Dynamic correction method for feedback current in fault-tolerant operation transition stage of motor

Abstract

The invention discloses a dynamic correction method for feedback current in a fault-tolerant operation transition stage of a motor. The method comprises the steps of firstly judging a current operation stage of a motor according to a motor fault diagnosis algorithm, calculating expected current and feedback current of a current controller according to the current operation stage of the motor, and dynamically correcting the feedback current of the current controller by using a combination of a predicted value and a measured value when the motor is in a transition stage; and finally, the expected current and the feedback current are sent to a current controller to realize current closed-loop control. The dynamic correction method for the feedback current in the transition stage is simple in implementation process, and normal operation of the motor is not affected. In addition, the method can be combined with a fault-tolerant operation method, so that the motor system can be stably transited to a corresponding fault-tolerant operation algorithm after the current sensor breaks down, and the current impact caused by a current blind area is reduced.

Description

Technical Field

[0001] This invention relates to a method for correcting motor current, and to the field of motor drive and control technology, specifically to a method for dynamically correcting feedback current during the fault-tolerant operation transition phase of a motor. Background Technology

[0002] Accurate current measurement is crucial for achieving high-performance closed-loop vector control in motor systems. However, harsh operating environments such as high temperature, high humidity, and strong vibration can cause current sensors to malfunction, affecting motor control performance, causing periodic fluctuations in torque and speed, and reducing motor efficiency. Severe faults such as open-circuit failures and jamming can even lead to system shutdown. In certain specialized applications (such as electric vehicles), it is often necessary for the motor system to continue operating even when the current sensor fails. Therefore, researching fault-tolerant control strategies under current sensor failure conditions is of great significance.

[0003] Significant progress has been made in current sensor fault diagnosis algorithms and fault-tolerant operation methods for motor systems after sensor failure. For current sensor fault diagnosis, fault detection can be achieved by utilizing current characteristics (including the third-order difference operator and the second-order difference operator for measured current) and the residual between the measured and estimated values. Regarding fault-tolerant operation methods for motor drive systems, existing research shows that using the remaining healthy phase current sensor for fault-tolerant operation has better application prospects. The current mainstream method involves designing a current observer to estimate the motor stator current and thus achieve fault-tolerant operation of the motor system; this method can achieve good current control performance.

[0004] Although significant research has been conducted on fault diagnosis algorithms for current sensors and fault-tolerant operation methods for motor systems after sensor failures, no scholars have yet addressed the current blind zone issue arising during the fault location phase (i.e., the transition phase) due to the unknown actual current of the faulty phase. Existing methods all ignore the impact of the current blind zone, still using current measurements including those of the faulty phase for direct feedback. This can easily lead to control instability and even false triggering of overcurrent protection, causing system shutdown. This is the main reason why existing fault-tolerant strategies are difficult to apply in practice. Summary of the Invention

[0005] To address the problems existing in the background art, this invention provides a method for dynamically correcting the feedback current during the fault-tolerant operation transition phase of a motor. This invention divides the motor into three operating phases: a normal operating phase, a transition phase, and a fault-tolerant operating phase. During the transition phase, a combination of measured and predicted current values ​​is used to dynamically correct the feedback current of the current controller, reducing the impact of the current dead zone.

[0006] The technical solution adopted in this invention is: The method for dynamic correction of feedback current during the fault-tolerant operation transition phase of a motor according to the present invention includes: Step 1) Obtain the operating measurement values ​​of the permanent magnet synchronous motor, and then determine the operating stage of the permanent magnet synchronous motor through the motor fault diagnosis algorithm.

[0007] Step 2) Obtain the current control quantity based on the operating stage of the permanent magnet synchronous motor and the current prediction model.

[0008] Step 3) During different operating stages of the permanent magnet synchronous motor, the current control quantity is input into the current controller of the permanent magnet synchronous motor. After processing, the signal is transformed and modulated to obtain a switching signal, which is then applied to the inverter of the permanent magnet synchronous motor to achieve closed-loop control of the permanent magnet synchronous motor after dynamic current correction.

[0009] In step 1), the operating stages of the permanent magnet synchronous motor include normal operation, transition, and fault-tolerant operation. The motor fault diagnosis algorithm determines the specific operating stage by first using two current sensors to measure the A-phase current of the permanent magnet synchronous motor in real time. i Am and B-phase current measurement value i Bm During the measurement process, the A-phase abnormal time of the permanent magnet synchronous motor was obtained. t eA and Phase B abnormal time t eB This allows us to determine the fault flag position of phase A. Fault A and B-phase fault flag Fault B The final operating stage of the permanent magnet synchronous motor is determined as follows: like t eA =0 and t eB If the value is 0, the permanent magnet synchronous motor is in normal operation.

[0010] If 0 < t eA ≤ T fault or 0< t eB ≤ T fault , T fault During the fault time, the permanent magnet synchronous motor is in the transition phase.

[0011] like Fault A =1 or Fault BIf the value is 1, then the permanent magnet synchronous motor is in the fault-tolerant operation stage.

[0012] The abnormal time of phase A of the permanent magnet synchronous motor t eA and Phase B abnormal time t eB as follows:

[0013] in, and These represent the current control time. kT s and the previous control time ( k -1) T s The abnormal time of phase A, and They represent kT s Time and ( k -1) T s The abnormal time of phase B at time 1; T s This indicates the control cycle duration of the permanent magnet synchronous motor; i A ( k )and i B ( k ) respectively represent kT s The residual current of phase A and phase B at time t; I th This represents the current residual threshold.

[0014] The aforementioned A-phase fault flag bit Fault A and B-phase fault flag Fault B as follows:

[0015] when Fault A A value of 1 or 0 indicates that the current sensor measuring the current of phase A is faulty or healthy, respectively; when Fault B A value of 1 or 0 indicates that the current sensor measuring the B-phase current is either faulty or healthy, respectively.

[0016] The A-phase current residual i A and B-phase current residual i B as follows:

[0017] in, i A * and i B * These represent the reference values ​​for the A-phase and B-phase currents of the permanent magnet synchronous motor, respectively. e The electrical angle of the permanent magnet synchronous motor; i d * and i q * Let represent the desired d-axis and q-axis currents of the permanent magnet synchronous motor, respectively, derived from the rotational angular velocity of the permanent magnet synchronous motor. r get.

[0018] The operating measurements of a permanent magnet synchronous motor include the A-phase current measurement. i Am and B-phase current measurement value i Bm and the rotational angular velocity of the permanent magnet synchronous motor r .

[0019] In step 2), when the permanent magnet synchronous motor is in normal operation, the desired current and feedback current of the current controller are first determined as follows:

[0020] in, and These represent the desired currents along the d-axis and q-axis of the current controller, respectively. i d * and i q * Let represent the desired d-axis and q-axis currents of the permanent magnet synchronous motor, respectively. and These represent the d-axis and q-axis feedback currents of the current controller, respectively. i dm and i qm These represent the measured values ​​of the d-axis and q-axis currents of the permanent magnet synchronous motor, respectively.

[0021] Then, based on the current prediction model during normal operation, the measured d-axis current value of the permanent magnet synchronous motor is... i dmand q current measurement value i qm In the input current prediction model, the predicted d-axis current value is obtained in real time. i dmp and q current prediction value i qmp When entering the transition phase, the predicted d-axis current value at the final moment of the normal operation phase will be used. i dmp and q current prediction value i qmp The initial prediction values ​​of the improved current prediction model are used as the initial moment of the transition phase.

[0022] When a permanent magnet synchronous motor is in normal operation, the current control quantity is directly the desired current and feedback current of the current controller.

[0023] The current prediction model under normal operation is as follows:

[0024]

[0025]

[0026] in, i mp ( k () indicates the normal operation phase kT s Predicted current value of permanent magnet synchronous motor at any time. T s This indicates the control cycle duration of the permanent magnet synchronous motor. i mp ( k )=[ i dmp ( k ) i qmp ( k )] T , i dmp ( k )and i qmp ( k ) respectively represent kT s Predicted d-axis and q-axis current values ​​of a permanent magnet synchronous motor at any given time. i m ( k -1)=[ i dm ( k -1) i qm (k -1)] T , i dm ( k -1) and i qm ( k -1) respectively represent ( k -1) T s The measured values ​​of d-axis and q-axis current of the permanent magnet synchronous motor at any given time, where T represents the transpose of the matrix; and Let these represent the discrete current state matrix and the current state matrix, respectively. and Represent the discrete voltage state matrix and the voltage state matrix, respectively. and Let represent the discrete state matrix of the flux linkage and the state matrix of the flux linkage, respectively; u * ( k -1) represents ( k -1) T s Reference value of stator voltage for permanent magnet synchronous motor at all times. u * ( k -1)=[ u d * ( k -1) u q * ( k -1)] T , u d * ( k -1) and u q * ( k -1) respectively represent ( k -1) T s Reference values ​​for the d-axis and q-axis stator voltages of the permanent magnet synchronous motor at all times; fn This indicates the nominal value of the permanent magnet flux linkage in a permanent magnet synchronous motor. Represents the identity matrix; R sn This indicates the nominal value of the stator phase resistance of a permanent magnet synchronous motor. L dn and L qn These represent the nominal values ​​of the stator inductance along the d-axis and q-axis of the permanent magnet synchronous motor, respectively. e This indicates the electrical angular velocity of the permanent magnet synchronous motor.

[0027] In step 2), when the permanent magnet synchronous motor is in the transition phase, the desired current of the current controller is the same as that in the normal operation phase. The feedback current of the current controller is dynamically corrected through a feedback current dynamic correction method, as follows: First, an improved current prediction model is established, as follows:

[0028] in, i p ( k )and i p ( k -1) indicates the transition phase kT s Time and ( k -1) T s The optimized current prediction value for the permanent magnet synchronous motor at any given time is obtained by using the current prediction value from the previous time step as the initial current prediction value for the current time step. i p ( k )=[ i dp ( k ) i qp ( k )] T , i dp ( k )and i qp ( k ) respectively represent kT s Predicted and optimized values ​​for the d-axis and q-axis currents of a permanent magnet synchronous motor at any given time; Represents the discrete state matrix of the current. Represents the discrete state matrix of voltage. Represents the discrete state matrix of the magnetic flux linkage; i mp ( k -1) indicates the normal operating phase ( k -1) T s Predicted current value of permanent magnet synchronous motor at any time; u * ( k -1) represents ( k -1) T s Reference value of stator voltage of permanent magnet synchronous motor at all times; fn This indicates the nominal value of the permanent magnet flux linkage in a permanent magnet synchronous motor. t e Indicates the maximum abnormal time. t e =max( t eA , t eB ); T s This indicates the duration of the control cycle for a permanent magnet synchronous motor.

[0029] Based on the improved current prediction model, the optimized current prediction value of the permanent magnet synchronous motor during the transition phase is obtained, and the corrected feedback current of the current controller is calculated as follows:

[0030] in, Indicating the transition phase kT s The feedback current of the permanent magnet synchronous motor at all times. i F0 ( k )=[ i d F0 ( k ) i q F0 ( k )] T , i d F0 ( k )and i q F0 ( k ) respectively represent the transition phase kT s Given the d-axis and q-axis feedback currents of the permanent magnet synchronous motor at constant time, then the d-axis feedback current of the current controller... i d,fdb = i d F0 q-axis feedback current i q,fdb = i q F0 .

[0031] When the permanent magnet synchronous motor is in the transition phase, the current control quantity is the desired current of the current controller and the corrected feedback current.

[0032] In step 2), when the permanent magnet synchronous motor is in the fault-tolerant operation stage, the existing fault-tolerant operation method is used to correct the feedback current of the permanent magnet synchronous motor in order to achieve fault-tolerant operation of the permanent magnet synchronous motor. The current control quantity is the expected current of the current controller and the corrected feedback current.

[0033] In step 3), the current control quantity is input into the current controller of the permanent magnet synchronous motor for closed-loop control, and the d-axis reference voltage is obtained after processing. u d * and q-axis reference voltage u q * d-axis reference voltage u d * and q-axis reference voltage u q * Obtain the stationary coordinate system after coordinate transformation Shaft reference voltage u α * and Shaft reference voltage u β * ,Will Shaft reference voltage u α * and Shaft reference voltage u β * The voltage is modulated as input to the Space Vector Pulse Width Modulation (SVPWM) algorithm to ultimately obtain the switching signal.

[0034] The beneficial effects of this invention are: 1. This invention divides motor operation into normal operation stage, transition stage and fault-tolerant operation stage. The proposed dynamic correction strategy for feedback current in the transition stage is simple to implement and does not affect the control performance of the motor during normal operation.

[0035] 2. This invention uses a combination of measured and predicted values ​​to dynamically correct the feedback current during the transition phase, which can reduce the current surge caused by the current blind zone. It can also be combined with fault-tolerant operation methods to enable the motor system to smoothly transition to the corresponding fault-tolerant operation algorithm after the current sensor fails. Attached Figure Description

[0036] Figure 1 This is a control block diagram of the method of the present invention; Figure 2 The waveform diagram shows the experimental results when the B-phase current sensor malfunctions without the addition of a transition phase feedback current correction. Figure 3 The experimental results waveform diagram of the transition phase feedback current correction proposed in this invention when the B-phase current sensor fails. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0038] like Figure 1 As shown, the method for dynamic correction of feedback current during the fault-tolerant operation transition phase of the motor according to the present invention is as follows: Step 1) Obtain the operating measurement values ​​of the permanent magnet synchronous motor, and then determine the operating stage of the permanent magnet synchronous motor through the motor fault diagnosis algorithm. The operating stages of the permanent magnet synchronous motor include the normal operation stage, the transition stage, and the fault-tolerant operation stage. Specifically, the motor fault diagnosis algorithm determines the operating stage of the motor by first using two current sensors to measure the A-phase current of the permanent magnet synchronous motor in real time. i Am and B-phase current measurement value i Bm During the measurement process, the A-phase abnormal time of the permanent magnet synchronous motor was obtained. t eA and Phase B abnormal time t eB This allows us to determine the fault flag position of phase A. Fault A and B-phase fault flag Fault B The final operating stage of the permanent magnet synchronous motor is determined as follows: like t eA =0 and t eB If the value is 0, the permanent magnet synchronous motor is in normal operation.

[0039] If 0 < t eA ≤ T fault or 0< t eB ≤ T fault , T fault During the fault time, the permanent magnet synchronous motor is in the transition phase.

[0040] like Fault A =1 or Fault BIf the value is 1, then the permanent magnet synchronous motor is in the fault-tolerant operation stage.

[0041] A-phase abnormal time of permanent magnet synchronous motor t eA and Phase B abnormal time t eB as follows: ; in, and These represent the current control time. kT s and the previous control time ( k -1) T s The abnormal time of phase A, and They represent kT s Time and ( k -1) T s The abnormal time of phase B at time _____. k For any natural number greater than 0, t eA and t eB initial value t eA (0) and t eB (0) is 0; T s This indicates the control cycle duration of the permanent magnet synchronous motor; i A ( k )and i B ( k ) respectively represent kT s The residual current of phase A and phase B at time t; I th This represents the current residual threshold.

[0042] Phase A current residual i A and B-phase current residual i B as follows:

[0043] in, i A * and iB * These represent the reference values ​​for the A-phase and B-phase currents of the permanent magnet synchronous motor, respectively. e The electrical angle of the permanent magnet synchronous motor is the rotational angular velocity obtained from the position sensor. r Calculated; i d * and i q * Let represent the desired d-axis and q-axis currents of the permanent magnet synchronous motor, respectively, derived from the rotational angular velocity of the permanent magnet synchronous motor. r Specifically, it is obtained from preset torque commands. T e * and the current rotational angular velocity of the permanent magnet synchronous motor r Obtained by looking up the table.

[0044] Phase A fault flag Fault A and B-phase fault flag Fault B as follows: ; when Fault A A value of 1 or 0 indicates that the current sensor measuring the current of phase A is faulty or healthy, respectively; when Fault B A value of 1 or 0 indicates that the current sensor measuring the B-phase current is either faulty or healthy, respectively.

[0045] The operating measurements of a permanent magnet synchronous motor include the A-phase current measurement. i Am and B-phase current measurement value i Bm and the rotational angular velocity of the permanent magnet synchronous motor r .

[0046] Step 2) Obtain the current control quantity based on the operating stage of the permanent magnet synchronous motor and the current prediction model.

[0047] When the permanent magnet synchronous motor is in normal operation, the desired current and feedback current of the current controller are first determined as follows:

[0048] in, and These represent the desired currents along the d-axis and q-axis of the current controller, respectively.i d * and i q * Let represent the desired d-axis and q-axis currents of the permanent magnet synchronous motor, respectively. and These represent the d-axis and q-axis feedback currents of the current controller, respectively. i dm and i qm These represent the measured values ​​of the d-axis and q-axis currents of the permanent magnet synchronous motor, respectively, derived from the measured values ​​of the A and B phase currents of the permanent magnet synchronous motor. i Am and i Bm It is obtained through Park coordinate transformation.

[0049] Then, based on the current prediction model during normal operation, it is as follows: ; ; ; in, i mp ( k () indicates the normal operation phase kT s Predicted current value of permanent magnet synchronous motor at any time. T s This indicates the control cycle duration of the permanent magnet synchronous motor. i mp ( k )=[ i dmp ( k ) i qmp ( k )] T , i dmp ( k )and i qmp ( k ) respectively represent kT s Predicted d-axis and q-axis current values ​​of a permanent magnet synchronous motor at any given time. i m ( k -1)=[ i dm ( k -1) i qm ( k -1)] T ,i dm ( k -1) and i qm ( k -1) respectively represent ( k -1) T s The measured values ​​of d-axis and q-axis current of the permanent magnet synchronous motor at any given time, where T represents the transpose of the matrix; and Let these represent the discrete current state matrix and the current state matrix, respectively. and Represent the discrete voltage state matrix and the voltage state matrix, respectively. and Let represent the discrete state matrix of the flux linkage and the state matrix of the flux linkage, respectively; u * ( k -1) represents ( k -1) T s Reference value of stator voltage for permanent magnet synchronous motor at all times. u * ( k -1)=[ u d * ( k -1) u q * ( k -1)] T , u d * ( k -1) and u q * ( k -1) respectively represent ( k -1) T s Reference values ​​for the d-axis and q-axis stator voltages of the permanent magnet synchronous motor at all times; fn This indicates the nominal value of the permanent magnet flux linkage in a permanent magnet synchronous motor. Represents the identity matrix; R sn This indicates the nominal value of the stator phase resistance of a permanent magnet synchronous motor. L dn and L qn These represent the nominal values ​​of the stator inductance along the d-axis and q-axis of the permanent magnet synchronous motor, respectively. e The electrical angular velocity of a permanent magnet synchronous motor is expressed by its rotational angular velocity. r Obtained through calculation.

[0050] The d-axis current measurement value of the permanent magnet synchronous motor i dm and q current measurement value i qm In the input current prediction model, the predicted d-axis current value is obtained in real time. i dmp and q current prediction value i qmp This is to correct the current controller feedback value in case of sensor malfunction. When entering the transition phase, the predicted d-axis current value at the final moment of the normal operation phase is used. i dmp and q current prediction value i qmp The initial prediction values ​​of the improved current prediction model are used as the initial moment of the transition phase.

[0051] When a permanent magnet synchronous motor is in normal operation, the current control quantity is directly the desired current and feedback current of the current controller.

[0052] When the permanent magnet synchronous motor is in the transition phase, the desired current of the current controller is the same as that in the normal operation phase. The feedback current of the current controller is dynamically corrected through a dynamic correction method, as follows: First, an improved current prediction model is established, as follows:

[0053] in, i p ( k )and i p ( k -1) indicates the transition phase kT s Time and ( k -1) T s The optimized current prediction value for the permanent magnet synchronous motor at any given time is obtained by using the current prediction value from the previous time step as the initial current prediction value for the current time step. i p ( k )=[ i dp ( k ) i qp ( k )] T , i dp ( k )and iqp ( k ) respectively represent kT s Predicted and optimized values ​​for the d-axis and q-axis currents of a permanent magnet synchronous motor at any given time; Represents the discrete state matrix of the current. Represents the discrete state matrix of voltage. Represents the discrete state matrix of the magnetic flux linkage; i mp ( k -1) indicates the normal operating phase ( k -1) T s Predicted current value of permanent magnet synchronous motor at any time; u * ( k -1) represents ( k -1) T s Reference value of stator voltage of permanent magnet synchronous motor at all times; fn This indicates the nominal value of the permanent magnet flux linkage in a permanent magnet synchronous motor. t e Indicates the maximum abnormal time. t e =max( t eA , t eB ); T s This indicates the duration of the control cycle for a permanent magnet synchronous motor.

[0054] Based on the improved current prediction model, the optimized current prediction value of the permanent magnet synchronous motor during the transition phase is obtained, and the corrected feedback current of the current controller is calculated as follows:

[0055] in, Indicating the transition phase kT s The feedback current of the permanent magnet synchronous motor at all times. i F0 ( k )=[ i d F0 ( k ) i q F0 ( k )] T , i d F0 ( k )andi q F0 ( k ) respectively represent the transition phase kT s Given the d-axis and q-axis feedback currents of the permanent magnet synchronous motor at constant time, then the d-axis feedback current of the current controller... i d,fdb = i d F0 q-axis feedback current i q,fdb = i q F0 .

[0056] When the permanent magnet synchronous motor is in the transition phase, the current control quantity is the desired current of the current controller and the corrected feedback current.

[0057] When the permanent magnet synchronous motor is in the fault-tolerant operation stage, the existing fault-tolerant operation method is used to correct the feedback current of the permanent magnet synchronous motor in order to achieve fault-tolerant operation of the permanent magnet synchronous motor. The current control quantity is the expected current of the current controller and the corrected feedback current.

[0058] Step 3) During different operating stages of the permanent magnet synchronous motor, the current control quantity is input into the current controller of the permanent magnet synchronous motor for closed-loop control. The current controller can be a proportional-integral (PI) controller, and the d-axis reference voltage is obtained after processing. u d * and q-axis reference voltage u q * d-axis reference voltage u d * and q-axis reference voltage u q * Obtain the stationary coordinate system after coordinate transformation Shaft reference voltage u α * and Shaft reference voltage u β * ,Will Shaft reference voltage u α * and Shaft reference voltage u β *The voltage is modulated as input to the Space Vector Pulse Width Modulation (SVPWM) algorithm to obtain a switching signal, which is then applied to the inverter of the permanent magnet synchronous motor to achieve closed-loop control of the permanent magnet synchronous motor after dynamic current correction.

[0059] To verify the effectiveness and superiority of the proposed method for dynamic correction of feedback current during the fault-tolerant operation transition phase of a motor, experimental verification was conducted. The control cycle of the algorithm during the experiment was... T s =50us, downtime T fault =250us. The experiment uses an interior permanent magnet synchronous motor (IPMSM) as an example; the parameters are shown in Table 1. Table 1

[0060] The method proposed in this invention was experimentally verified by combining it with an existing fault-tolerant operation method (Fault-Tolerant Control of Primary Permanent-Magnet Linear Motors With Single Phase Current Sensor for Subway Applications). Under operating conditions of a motor speed of 1000 r / min and a given torque of 200 N·m, a disconnection fault occurred in the B-phase current sensor, as shown below. Figure 2 and Figure 3 As shown, experimental results are presented for the method without transition stage feedback current correction and the method with transition stage feedback current dynamic correction introduced in this invention, respectively. The first row shows the feedback current of the current controller. i d,fdb and i q,fdb The experimental waveforms, the second line shows the expected current along the d-axis of the motor. i d * Actual current i d Waveform, q-axis desired current i q * Actual current i q The waveform, the third line shows the actual three-phase current of the motor. i A , i B , i C Waveform, fourth line is the fault flag bit FaultB Waveform diagram. In the diagram, "Stage I" represents the normal operation stage, "Stage II" represents the transition stage, and "Stage III" represents the fault-tolerant operation stage. Experimental results show that combining this invention with existing fault-tolerant operation methods can achieve continuous operation of the motor system under B-phase current sensor failure. However, in the transition stage, if the influence of the current feedback blind zone is not considered and the measured value is used directly for feedback, a large current surge will occur. This invention, by using the measured value… i dm , i qm and predicted value i dp , i qp At the same time, the feedback current is corrected, reducing the current surge of phase B from 286.9A to 235.6A and the current surge of phase C from -296.3A to -254.9A, with a surge reduction of 17.9%.

[0061] The above description of the embodiments is provided to enable those skilled in the art to understand and apply the present invention. Those skilled in the art can readily make various modifications to the above embodiments and apply the general principles described herein to other embodiments without creative effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made to the present invention by those skilled in the art based on the disclosure thereof should be within the scope of protection of the present invention.

Claims

1. A method for dynamic correction of feedback current during a transition phase of fault-tolerant operation of an electric machine, characterized in that, Comprising: Step 1) obtaining the running measurement value of the permanent magnet synchronous motor, and then judging the running stage of the permanent magnet synchronous motor through the motor fault diagnosis algorithm; Step 2) obtaining the current control quantity according to the running stage of the permanent magnet synchronous motor and the current prediction model; Step 3) under different running stages of the permanent magnet synchronous motor, input the current control quantity into the current controller of the permanent magnet synchronous motor, process it, and then obtain the switching signal after transformation and voltage modulation and apply it to the inverter of the permanent magnet synchronous motor, so as to realize the closed-loop control of the permanent magnet synchronous motor after current dynamic correction.

2. The method of claim 1, wherein: In the step 1), the operation stage of the permanent magnet synchronous motor includes a normal operation stage, a transition stage and a fault-tolerant operation stage, and the operation stage of the motor is determined by a motor fault diagnosis algorithm, specifically, first, the A-phase current measurement value and the B-phase current measurement value of the permanent magnet synchronous motor are measured in real time by using two current sensors respectively i Am , and then the A-phase abnormal time i Bm and the B-phase abnormal time t eA of the permanent magnet synchronous motor are obtained during the measurement process t eB , and then the A-phase fault flag Fault A and the B-phase fault flag Fault B are determined, and finally the operation stage of the permanent magnet synchronous motor is determined as follows: If t eA = 0 and t eB = 0, the permanent magnet synchronous motor is in normal operation stage; if 0 t eA ≤ T fault or 0 t eB ≤ T fault , T fault is the fault time, then the permanent magnet synchronous motor is in the transition stage; If Fault A = 1 or Fault B = 1, the permanent magnet synchronous motor is in a fault-tolerant operating phase.

3. The method of claim 2, wherein: The A-phase abnormal time of the permanent magnet synchronous motor t eA And the B-phase abnormal time t eB As follows: ； wherein, and respectively represent the A-phase abnormal time at the current control time kT s and the last control time k -1) T s respectively represent the B-phase abnormal time at the current control time and respectively represent kT s the current control time and k -1) T s the last control time; T s represents the control cycle length of the permanent magnet synchronous motor; i A k ) and i B k respectively represent the A-phase current residual and the B-phase current residual at the current control time kT s and the last control time; I th represents the current residual threshold value;​​ The A-phase fault flag bit Fault A and the B-phase fault flag bit Fault B as follows: ； When Fault A represents a current sensor fault or health measuring phase A current when Fault B represents a current sensor fault or health measuring phase B current when 4. The method of claim 3, wherein: the A-phase current residual i A and the B-phase current residual i B as follows: ； wherein, i A * and i B * respectively represent the A-phase and B-phase current reference values of the permanent magnet synchronous motor; e is the electrical angle of the permanent magnet synchronous motor; i d * and i q * respectively represent the d-axis and q-axis desired currents of the permanent magnet synchronous motor, obtained from the rotational angular velocity of the permanent magnet synchronous motor r . The operating measurements of the permanent magnet synchronous motor include an A-phase current measurement of the permanent magnet synchronous motor i Am and a B-phase current measurement i Bm and a rotational angular velocity of the permanent magnet synchronous motor r .

5. The method of claim 2, wherein: In step 2), when the permanent magnet synchronous motor is in normal running stage, first determine the expected current and feedback current of the current controller as follows: ； wherein, and id*and iq*denote the d-axis and q-axis desired currents of the current controller, i d * and i q * id*and iq*denote the d-axis and q-axis desired currents of the permanent magnet synchronous machine, and id and iq denote the d-axis and q-axis feedback currents of the current controller; i dm and i qm id and iq denote the d-axis and q current measurements of the permanent magnet synchronous machine; Then based on the current prediction model under normal operation phase, the d-axis current measurement value of permanent magnet synchronous motor i dm and q current measurement value i qm The d-axis current prediction value in the input current prediction model is obtained in real time i dmp and q current prediction value i qmp When entering the transition phase, the d-axis current prediction value at the final time of the normal operation phase i dmp and q current prediction value i qmp As the initial value of the improved current prediction model at the initial time of the transition phase; When the permanent magnet synchronous motor is in normal running stage, the current control quantity is directly the expected current and feedback current of the current controller.

6. The method of claim 5, wherein: The current prediction model under the normal running stage is as follows: ； ； ； wherein, i mp ( k ) represents the current prediction value of the permanent magnet synchronous motor at the time point kT s , T s represents the control period length of the permanent magnet synchronous motor, i mp ( k )=[ i dmp ( k ) i qmp ( k )] T , i dmp ( k ) and i qmp ( k ) respectively represent the d-axis and q-axis current prediction values of the permanent magnet synchronous motor at the time point kT s , i m ( k -1)=[ i dm ( k -1) i qm ( k -1)] T , i dm ( k -1) and i qm ( k -1) respectively represent the d-axis and q-axis current measurement values of the permanent magnet synchronous motor at the time point k T s , and respectively represent the current discrete state matrix and the current state matrix, and respectively represent the voltage discrete state matrix and the voltage state matrix, and respectively represent the flux linkage discrete state matrix and the flux linkage state matrix; u * ( k -1) represents the stator voltage reference value of the permanent magnet synchronous motor at the time point k T s , u * (​​ k -1)=[ u d * ( k -1) u q * ( k -1)] T , u d * ( k -1) and u q * ( k -1) respectively represent k -1) T s the d-axis and q-axis stator voltage reference values of the permanent magnet synchronous motor at time instant fn represents the nominal value of the permanent magnet flux linkage of the permanent magnet synchronous motor; represents the identity matrix; R sn represents the nominal value of the stator phase resistance of the permanent magnet synchronous motor, L dn and L qn represent the nominal values of the d-axis and q-axis stator inductances of the permanent magnet synchronous motor, respectively; e represents the electrical angular speed of the permanent magnet synchronous motor.

7. The method of claim 2, wherein: In step 2), when the permanent magnet synchronous motor is in transition stage, the expected current of the current controller is the same as that in normal running stage, and the feedback current of the current controller is dynamically corrected by the feedback current dynamic correction method, as follows: First, an improved current prediction model is established, which is as follows: ； wherein, i p ( k ) and i p ( k -1) represents the transition stage under kT s moment and( k -1) T s the current prediction value of the permanent magnet synchronous motor at the moment, the current prediction value at the previous moment is taken as the current prediction initial value, i p ( k )=[ i dp ( k ) i qp ( k )] T , i dp ( k ) and i qp ( k ) respectively represent kT s the d-axis and q-axis current prediction optimization values of the permanent magnet synchronous motor at the moment; represents the current discrete state matrix, represents the voltage discrete state matrix, represents the flux linkage discrete state matrix; i mp ( k -1) represents the normal operation stage under k -1) T s the current prediction value of the permanent magnet synchronous motor at the moment; u * ( k -1) represents k -1) T s the stator voltage reference value of the permanent magnet synchronous motor at the moment; fn represents the nominal value of the permanent magnet flux linkage of the permanent magnet synchronous motor; t e represents the maximum abnormal time, t e =max( t eA , t eB ); T s represents the control period length of the permanent magnet synchronous motor; According to the improved current prediction model, the current prediction optimization value of the permanent magnet synchronous motor in the transition stage is obtained, so as to calculate the corrected feedback current of the current controller as follows: ； wherein, represent the d-axis and q-axis feedback currents of the PMSM at the transition stage, kT s the d-axis and q-axis feedback currents of the PMSM at the instant, i F0 k i d F0 k i q F0 k T , i d F0 k i q F0 k kT s the d-axis and q-axis feedback currents of the PMSM at the instant, i d,fdb = i d F0 the d-axis and q-axis feedback currents of the PMSM at the instant, i q,fdb = i q F0 ;​​​​​​​​​​ When the permanent magnet synchronous motor is in transition stage, the current control quantity is the expected current and the corrected feedback current of the current controller.

8. The method of claim 2, wherein: In step 2), when the permanent magnet synchronous motor is in fault-tolerant running stage, the existing fault-tolerant running method is used to correct the feedback current of the permanent magnet synchronous motor to realize the fault-tolerant running of the permanent magnet synchronous motor, and the current control quantity is the expected current and the corrected feedback current of the current controller.

9. The motor fault-tolerant running transition stage feedback current dynamic correction method of claim 1, characterized in that: The current control amount in step 3) is input into the current controller of the permanent magnet synchronous motor for closed-loop control, and the d-axis reference voltage and the q-axis reference voltage are obtained after processing u d * and the q-axis reference voltage u q * The d-axis reference voltage and the q-axis reference voltage are obtained after processing u d * and the q-axis reference voltage u q * The d-axis reference voltage and the q-axis reference voltage are obtained after processing u α * and the q-axis reference voltage u β * The d-axis reference voltage and the q-axis reference voltage are obtained after processing u α * and the q-axis reference voltage u β * The d-axis reference voltage and the q-axis reference voltage are obtained after processing, and the switching signal is finally obtained as the input of the space vector pulse width modulation (SVPWM) algorithm.​​​​

Images