Low copper loss fault-tolerant control strategy for five-phase permanent magnet synchronous motor with winding end short-circuit fault

Abstract

The invention discloses a low copper loss fault-tolerant control strategy for short-circuit fault at the end of the winding of a five-phase permanent magnet synchronous motor, which belongs to the field of motors. The invention solves the problem that the existing fault-tolerant strategy for controlling the motor at the end of the winding short-circuit fault will cause the motor to have a high copper loss in the fault-tolerant operation state. The fault-tolerant control strategy of the invention when the end short-circuit fault occurs in the A-phase winding is as follows: the fault-tolerant current passed through the remaining phases is adjusted to consist of two parts, each of which is a torque fluctuation suppression current, and the magnetomotive force synthesized by the four-phase torque fluctuation suppression current is used to eliminate the torque fluctuation term in the magnetomotive force generated by the short-circuit current of the fault phase, thereby suppressing the torque fluctuation caused by the short-circuit current of the fault phase, and the copper loss is low compared to the traditional method; the other part is a torque compensation current, and the magnetomotive force synthesized by the four-phase torque compensation current is used to be the same as the magnetomotive force synthesized by the five-phase current of the stator in the normal state of the motor, to ensure that the motor outputs the average torque in the normal operating state.

Description

Technical Field

[0001] The invention relates to a multi-phase permanent magnet synchronous motor winding fault tolerance control technology, belonging to the field of motors. Background Art

[0002] Compared with the traditional three-phase permanent magnet synchronous motor, the five-phase permanent magnet synchronous motor has phase redundancy characteristics. After one or more phases of the winding fail, the motor control strategy can be switched to achieve fault-tolerant operation under fault conditions. In order to improve the fault tolerance of the five-phase permanent magnet synchronous motor and the operating performance under fault tolerance, the motor is often driven by an open winding in conjunction with a full-bridge or five-phase six-bridge arm inverter, which guarantees the independent operation of each phase of the motor to the greatest extent. When one or some phases of the motor winding fail, the remaining phases will not be affected by the fault. The short-circuit fault at the end of the motor winding is usually caused by the short circuit of the inverter switch tube and the poor insulation of the motor winding coil. When a short-circuit fault occurs at the end of the winding, the average output torque of the motor decreases, and the rotating rotor permanent magnet magnetic field induces an uncontrollable short-circuit current in the faulty phase winding. The short-circuit current will cause a significant increase in the motor torque fluctuation, resulting in severe mechanical vibration of the system, and a decrease in output torque performance and operating stability.

[0003] In order to overcome the above problems, the prior art passes fault-tolerant current to the remaining phases when a short-circuit fault occurs in one phase. This operation mode will cause an increase in copper loss. In order to cope with the problem of increased copper loss, the prior art adopts a strategy when passing fault-tolerant current to the remaining phases based on the principle of constant synthetic magnetomotive force and the minimum copper loss constraint. Although the rotating magnetomotive force under normal operating conditions can be reconstructed, the copper loss is still relatively high and there is room for further reduction. Summary of the invention

[0004] In view of the problem that the existing fault-tolerant strategy for controlling the motor with a short-circuit fault at the end of the winding will result in high copper loss of the motor in the fault-tolerant operating state, the present invention provides a low copper loss fault-tolerant control strategy for a short-circuit fault at the end of the winding of a five-phase permanent magnet synchronous motor.

[0005] The low copper loss fault-tolerant control strategy for the short-circuit fault at the end of the winding of the five-phase permanent magnet synchronous motor described in the present invention is as follows:

[0006] Adjust the B, C, D, E phase winding current according to:

[0007]

[0008]

[0009]

[0010]

[0011]

[0012] The system works to suppress the decrease of average output torque and increase of torque fluctuation caused by short circuit fault at the end of phase A winding, and reduces the copper loss of winding under fault-tolerant control state.

[0013] In the formula, I m is the amplitude of the current in the B, C, D, and E phase windings under normal conditions, ω e is the electrical angular velocity of the motor; I A " is the steady-state short-circuit current amplitude of the A-phase winding after an end short-circuit fault occurs.

[0014] Preferably, the steady-state short-circuit current amplitude I of the A-phase winding after an end short-circuit fault occurs is A "according to

[0015] Get,

[0016] Where N is the number of series turns of the A-phase winding, ξ w4 is the fundamental winding factor, Φ PM is the permanent magnetic flux linked with the A-phase winding, R A is the A phase winding resistance, L AA is the self-inductance of phase A winding.

[0017] Preferably, the interphase mutual inductance value of the five-phase permanent magnet synchronous motor winding is not higher than 4% of the self-inductance, wherein the interphase mutual inductance value of the A-phase winding and other windings should satisfy the following formula:

[0018]

[0019] Where: M AB is the mutual inductance between phase A and phase B windings, M AC is the mutual inductance between phase A and phase C windings, M AD is the mutual inductance between phase A and phase D windings, M AE is the mutual inductance between phase A and phase E windings, L AA is the self-inductance of phase A winding.

[0020] Preferably, the no-load back-EMF harmonic distortion rate THD of the five-phase permanent magnet synchronous motor is emf Less than 15%, no-load back EMF harmonic distortion rate THD emf Press the formula to obtain:

[0021]

[0022] Where: E1 is the no-load back EMF fundamental amplitude, E i is the amplitude of the i-th harmonic of the no-load back EMF, and i is the harmonic order of the no-load back EMF.

[0023] Preferably, when the motor is in normal operation, that is, when there is no short-circuit fault at the winding end, the currents of the motor A, B, C, D, and E phase windings are:

[0024] i A =I m cos(ω e t)

[0025]

[0026]

[0027]

[0028]

[0029] Where: i A ,i B ,i C ,i D ,i E are the motor A, B, C, D, and E phase winding currents under normal operating conditions, I m It is the amplitude of the current in the B, C, D, and E phase windings under normal conditions.

[0030] Preferably, the rotor of the five-phase permanent magnet synchronous motor adopts surface-mounted permanent magnets. Specific types of surface-mounted permanent magnets that can be adopted include: tile-shaped permanent magnets, sinusoidal permanent magnets, eccentric permanent magnets or Halbach array permanent magnets.

[0031] Preferably, a five-phase full-bridge or five-phase six-bridge-arm inverter is used to power the five-phase permanent magnet synchronous motor.

[0032] The beneficial effects of the invention are as follows: the invention discloses a low copper loss fault-tolerant control strategy for a short-circuit fault at the end of a winding of a five-phase permanent magnet synchronous motor. When the strategy is applied for fault-tolerant control, the five-phase permanent magnet synchronous motor is required to meet the following two conditions: first, the mutual inductance between the motor phases is not higher than 4% of the self-inductance, and there is almost no magnetic coupling between the phases. When a short-circuit fault occurs at the end of a single-phase winding of the motor, the currents of the faulty phase and the remaining normal phase windings will not affect each other; second, the harmonic distortion rate of the motor back-electromotive force is lower than 15%, and the sinusoidality of the motor no-load back-electromotive force waveform is relatively high. When a short-circuit fault occurs at the end of a single-phase winding of the motor, the no-load back-electromotive force waveform of the motor is close to a sine, and the current waveform of the faulty phase is also close to a sine.

[0033] The adoption of the strategy of the present invention can not only effectively reduce the torque fluctuation caused by the short-circuit fault at the end of one-phase winding of a five-phase permanent magnet synchronous motor, improve the average output torque of the motor under the fault-tolerant state, but also reduce the winding copper loss under the fault-tolerant operating state. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 This is a diagram of the winding spatial arrangement of a five-phase permanent magnet synchronous motor;

[0035] Figure 2 It is a schematic diagram of the five-phase full-bridge inverter topology;

[0036] Figure 3 It is a schematic diagram of the topology of a five-phase six-bridge-arm inverter;

[0037] Figure 4 This is the waveform diagram of the self-inductance and mutual inductance of each phase of a five-phase permanent magnet synchronous motor using a 10-slot, 8-pole single-layer fractional-slot concentrated winding (taking phase A as an example); Figure 4 (a) is the waveform of AB mutual inductance and A phase self-inductance. Figure 4 (b) is the waveform of AC mutual inductance and phase A self-inductance. Figure 4 (c) is the waveform of AD mutual inductance and A phase self-inductance. Figure 4 (d) is the waveform of AE mutual inductance and A phase self-inductance;

[0038] Figure 5 This is the no-load back EMF waveform and harmonic analysis of a 10-slot, 8-pole, single-layer, fractional-slot concentrated winding five-phase motor with a Halbach permanent magnet array rotor (taking phase A as an example); Figure 5 (a) is the no-load back EMF waveform, Figure 5 (b) is the harmonic waveform;

[0039] Figure 6 It is the short-circuit current waveform in the A-phase winding after the end short-circuit fault occurs in the A-phase winding;

[0040] Figure 7 This is the current waveform of the remaining B, C, D, and E phase windings when the proposed low copper loss fault-tolerant control strategy is applied after the end short circuit fault occurs in the A phase winding;

[0041] Figure 8 It is the current waveform of the remaining B, C, D, and E phase windings when the existing low copper loss fault-tolerant control strategy is applied after the end short circuit fault occurs in the A phase winding;

[0042] Fig. 9 It is a torque waveform comparison diagram when the motor is in normal operating state, in an uncontrolled state of short-circuit fault at the end of the A-phase winding, and in a fault-tolerant control state of short-circuit fault at the end of the A-phase winding using the low copper loss fault-tolerant control strategy proposed by the present invention and the existing one. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] It should be noted that, in the absence of conflict, the embodiments of the present invention and the features in the embodiments may be combined with each other.

[0045] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but they are not intended to limit the present invention.

[0046] Specific implementation method 1: The following is combined Figures 1 to 3 The present embodiment is described. The low copper loss fault-tolerant control strategy for the short-circuit fault at the end of the winding of the five-phase permanent magnet synchronous motor described in the present embodiment is that the five-phase permanent magnet synchronous motor adopts an open winding form, and the spatial arrangement of each phase winding is as follows: Figure 1 As shown, using Figure 2 The five-phase full-bridge inverter shown in Figure 3 The five-phase six-leg inverter topology shown drives a five-phase motor and supplies power to each phase winding independently. When the motor is in normal operation, that is, when there is no short-circuit fault at the end of one phase winding, the current of each phase is:

[0047] i A =I m cos(ω e t)

[0048]

[0049]

[0050]

[0051]

[0052] Among them, i A ,i B ,i C ,i D ,i E They are the winding currents of phases A, B, C, D, and E under normal operation, and the current amplitudes of each phase are equal, all of which are I m ,ω e is the electrical angular velocity of the motor.

[0053] At this time, the magnetomotive force F of the five-phase current of the motor stator under normal condition is nor for:

[0054]

[0055] Among them, b4 is the synthetic magnetomotive force coefficient, and θ is the spatial position angle. It can be seen from the above formula that the synthetic magnetomotive force of the five-phase motor under normal operating conditions can be equivalent to the spatial rotating phase.

[0056] When the mutual inductance between phases of a five-phase permanent magnet synchronous motor is small, that is, the mutual inductance between phases is not higher than 4% of the self-inductance, there is almost no magnetic coupling between the motor phases. Therefore, when a short circuit fault occurs at the end of one phase winding of the motor, the current of the faulty phase and the remaining normal phase winding will not affect each other. In addition, if the sinusoidality of the motor no-load back-EMF waveform is high, that is, the back-EMF harmonic distortion rate THD emf When the motor has a short circuit fault at the end of one phase winding, the waveform of the motor's no-load back-EMF is close to a sine wave, and the waveform of the fault phase current is also close to a sine wave.

[0057] Taking the end short circuit fault of phase A as an example (the processing method of other phases is the same as that of phase A), the steady-state short-circuit current i of the fault phase is given as A "'s expression:

[0058]

[0059] Where N is the number of series turns of the A-phase winding, ξ w4 is the fundamental winding factor, Φ PM is the permanent magnetic flux linked with the A-phase winding, R A is the A phase winding resistance, L AA is the inductance of the A-phase winding, θ0 is the angle between the permanent magnet rotor d-axis and the A-phase winding axis when a short circuit fault occurs, so I A "according to Get.

[0060] When the motor is in the uncontrolled state of short circuit fault at the end of phase A winding, the synthetic magnetomotive force F fau for:

[0061]

[0062] where cos(ω e t-4θ) term and sin(ω e t-4θ) term has the same direction of rotation of the magnetomotive force space. fau With F nor By comparison, cos(ω e The magnetomotive force corresponding to the term t-4θ) is proportional to the average output torque of the motor, while sin(ω e The magnetomotive force corresponding to the term t-4θ) will neither produce an average torque nor torque fluctuations. Similarly, cos(ω e t+4θ) term and sin(ω et+4θ) term has the same direction of rotation of the magnetomotive force space, but cos(ω e t+4θ) term, sin(ω e t+4θ) term corresponds to the spatial rotation direction of the magnetomotive force and cos(ω e t-4θ) term, sin(ω e t-4θ) term corresponds to the opposite direction of the magnetomotive force space rotation, so cos(ω e t+4θ) term and sin(ω e t+4θ) term not only cannot generate output torque, but also causes torque fluctuation. e t+4θ) term and sin(ω e t+4θ) term, we can see that cos(ω e The coefficient of the term t+4θ is (-b4I m / 2), sin(ω e The coefficient of the term t+4θ is (-b4I A Therefore, when a short-circuit fault occurs at the end of one phase winding of the motor, the increase in the torque fluctuation of the motor is caused by the short-circuit phase fault current on the one hand, and on the other hand, it is caused by the inability of the remaining normal phase winding current to synthesize a circular rotating magnetomotive force after a one-phase winding of the motor fails.

[0063] In order to perform fault-tolerant control on the short-circuit fault at the end of the motor winding, when the end short-circuit fault occurs in the A-phase winding of the motor, the compensation current corresponding to the proposed low copper loss fault-tolerant control strategy is introduced into the remaining B, C, D, and E-phase windings, which are i B ',i C ',i D 'and i E ':

[0064]

[0065] It can be seen from the above formula that the fault tolerance current of each phase winding consists of two parts, namely, the fault tolerance current of phase B winding i B 'Include i B_I 'and i B_II ', C phase winding fault tolerance current i C 'Include i C_I 'and i C_II ', D phase winding fault tolerance current i D 'Include i D_I 'and i D_II ', E phase winding fault tolerance current i E 'Include i E_I 'and i E_II '.

[0066] Given iB_I ',i C_I ',i D_I ',i E_I 'As shown below:

[0067]

[0068]

[0069] Derivation B_I ',i C_I ',i D_I ',i E_I The synthetic magnetomotive force F ftc_I As shown below:

[0070]

[0071] When a short circuit fault occurs at the end of the winding of phase A, the magnetomotive force F generated by the short circuit current of the fault phase A "for:

[0072]

[0073] Contrast F A " and F ftc_I It can be seen that F ftc_I sin(ω e t+4θ) term and F A "sin(ω e t+4θ) term coefficients is zero, and the two can cancel each other out, that is, F ftc_I Can eliminate F A "The sin(ω) that causes torque fluctuation e t+4θ) term, thereby suppressing the torque fluctuation caused by the short-circuit current of the fault phase, so i B_I ',i C_I ',i D_I ',i E_I ' is the torque fluctuation suppression current, and the first part of the torque fluctuation suppression current i B_I ',i C_I ',i D_I ',i E_I The existence of ' can reduce copper consumption. The copper consumption of the strategy of the present invention will be analyzed later compared with the prior art.

[0074] Given i B_II ',i C_II ',i D_II ',i E_II 'As shown below:

[0075]

[0076] Derivation of B, C, D, E phase torque compensation current i B_II ',i C_II ',i D_II ',i E_II The synthetic magnetomotive force F ftc_II As shown below:

[0077]

[0078] Contrast F ftc_II and F nor It can be seen that F ftc_II With F nor The same, that is, i B_II ',i C_II ',i D_II ',i E_II 'It can synthesize the magnetic motive force under normal operating conditions, thereby ensuring the average torque of the motor under normal operating conditions. Therefore, i B_II ',i C_II ',i D_II ',i E_II ' is the torque compensation current.

[0079] F A ", F ftc_I and F ftc_II By superposition, the synthetic magnetomotive force F of the stator five-phase current can be obtained when the motor A phase winding has an end short circuit fault and the proposed low copper loss fault-tolerant control strategy is applied. ftc , as shown below:

[0080]

[0081] Contrast F ftc and F nor It can be seen that after applying the low copper loss fault-tolerant control strategy for the short-circuit fault at the end of the five-phase permanent magnet synchronous motor winding, the motor can synthesize the rotating magnetic motive force under normal operation, that is, cos(ω e t-4θ) term. In the above formula, sin(ω e t-4θ) term space rotation direction and cos(ω e t-4θ) item is the same, which will not cause the motor torque fluctuation to increase in the fault tolerance state. ftc does not contain cos(ω e t-4θ) term has the opposite direction of spatial rotation, that is, it does not contain cos(ω e t+4θ) term and sin(ω e t+4θ), so the proposed low copper loss fault-tolerant control strategy can suppress the torque fluctuation caused by the short-circuit fault at the motor winding end.

[0082] In summary, the B, C, D, and E phase winding currents i corresponding to the proposed low copper loss fault-tolerant control strategy are B ',i C ',i D 'and i E 'for:

[0083]

[0084]

[0085]

[0086]

[0087]

[0088] The copper loss advantage of the strategy of the present invention compared with the prior art is analyzed below.

[0089] The existing low copper loss fault-tolerant control strategy for short-circuit fault at the end of the winding of a five-phase permanent magnet synchronous motor is given. This strategy is derived based on the principle of constant synthetic magnetomotive force and the minimum copper loss constraint. According to the existing low copper loss fault-tolerant control strategy, when a short-circuit fault occurs at the end of the A-phase winding, the fault-tolerant current flowing through the remaining B, C, D, and E-phase windings is:

[0090]

[0091]

[0092]

[0093]

[0094] In the formula, i B_cm ',i C_cm ',i D_cm ',i E_cm ' are the B, C, D, and E phase winding currents corresponding to the existing low copper loss fault-tolerant control strategy.

[0095] After applying the existing low copper loss fault-tolerant control strategy, the synthetic magnetic motive force F of the five-phase current of the motor stator is ftc_cm for:

[0096]

[0097] Contrast F ftc_cm With F norIt can be seen that after applying the existing low copper loss fault-tolerant control strategy, the motor can reconstruct the rotating magnetic motive force under normal operating conditions, suppress the torque fluctuation caused by the short-circuit fault at the end of the motor winding, and improve the output torque of the motor under fault-tolerant conditions.

[0098] The copper consumption of the existing strategy and the strategy of the present invention is further compared:

[0099] The copper loss Copper_loss' generated when the five-phase permanent magnet synchronous motor is operated according to the strategy of the present invention is as follows:

[0100]

[0101] Copper loss generated when a five-phase permanent magnet synchronous motor is operated according to the existing strategy _cm As shown below:

[0102]

[0103] Comparison of Copper_loss' and Copper_loss _cm It can be seen that Copper_loss _cm Greater than Copper_loss', Copper_loss _cm Higher than Copper_loss' (0.2847R A I A "2 / 2), it is proved that the proposed low copper loss fault-tolerant control strategy has lower copper loss than the existing low copper loss fault-tolerant control strategy, and the proposed fault-tolerant control strategy has the advantage of low copper loss.

[0104] Specific implementation method 2: The following is combined Figures 1 to 9 A specific example is given to illustrate this implementation mode. In this implementation mode, the low copper loss fault-tolerant control strategy for the short-circuit fault at the end of the winding of the five-phase permanent magnet synchronous motor is described. The five-phase permanent magnet synchronous motor adopts an open winding form, and the spatial arrangement of each phase winding is as follows: Figure 1 As shown, using Figure 2 The five-phase full-bridge inverter shown in Figure 3 The five-phase six-leg inverter topology shown drives a five-phase motor and supplies power to each phase winding independently. When the motor is in normal operation, that is, when there is no short-circuit fault at the end of one phase winding, the current of each phase is:

[0105] i A =60cos(ω e t)

[0106]

[0107]

[0108]

[0109]

[0110] Among them, i A ,i B ,i C ,i D ,i E They are the A, B, C, D, and E phase winding currents under normal operation. The current amplitudes of each phase are equal, all 60A, that is, I m =60A.

[0111] Since the five-phase permanent magnet synchronous motor adopts 10-slot 8-pole single-layer fractional slot concentrated winding, the mutual inductance between the motor phases is very small compared with the self-inductance. Figure 4 As shown, taking the A-phase winding as an example, the self-inductance, mutual inductance and the ratio of mutual inductance to self-inductance of the A-phase winding are shown in Table 1:

[0112] Table 1

[0113] <![CDATA[L AA ]]> <![CDATA[M AB ]]> <![CDATA[M AC ]]> <![CDATA[M AD ]]> <![CDATA[M AE ]]> 913.91uH 16.89uH 5.71uH 5.71uH 16.90uH <![CDATA[M AB / L AA ]]> <![CDATA[M AC / L AA ]]> <![CDATA[M AD / L AA ]]> <![CDATA[M AE / L AA ]]> - 1.85％ 0.62％ 0.62％ 1.85％ -

[0114] In the above table, L AA is the self-inductance of phase A winding, M AB is the mutual inductance between phase A winding and phase B winding, M AC is the mutual inductance between the A-phase winding and the C-phase winding, M AD is the mutual inductance between the A-phase winding and the D-phase winding, M AE is the mutual inductance between the A-phase winding and the E-phase winding.

[0115] The smaller mutual inductance indicates that there is almost no magnetic coupling between the motor phases. Therefore, when a short-circuit fault occurs at the end of one phase winding of the motor, the currents of the faulty phase and the remaining normal phase windings will not affect each other.

[0116] In addition, the motor rotor adopts Halbach permanent magnet array, and the motor no-load back EMF waveform has a high sinusoidal degree, such as Figure 5 As shown in the figure, it can be seen from the harmonic analysis of the back EMF that the back EMF contains only a small amount of 7th and 13th harmonics, and the no-load back EMF harmonic distortion rate THD emf =6.35%. Since the no-load back EMF waveform of the motor is close to sine, when a short circuit fault occurs at the end of one phase winding of the motor, the waveform of the current in the fault phase is also close to sine. Taking the end short circuit fault of the A phase winding as an example, the waveform of the steady-state short circuit current of the fault phase is given as follows: Figure 6 As shown, the expression of short-circuit current of phase A winding is: A ″=-60.66sin(ω e t)

[0117] Among them, iA " is the short-circuit current of phase A winding after an end short-circuit fault occurs. The short-circuit current amplitude is 60.66A, that is, I A =60.66A.

[0118] When a short circuit occurs at the end of the motor A phase winding, I m =60A, I A "=60.66A Substitute into the proposed low copper loss fault-tolerant control strategy B, C, D, E phase winding current i B ',i C ',i D 'and i E ' in the expression:

[0119]

[0120]

[0121]

[0122]

[0123]

[0124] Calculated:

[0125]

[0126] The B, C, D, and E phase winding current waveforms corresponding to the proposed low copper loss fault-tolerant control strategy are shown in Figure 2. Figure 7 shown.

[0127] Similarly, I m =60A, I A "=60.66A Substitute into the existing low copper loss fault-tolerant control strategy B, C, D, E phase winding current i B_cm ',i C_cm ',i D_cm ',i E_cm ' in the expression:

[0128]

[0129]

[0130]

[0131]

[0132] Calculated:

[0133]

[0134] The B, C, D, and E phase winding current waveforms corresponding to the existing low copper loss fault-tolerant control strategy are as follows: Figure 8 shown.

[0135] The torque waveforms of the motor under normal operation, uncontrolled short-circuit fault at the end of the A-phase winding, and fault-tolerant control of the short-circuit fault at the end of the A-phase winding using the proposed and existing low copper loss fault-tolerant control strategies are shown in the figure below. Fig. 9 As shown in Table 2, combined with the specific values ​​in Table 2, it can be seen that the proposed and existing low copper loss fault-tolerant control strategies can effectively reduce the torque fluctuation caused by the short-circuit fault at the end of the motor winding and improve the output torque of the motor in the fault-tolerant state. Further comparison of the motor copper loss corresponding to the proposed and existing low copper loss fault-tolerant control strategies shows that the copper loss of the proposed fault-tolerant control strategy is 723.52W, which is lower than the copper loss of the existing low copper loss fault-tolerant control strategy (749.64W), proving that the proposed five-phase permanent magnet synchronous motor winding end short-circuit fault-tolerant control strategy has the advantage of low copper loss.

[0136] Table 2

[0137]

[0138] Although the present invention is described herein with reference to specific embodiments, it should be understood that these embodiments are merely examples of the principles and applications of the present invention. It should therefore be understood that many modifications may be made to the exemplary embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that the various dependent claims and features described herein may be combined in a manner different from that described in the original claims. It should also be understood that the features described in conjunction with a single embodiment may be used in other described embodiments.

Claims

1. A low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor with a short-circuit fault at the winding end, characterized in that: The fault-tolerant control strategy of the five-phase permanent magnet synchronous motor when the A-phase winding has an end short-circuit fault is as follows: Adjust the B, C, D, E phase winding current according to: The system works to suppress the decrease of average output torque and increase of torque fluctuation caused by short circuit fault at the end of phase A winding, and reduces the copper loss of winding under fault-tolerant control state. In the formula, I m is the amplitude of the current in the B, C, D, and E phase windings under normal conditions, ω e is the electrical angular velocity of the motor; I A " is the steady-state short-circuit current amplitude of the A-phase winding after an end short-circuit fault occurs.

2. The low copper loss fault-tolerant control strategy for the short-circuit fault at the end of the winding of the five-phase permanent magnet synchronous motor according to claim 1 is characterized in that: The steady-state short-circuit current amplitude I of the A-phase winding after an end short-circuit fault occurs A "according to Get, Where N is the number of series turns of the A-phase winding, ξ w4 is the fundamental winding factor, Φ PM is the permanent magnetic flux linked with the A-phase winding, R A is the A phase winding resistance, L AA is the self-inductance of phase A winding.

3. The low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor winding end short-circuit fault according to claim 1 or 2, characterized in that: The phase-to-phase mutual inductance of the five-phase permanent magnet synchronous motor winding is less than 4% of the self-inductance, where the phase-to-phase mutual inductance of the A-phase winding and other windings should satisfy the following formula: Where: M AB is the mutual inductance between phase A and phase B windings, M AC is the mutual inductance between phase A and phase C windings, M AD is the mutual inductance between phase A and phase D windings, M AE is the mutual inductance between phase A and phase E windings, L AA is the self-inductance of phase A winding.

4. The low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor winding end short-circuit fault according to claim 3 is characterized in that: No-load back-EMF harmonic distortion THD of five-phase permanent magnet synchronous motor emf Less than 15%, no-load back EMF harmonic distortion rate THD emf Get it by pressing: Where: E1 is the no-load back EMF fundamental amplitude, E i is the amplitude of the i-th harmonic of the no-load back EMF, and i is the harmonic order of the no-load back EMF.

5. The low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor winding end short-circuit fault according to claim 1 is characterized in that: When the motor is in normal operation, that is, when there is no short-circuit fault at the winding end, the currents of the motor A, B, C, D, and E phase windings are: i A =I m cos(ω e t) Where: i A ,i B ,i C ,i D ,i E are the motor A, B, C, D, and E phase winding currents under normal operating conditions, I m It is the amplitude of the current in the B, C, D, and E phase windings under normal conditions.

6. The low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor winding end short-circuit fault according to claim 1 is characterized in that: The rotor of the five-phase permanent magnet synchronous motor uses surface-mounted permanent magnets.

7. The low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor winding end short-circuit fault according to claim 6 is characterized in that: The types of surface mounted permanent magnets include: tile-shaped permanent magnets, sinusoidal permanent magnets, eccentric permanent magnets or Halbach array permanent magnets.

8. The low copper loss fault-tolerant control strategy for a five-phase permanent magnet synchronous motor winding end short-circuit fault according to claim 1, characterized in that: A five-phase full-bridge or five-phase six-bridge-arm inverter is used to power the five-phase permanent magnet synchronous motor.

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