Minimum copper loss fault-tolerant control method for multi-mode double-five-phase permanent magnet synchronous motor under two-phase open-circuit fault

Abstract

The invention discloses a minimum copper loss fault-tolerant control method for a multi-mode double-five-phase permanent magnet synchronous motor under a two-phase open-circuit fault, and the method comprises the steps: building a mathematical model of the multi-mode double-five-phase permanent magnet synchronous motor under the two-phase open-circuit fault, and dividing four working modes according to different current injection modes of an inner stator winding and an outer stator winding; deducing reduced order decoupling matrixes of adjacent two-phase open-circuit faults and non-adjacent two-phase open-circuit faults respectively, and deducing fault-tolerant current expressions under two fault types based on the matrixes; defining current distribution coefficients of the outer stator and the inner stator, and constructing a Lagrange equation based on a minimum copper consumption principle so as to determine values of the current distribution coefficients; and the optimal operation mode is selected according to the copper loss of each mode under different torques. According to the invention, fault-tolerant control under the two-phase open-circuit fault of the multi-mode double five-phase permanent magnet synchronous motor is realized, the copper loss after fault tolerance of the motor is effectively reduced, and the safety and stability of a control system after the fault of the motor are improved.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of open-circuit fault tolerant control of multiphase motor, and particularly relates to a minimum copper loss fault-tolerant control method of a multi-mode dual five-phase permanent magnet synchronous motor under two-phase open-circuit fault. It is suitable for occasions with high requirements for motor reliability and continuity in aerospace, electric vehicles and the like. BACKGROUND

[0002] The multiphase permanent magnet synchronous motor has advantages of high power density, high efficiency and high reliability, and has a very broad application prospect in the fields of new energy vehicles, aerospace and the like. In particular, the multiphase motor improves the redundancy of the system due to the increase in the number of phases, and can realize undisturbed operation after fault by using a fault-tolerant control algorithm without changing the hardware structure. The short-circuit and open-circuit faults of the motor winding are common faults of the motor drive system, but since the short-circuit fault can be converted into an open-circuit fault for processing, the fault-tolerant control for the open-circuit fault of the multiphase motor has become a research hotspot at home and abroad.

[0003] When a single-phase or multi-phase open-circuit fault occurs in the multiphase motor, the rotating magnetic motive force will be distorted, resulting in an increase in torque ripple. In order to ensure the safe operation of the motor, according to the principle of constant magnetic motive force, a constant circular rotating magnetic field can be obtained by adjusting the amplitude and phase of the remaining phase current. With the increase in the number of phases, the influence of the open-circuit fault will be relatively weakened, but different fault-tolerant control methods need to be proposed based on the structural characteristics of the motor in order to maximize the advantages of the motor.

[0004] At present, the research on the open-circuit fault-tolerant control method of the multiphase permanent magnet synchronous motor mainly focuses on how to suppress the torque ripple and calculate the optimal fault current. However, the above control algorithm cannot be well applied to the multi-mode dual five-phase permanent magnet synchronous motor, and the advantages of the multi-operation mode of the motor cannot be brought into play. At present, there is little research on the dual-phase open-circuit fault-tolerant control of the motor, and there is no corresponding fault-tolerant control strategy considering the minimum copper loss as an optimization principle to improve the algorithm. Based on the above consideration, the present application is a minimum copper loss fault-tolerant control method of a multi-mode dual five-phase permanent magnet synchronous motor under two-phase open-circuit fault. According to the characteristics of the multi-mode operation of the dual-stator motor, the Lagrange equation is constructed based on the minimum copper loss principle in different modes, and the optimal distribution coefficient of the inner and outer stators is obtained. At the same time, according to the copper loss discriminant, the mode is selected. Compared with the traditional fault-tolerant control, the copper loss is effectively reduced, and high-performance fault-tolerant control in the full torque range is realized. SUMMARY

[0005] The present application aims to solve the problem of fault-tolerant control of the existing multi-mode dual five-phase permanent magnet synchronous motor under two-phase open circuit fault. According to the characteristics of multi-mode operation of the dual stator motor, the optimal distribution coefficients of the inner and outer stators are obtained based on the principle of minimum copper loss by constructing the Lagrange equation in different modes. At the same time, according to the copper loss discriminant, the mode selection is carried out, which effectively reduces the copper loss compared with the traditional fault-tolerant control, and realizes high-performance fault-tolerant control in the full torque range.

[0006] To achieve the technical purpose, the present application adopts the following technical solutions:

[0007] A minimum copper loss fault-tolerant control method of a multi-mode dual five-phase permanent magnet synchronous motor under two-phase open circuit fault, comprising the following steps:

[0008] Step 1, establishing a two-phase open circuit fault model of a multi-mode dual five-phase permanent magnet synchronous motor;

[0009] Step 2, removing the elements corresponding to the fault phase in the transformation matrix, constructing an orthogonal reduced-order decoupling matrix, and deducing the fault-tolerant current expressions of adjacent two-phase and non-adjacent two-phase open circuit faults based on the principle of constant magnetic motive force;

[0010] Step 3, obtaining the torque formula of the multi-mode dual five-phase motor by normal five-phase coordinate transformation combined with the reduced-order decoupling transformation matrix in step 2;

[0011] Step 4, according to the torque equation obtained in step 3, setting up two modes of motor fault-tolerant operation, mode one injecting q-axis current i qi into the inner stator winding, and mode two injecting d-axis current i di into the inner stator winding, and simultaneously deducing the copper loss calculation formula under the two modes according to the current injection mode of the inner and outer stator windings in the two modes;

[0012] Step 5, setting the distribution coefficients X and Y of the d-q axis currents of the inner and outer stator windings, constructing the Lagrange equation by the torque formula obtained in step 3 and the copper loss calculation formula obtained in step 4, and deducing the fault-tolerant current reference value under the two modes based on the principle of minimum copper loss, so as to determine the values of X and Y;

[0013] Step 6, comparing the copper losses of mode one and mode two in the full torque range to determine the selection of mode one and mode two for fault-tolerant control; the specific method includes offline calculation and table selection, and online comparison of copper loss size to select the working mode;

[0014] Step 7, detecting the speed of the multi-mode dual five-phase permanent magnet synchronous motor as the speed feedback n of the motor, comparing the given speed n* with the feedback speed n to obtain the speed error e r of the motor, and adopting a PI controller to control the speed error e rThe q-axis current of the multi-mode dual five-phase permanent magnet synchronous motor is calculated, and the output of the PI controller is the given q-axis current i q1 ;

[0015] In step 8, the total current i q1 obtained in step 7 is input into the current distribution calculation module. First, the working mode is determined according to step 6, and then the current size input into the outer stator and the inner stator is determined according to X and Y obtained in step 5, respectively;

[0016] In step 9, the feedback current components i d / q1o_back , i d / q3o_back , i d / q1i_back , i d / q3i_back obtained by the current sensor are compared with the given current components i d / qo1 , i d / q3o , i d / qi1 , i d / q3i obtained in step 8, and the error is input into the PI controller to obtain the given voltage signal in the synchronous rotating coordinate system;

[0017] In step 10, the given voltage signal in the synchronous rotating orthogonal coordinate system is input into the carrier-based pulse width modulation (CPWM) module after coordinate transformation to obtain the switching signal of each phase. Then the obtained switching signal is input into the inverter to control the motor, realizing the two-phase open-circuit fault-tolerant control of the multi-mode dual five-phase permanent magnet synchronous motor.

[0018] Further, the d-q axis flux linkage and voltage model in the two-phase open-circuit fault state in step 1 are as follows:

[0019]

[0020] Where ψ do / qo , ψ di / qi represent the d-q axis flux linkage of the outer stator winding and the inner stator winding, respectively; L do / qo and L di / qi represent the d-q axis self-inductance of the outer stator winding and the inner stator winding, respectively, and L do =L qo , L di =L qi ; i do / qo , i di / qi represent the d-q axis current of the outer stator winding and the inner stator winding, respectively; ψ fo is the flux linkage of the outer stator permanent magnet; ψ fi is the flux linkage of the inner stator permanent magnet, and M d / q is the mutual inductance between the inner and outer stators; K fis the excitation coefficient, which is used to represent the influence ability of the excitation winding to the external air-gap flux linkage;

[0021]

[0022] wherein u do / qo , u di / qi represent the dq-axis voltages of the outer stator winding and the inner stator winding respectively; R o / i are the phase resistances of the outer stator and the inner stator respectively; ω e is the electrical angular velocity of the motor.

[0023] Further, the specific process of the step 2 is as follows:

[0024] Suppose that open-circuit faults occur in the B and E phases, the elements related to the fault phases are removed, an orthogonal matrix is constructed, and a reduced-order decoupling Clarke transformation matrix is obtained as follows:

[0025]

[0026] wherein T Clarke BE is the reduced-order Clarke matrix under the open-circuit of the B and E phases, and δ=2π / 5 is the included angle between the adjacent two phases of the motor;

[0027] When open-circuit faults occur in the C and D phase windings, the elements related to the fault phases are removed, and a reduced-order decoupling Clarke transformation matrix obtained is as follows:

[0028]

[0029] wherein T Clarke CD is the reduced-order Clarke matrix under the open-circuit of the C and D phases;

[0030] The Park transformation matrices under the two fault types are as follows:

[0031]

[0032] wherein T Park 2 is the reduced-order Park matrix under the double-phase open-circuit fault, and θ e is the electrical angle;

[0033] The fault-tolerant current expression after the open-circuit of the B and E phases is derived as follows:

[0034]

[0035] wherein i A , i C , i D represent the five-phase currents of the outer stator of the motor respectively; I mis the fundamental current effective value;

[0036] The fault-tolerant current expression of C, D phase open circuit is derived as:

[0037]

[0038] where, i A , i B , i E respectively represent five-phase currents of the motor outer stator; I m is the fundamental current effective value;

[0039] 4. The method of claim 1, wherein the step 3 is specifically:

[0040] According to the magnetic co-energy method, the formula for solving the motor electromagnetic torque T e is:

[0041]

[0042] where, W co is the magnetic co-energy of the motor; θ m is the mechanical angle of the motor; I so , I si are the phase current vectors of the motor outer stator winding and inner stator winding respectively; L so , L si are the inductance matrices of the motor outer stator winding and inner stator winding respectively; P o , P i are the pole pairs of the motor outer stator and inner stator winding; θ e is the electrical angle; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage;

[0043] The torque formula is obtained as:

[0044]

[0045] where, M d / q is the mutual inductance of the inner and outer stators; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage;

[0046] Since both sets of windings are star-connected, and the inner and outer stators are partitioned and isolated, the coupling degree of the two in the magnetic circuit is low, and the mutual inductance is very small, so M d / q is approximately 0; the torque formula is simplified as:

[0047]

[0048] Further, the step 4 specific process is:

[0049] Step 4.1: From the torque formula of step 3, when the main drive outer stator winding occurs open circuit fault, the auxiliary drive inner stator winding is used to compensate torque, when the inner stator injects i qi For mode 1, the corresponding torque formula at this time is:

[0050]

[0051] When the inner stator winding injects i di For mode 2, the torque formula at this time is:

[0052]

[0053] Where, K f is the defined magnetic modulation coefficient, which represents the strength of the inner stator adjustment ability to the outer air gap magnetic field; P o , P i is the pole pair number of the motor outer stator and inner stator winding; i do / qo , i di / qi represent the outer stator winding, inner stator winding d-q axis current respectively; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage;

[0054] Step 4.2: The copper loss formula of the motor can be expressed as:

[0055] P Cu = R o (i A 2 +i B 2 +i C 2 +i D 2 +i E 2 )+ R i (i a 2 +i b 2 +i c 2 +i d 2 +i e 2 )

[0056] Where, P cu represents the motor copper loss; i A , i B , i C , i D , iE i1, i2, i3, i4, i5represent five-phase currents of the outer stator of the motor; i a b c d e i1, i2, i3, i4, i5represent five-phase currents of the inner stator of the motor; R o / i R1, R2, R3, R4, R5are phase resistances of the outer stator and the inner stator, respectively;

[0057] After the outer stator of the motor has a two-phase open-circuit fault, the fault-tolerant currents obtained in step 2 under the two fault types are brought in respectively, and the copper loss expression is transformed into the synchronous rotating coordinate system to obtain the copper loss formula P M1 under mode 1 as follows:

[0058] P M1 = 2.5R o i qo 2 + 2.5R i i qi 2

[0059] The copper loss formula P M2 under mode 2 is as follows:

[0060] P M2 = 2.5R o i qo 2 + 2.5R i i di 2

[0061] Further, the specific process of step 5 is as follows:

[0062] Step 5.1: define the coefficients X and Y of the injection currents of the outer stator and the inner stator winding as follows:

[0063] X[i do i qo i do3 i qo3 i0] = XT Park T Clarke [i A i B i C i D i E ]

[0064] Y[i di i qi i di3 i qi3 i0] = YT Park T Clarke [i a ​​​​i b i c i d i e ]

[0065] where, i do / qo , i di / qi represent the fundamental d-q axis currents of outer stator winding, inner stator winding respectively; i do3 / qo3 , i di3 / qi3 represent the third harmonic d-q axis currents of outer stator winding, inner stator winding respectively; i A , i B , i C , i D , i E represent the five-phase currents of motor outer stator respectively; i a , i b , i c , i d , i e represent the five-phase currents of motor inner stator respectively;

[0066] is normal five-order Clarke matrix;

[0067] is normal five-order Park matrix;

[0068] In order to keep the torque unchanged, in mode 1, the following is derived:

[0069]

[0070] where, ψ fo is outer stator permanent magnet flux linkage; ψ fi is inner stator permanent magnet flux linkage;

[0071] Similarly, in mode 2, the following is derived:

[0072]

[0073] where, P i is the number of inner stator pole pairs; K f is the defined magnet adjustment coefficient, which represents the strength of the inner stator adjustment ability to the outer air gap magnetic field; T e is the motor electromagnetic torque;

[0074] Step 5.2: When the motor works in mode 1, based on the mode 1 torque formula and mode 1 copper loss formula in step 4, the Lagrange function is constructed to obtain:

[0075] L = 2.5R o i qo 2 + 2.5Ri i qi 2

[0076] + λ [T e - 2.5 (P o ψ fo i qo + P i ψ fi i qi )]

[0077] Where, L represents the Lagrange function; R o / i are the phase resistance of outer stator and inner stator respectively; λ is the Lagrange multiplier;

[0078] The partial derivatives of the formula i qo , i qi , λ are solved respectively, and they are equal to 0, to obtain:

[0079]

[0080] The formula is solved to obtain:

[0081]

[0082] The current distribution coefficient under mode 1 is derived:

[0083]

[0084] When the motor works in mode 2, based on the mode 2 torque formula and the mode 2 copper loss formula in step 4, the Lagrange function is constructed, and the following is obtained:

[0085]

[0086] The partial derivatives of the formula i qo , i qi , λ are solved respectively, and they are equal to 0, to obtain:

[0087]

[0088] The formula is solved to obtain:

[0089]

[0090] The current distribution coefficient under mode 2 is derived:

[0091]

[0092] Further, the specific process of step 6, mode selection based on the minimum copper loss principle, is as follows:

[0093] According to the current distribution coefficient calculated in step 5, the current of the inner stator and the outer stator is brought into the copper loss formula in step 4 again, and the difference is obtained, so as to obtain a mode selection discriminant:

[0094] Delta=P M2 -P M1

[0095] Wherein, Delta represents the copper loss difference of two modes; P M1 represents the copper loss formula under mode 1; P M2 represents the copper loss formula under mode 2.

[0096] Based on the results of the above formula, the mode selection is carried out, so as to ensure that the motor is always in the running state with the minimum copper loss under different working conditions.

[0097] Compared with the prior art, the beneficial effects of the present application are:

[0098] 1. The present application proposes a minimum copper loss fault-tolerant control method of a multi-mode double five-phase permanent magnet synchronous motor under two-phase open circuit fault, according to the principle of constant magnetic motive force, the amplitude and phase of the residual phase current can be adjusted to obtain a constant circular rotating magnetic field, so as to realize disturbance-free operation after fault, ensure that the output torque before and after fault is equal, and realize fault-tolerant operation under two-phase open circuit fault.

[0099] 2. The fault-tolerant control method of the present application, compared with the traditional algorithm, has no characteristics according to the multi-mode operation of the double stator motor, and the optimal distribution coefficient of the inner and outer stators is obtained based on the Lagrange equation under different modes according to the minimum copper loss principle, and the mode selection is carried out according to the copper loss discriminant, compared with the traditional fault-tolerant control, the copper loss is effectively reduced, and high-performance fault-tolerant control in the full torque range is realized.

[0100] 3. The PWM modulation method adopted by the present application is carrier-based pulse width modulation (CPWM), compared with the current hysteresis modulation method used in the traditional fault-tolerant algorithm, CPWM has a fixed modulation period, which can reduce the switching loss of the inverter. BRIEF DESCRIPTION OF DRAWINGS

[0101] Figure 1 It is a control block diagram of a two-phase open circuit fault fault-tolerant control method of a multi-mode double five-phase permanent magnet synchronous motor;

[0102] Figure 2 It is a current and torque waveform diagram of the motor under the condition that the outer stator BE two-phase open circuit fault occurs when the motor load is 8.7Nm, and the motor is based on mode 2 from normal operation-open circuit fault-classic fault-tolerant-new fault-tolerant operation;

[0103] Figure 3The current and torque waveform diagram of the motor based on mode 1 from normal operation-open circuit fault-classical fault tolerance-new fault tolerance operation under the condition that the motor load is 4.3 Nm and the outer stator CD two-phase open circuit fault occurs;

[0104] Figure 4 The current and torque waveform diagram of the motor based on mode 1 from normal operation-open circuit fault-classical fault tolerance-new fault tolerance operation under the condition that the motor load is 2 Nm and the inner stator BE two-phase open circuit fault occurs; DETAILED DESCRIPTION

[0105] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work fall within the protection scope of the present application.

[0106] Figure 1 The control block diagram of the fault tolerance control method of the multi-mode dual five-phase permanent magnet synchronous motor under two-phase open circuit fault is shown, and the specific implementation steps of the method will be described in detail below in combination with the control block diagram:

[0107] A fault tolerance control method of a multi-mode dual five-phase permanent magnet synchronous motor under two-phase open circuit, comprising the following steps:

[0108] Step 1, establishing a fault model of a multi-mode dual five-phase permanent magnet synchronous motor under two-phase open circuit;

[0109] The d-q axis flux linkage and voltage model under the two-phase open circuit fault state is:

[0110]

[0111] Wherein, ψ do / qo , ψ di / qi represent the d-q axis flux linkage of the outer stator winding and the inner stator winding respectively; L do / qo and L di / qi represent the d-q axis self-inductance of the outer stator winding and the inner stator winding respectively, and L do =L qo , L di =L qi ; i do / qo , i di / qi represent the d-q axis current of the outer stator winding and the inner stator winding respectively; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage, M d / q is the mutual inductance of the inner and outer stators; K fis the excitation coefficient, which is used to represent the influence ability of the excitation winding to the external air-gap flux linkage;

[0112]

[0113] wherein, u do / qo , u di / qi represent the dq-axis voltages of the outer stator winding and the inner stator winding respectively; R o / i are the phase resistances of the outer stator and the inner stator respectively; ω e is the electrical angular velocity of the motor.

[0114] Step 2, construct the orthogonal degradation decoupling matrix, and derive the fault-tolerant current expressions under two types of faults;

[0115] Assuming that open-circuit faults occur in phases B and E, remove the elements related to the fault phases, construct an orthogonal matrix, and obtain the reduced-order decoupling Clarke transformation matrix as follows:

[0116]

[0117] wherein, T Clarke BE is the reduced-order Clarke matrix under open-circuit of phases B and E, and δ=2π / 5 is the included angle between adjacent two phases of the motor;

[0118] When open-circuit faults occur in phases C and D, remove the elements related to the fault phases, and obtain the reduced-order decoupling Clarke transformation matrix as follows:

[0119]

[0120] wherein, T Clarke CD is the reduced-order Clarke matrix under open-circuit of phases C and D;

[0121] The Park transformation matrices under two types of faults are as follows:

[0122]

[0123] wherein, T Park 2 is the reduced-order Park matrix under double-phase open-circuit faults, and θ e is the electrical angle;

[0124] The fault-tolerant current expression after open-circuit of phases B and E is derived as follows:

[0125]

[0126] wherein, i A , i C , i DIa, Ib, Ic, Id, Ie m is the fundamental current effective value;

[0127] The fault-tolerant current expression of C, D phase open circuit is derived as:

[0128]

[0129] wherein, i A , i B , i E respectively represent the five-phase current of the motor outer stator; I m is the fundamental current effective value;

[0130] Step 3, the torque formula of the multi-mode double five-phase permanent magnet synchronous motor is derived;

[0131] According to the magnetic co-energy method, the formula of the motor electromagnetic torque T e is solved as:

[0132]

[0133] wherein, W co is the magnetic co-energy of the motor; θ m is the mechanical angle of the motor; I so , I si are the phase current vectors of the motor outer stator winding and inner stator winding respectively; L so , L si are the inductance matrices of the motor outer stator winding and inner stator winding respectively; P o , P i are the pole pairs of the motor outer stator and inner stator winding; θ e is the electrical angle; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage;

[0134] The torque formula is solved as:

[0135]

[0136] wherein, M d / q is the mutual inductance of the inner and outer stators; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage;

[0137] Since both sets of windings are star-connected, and the inner and outer stators are partitioned and isolated, the coupling degree of the two in the magnetic circuit is low, and the mutual inductance is very small, so M d / q is approximately 0; the torque formula is simplified as:

[0138]

[0139] Step 4, set up two modes of motor fault-tolerant operation, derive the copper loss calculation formula under two modes;

[0140] Step 4.1: from the torque formula described in step 3, when the main drive outer stator winding occurs open circuit fault, the auxiliary drive inner stator winding is used to compensate torque, when the inner stator injects i qi For mode 1, the corresponding torque formula at this time is:

[0141]

[0142] When the inner stator winding injects idi, the torque formula at this time is:

[0143]

[0144] Where, K f is the defined flux modulation coefficient, which represents the strength of the inner stator to the outer air gap magnetic field regulation ability; P o , P i is the pole pair number of the motor outer stator and inner stator winding; i do / qo , i di / qi represent the outer stator winding, inner stator winding d-q axis current respectively; ψ fo is the outer stator permanent magnet flux linkage; ψ fi is the inner stator permanent magnet flux linkage;

[0145] Step 4.2: the copper loss formula of the motor can be expressed as:

[0146] P Cu = R o (i A 2 +i B 2 +i C 2 +i D 2 +i E 2 )+ R i (i a 2 +i b 2 +i c 2 +i d 2 +i e 2 )

[0147] Where, P cu represents the copper loss of the motor; i A , i B , iC , i D , i E , i a , i b , i c , i d , i e , i o / i , i

[0148] After two-phase open-circuit fault occurs in the outer stator, the fault-tolerant currents obtained in step 2 under the two fault types are brought in respectively, and the copper loss expression is transformed into the synchronous rotating coordinate system to obtain the copper loss formula P M1 under mode 1 as follows:

[0149] P M1 = 2.5R o i qo 2 + 2.5R i i qi 2

[0150] The copper loss formula P M2 under mode 2 is as follows:

[0151] P M2 = 2.5R o i qo 2 + 2.5R i i di 2

[0152] Step 5, the current distribution coefficients of the outer stator and the inner stator are set up, and the current distribution coefficients are derived based on the minimum copper loss by establishing the Lagrange equation;

[0153] Step 5.1: define the coefficients X and Y of the current injected by the outer stator and the inner stator winding respectively to obtain:

[0154] X[i do i qo i do3 i qo3 i0] = XT Park T Clarke [i A i B i C i D i E ]

[0155] Y[i di i qi i di3 iqi3 i0] = YT Park T Clarke [i a i b i c i d i e

[0156] where i do / qo , i di / qi represent the fundamental d-q axis currents of outer stator winding and inner stator winding respectively; i do3 / qo3 , i di3 / qi3 represent the third harmonic d-q axis currents of outer stator winding and inner stator winding respectively; i A , i B , i C , i D , i E represent the five-phase currents of motor outer stator respectively; i a , i b , i c , i d , i e represent the five-phase currents of motor inner stator respectively;

[0157] is normal five-order Clarke matrix;

[0158] is normal five-order Park matrix;

[0159] In order to keep the torque unchanged, in mode 1, the following is derived:

[0160]

[0161] where ψ fo is outer stator permanent magnet flux linkage; ψ fi is inner stator permanent magnet flux linkage;

[0162] Similarly, in mode 2, the following is derived:

[0163]

[0164] where P i is the number of inner stator pole pairs; K f is the defined magnet adjustment coefficient, which represents the strength of the inner stator adjustment ability to the outer air gap magnetic field; T e is the motor electromagnetic torque;

[0165] Step 5.2: When the motor works in mode 1, based on the mode 1 torque formula and the mode 1 copper loss formula in step 4, the Lagrange function is constructed to obtain:

[0166] ​L = 2.5R o i qo 2 + 2.5R i i qi 2

[0167] + λ [T e - 2.5 (P o ψ fo i qo + P i ψ fi i qi ]

[0168] wherein, L represents a Lagrange function; R o / i are phase resistances of the outer stator and the inner stator respectively; λ is a Lagrange multiplier;

[0169] Partial derivatives of i qo , i qi and λ in the formula are solved respectively, and are equal to 0, to obtain:

[0170]

[0171] Solving the formula obtains:

[0172]

[0173] The current distribution coefficient under mode 1 is derived in turn:

[0174]

[0175] When the motor works in mode 2, based on the mode 2 torque formula and the mode 2 copper loss formula in step 4, a Lagrange function is constructed, to obtain:

[0176]

[0177] Partial derivatives of i qo , i qi and λ in the formula are solved respectively, and are equal to 0, to obtain:

[0178]

[0179] Solving the formula obtains:

[0180]

[0181] The current distribution coefficient under mode 2 is derived in turn:

[0182]

[0183] Step 6, mode selection based on the minimum copper loss principle;

[0184] According to the current distribution coefficient calculated in step 5, the copper loss formula in step 4 is used to recalculate the current of the inner stator and the outer stator, and the difference is obtained to obtain the mode selection discriminant:

[0185] Δ = P M2 -P M1

[0186] Based on the results of the above formula, the mode selection is performed to ensure that the motor is always in the state of minimum copper loss under different working conditions.

[0187] Step 7, detect the speed of the multi-mode dual five-phase permanent magnet synchronous motor as the speed feedback n of the motor, compare the given speed n* with the feedback speed n to obtain the speed error e of the motor r , and use a PI controller to calculate the q-axis current of the multi-mode dual five-phase permanent magnet synchronous motor according to the speed error e r ; the output of the PI controller is the given q-axis current i q1 ;

[0188] Step 8, according to the total current i q1 obtained in step 7, input it into the current distribution calculation module, first determine the working mode according to step 6, then determine the current size input to the outer stator and the inner stator according to X and Y obtained in step 5 respectively;

[0189] Step 9, compare the feedback current components i d / q1o_back , i d / q3o_back , i d / q1i_back , i d / q3i_back obtained by the current sensor with the given current components i d / qo1 , i d / q3o , i d / qi1 , i d / q3i obtained in step 8, and send the error to the PI controller to obtain the given voltage signal in the synchronous rotating coordinate system;

[0190] Step 10, input the given voltage signal in the synchronous rotating orthogonal coordinate system obtained in step 9 into the carrier-based pulse width modulation (CPWM) module after coordinate transformation, obtain the switching signal of each phase, and then input the obtained switching signal into the inverter to control the motor, realize the two-phase open circuit fault tolerance control of the multi-mode dual five-phase permanent magnet synchronous motor.

[0191] Figure 2 is the BE two-phase open circuit fault of the motor, the fault tolerance control is performed based on mode 2, and the torque is 8.7 Nm; Figure 3is the CD two-phase open circuit fault of the motor, the fault-tolerant control is based on mode 1, and the torque is 4.3 Nm. In the two experimental processes, the motor experiences four running states of normal operation, open circuit fault, classic fault-tolerant and new fault-tolerant, and the torque and current waveforms of the motor in the four processes are indicated in the pictures. When the fault-tolerant control method used in the application is used, the fault-tolerant effect is obvious, and the overall copper loss of the motor is reduced.

[0192] Figure 4 is the verification of the fault-tolerant control strategy used in the application when two-phase open circuit occurs in the inner stator, and the results show that the control method used in the application is suitable for both the inner stator and the outer stator, and has good applicability.

[0193] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the application, but not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the application.

Claims

1. A method for minimum copper loss fault-tolerant control of a multi-mode dual five-phase permanent magnet synchronous motor under two-phase open-circuit faults, characterized in that, Includes the following steps: Step 1: Establish a two-phase open-circuit fault model for a multi-mode dual five-phase permanent magnet synchronous motor; Step 2: Remove the elements corresponding to the fault in the transformation matrix, construct an orthogonal reduced-order decoupling matrix, and derive the fault-tolerant current expression for open-circuit faults between adjacent phases and between non-adjacent phases based on the principle of constant magnetomotive force. Step 3: Obtain the torque formula of the multi-mode dual five-phase motor by combining the normal five-phase coordinate transformation with the order reduction and decoupling transformation matrix in Step 2. Step 4: Based on the torque equation obtained in Step 3, establish two fault-tolerant operation modes for the motor. In Mode 1, inject q-axis current i into the stator winding. qi Mode 2, injecting d-axis current i into the internal stator winding di Meanwhile, based on the current injection methods of the inner and outer stator windings in the two modes, the copper loss calculation formulas for the two modes are derived. Step 5: Establish the distribution coefficients X and Y of the dq axis current of the inner and outer stator windings. Construct the Lagrange equation through the torque formula obtained in Step 3 and the copper loss calculation formula obtained in Step 4. Derive the fault-tolerant current reference values ​​based on the principle of minimum copper loss in the two modes. Combine the reference values ​​of the outer stator current when the motor is running normally to determine the values ​​of X and Y. Step 6: Determine whether to use Mode 1 or Mode 2 for fault-tolerant control by comparing the copper losses of Mode 1 and Mode 2 across the entire torque range; Specific methods include offline calculation followed by table lookup and online comparison of copper consumption to select the working mode; Step 7: Detect the speed of the multi-mode dual five-phase permanent magnet synchronous motor, using it as the motor speed feedback n. Compare the given speed n* with the feedback speed n to obtain the motor speed error e. r A PI controller is used based on the speed error e r The q-axis current of the multi-mode dual five-phase permanent magnet synchronous motor is calculated, and the output of the PI controller is the given q-axis current i. q1 ; Step 8, based on the total current i obtained in step 7 q1 The input is fed into the current distribution calculation module. First, the working mode is determined according to step 6. Then, the magnitude of the current input to the outer stator and the inner stator is determined according to X and Y obtained in step 5, respectively. Step 9, convert the feedback current component i obtained from the current sensor d / q1o_back i d / q3o_back i d / q1i_back i d / q3i_back The given current component i obtained in step 8 d / qo1 i d / q3o i d / qi1 i d / q3i The comparison is performed, and the error is fed into the PI controller to obtain the given voltage signal in the synchronous rotating coordinate system; Step 10: The given voltage signal in the obtained synchronous rotating orthogonal coordinate system is transformed and then input into the carrier-based pulse width modulation (CPWM) module to obtain the switching signals of each phase. The obtained switching signals are then input into the inverter to control the motor, realizing the two-phase open-circuit fault-tolerant control of the multi-mode dual five-phase permanent magnet synchronous motor.

2. The method according to claim 1, characterized in that, The dq-axis flux linkage and voltage model under the two-phase open-circuit fault state in step 1 is as follows: Where, ψ do / qo , ψ di / qi These represent the dq-axis flux linkages of the outer stator winding and the inner stator winding, respectively; L do / qo and L di / qi Let L represent the dq-axis self-inductance of the outer stator winding and the inner stator winding, respectively, and L... do =L qo L di =L qi i do / qo i di / qi These represent the dq-axis currents of the outer stator winding and the inner stator winding, respectively; ψ fo It is the magnetic flux linkage of the external stator permanent magnet; ψ fi It is the internal stator permanent magnet flux linkage, M d / q It is the mutual inductance between the inner and outer stators; K f It is the excitation coefficient, which represents the ability of the excitation winding to influence the external air gap flux linkage; Among them, u do / qo u di / qi These represent the dq-axis voltages of the outer stator winding and the inner stator winding, respectively; R o / i These are the phase resistances of the outer stator and the inner stator, respectively; ω e This is the electric angular velocity of the motor.

3. The method according to claim 1, characterized in that, The specific process of step 2 is as follows: Assuming an open-circuit fault occurs in phases B and E, removing fault-related elements and constructing an orthogonal matrix yields the reduced-order decoupling Clarke transform matrix: Among them, T Clarke BE It is the reduced-order Clarke matrix with phases B and E open circuit, δ = 2π / 5, which is the angle between two adjacent phases of the motor; When an open-circuit fault occurs in the C and D phase windings, removing the elements associated with the fault yields the reduced-order decoupling Clarke transform matrix: Among them, T Clarke CD It is a reduced-order Clarke matrix under open-circuit C and D phases; The Park transformation matrices for the two fault types are: Among them, T Park 2 It is the reduced-order Park matrix under a two-phase open-circuit fault, θ e It is an electrical angle; The expression for the fault-tolerant current after phases B and E are open-circuited is derived as follows: Among them, i A i C i D These represent the five-phase currents of the motor's external stator; I m It is the effective value of the fundamental current; The expression for the fault-tolerant current after phases C and D are open-circuited is derived as follows: Among them, i A i B i E These represent the five-phase currents of the motor's external stator; I m It is the effective value of the fundamental current.

4. The method according to claim 1, characterized in that, Step 3 specifically involves: The electromagnetic torque T of the motor can be solved using the magnetic co-energy method. e The formula is: Among them, W co It is the magnetic co-energy of the motor; θ m It is the mechanical angle of the motor; I so I si These are the phase current vectors of the outer stator winding and the inner stator winding of the motor, respectively; L so L si These are the inductance matrices for the outer stator winding and the inner stator winding of the motor, respectively; P o P i θ represents the number of pole pairs in the outer and inner stator windings of the motor; e It is an electrical angle; ψ fo It is the magnetic flux linkage of the external stator permanent magnet; ψ fi It is the inner stator permanent magnet flux linkage; The torque formula is obtained by solving for: Among them, M d / q It is the mutual inductance between the inner and outer stators; ψ fo It is the magnetic flux linkage of the external stator permanent magnet; ψ fi It is the inner stator permanent magnet flux linkage; Because both windings are star-connected and the inner and outer stators are isolated, their magnetic coupling is low and mutual inductance is small. Therefore, M d / q Approximately 0; the torque formula simplifies to:

5. The method according to claim 1, characterized in that, Step 4 specifically involves: Step 4.1: Based on the torque formula described in Step 3, when an open-circuit fault occurs in the main drive outer stator winding, the auxiliary drive inner stator winding is used to compensate for the torque. When the inner stator is injected with i qi For mode 1, the corresponding torque formula is: When the inner stator winding is injected with i di For mode 2, the torque formula is: Among them, K f The magnetic adjustment coefficient, defined as P, represents the strength of the inner stator's ability to adjust the external air gap magnetic field; o P i i represents the number of pole pairs in the outer and inner stator windings of the motor; do / qo i di / qi These represent the dq-axis currents of the outer stator winding and the inner stator winding, respectively; ψ fo It is the magnetic flux linkage of the external stator permanent magnet; ψ fi It is the inner stator permanent magnet flux linkage; Step 4.2: The formula for the copper loss of the motor can be expressed as: P Cu =R o (i A 2 +i B 2 +i C 2 +i D 2 +i E 2 )+R i (i a 2 +i b 2 +i c 2 +i d 2 +i e 2 ) Among them, P cu Indicates the copper loss of the motor; i A i B i C i D i E These represent the five-phase currents of the motor's external stator; i a i b i c i d i e These represent the five-phase currents of the stator inside the motor; R o / i These are the phase resistances of the outer stator and the inner stator, respectively; After a two-phase open-circuit fault occurs in the outer stator, the fault-tolerant currents under the two fault types obtained in step 2 are substituted into the equations, and the copper loss expression is transformed to the synchronous rotating coordinate system to obtain the copper loss formula P under mode 1. M1 for: P M1 =2.5R o i qo 2 +2.5R i i qi 2 Copper loss formula P under mode 2 M2 for: P M2 =2.5R o i qo 2 +2.5R i i di 2 6. The method according to claim 1, characterized in that, Step 5 specifically involves: Step 5.1: Define the coefficients of the injected current in the outer stator and inner stator windings as X and Y, respectively, and obtain: X[i do I qo I do3 I qo3 i0]=XT Park T Clarke [i A I B I C I D I E ] Y[i di i qi i di3 i qi3 i0]=YT Park T Clarke [i a i b i c i d i e ] Among them, i do / qo i di / qi These represent the fundamental dq-axis currents of the outer stator winding and the inner stator winding, respectively; i do3 / qo3 i di3 / qi3 These represent the dq-axis currents in the third-dimensional space of the outer stator winding and the inner stator winding, respectively; i A i B i C i D i E These represent the five-phase currents of the motor's external stator; i a i b i c i d i e These represent the five-phase currents of the stator inside the motor; It is a normal fifth-order Clarke matrix; It is a normal fifth-order Park matrix; To keep the torque constant, the following is derived in Mode 1: Where, ψ fo It is the magnetic flux linkage of the external stator permanent magnet; ψ fi It is the inner stator permanent magnet flux linkage; Similarly, in Mode 2, the derivation is as follows: Among them, P i K is the number of pole pairs of the inner stator; f The magnetic adjustment coefficient, T, is defined to represent the strength of the inner stator's ability to adjust the external air gap magnetic field; e This refers to the electromagnetic torque of the motor. Step 5.2: When the motor is operating in mode 1, based on the mode 1 torque formula and mode 1 copper loss formula from step 4, construct the Lagrangian function to obtain: L=2.5R o i qo 2 +2.5R i i qi 2 +λ[T e -2.5(P o ψ mo i qo +P i ψ mi i qi )] Where L represents the Lagrangian function; R o / i λ represents the phase resistance of the outer stator and the inner stator, respectively; λ is the Lagrange multiplier. For i in the formula qo i qi Taking the partial derivatives of λ and λ respectively, and setting them equal to 0, we get: Solving the formula yields: The current distribution coefficient under mode 1 is then derived: When the motor is operating in mode 2, based on the mode 2 torque formula and mode 2 copper loss formula in step 4, a Lagrangian function is constructed, yielding: For i in the formula qo i qi Taking the partial derivatives of λ and λ respectively, and setting them equal to 0, we get: Solving the formula yields: The current distribution coefficient under mode 2 is then derived:

7. The method according to claim 1, characterized in that, Step 6, the mode selection based on the principle of minimizing copper loss, is as follows: Based on the current distribution coefficient calculated in step 5, the currents of the inner stator and outer stator are substituted back into the copper loss formula in step 4, and the difference is calculated to obtain the mode selection discriminant: Δ=P M2 -P M1 Where Δ represents the difference in copper loss between the two modes; P M1 This represents the copper loss formula under mode 1; P M2 This represents the copper loss formula under mode 2; Based on the results of the above formula, mode selection is performed to ensure that the motor is always in the operating state with the minimum copper consumption under different working conditions.

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