Natural fault-tolerant control method for multivariable combined diagnosis of symmetric six-phase permanent magnet synchronous motor

Abstract

The invention discloses a natural fault-tolerant control method for multivariable combined diagnosis of a symmetric six-phase permanent magnet synchronous motor, and the method comprises the steps: firstly, calculating an electrical angle and a mechanical rotating speed according to a motor encoder signal; secondly, obtaining a d-q plane torque current reference value through rotating speed closed-loop control; thirdly, six-phase current of the motor is collected, and the actual current value of the decoupling sub-plane is calculated; then, a d-q plane voltage reference value is obtained through a proportional-integral regulator; then, x-y plane voltage and a-b plane current are collected in real time, and an output result of the fault diagnosis module is obtained; then, x-y plane voltage reference values in different modes are selected according to output results of the fault diagnosis module; then, a six-phase voltage reference value is obtained through inverse decoupling transformation; and finally, obtaining a driving signal of a six-phase inverter according to comparison between the modulated wave and a set carrier wave, and realizing the natural fault-tolerant control method for the symmetric six-phase permanent magnet synchronous motor without current reconstruction.

Description

Technical Field

[0001] This invention relates to a motor control method, and more particularly to a motor fault-tolerant control method. Background Technology

[0002] In recent years, multiphase motors have become core drive components in critical equipment such as ships and aerospace due to their high efficiency and strong redundancy. Because of the specific nature of their applications, they require extremely high operational stability and reliability; even minor faults can lead to serious accidents. When multiphase motors operate under high loads for extended periods, the windings are prone to continuous heating due to various factors, leading to insulation aging, breakdown, and even open circuits. If such faults are not addressed promptly, they can cause a sharp drop in motor performance and amplify the impact of the fault. Therefore, accurate detection and intervention of fault-tolerant control within a very short time after a fault occurs is the core of current research and is of great significance for improving system safety and redundancy.

[0003] Currently, there is considerable research on fault-tolerant control for open-circuit faults in multiphase motor windings. Different offline or online algorithms are used to solve for the fault-tolerant current reference value, and then a corresponding controller is designed to track and control it to achieve the pre-fault operating effect. However, due to the large number of phases in multiphase motors, this method requires fault diagnosis and fault location before switching to fault-tolerant control. Furthermore, the corresponding fault-tolerant current reference expression needs to be stored for different phase winding open circuits, increasing program storage space and fault location time. Therefore, it is necessary to simplify the fault diagnosis and location scheme and design a simpler fault-tolerant control algorithm.

[0004] To address the aforementioned issues, a natural fault-tolerant control method based on harmonic plane open-loop operation has been proposed for multiphase motor drive systems, but research on symmetrical six-phase permanent magnet synchronous motors has not yet been conducted. Furthermore, existing fault diagnosis algorithms, which use single variables for diagnosis, are prone to misdiagnosis under extreme conditions such as sudden load changes. Therefore, a fault diagnosis algorithm based on multivariate joint analysis and a corresponding fault-tolerant control strategy are needed. Summary of the Invention

[0005] Purpose of the invention: Based on the above problems, this invention proposes a natural fault-tolerant control method for multi-variable joint diagnosis of symmetrical six-phase permanent magnet synchronous motors. This method utilizes multiple variables for joint fault diagnosis, reducing the risk of misdiagnosis and improving robustness and versatility.

[0006] Technical solution: A natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor, comprising the following steps:

[0007] Step 1: Calculate the motor speed n and the real-time rotor angle θ based on the output signal of the motor encoder. e ;

[0008] Step 2: Based on the motor speed n and the speed reference value n* The deviation is used to obtain the q-axis current reference value through the speed PI regulator. And set the d-axis current reference value. =0;

[0009] Step 3: Collect the six-phase current values ​​i of the motor based on the current sensor. A i B i C i U i V i W After vector space decoupling transformation, the dq subplane and xy subplane i are calculated. d i q i x i y ;

[0010] Step 4: Based on the dq subplane current value i d i q Compared with the subplane current reference value in step 2 , The reference value of the dq subplane voltage is obtained after passing through a PI regulator. , ;

[0011] Step 5: Based on whether the xy subplane voltage obtained from real-time acquisition and calculation exceeds the threshold, and whether the α-β subplane current trajectory is circular, obtain the fault diagnosis output result;

[0012] Step 6: Select different xy subplane voltage reference values ​​based on the fault diagnosis output results from Step 5: When the motor is operating in normal operating mode, the xy subplane voltage reference value is... , When the motor operates in fault-tolerant mode, the reference value for the xy subplane voltage is... , ;

[0013] Step 7: Based on the subplane voltage reference value, obtain the six-phase voltage reference value of the motor through inverse decoupling transformation. , , , , , ;

[0014] Step 8: The drive signal for the switching transistor is formed by comparing the six-phase voltage reference value and the carrier wave, thereby realizing the fault-tolerant control of the symmetrical six-phase permanent magnet synchronous motor.

[0015] Furthermore, in step 5, the xy subplane voltage is collected in real time during motor operation. , ,when or When this happens, it is determined that the motor has malfunctioned. , These are the preset threshold values ​​for the xy subplane voltages, respectively.

[0016] Furthermore, in step 5, the xy subplane voltage is tested when the motor experiences a winding open-circuit fault, and used as a threshold. , .

[0017] Furthermore, in step 5, the presence or absence of a fault is further determined by detecting whether the tangent of the α-β subplane current deviates from the circular trajectory at each moment.

[0018] Furthermore, in step 5, during motor operation, the phase current values ​​of the symmetrical six-phase permanent magnet synchronous motor are acquired in real time, and the α-β subplane current is obtained according to the vector space decoupling transformation; based on the α-β subplane current expression, the α-β plane current value i at a specific moment in each control cycle is obtained. α0 i β0 When the system is running stably, point (i) α0 i β0 The equation of the tangent line at point () is expressed as: In each control cycle, substitute the horizontal coordinate i α0 The ordinate value of the tangent equation is calculated to determine whether the system is operating normally or in a faulty state.

[0019] Furthermore, in step 6, when the motor is operating in normal operating mode, the reference value of the xy subplane voltage is... , It is obtained from the closed-loop control of the xy subplane current.

[0020] Furthermore, in step 6, when the motor is operating in fault-tolerant mode, the closed-loop current circuit of the xy subplane is disconnected, and open-loop operation is directly selected. At this time, the reference value of the xy subplane voltage is... , Use the preset values.

[0021] A natural fault-tolerant control system for multivariable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor includes: an angle calculation module for performing step 1; a speed control module for performing step 2; a current conversion module for performing step 3; a fundamental current control module for performing step 4; a fault diagnosis module for performing step 5; a fault-tolerant control module for performing step 6; an anti-decoupling module for performing step 7; and an inverter control module for performing step 8.

[0022] Beneficial effects: The method of this invention obtains the fault diagnosis output by judging whether the xy plane voltage exceeds the set threshold during normal operation and whether the α-β plane current trajectory deviates from the circle. The multi-variable joint diagnosis method reduces the risk of misdiagnosis and improves the robustness of the fault diagnosis module. After the system experiences a winding open circuit fault, it implements a natural fault-tolerant control strategy of xy plane voltage open-loop operation by disconnecting the xy plane current closed loop. This eliminates the need for a cumbersome fault location process and reduces program storage space and computation time. Attached Figure Description

[0023] Figure 1 This is a control block diagram of the method of the present invention;

[0024] Figure 2 This is a simplified circuit topology diagram of the symmetrical six-phase permanent magnet synchronous motor drive system of the present invention;

[0025] Figure 3 This is a schematic diagram showing the simulation results of the rotational speed and torque during normal operation of the present invention;

[0026] Figure 4 This is a schematic diagram of the simulation results of the current in the dq plane and xy plane during normal operation of the present invention;

[0027] Figure 5 This is a schematic diagram of the simulation results of the rotational speed and torque during fault-tolerant operation of the present invention;

[0028] Figure 6 This is a schematic diagram of the simulation results of the dq plane and xy plane currents during fault-tolerant operation of the present invention. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments.

[0030] like Figure 1 As shown, a natural fault-tolerant control method for multivariable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor includes the following steps:

[0031] Step 1: Based on the output signal of the motor encoder, obtain the motor speed n and the real-time rotor angle θ according to the mechanical speed and electrical angle calculation formulas. e .

[0032] Step 2: Based on the calculated rotational speed n and the set reference rotational speed n * The deviation is used to obtain the q-axis current reference value through the speed PI regulator. The d-axis current reference value is set to =0.

[0033] Step 3: Based on the six-phase winding current value i collected by the current sensorA i B i C i U i V i W The current values ​​i in the dq subplane, xy subplane, and α-β subplane are calculated after vector space decoupling transformation. d i q i x i y i ɑ i β .

[0034] Wherein, the vector space decoupling transformation matrix T vsd As shown in equation (1).

[0035] (1)

[0036] Step 4: Based on the dq subplane current value i d i q Compared with the subplane current reference value in step 2 , The reference value of the dq subplane voltage is obtained after passing through a PI regulator. , .

[0037] Step 5: Based on whether the xy subplane voltage obtained through real-time acquisition and calculation exceeds the threshold, and whether the α-β subplane current tangent deviates from the circular trajectory, the output result of the fault diagnosis module is obtained.

[0038] When the motor is running and there is no open-circuit fault in the windings, the XY subplane voltage obtained from the closed-loop output of the XY subplane current fluctuates around 0, indicating that the six-phase winding currents are in balance. However, when an open-circuit fault occurs, the single-phase current is 0, and the currents of the other five phases become unbalanced, leading to an increase in the XY subplane current and ultimately a larger XY subplane voltage. Therefore, the actual voltage value of the motor's XY subplane is calculated in real time. , and respectively compared with the set threshold. , In comparison, when any of the conditions in equation (2) is met, it indicates that the motor has an open-circuit fault in the winding and needs to be switched to natural fault-tolerant control.

[0039] (2)

[0040] Among them, threshold , The setting is achieved by testing the xy subplane voltage when the motor experiences an open-circuit winding fault.

[0041] On the other hand, to ensure the real-time performance and effectiveness of fault diagnosis, based on the calculated α-β subplane current i ɑ i β The expression yields the α-β subplane current value at a specific moment in each control cycle, denoted as i. α0 i β0 Therefore, when the system is running stably, the equation of the tangent at that point can be obtained as shown in equation (3):

[0042] (3)

[0043] When a motor experiences a winding open-circuit fault, the α-β sub-plane current trajectory changes from a circle during normal operation to an ellipse. The tangent equation at that point is quickly calculated based on the real-time value of the plane current and compared with the tangent equation during stable operation. If the trajectory deviates, it indicates a winding open-circuit fault, causing the plane current trajectory to no longer be a standard circle. Taking an open-circuit A-phase winding as an example, the α-β sub-plane current trajectory at this time has a major semi-axis equal to i. q The minor semi-axis is equal to 1 / 2i q The ellipse is such that the equation of the tangent line at every point on it is:

[0044] (4)

[0045] In each control cycle, substitute the horizontal coordinate i α0 Simultaneously calculate the ordinate values ​​of the two tangent equations, and their relationship with the ordinate i of the point. β0 By comparing the data, it can be determined whether the system is operating normally or experiencing a malfunction.

[0046] Step 6: Select different xy subplane voltage reference values ​​based on the output results of the fault diagnosis module. When the system is operating in normal mode, the xy subplane voltage reference values ​​are... , When the system operates in fault-tolerant mode, the reference value for the xy-plane voltage is... , .

[0047] The symmetrical six-phase permanent magnet synchronous motor is in normal operating mode, at which time the reference value of the xy subplane voltage is... , This is obtained from the closed-loop control of the XY subplane current. If a winding open-circuit fault occurs in the system, and the fault diagnosis module output is valid, the XY subplane current closed-loop circuit is disconnected, and open-loop operation is directly selected. At this time, the XY plane voltage reference value is... , Use the preset values.

[0048] Step 7: Based on the subplane voltage reference value, obtain the six-phase voltage reference value through inverse decoupling transformation. , , , , , .

[0049] Step 8: The drive signal for the switching transistor is generated by comparing the six-phase voltage reference value and the carrier wave, thereby realizing the fault-tolerant control of the symmetrical six-phase permanent magnet synchronous motor.

[0050] A natural fault-tolerant control system for multivariable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor includes: an angle calculation module for performing step 1; a speed control module for performing step 2; a current conversion module for performing step 3; a fundamental current control module for performing step 4; a fault diagnosis module for performing step 5; a fault-tolerant control module for performing step 6; an anti-decoupling module for performing step 7; and an inverter control module for performing step 8.

[0051] To verify the technical problem of the present invention, based on Figure 1 The control block diagram shown and Figure 2 The system topology is shown, and a simulation model was built. In this embodiment, the reference speed is set to 800 r / min, and the load torque is set to 5 N·m. The fault-tolerant operation of the symmetrical six-phase permanent magnet synchronous motor after phase A is open-circuited is simulated and verified.

[0052] During normal operation:

[0053] like Figure 3 As shown, the steady-state speed is 800 r / min, and the electromagnetic torque output by the motor is 5 N·m. The actual value can track the reference value.

[0054] like Figure 4 As shown, i q The current value is 8A, which is consistent with the electromagnetic torque calculation results based on the number of motor pole pairs and parameters such as flux linkage. The remaining subplane currents i... d i x i y All values ​​are 0, which meets the basic requirements for motor control.

[0055] During fault-tolerant operation:

[0056] like Figure 5 As shown, the steady-state speed can still fluctuate around 800 r / min, and the output electromagnetic torque can still reach a relatively stable 5 N·m, indicating that the fault-tolerant control algorithm is effective.

[0057] like Figure 6As shown, due to the fault-tolerant open-loop control of the xy subplane, therefore i x The appearance of i α The alternating currents are of the same frequency but opposite amplitude, and the currents in the other subplanes are consistent with normal operation.

[0058] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor, characterized in that, Includes the following steps: Step 1: Calculate the motor speed n and the real-time rotor angle θ based on the output signal of the motor encoder. e ; Step 2: Based on the motor speed n and the speed reference value n * The deviation is used to obtain the q-axis current reference value through the speed PI regulator. And set the d-axis current reference value. =0; Step 3: Collect the six-phase current values ​​i of the motor based on the current sensor. A i B i C i U i V i W After vector space decoupling transformation, the dq subplane and xy subplane i are calculated. d i q i x i y ; Step 4: Based on the dq subplane current value i d i q Compared with the subplane current reference value in step 2 , The reference value of the dq subplane voltage is obtained after passing through a PI regulator. , ; Step 5: Based on whether the xy subplane voltage obtained from real-time acquisition and calculation exceeds the threshold, and whether the α-β subplane current trajectory is circular, obtain the fault diagnosis output result; Step 6: Select different xy subplane voltage reference values ​​based on the fault diagnosis output results from Step 5: When the motor is operating in normal operating mode, the xy subplane voltage reference value is... , When the motor operates in fault-tolerant mode, the reference value for the xy subplane voltage is... , ; Step 7: Based on the subplane voltage reference value, obtain the six-phase voltage reference value of the motor through inverse decoupling transformation. , , , , , ; Step 8: The drive signal for the switching transistor is formed by comparing the six-phase voltage reference value and the carrier wave, thereby realizing the fault-tolerant control of the symmetrical six-phase permanent magnet synchronous motor.

2. The natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor according to claim 1, characterized in that, In step 5, the xy subplane voltage is collected in real time during motor operation. , ,when or When this happens, it is determined that the motor has malfunctioned. , These are the preset threshold values ​​for the xy subplane voltages, respectively.

3. The natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor according to claim 2, characterized in that, In step 5, the xy subplane voltage is tested when the motor experiences a winding open-circuit fault, and used as a threshold. , .

4. The natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor according to any one of claims 1-3, characterized in that, In step 5, the presence or absence of a fault is further determined by detecting whether the tangent of the α-β subplane current deviates from the circular trajectory at each moment.

5. The natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor according to claim 4, characterized in that, In step 5, during motor operation, the phase current values ​​of the symmetrical six-phase permanent magnet synchronous motor are collected in real time, and the α-β subplane current is obtained according to the vector space decoupling transformation; based on the α-β subplane current expression, the α-β plane current value i at a specific moment in each control cycle is obtained. α0 i β0 When the system is running stably, point (i) α0 i β0 The equation of the tangent line at point () is expressed as: ; In each control cycle, substitute the horizontal coordinate i α0 The ordinate value of the tangent equation is calculated to determine whether the system is operating normally or in a faulty state.

6. The natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor according to claim 4, characterized in that, In step 6, when the motor is operating in normal mode, the reference value of the xy subplane voltage is... , It is obtained from the closed-loop control of the xy subplane current.

7. The natural fault-tolerant control method for multi-variable joint diagnosis of a symmetrical six-phase permanent magnet synchronous motor according to claim 4, characterized in that, In step 6, when the motor is operating in fault-tolerant mode, the closed-loop current circuit of the xy subplane is disconnected, and open-loop operation is directly selected. At this time, the reference value of the xy subplane voltage is... , Use the preset values.

8. The control system according to any one of claims 1-7, characterized in that, include: The following modules are used to execute the following steps: angle calculation module for step 1; speed control module for step 2; current conversion module for step 3; fundamental current control module for step 4; fault diagnosis module for step 5; fault-tolerant control module for step 6; decoupling module for step 7; and inverter control module for step 8.

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