Fault-tolerant operation method for switch tube faults of multi-phase permanent magnet synchronous motors

Abstract

The present application provides a fault-tolerant operation method for a multi-phase permanent magnet synchronous motor switch tube, particularly in the field of multi-phase motor fault-tolerant control. The method comprises: determining a phase current reconstruction matrix under a faulty half-cycle and a healthy half-cycle corresponding to the faulty switch tube, defined as a fault state reconstruction matrix K f and health state reconstruction matrix K h ; When the inverter is in the fault half cycle, based on K f Reconstruct the phase current reference value of the remaining switch tubes of the inverter except the faulty switch tube, and control the inverter operation based on the phase current reference value; when the inverter is in the healthy half cycle, based on K h The phase current reference values of each inverter switch are reconstructed to control the inverter operation. This method can suppress torque fluctuations and improve the stability of multi-phase permanent magnet synchronous motors under fault conditions.

Description

Technical Field

[0001] The present application relates to the field of multi-phase motor fault-tolerant control, and in particular provides a method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes. Background Art

[0002] The open-circuit fault of the switch tube is the main source of inverter failure. The open-circuit fault of the switch tube will cause problems such as phase current distortion and torque oscillation, and it is easy to cause secondary faults. Since the open-circuit fault of the switch tube will not cause serious damage to the drive system of the multi-phase permanent magnet synchronous motor in a short period of time, there is relatively ample time to implement fault diagnosis and fault-tolerant control through the algorithm. Since the single-circuit open-circuit fault of the switch tube divides the fault phase into healthy and faulty half-cycles, the single-phase open-circuit fault-tolerant algorithm of the multi-phase permanent magnet synchronous motor can be used for fault-tolerant control in the faulty half-cycle, and the healthy state can be returned to the healthy control algorithm of the multi-phase permanent magnet synchronous motor. However, the fault-tolerant method in the related art will cause transient torque fluctuations during switching, causing instability of the multi-phase permanent magnet synchronous motor. Summary of the Invention

[0003] Based on this, it is necessary to provide a fault-tolerant operation method for the switching tube of a multi-phase permanent magnet synchronous motor to address the above technical problems, which can effectively suppress torque fluctuations.

[0004] The present application provides a method for fault-tolerant operation of a multi-phase permanent magnet synchronous motor with a switching tube fault, the method comprising:

[0005] In response to a switch failure of the inverter, determining the faulty switch; wherein, in the case where the switch failure of the inverter occurs, one working cycle of the inverter includes a faulty half cycle and a healthy half cycle;

[0006] Determine the phase current reconstruction matrix under the fault half cycle and the phase current reconstruction matrix under the healthy half cycle corresponding to the faulty switch tube, which are defined as the fault state reconstruction matrix K f and health state reconstruction matrix K h , fault state reconstruction matrix K f and health state reconstruction matrix K h They are all determined based on the fundamental subspace current and the third harmonic subspace current;

[0007] When the inverter is in the fault half cycle, the matrix is reconstructed based on the fault state. K f Reconstructing the phase current reference values of the remaining switch tubes in the inverter except the faulty switch tube, and controlling the inverter operation based on the phase current reference values to drive the multi-phase permanent magnet synchronous motor to operate;

[0008] When the inverter is in the healthy half cycle, the matrix is reconstructed based on the healthy state. K h The phase current reference value of each switch tube in the inverter is reconstructed, and the inverter operation is controlled based on the phase current reference value to drive the multi-phase permanent magnet synchronous motor to operate.

[0009] In one embodiment, determining a phase current reconstruction matrix in a fault half-cycle corresponding to a faulty switch includes:

[0010] Based on the characteristics of the fundamental subspace and third harmonic subspace of a multiphase permanent magnet synchronous motor, a phase current reconstruction matrix is established for the half-cycle of a switch open-circuit fault. The phase current reconstruction matrix includes multiple reconstruction coefficients. In the switch fault state, the orthogonality between the fundamental subspace and the third harmonic subspace does not exist.

[0011] The electromagnetic torque formula of the multi-phase permanent magnet synchronous motor is used to determine the reconstruction coefficient of the phase current reconstruction matrix without increasing the torque ripple.

[0012] In one embodiment, the fault state reconstruction matrix K f including a first fault matrix and a second fault matrix;

[0013] The first fault matrix is a mapping matrix from the fundamental subspace to the third harmonic subspace, and the second fault matrix is a mapping matrix from the third harmonic subspace to the fundamental subspace.

[0014] In one embodiment, based on the characteristics of the fundamental subspace and the third harmonic subspace of the multi-phase permanent magnet synchronous motor, a phase current reconstruction matrix is established under a half-cycle of a switch tube open circuit fault, including: establishing a first fault matrix by injecting the fundamental current into the third harmonic subspace; establishing a second fault matrix by injecting the third harmonic current into the fundamental subspace;

[0015] Among them, both the first fault matrix and the second fault matrix include multiple reconstruction coefficients. The reconstruction coefficients in the first fault matrix are the correlation coefficients of the fundamental current mapped to the third harmonic subspace, and the reconstruction coefficients in the second fault matrix are the correlation coefficients of the third harmonic current mapped to the fundamental subspace.

[0016] In one embodiment, the reconstruction coefficients of the first fault matrix are established in the following manner:

[0017] ;

[0018] in, and They represent the third harmonic subspace 、 Fundamental current on the shaft; and Represent the fundamental subspace 、 Fundamental current on the shaft; K xyf is the reconstruction coefficient in the first fault matrix, which is used to represent the correlation coefficient needed to map the y-axis current to the x-axis (x, y = 、 、 );

[0019] The reconstruction coefficients of the second fault matrix are established as follows:

[0020] ;

[0021] in, and Represent the fundamental subspace 、 Third harmonic current on the shaft; and They represent the third harmonic subspace 、 Third harmonic current on the shaft; K xyf is the reconstruction coefficient in the second fault matrix, which is used to represent the correlation coefficient needed to map the y-axis current to the x-axis (x, y = 、 、 ).

[0022] In one embodiment, the electromagnetic torque formula of the multi-phase permanent magnet synchronous motor is used to determine the reconstruction coefficient of the phase current reconstruction matrix without increasing the torque ripple, including:

[0023] Step a: determining the torque ripple term using the electromagnetic torque formula; in the fault-open state of the switch tube, the current component of the fundamental subspace is coupled with the current component of the third harmonic subspace, resulting in torque ripple;

[0024] Step b, determining a coefficient of the torque fluctuation term, and determining the first equation based on the coefficient of the torque fluctuation term being zero;

[0025] Step c, determining a second equation based on the phase current corresponding to the faulty switch being zero;

[0026] Step d: determining a third equation based on the symmetry of phase currents corresponding to the remaining switching tubes in the inverter except the faulty switching tube;

[0027] Step e: solving the first equation, the second equation, and the third equation to determine the values of the reconstruction coefficients in the phase current reconstruction matrix.

[0028] In one embodiment, the coefficient of the torque ripple term includes 3 i q3 ψ m1 + i q1 ψ m3 ;

[0029] In step b: based on the coefficient of the torque fluctuation term being zero, a first equation is determined, including:

[0030] 3 i q3 ψ m1 + i q1 ψ m3 Forced to zero, we get ;

[0031] Based on the coefficient of the torque ripple term being zero and , we get the first equation; the first equation includes multiple equations, which are as follows:

[0032] ,

[0033] ,

[0034] ,

[0035] ;

[0036] in, K xyf is the reconstruction coefficient in the phase current reconstruction matrix (x, y = 、 、 ).

[0037] In one embodiment, the second equation in step c is as follows:

[0038] ,

[0039] ;

[0040] in, and The size of is related to the position of the fault switch tube in the multi-phase permanent magnet synchronous motor.

[0041] The third procedure in step d is:

[0042] ;

[0043] in, i m and i n Indicates the phase current corresponding to the remaining switching tubes in the inverter except the faulty switching tube, and the phase current i m and phase current i n symmetry; and The size of is related to the position of the fault switch tube in the multi-phase permanent magnet synchronous motor.

[0044] In one embodiment, step e, solving the first equation, the second equation, and the third equation to determine the values of the reconstruction coefficients in the phase current reconstruction matrix, includes:

[0045] Solving the first equation, the second equation, and the third equation to obtain multiple sets of reconstruction coefficient values, wherein the values of a set of reconstruction coefficients can determine a phase current reconstruction matrix;

[0046] Based on the constraint of minimizing copper loss, an optimal set of reconstruction coefficient values is determined from multiple sets of reconstruction coefficient values and is used as the values of the reconstruction coefficients in the phase current reconstruction matrix.

[0047] In one embodiment, the health state reconstruction matrix K h It includes multiple reconstruction coefficients, which are selected based on the fluctuation of electromagnetic torque so that the torque fluctuation is zero; wherein the healthy state reconstruction matrix K h The reconstruction coefficient in is expressed as:

[0048] ;

[0049] in, K xyh Reconstructing the matrix for health K h The reconstruction coefficient in , K xyh Indicates the correlation coefficient (x, y = 、 、 ); and represents the coordinate axis in the fundamental subspace; and Represents the coordinate axes in the third harmonic subspace.

[0050] The above-mentioned method for operating a multi-phase permanent magnet synchronous motor with a fault-tolerant switch tube is to determine the faulty switch tube in response to a switch tube fault of the inverter; when a switch tube fault is detected, one working cycle of the inverter is divided into a fault half cycle. K f and healthy half cycle K h ; In the fault half cycle, the matrix is reconstructed based on the fault state K f Adjust the phase current reference values of the remaining switch tubes except the faulty switch tube to ensure that the fault phase current is zero and optimize the symmetry and torque fluctuation of the remaining phase current; reconstruct the matrix based on the healthy state in the healthy half cycle K h Adjust the phase current reference values of all switching tubes to ensure a reasonable current distribution. This method can effectively suppress torque fluctuations and improve the stability and reliability of multi-phase permanent magnet synchronous motors under fault conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 Flowchart of a method for operating a multi-phase permanent magnet synchronous motor with fault tolerance of a switching tube in accordance with an embodiment;

[0052] Figure 2 A diagram of a conduction path of a switch tube in a power electronic circuit when current flows in both directions in one embodiment;

[0053] Figure 3 A flowchart of determining a phase current reconstruction matrix in a fault half-cycle corresponding to a faulty switch in one embodiment;

[0054] Figure 4 is a structural diagram of a phase current reconstruction matrix in one embodiment;

[0055] Figure 5 A flowchart for determining reconstruction coefficients of a phase current reconstruction matrix in one embodiment;

[0056] Figure 6 A flowchart for determining values of reconstruction coefficients in a phase current reconstruction matrix in one embodiment;

[0057] Figure 7 is a block diagram of a fault-tolerant control system of a multi-phase permanent magnet synchronous motor in one embodiment;

[0058] Figure 8 Figure 1 shows the torque and phase current waveforms of a multi-phase motor in a healthy state and in a fault state when the motor torque is 1.5 Nm and the speed is 500 rpm, with the switch tube on phase B open-circuit fault.

[0059] Figure 91 is a torque and phase current waveform diagram of a multi-phase motor using the ML constrained fault-tolerant control algorithm when the motor torque is 1.5 Nm and the speed is 500 rpm in an embodiment and the switch tube on phase B is open-circuited. DETAILED DESCRIPTION

[0060] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0061] In one embodiment, Figure 1 As shown, a method for fault-tolerant operation of a multi-phase permanent magnet synchronous motor is provided, the method comprising the following steps:

[0062] Step 101: In response to a switch failure of an inverter, determine the faulty switch; wherein, in the case where the switch failure of the inverter occurs, one working cycle of the inverter includes a faulty half cycle and a healthy half cycle.

[0063] When an inverter switch fails, it's necessary to identify the faulty switch. This can be achieved by detecting current anomalies or voltage fluctuations. When a switch fails, the inverter's operating cycle is divided into two parts: a faulty half-cycle and a healthy half-cycle.

[0064] During the fault half-cycle, the faulty switch tube cannot work normally, and the current bypasses the fault point through the free diode or other paths. During the healthy half-cycle, the switch tube works normally and the current can flow through the current path of the switch tube.

[0065] It should be noted that if Figure 2 As shown in the figure, the conduction path of the switch tube in the power electronic circuit when the current flows in both directions, where S nu and S n1 Indicates the switch tube of the nth bridge arm (the subscript represents the position number), D nu and D nd Indicates the diode connected in parallel (for freewheeling), and the arrow (→) indicates the current path; i n Indicates the nth phase current, i n >0, the current flows from the bridge arm to the permanent magnet synchronous motor, i n <0 when the current flows in the reverse direction through D nu or D nd Flow to the bridge arm. In the figure (a) and (b) correspond to i n >0 and i n<0 working state of two current directions. This power electronic circuit structure is commonly used in inverter bridge arm design, especially in multi-phase motor drive systems. When an open-circuit fault occurs in a switch tube, the current can still flow through the corresponding diode, thereby maintaining the operation of the phase motor drive system, reflecting the fault tolerance capability of the power electronic circuit. Figure 2 The use of different colored paths (blue and red) can intuitively display the current flow in healthy and faulty states. The blue path represents the current flow in a healthy state, and the red path represents the current flow in a faulty state.

[0066] Step 102: Determine the phase current reconstruction matrix in the fault half cycle and the phase current reconstruction matrix in the healthy half cycle corresponding to the faulty switch tube, which are defined as the fault state reconstruction matrix K f and health state reconstruction matrix K h , fault state reconstruction matrix K f and health state reconstruction matrix K h Both are determined based on the fundamental subspace current and the third harmonic subspace current.

[0067] Pre-calculate the phase current reconstruction matrix corresponding to the fault half-cycle of each phase switch tube K f and the phase current reconstruction matrix under the healthy half cycle K h , respectively defined as the fault state reconstruction matrix K f and health state reconstruction matrix K h Fault state reconstruction matrix K f and health state reconstruction matrix K h Based on the fundamental subspace current and the third harmonic subspace current, it ensures that the current distribution is reasonable under the fault state and reduces the torque fluctuation. K f Used to adjust the phase current distribution under the fault half cycle. Healthy state reconstruction matrix K h It is used to adjust the phase current distribution in the healthy half cycle to ensure that transient torque fluctuations can be reduced during mode switching.

[0068] Pre-calculate and store the corresponding switching tube of each phase K f and K h For example, when the switch tube of phase A fails, the K fA andK hA , when the switch tube of phase B fails, the K fB and K hB , and so on. When a switch tube of a certain phase fails, quickly identify which phase the faulty switch tube is and directly call the corresponding switch tube K f and K h .

[0069] Step 103: When the inverter is in a fault half-cycle, reconstruct the matrix based on the fault state K f The phase current reference values of the remaining switch tubes in the inverter except the faulty switch tube are reconstructed, and the operation of the inverter is controlled based on the phase current reference values to drive the operation of the multi-phase permanent magnet synchronous motor.

[0070] When the switch tube of the inverter fails, it is necessary to reconstruct the matrix based on the fault state within the fault half cycle. K f Adjust the phase current reference value of the remaining switch tubes except the faulty switch tube. During the fault half cycle, use the pre-calculated and stored fault state matrix corresponding to the faulty switch tube to reconstruct the matrix. K f , where the fault state reconstruction matrix contains multiple reconstruction coefficients, which are used to map the current component of the fundamental subspace to the third harmonic subspace to ensure that the fault phase current is zero.

[0071] Based on the reconstructed phase current reference value, a control signal is generated through deadbeat control or other control strategies to drive the remaining switches of the inverter. The inverter outputs an adjusted voltage to drive the multi-phase permanent magnet synchronous motor to continue operating.

[0072] Step 104: When the inverter is in a healthy half cycle, reconstruct the matrix based on the healthy state K h The phase current reference value of each switch tube in the inverter is reconstructed, and the inverter operation is controlled based on the phase current reference value to drive the multi-phase permanent magnet synchronous motor to operate.

[0073] When the inverter's switch tube is in a healthy half cycle, the matrix is reconstructed based on the healthy state. K h Reconstruct the phase current reference value of each switch tube. In the healthy half cycle, use the pre-calculated and stored healthy state reconstruction matrix corresponding to the faulty switch tube K h ,The healthy state reconstruction matrix contains multiple reconstruction coefficients used to optimize the current distribution in the fundamental and third harmonic subspaces, ensuring the symmetry and efficiency of the current.

[0074] Based on the adjusted phase current reference value, deadbeat control or other control strategies are used to generate control signals to drive the inverter's switches. The inverter then outputs an optimized voltage to drive the multi-phase permanent magnet synchronous motor to continue operating.

[0075] In this embodiment, the method determines the faulty switch tube in response to the switch tube failure of the inverter; when the switch tube failure is detected, a working cycle of the inverter is divided into a fault half cycle. K f and healthy half cycle K h ; In the fault half cycle, the matrix is reconstructed based on the fault state K f Adjust the phase current reference values of the remaining switch tubes except the faulty switch tube to ensure that the fault phase current is zero and optimize the symmetry and torque fluctuation of the remaining phase current; reconstruct the matrix based on the healthy state in the healthy half cycle K h Adjust the phase current reference values of all switching tubes to ensure a reasonable current distribution. This method can effectively suppress torque fluctuations and improve the stability and reliability of multi-phase permanent magnet synchronous motors under fault conditions.

[0076] In one embodiment, Figure 3 As shown, determining the phase current reconstruction matrix in the fault half-cycle corresponding to the faulty switch tube includes the following steps:

[0077] Step 301: Based on the characteristics of the fundamental subspace and the third harmonic subspace of the multi-phase permanent magnet synchronous motor, a phase current reconstruction matrix is established under the half-cycle of the switch tube open circuit fault. The phase current reconstruction matrix includes multiple reconstruction coefficients; wherein, in the switch tube fault state, the orthogonality of the fundamental subspace and the third harmonic subspace does not exist.

[0078] During normal operation of a multiphase permanent magnet synchronous motor (PMSM), the fundamental and third harmonic subspaces typically maintain orthogonality—that is, they are independent and do not interfere with each other. However, when a switch fails, the orthogonality between the fundamental and third harmonic subspaces is broken, causing the interaction between the fundamental and third harmonic subspaces to affect the current distribution. Therefore, it is necessary to establish a phase current reconstruction matrix containing multiple reconstruction coefficients to adjust the current distribution and ensure stable operation of the multiphase permanent magnet synchronous motor despite switch failures.

[0079] Step 302: Using the electromagnetic torque formula of the multi-phase permanent magnet synchronous motor, determine the reconstruction coefficients of the phase current reconstruction matrix without increasing the torque ripple.

[0080] Electromagnetic torque is affected by the fundamental and third harmonic current components. Under fault conditions, the orthogonality of the fundamental and third harmonic subspaces is destroyed, resulting in the appearance of additional torque fluctuation components. To eliminate these additional torque fluctuation components, the reconstruction coefficients of the phase current reconstruction matrix can be adjusted to zero. For example, by properly setting the current distribution in the fundamental and third harmonic subspaces, the fluctuations caused by the interaction between the fundamental and third harmonics can be offset.

[0081] Similarly, it is also necessary to ensure that the fault phase current is zero in a faulty state. For example, when an open-circuit fault occurs in a phase switch, the current in that phase must be zero during the fault half-cycle. To further optimize this, symmetry constraints on the remaining phase currents are introduced to ensure that the currents of certain phases remain symmetrical in the fundamental subspace. For example, in a five-phase permanent magnet synchronous motor, the currents of phases A and C should be equal in the fundamental subspace.

[0082] In one embodiment, the fault state reconstruction matrix K f including a first fault matrix and a second fault matrix;

[0083] The first fault matrix is a mapping matrix from the fundamental subspace to the third harmonic subspace, and the second fault matrix is a mapping matrix from the third harmonic subspace to the fundamental subspace.

[0084] The first fault matrix maps the current components in the fundamental subspace to the third harmonic subspace, while the second fault matrix maps the current components in the third harmonic subspace to the fundamental subspace. This mapping mechanism allows the currents in the fundamental and third harmonic subspaces to compensate for each other during a fault condition, thereby eliminating torque ripple.

[0085] In one embodiment, based on the characteristics of the fundamental subspace and the third harmonic subspace of a multi-phase permanent magnet synchronous motor, a phase current reconstruction matrix is established under a half-cycle of a switch tube open-circuit fault, including: establishing a first fault matrix by injecting a fundamental current into the third harmonic subspace; establishing a second fault matrix by injecting a third harmonic current into the fundamental subspace; wherein, both the first fault matrix and the second fault matrix include multiple reconstruction coefficients, the reconstruction coefficients in the first fault matrix are correlation coefficients of the fundamental current mapped to the third harmonic subspace, and the reconstruction coefficients in the second fault matrix are correlation coefficients of the third harmonic current mapped to the fundamental subspace.

[0086] The fault state reconstruction matrix consists of two parts: a first fault matrix and a second fault matrix. The first fault matrix is established by injecting the fundamental current into the third harmonic subspace. The first fault matrix can map the current components in the fundamental subspace to the third harmonic subspace to compensate for the current loss under the fault state. The second fault matrix is established by injecting the third harmonic current into the fundamental subspace. The second fault matrix can map the current components in the third harmonic subspace to the fundamental subspace to ensure a reasonable current distribution under the fault state.

[0087] The reconstruction coefficients in the first fault matrix and the second fault matrix respectively determine the degree to which the fundamental current is mapped to the third harmonic subspace and the third harmonic current is mapped to the fundamental subspace, thereby ensuring that under a fault condition, the currents between the fundamental and third harmonic subspaces can compensate each other.

[0088] In one embodiment, the reconstruction coefficients of the first fault matrix are established in the following manner:

[0089] ;

[0090] in, and They represent the third harmonic subspace 、 Fundamental current on the shaft; and Represent the fundamental subspace 、 Fundamental current on the shaft; K xyf is the reconstruction coefficient in the first fault matrix, which is used to represent the correlation coefficient needed to map the y-axis current to the x-axis (x, y = 、 、 ).

[0091] When a switch failure occurs, the orthogonality between the fundamental and third harmonic subspaces no longer exists due to the reduction of degrees of freedom. For the fundamental subspace, consider the state where the switch failure does not occur. 、 When a switch failure occurs, in order to adjust the fault phase current to ensure that the fault phase current is zero, the first fault matrix can be used to consider the 、 Fundamental current is injected into the axis.

[0092] The reconstruction coefficients of the first fault matrix are established in the following way: the fundamental current in the third harmonic subspace and The fundamental current in the fundamental subspace and By the reconstruction coefficients in the first fault matrix K xyf The reconstruction coefficient in the first fault matrix is used to indicate the degree of correlation required to map the current in the fundamental subspace to the third harmonic subspace, thereby achieving reasonable current distribution and minimization of torque fluctuation under fault conditions.

[0093] In one embodiment, the reconstruction coefficients of the second fault matrix are established in the following manner:

[0094] ;

[0095] in, and Represent the fundamental subspace 、 Third harmonic current on the shaft; and They represent the third harmonic subspace 、 Third harmonic current on the shaft; K xyf is the reconstruction coefficient in the second fault matrix, which is used to represent the correlation coefficient needed to map the y-axis current to the x-axis (x, y = 、 、 ).

[0096] Similar to the first fault matrix, only the 、 When a switch failure occurs, in order to adjust the fault phase current to ensure that the fault phase current is zero, the second fault matrix can be used to consider the third harmonic current on the axis. 、 The third harmonic current is injected into the axis.

[0097] The reconstruction coefficients of the second fault matrix are established in the following way: the third harmonic current in the fundamental subspace and The third harmonic current in the third harmonic subspace and By the reconstruction coefficients in the second fault matrix K xyf The reconstruction coefficient in the second fault matrix is used to indicate the degree of correlation required to map the current in the third harmonic subspace to the fundamental subspace, thereby achieving a reasonable current distribution and minimizing torque fluctuations under fault conditions.

[0098] In one embodiment, Figure 4The figure shows the structure of a phase current reconstruction matrix for fault-tolerant control of a multiphase permanent magnet synchronous motor. The figure contains multiple adders and reconstruction coefficients, which are used to adjust the current distribution in the fundamental and third harmonic subspaces to ensure a reasonable current distribution under fault conditions and reduce torque ripple.

[0099] The reconstruction coefficients from the fundamental subspace to the third harmonic subspace are K α3α1f 、 K β3α1 、 K β3β1f as well as K β3α1f , the reconstruction coefficients from the third harmonic subspace to the fundamental subspace are K α1β3f 、 K β1α3f 、 K β1β3f as well as K α1α3f The adder (+) is used to add the current components of the fundamental harmonic subspace and the third harmonic subspace to form a final phase current reference value.

[0100] Current component i α1 is the current component on the α-axis of the fundamental subspace. i β1 is the current component on the β axis of the fundamental subspace. i α3 is the current component on the α-axis of the third harmonic subspace. i β3 is the current component on the β-axis of the third harmonic subspace.

[0101] The mapping from the fundamental subspace current to the third harmonic subspace current is: i α31 = K α3α1f ⋅ i α1 , i β31 = K α3β1f ⋅ i β1 , i β31 = K β3α1f ⋅ i α1 , i α31 = K β3β1f ⋅ i β1 .

[0102] The mapping from the third harmonic subspace current to the fundamental subspace current is: i α13 = K α1α3f ⋅ i α3 , i α13 = K α1β3f ⋅ i β3 , i β13 = K β1α3f ⋅ i α3 , i β13 = K β1β3f ⋅ i β3 .

[0103] The phase current reference value is generated by adding the current component of the fundamental subspace and the current component of the third harmonic subspace through an adder to generate the final phase current reference value:

[0104] i α11 + i α13 = i α1r , i α31 + i α33 = i α3r , i β11 + i β13 = i β1r , i β31 + i β33 = i β3r .

[0105] The reconstruction coefficient and the adder work together to ensure that the fault phase current is zero when the switch tube is open-circuited. By adjusting the reconstruction coefficient, a reasonable current distribution can be achieved under different operating conditions to ensure the smooth operation of the multi-phase permanent magnet synchronous motor.

[0106] In one embodiment, Figure 5As shown, the electromagnetic torque formula of the multi-phase permanent magnet synchronous motor is used to determine the reconstruction coefficient of the phase current reconstruction matrix without increasing the torque ripple, including the following steps:

[0107] Step a: determine the torque fluctuation term by the electromagnetic torque formula; in the open state of the switch tube fault, the current component of the fundamental subspace is coupled with the current component of the third harmonic subspace, resulting in torque fluctuation.

[0108] Using the electromagnetic torque formula of the multi-phase permanent magnet synchronous motor, the phase current reconstruction coefficient matrix reconstruction coefficient is determined without increasing the torque ripple. The electromagnetic torque of the fault state permanent magnet synchronous motor can be obtained by the following formula:

[0109] ;

[0110] in, θ Indicates electrical angle; and Represent the fundamental subspace 、 Fundamental current on the shaft; and They represent the third harmonic subspace 、 Third harmonic current on the shaft; and Represent the fundamental subspace 、 Third harmonic current on the shaft; and They represent the third harmonic subspace 、 The fundamental current on the axis can be obtained by multiplying the Park change matrix in the healthy state of the multi-phase motor with the motor dq axis current; T e represents electromagnetic torque; ψ m1 and ψ m3 They represent the flux linkage of the fundamental wave and the third harmonic respectively; E αβ Indicates Electromotive force in the coordinate system; ω Indicates the rotation rate of the rotor of a multi-phase permanent magnet synchronous motor; i αβ is the phase current vector; p Indicates the number of pole pairs, which refers to the number of magnetic pole pairs on the rotor of a permanent magnet synchronous motor; ψ αβ represents the magnetic flux vector. 、 Represent the fundamental subspace On-axis current components and third harmonic subspace Current component on the axis; 、 Represent the fundamental subspace On-axis current components and third harmonic subspace Current component on the axis; K xyf is the reconstruction coefficient, which is used to represent the correlation coefficient needed to map the y-axis current to the x-axis (x, y = 、 、 ).

[0111] When the switch is faulted and open, the current component in the fundamental subspace couples with the current component in the third harmonic subspace, resulting in torque ripple. The relevant component of the reconstruction matrix coefficient in the electromagnetic torque expression is the product of the fundamental and third harmonic components, i.e., the torque ripple component.

[0112] Step b: determining the coefficient of the torque fluctuation term, and determining the first equation based on the coefficient of the torque fluctuation term being zero.

[0113] The expanded electromagnetic torque equation includes interaction terms between the fundamental and third harmonic components, which contribute to torque ripple. To eliminate torque ripple, the coefficients of the phase current reconstruction matrix must be adjusted so that the torque ripple term is zero. By setting the torque ripple term to zero, the first equation for determining the coefficients of the phase current reconstruction matrix can be established.

[0114] Step c: determining a second equation based on the phase current corresponding to the faulty switch being zero.

[0115] When an open-circuit fault occurs in a certain switch tube, the corresponding phase current is zero within the fault half-cycle. In the fault state, the current cannot pass through the faulty switch tube and needs to drop to zero quickly through the free diode. In order to ensure that the fault phase current is zero, the coefficients of the second equation constraining the phase current reconstruction matrix can be established. For example, taking a five-phase permanent magnet synchronous motor as an example, if an open-circuit fault occurs in phase B, the current of phase B must be zero within the fault half-cycle. By adjusting the coefficients of the phase current reconstruction matrix, it can be ensured that the fault phase current is zero in the fault state, thereby avoiding the impact of the fault phase current on the operation of the permanent magnet synchronous motor.

[0116] Step d: determining a third equation based on the symmetry of the phase currents corresponding to the remaining switching tubes in the inverter except the faulty switching tube.

[0117] In an inverter, the phase currents corresponding to the remaining switches, excluding the faulty switch, should remain symmetrical. When a switch in a phase fails, the currents in the remaining phases must be redistributed to compensate for the loss of the faulty phase. To ensure the symmetry of the remaining phase currents, a third equation can be established to constrain the coefficients of the phase current reconstruction matrix. For example, in the fundamental subspace, taking a five-phase permanent magnet synchronous motor as an example, the currents in phases A and C should be equal, and the currents in phases D and E should also be equal. This ensures the symmetry of the remaining phase currents.

[0118] Step e: solving the first equation, the second equation, and the third equation to determine the values of the reconstruction coefficients in the phase current reconstruction matrix.

[0119] The first equation is based on the coefficient of eliminating the torque fluctuation term being zero, ensuring that the coupling between the current components of the fundamental subspace and the third harmonic subspace does not cause torque fluctuation. The second equation is based on the phase current corresponding to the faulty switch tube being zero, ensuring that the impact of the faulty phase current on the operation of the permanent magnet synchronous motor is minimized. The third equation is based on the symmetry of the phase currents corresponding to the remaining switch tubes in the inverter, ensuring the symmetry of the remaining phase currents and optimizing the performance of the permanent magnet synchronous motor. By solving the three equations simultaneously, the reconstruction coefficient value in the phase current reconstruction matrix can be determined. The reconstruction coefficient value can be used to adjust the current distribution in the fundamental subspace and the third harmonic subspace to ensure that the permanent magnet synchronous motor can operate smoothly under fault conditions and keep the torque fluctuation minimized.

[0120] In one embodiment, the coefficients of the torque fluctuation term include 3 i q3 ψ m1 + i q1 ψ m3 ;

[0121] In step b: based on the coefficient of the torque fluctuation term being zero, a first equation is determined, including:

[0122] 3 i q3 ψ m1 + i q1 ψ m3 Forced to zero, we get ;

[0123] Based on the coefficient of the torque ripple term being zero and , we get the first equation; the first equation includes multiple equations, which are as follows:

[0124] ,

[0125] ,

[0126] ,

[0127] ;

[0128] in, K xyf is the reconstruction coefficient in the phase current reconstruction matrix (x, y = 、 、 ).

[0129] Set the direct-axis reference current to 0. As shown in the table below, after classification, the torque ripple components only produce secondary and quaternary torque ripples instead of constant torque.

[0130]

[0131] It should be noted that the torque fluctuation component can be obtained by analyzing the electromagnetic torque formula of the multi-phase permanent magnet synchronous motor. The specific calculation method is as follows:

[0132] ;

[0133] Among them, the part related to the reconstruction matrix coefficient in the electromagnetic torque expression is the product of the fundamental wave and the third harmonic component, that is, the torque fluctuation component.

[0134] It can be seen from the above table that 3 i q3 ψ m1 + i q1 ψ m3 should be set to zero to eliminate torque ripple. Therefore, the q3-axis current in the third harmonic subspace under fault conditions ( i q3 ) needs to be represented as:

[0135] .

[0136] Therefore, combined with the torque fluctuation component, the coefficient of the torque fluctuation component can be simplified to obtain the first equation, which includes the above four equations.

[0137] In one embodiment, the second equation in step c is as follows:

[0138] ,

[0139] ;

[0140] in, and The size of is related to the position of the fault switch tube in the multi-phase permanent magnet synchronous motor.

[0141] In order to ensure that the fault phase current is zero, the coefficients of the second equation constraining the phase current reconstruction matrix can be established. For example, taking a five-phase permanent magnet synchronous motor as an example, assuming that an open circuit fault occurs in phase B, and The angle can be 1.2π and 0.4π, and the second equation is:

[0142] ,

[0143] ;

[0144] The second equation can ensure that the B-phase current is zero throughout the entire operating cycle of the permanent magnet synchronous motor.

[0145] In one embodiment, the third equation in step d is:

[0146] ;

[0147] in, i m and i n Indicates the phase current corresponding to the remaining switching tubes in the inverter except the faulty switching tube, and the phase current i m and phase current i n symmetry; and The size of is related to the position of the faulty switch tube.

[0148] For example, based on the principle of symmetry of the residual phase current, taking a five-phase permanent magnet synchronous motor as an example, assuming that when an open-circuit fault occurs in phase B, the phase current of phase A should be equal to the phase current of phase C in the fundamental subspace. A third equation can be established to constrain the coefficients of the phase current reconstruction matrix. In this case, the third equation is:

[0149] ;

[0150] in, i a1 and i c1 Represent the phase currents of phase A and phase C in the fundamental subspace respectively.

[0151] In one embodiment, Figure 6 As shown, step e, solving the first equation, the second equation, and the third equation to determine the value of the reconstruction coefficient in the phase current reconstruction matrix, includes the following steps:

[0152] Step 601: Solve the first equation, the second equation, and the third equation to obtain multiple sets of reconstruction coefficient values, wherein the value of a set of reconstruction coefficients can determine a phase current reconstruction matrix.

[0153] Taking a five-phase permanent magnet synchronous motor as an example, assuming that an open circuit fault occurs in phase B, the second equation and The angle can be 1.2π and 0.4π. The third equation calculates that the phase current of phase A should be equal to the phase current of phase C.

[0154] Furthermore, the first equation includes four equations, namely:

[0155] ,

[0156] ,

[0157] ,

[0158] .

[0159] The second equation is:

[0160] ,

[0161] .

[0162] The third equation is:

[0163] .

[0164] By jointly calculating the three equations, multiple sets of reconstruction coefficients are obtained. Each set of reconstruction coefficients corresponds to a phase current reconstruction matrix. The phase current reconstruction matrix is used to adjust the current distribution in the fundamental subspace and the third harmonic subspace to ensure a reasonable current distribution under fault conditions and reduce torque fluctuations.

[0165] Step 602: Based on the constraint of minimizing copper loss, determine an optimal set of reconstruction coefficient values from multiple sets of reconstruction coefficient values, and use the optimal set as the value of the reconstruction coefficient in the phase current reconstruction matrix.

[0166] Minimizing Copper Loss (ML) constraint. To minimize copper loss, it is necessary to calculate the effective value of the phase current in the healthy half-cycle and the fault half-cycle respectively. Therefore, based on the ML constraint, it can be expressed as:

[0167] ;

[0168] in,P cuf Indicates the copper loss during the fault half cycle; P cuh Indicates the copper loss under healthy half cycle; i xnh and i xnf (x= 、 、 , n=1, 3) represent the reconstruction current under healthy half cycle and fault half cycle respectively, R is the resistance of the permanent magnet synchronous motor winding.

[0169] The copper loss corresponding to each set of reconstruction coefficient values is calculated separately, and the copper losses corresponding to different sets of reconstruction coefficient values are compared. The set of reconstruction coefficient values with the lowest copper loss is selected as the optimal set, and its compliance with all constraints is verified. At this point, a phase current reconstruction matrix is determined based on this set of reconstruction coefficient values. This phase current reconstruction matrix corresponds to the multiphase permanent magnet synchronous motor with the lowest copper loss and torque ripple. For example, assuming there are three sets of reconstruction coefficient values, the copper loss corresponding to each set of reconstruction coefficient values is calculated separately. The copper losses corresponding to each set of reconstruction coefficient values are compared, and the set with the lowest copper loss is selected as the optimal set, thereby optimizing the performance and efficiency of the permanent magnet synchronous motor.

[0170] In one embodiment, the health state reconstruction matrix K h It includes multiple reconstruction coefficients, which are selected based on the fluctuation of electromagnetic torque so that the torque fluctuation is zero; wherein the healthy state reconstruction matrix K h The reconstruction coefficient in is expressed as:

[0171] ;

[0172] in, K xyh Reconstructing the matrix for health K h The reconstruction coefficient in , K xyh Indicates the correlation coefficient (x, y =) required to map the y-axis current to the x-axis in the healthy half cycle. 、 、 ); and represents the coordinate axis in the fundamental subspace; and Represents the coordinate axes in the third harmonic subspace.

[0173] For example, taking a five-phase permanent magnet synchronous motor as an example, assume that the B phase has an open circuit fault. To ensure that the B phase current is zero when switching between the fault state and the healthy state mode, the current is injected at this moment. α 1. β The reconstructed current of axis 1 should also have a current reference value of zero in phase B after Clarke transformation. Therefore, two constraints can be determined as follows:

[0174] .

[0175] According to the principle of symmetrical residual phase current, the current values of adjacent and non-adjacent phases must remain consistent before and after switching. Taking the open circuit fault of phase B as an example, the current values of phases A and D must remain consistent before and after switching. This constraint can be expressed as:

[0176] ;

[0177] in, f iah and f idh Respectively represent the A-phase and D-phase currents in the healthy half cycle; f iaf and f idf They represent the A-phase and D-phase currents during the fault half cycle respectively.

[0178] Therefore, in the healthy half-cycle, the above eight equations can be used to determine the eight reconstruction coefficient values of the healthy state reconstruction matrix.

[0179] In one embodiment, a current sensor is used to sample the current of a multi-phase permanent magnet synchronous motor, and a position sensor is used to detect the real-time speed and rotor position angle, thereby forming a closed-loop control system. The speed of the multi-phase permanent magnet synchronous motor is detected as the speed feedback n of the permanent magnet synchronous motor. The feedback speed is compared with a given speed to obtain a speed error e. The speed error e is input into a repetitive controller to calculate the q-axis current in the given fundamental subspace. A phase current reference value is calculated based on the rotor position angle and Park and Clarke variations. The difference between the phase current reference value and the measured value is used as input to a repetitive controller to obtain a reference voltage for each phase of the multi-phase permanent magnet synchronous motor. A voltage source inverter is then used to implement pulse width modulation (CPWM) to achieve undisturbed operation of the multi-phase permanent magnet synchronous motor in the event of an open-circuit fault in a single switch.

[0180] In one embodiment, the effective values of phase currents in two modes are used to establish an analysis method for torque derating when a single switch is open-circuited, and the torque derating corresponding to different faults is calculated based on a multi-phase motor model.

[0181] Determining the effective value of the phase current requires combining the coefficients of the healthy half cycle and the fault half cycle. The maximum effective value of the phase current (imaxrms ) can be expressed by the following formula:

[0182] ;

[0183] in, i 1fmax and i 3fmax are the maximum residual phase current amplitudes of the fundamental wave and the third harmonic in the fault half cycle respectively; i 1hmax and i 3hmax They are the maximum residual phase current amplitudes of the fundamental and third harmonic in the healthy half cycle respectively.

[0184] Based on the residual phase current amplitude, the correlation coefficient of each residual phase current amplitude is introduced k s , in order to better describe the relationship between the maximum phase current amplitude and the minimum phase current amplitude in a single switch tube fault. According to the determined current reconstruction coefficient, the amplitude of the maximum value of the remaining phase current can be obtained by k s Expressed as:

[0185] ;

[0186] in, i q1s is the maximum fundamental phase current of the q1 axis when a single switch fails; i q3s is the maximum fundamental phase current of the Q3 axis when a single switch fails, i q1s = K 13 i q3s .

[0187] Similar to the maximum phase current RMS, the minimum phase current RMS ( i minrms ) can also be determined by the amplitude of the fundamental and third harmonic residual phase currents, expressed as:

[0188] ;

[0189] in, i 1fmin and i 3fmin are the minimum residual phase current amplitudes of the fundamental wave and the third harmonic in the fault half cycle respectively; i 1hmin and i 3hmin They are the minimum residual phase current amplitudes of the fundamental and third harmonic in the healthy half cycle respectively.

[0190] In addition, the amplitudes of the fundamental and third harmonic minimum residual phase currents can be obtained from k s Expressed as:

[0191] .

[0192] For ML constraints, based on the symmetry of the residual phase current, the following formula can be used to select k s value:

[0193] .

[0194] From the above formula, we can see that no matter K 13 What is the value of ? k s = 0. Therefore, for the ML constraint, k s =0.

[0195] The combined rated torque and the maximum electromagnetic torque due to fault, the de-rating factor a of a multi-phase motor with a single switch tube open circuit fault can be calculated as:

[0196] ;

[0197] in, T es represents the maximum electromagnetic torque, T rated Indicates rated torque.

[0198] It should be noted that the calculation of the effective value of the phase current is combined with the fundamental and third harmonic current amplitudes in the healthy and faulty half-cycles to fully reflect the current characteristics of the multi-phase permanent magnet synchronous motor under fault conditions. k s The purpose is to better describe the relationship between the maximum phase current amplitude and the minimum phase current amplitude in a single switch tube fault, so as to more accurately evaluate the impact of the fault on the performance of the permanent magnet synchronous motor. k s =0 can ensure that copper loss is minimized, that is, k s = 0, the copper loss expression reaches its minimum, thus optimizing the efficiency of the multi-phase permanent magnet synchronous motor. The derating factor a can be obtained by comparing the maximum electromagnetic torque under fault conditions. T es With rated torque T rated ,The quantification of the impact of faults on the torque output ,capacity of permanent magnet synchronous motors provides an important basis for the ,fault-tolerant design and performance evaluation of multi-phase permanent magnet synchronous motors.

[0199] In one embodiment, Figure 7 As shown in the figure, the fault-tolerant control system block diagram of the multi-phase permanent magnet synchronous motor is shown. The dq to αβ transformation module converts the current in the dq coordinate system to the αβ coordinate system; α and β are the two axes of the stationary coordinate system. The current reconstruction module adjusts the phase current distribution through the current reconstruction matrix when a single switch tube fails, so that i α1 、 i β1 、 i α3 as well as i β3 Convert to i α1r 、 i α3r 、 i β1r as well as i β3r . Ensure that the fault phase current i α1r 、 i α3r 、 i β1r as well as i β3r The αβ to ABCDE transformation module converts the current in the αβ coordinate system to the ABCDE phase current of the multi-phase motor. i A 、 i B 、 i C 、 i D as well as i E The deadbeat control module generates a voltage control signal based on the predicted current value. U A 、 U B 、 U C 、 U D as well as U E , ensuring that the current of the multi-phase permanent magnet synchronous motor quickly tracks the reference value and reduces the steady-state error; deadbeat control is used to improve the accuracy of current control. The inverter module converts the control signal into the voltage source U required by the multi-phase permanent magnet synchronous motor. dc , drives a multi-phase permanent magnet synchronous motor; CPWM stands for pulse width modulation, which is used to control the output voltage of the inverter. The fault tolerance coefficient determination module determines the reconstruction coefficient K based on the current characteristics of the healthy and fault half-cycles. hand K f , ensuring reasonable current distribution under fault conditions, reducing copper loss and optimizing torque output; k13 is the reconstruction coefficient, which can be used to adjust the fundamental subspace current i q1 and the current in the third harmonic subspace i q3 The current prediction module uses the current at time k to calculate the distribution of .. Predicting the phase current of a multi-phase permanent magnet synchronous motor at time k+1 .. , providing a reference for deadbeat control and improving control accuracy. The phase-locked loop module detects the speed and position of the motor and provides feedback signals to the control system to ensure stable motor operation. The photoelectric encoder module detects the rotor position of the motor θ e , providing position feedback for the phase-locked loop. The PI controller is used to regulate the current to ensure that the current tracks the reference value. n and n * Typically, this number represents a phase or node, used to distinguish different phases or nodes. These modules work together to ensure fault-tolerant control in the event of an open-circuit switch failure, maintaining smooth operation and reducing torque ripple.

[0200] In one embodiment, Figure 8 As shown, Figure 8 The upper center section shows the torque waveform, with a phase current of 2 A / div and a torque of 0.6 Nm / div. The blue line represents the torque. Under healthy conditions, the torque ripple is approximately 3.2%, while under fault conditions (without the fault tolerance algorithm), the torque ripple increases to 13.5%. The lower center section shows the phase current waveforms, with the different colored lines (red, green, yellow, cyan, and purple) representing the currents of phases A, B, C, D, and E, respectively. Under healthy conditions, the phase currents are symmetrical and stable; under fault conditions, the phase current waveforms exhibit distortion and fluctuations. The time axis for both the entire healthy and faulty states uses 500 ms / div, while the time axis for the partial healthy and faulty states uses 20 ms / div.

[0201] The B-phase upper arm switch is configured to have an open-circuit fault, and the torque and phase current waveforms for both the healthy state and the fault state without fault-tolerant control are obtained. The speed reference is set to 500 rpm, and the load is 1.5 Nm. Due to the T3 interruption fault, the B-phase current can be divided into two states: healthy state and fault state. The fault state current is always zero. The torque ripple can be quantified as the peak-to-peak torque and the average torque ( R TR ) can be calculated as:

[0202] ;

[0203] Among them, T fmax 、T fmin and T favg They refer to maximum torque, minimum torque and average torque respectively.

[0204] Under open-circuit fault conditions, the phase current amplitude and phase change erratically. The torque fluctuation in the faulty state is 4.218 times that in the healthy state, severely impacting the normal operation of a multiphase permanent magnet synchronous motor. Based on this, the proposed fault-tolerant control method is applied to further reduce the torque fluctuation under open-circuit fault conditions of the high-arm switch. Figure 9 The torque and phase current waveforms of the proposed fault-tolerant control method under ML constraints are shown when the upper arm switch of phase B has an open-circuit fault. Under ML constraints, the torque ripple after implementing the proposed open-circuit fault-tolerant control method is 3.7%, which is basically consistent with the torque ripple under healthy conditions. The ML-constrained fault-tolerant control method achieves undisturbed operation in the event of an open-circuit fault.

[0205] The technical features of the above embodiments can be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0206] The above embodiments merely represent several implementation methods of the present application. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present application. It should be noted that a person of ordinary skill in the art may make various modifications and improvements without departing from the spirit of the present application, and these modifications and improvements fall within the scope of protection of the present application. Therefore, the scope of protection of the present application shall be determined by the appended claims.

Claims

1. A method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes, characterized in that: include: In response to a switch failure of the inverter, determining the faulty switch; wherein, in the case where the switch failure of the inverter occurs, one working cycle of the inverter includes a faulty half cycle and a healthy half cycle; Determine the phase current reconstruction matrix under the fault half cycle and the phase current reconstruction matrix under the healthy half cycle corresponding to the faulty switch tube, which are defined as the fault state reconstruction matrix K f and health state reconstruction matrix K h , the fault state reconstruction matrix K f and the health state reconstruction matrix K h All are determined based on the fundamental subspace current and the third harmonic subspace current; the healthy state reconstruction matrix K h The system includes multiple reconstruction coefficients, which are selected based on the fluctuation of electromagnetic torque to ensure zero torque fluctuation. The fault phase current is zero when the fault half-cycle switches to the healthy half-cycle. The reconstructed current injected at this moment has a zero current reference value in the fault phase after Clarke transformation. According to the principle of symmetrical residual phase current, the current values of adjacent and non-adjacent phases remain consistent before and after the switching between the fault half-cycle and the healthy half-cycle. When the inverter is in the fault half cycle, the matrix is reconstructed based on the fault state. K f Reconstructing phase current reference values of the remaining switching tubes in the inverter except the faulty switching tube, and controlling the inverter to operate based on the phase current reference values to drive the multi-phase permanent magnet synchronous motor to operate; When the inverter is in the healthy half cycle, the matrix is reconstructed based on the healthy state. K h Reconstructing a phase current reference value of each switch tube in the inverter, and controlling the inverter to operate based on the phase current reference value to drive the multi-phase permanent magnet synchronous motor to operate; Combined with the reconstruction coefficient under the healthy half cycle and the fault half cycle to determine the effective value of the phase current, the correlation coefficient of each amplitude of the residual phase current is introduced on the basis of the residual phase current amplitude. k s , to describe the relationship between the maximum phase current amplitude and the minimum phase current amplitude in a single switch tube fault; exist k s =0, the maximum electromagnetic torque is determined according to the phase current under fault condition T es , and utilize the maximum electromagnetic torque T es The ratio of the fault to the rated torque determines the derating factor, which is used to quantify the impact of the fault on the motor's torque output capacity. Among them, the fault state reconstruction matrix K f Including multiple reconstruction coefficients, respectively calculate the effective value of the phase current in the healthy half cycle and the fault half cycle, respectively calculate the copper loss corresponding to each set of reconstruction coefficient values, and select the set of reconstruction coefficient values with the smallest copper loss as the fault state reconstruction matrix K f The value of the reconstruction coefficient in .

2. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 1, wherein: Determining a phase current reconstruction matrix in a fault half-cycle corresponding to the faulty switch tube includes: Based on the characteristics of the fundamental subspace and the third harmonic subspace of the multi-phase permanent magnet synchronous motor, a phase current reconstruction matrix is established under a half-cycle of a switch tube open circuit fault, wherein the phase current reconstruction matrix includes multiple reconstruction coefficients; wherein, in the switch tube fault state, the orthogonality of the fundamental subspace and the third harmonic subspace does not exist; The electromagnetic torque formula of the multi-phase permanent magnet synchronous motor is used to determine the reconstruction coefficient of the phase current reconstruction matrix without increasing the torque ripple.

3. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 2, wherein: The fault state reconstruction matrix K f including a first fault matrix and a second fault matrix; The first fault matrix is a mapping matrix from the fundamental subspace to the third harmonic subspace, and the second fault matrix is a mapping matrix from the third harmonic subspace to the fundamental subspace.

4. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 3, wherein: Based on the characteristics of the fundamental subspace and the third harmonic subspace of the multi-phase permanent magnet synchronous motor, a phase current reconstruction matrix is established under a half-cycle of a switch tube open circuit fault, including: establishing the first fault matrix by injecting the fundamental current into the third harmonic subspace; establishing the second fault matrix by injecting the third harmonic current into the fundamental subspace; Among them, both the first fault matrix and the second fault matrix include multiple reconstruction coefficients, the reconstruction coefficients in the first fault matrix are the correlation coefficients of the fundamental current mapped to the third harmonic subspace, and the reconstruction coefficients in the second fault matrix are the correlation coefficients of the third harmonic current mapped to the fundamental subspace.

5. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 3, wherein: The reconstruction coefficients of the first fault matrix are established in the following way: ； in, and Respectively represent the third harmonic subspace 、 the fundamental current on the axis; and Represent the fundamental subspace 、 Fundamental current on the shaft; K xyf is the reconstruction coefficient in the first fault matrix, which is used to represent the correlation coefficient (x, y = 、 、 ); The reconstruction coefficients of the second fault matrix are established in the following way: ； in, and Respectively represent the fundamental subspace 、 said third harmonic current on the shaft; and Respectively represent the third harmonic subspace 、 said third harmonic current on the shaft; K xyf is the reconstruction coefficient in the second fault matrix, which is used to represent the correlation coefficient required to map the y-axis current to the x-axis (x, y = 、 、 ).

6. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 5, characterized in that: Using the electromagnetic torque formula of the multi-phase permanent magnet synchronous motor, the reconstruction coefficient of the phase current reconstruction matrix is determined without increasing the torque ripple, including: Step a, determining the torque ripple term by the electromagnetic torque formula; in the open state of the switch tube fault, the current component of the fundamental subspace is coupled with the current component of the third harmonic subspace to cause torque ripple; Step b, determining a coefficient of the torque fluctuation term, and determining a first equation based on the coefficient of the torque fluctuation term being zero; Step c, determining a second equation based on that the phase current corresponding to the faulty switch is zero; Step d: determining a third equation based on the symmetry of phase currents corresponding to the remaining switching tubes in the inverter except the faulty switching tube; Step e: solving the first equation, the second equation, and the third equation to determine the values of the reconstruction coefficients in the phase current reconstruction matrix.

7. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 6, characterized in that: The coefficients of the torque fluctuation term include 3 i q3 ψ m1 + i q1 ψ m3 ; In the step b: based on the coefficient of the torque fluctuation term being zero, a first equation is determined. include: 3 i q3 ψ m1 + i q1 ψ m3 Forced to zero, we get ; Based on the coefficient of the torque fluctuation term being zero and , the first equation is obtained; the first equation includes multiple equations, and the multiple equations are as follows: ， ， ， ； in, K xyf is the reconstruction coefficient in the phase current reconstruction matrix (x, y = 、 、 ), ψ m1 and ψ m3 denote the flux linkage of the fundamental wave and the third harmonic respectively, i q1 and i q3 They represent the q1-axis current in the fundamental subspace and the q3-axis current in the third harmonic subspace respectively.

8. The method for operating a multi-phase permanent magnet synchronous motor with fault tolerance for switching tube failures according to claim 6, wherein: The second equation in step c is as follows: ， ； in, and The size of is related to the position of the fault switch tube in the multi-phase permanent magnet synchronous motor; The third procedure in step d is: ； in, i m and i n Indicates the phase current corresponding to the remaining switch tubes in the inverter except the faulty switch tube, and the phase current i m and phase current i n symmetry; and The size of is related to the position of the fault switch tube in the multi-phase permanent magnet synchronous motor.

9. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 6, wherein: Step e, solving the first equation, the second equation, and the third equation to determine the values of the reconstruction coefficients in the phase current reconstruction matrix, includes: Solving the first equation, the second equation, and the third equation to obtain multiple sets of reconstruction coefficient values, wherein the values of a set of reconstruction coefficients can determine a phase current reconstruction matrix; Based on the constraint of minimizing copper loss, an optimal set of reconstruction coefficient values is determined from the multiple sets of reconstruction coefficient values, and is used as the value of the reconstruction coefficient in the phase current reconstruction matrix.

10. The method for operating a multi-phase permanent magnet synchronous motor with fault-tolerant switching tubes according to claim 1, characterized in that: The health state reconstruction matrix K h The reconstruction coefficient in is expressed as: ； in, K xyh Reconstructing the matrix for health K h The reconstruction coefficient in , K xyh Indicates the correlation coefficient (x, y = 、 、 ); and represents the coordinate axes in the fundamental wave subspace; and Denotes the coordinate axes in the third harmonic subspace.

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