth, and described stator contains 12 pole pieces.

20. the described motor of any one in 19 is characterized in that according to claim 16, described stator diameter is approximately 75mm, and isolated part thickness is approximately 2.5mm.

21. the described motor of any one in 20 is characterized in that according to claim 16, described stator is designed to linear machine.

22. the described motor of any one in 21 is characterized in that according to claim 16, described stator is for according to claim 1 to the described stator of 13 any one.

23. a linear machine is combined with the described stator of claim 1 to 13 any one.

24. a linear machine is combined with the described flux switch permanent magnet motor of any one in the claim 16 to 22.