Field weakening control method and device of permanent magnet synchronous motor and motor controller

Abstract

The invention provides a field weakening control method and device for a permanent magnet synchronous motor and a motor controller, and relates to the technical field of motor control, and the method comprises the steps: obtaining a d-axis current reference value and a torque reference value of the permanent magnet synchronous motor, so as to determine an output voltage; the maximum value of the output voltage of the permanent magnet synchronous motor is obtained, the d-axis limiting coefficient and the torque limiting coefficient of the permanent magnet synchronous motor are preset so as to determine the d-axis limiting maximum output voltage and the torque limiting maximum output voltage, and the d-axis limiting coefficient and the torque limiting coefficient are both 0-1; and wherein the d-axis limit coefficient is less than the torque limit coefficient; when the output voltage is larger than the d-axis limited maximum output voltage and smaller than the torque limited maximum output voltage, d-axis current closed-loop control is fed back, and the output voltage is controlled to be limited within a voltage limit circle through a d-axis regulator; when the output voltage is larger than the torque limit maximum output voltage, torque closed-loop control is added, a torque regulator is started to control the output voltage to be limited within a voltage limit circle, and the problems that existing motor control cannot achieve maximum torque output, the motor is out of control, and the safety risk is high are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a permanent magnet synchronous motor weak magnetic field control method, device and motor controller. Background Art

[0002] Permanent magnet synchronous motor is a high-performance motor used in the electric drive system of new energy vehicles. It has the advantages of high power density, high efficiency, small pulsating torque and a wide weak magnetic speed regulation range. It is the best choice for new energy vehicle drive motor.

[0003] As the speed of a permanent magnet synchronous motor increases, its output voltage gradually reaches the voltage output capacity limit and requires weak magnetic field control. Most existing weak magnetic field control schemes use a voltage feedback closed loop, increasing instructions to increase the d-axis current or reduce the q-axis current to achieve the purpose of reducing the output voltage. However, the existing control cannot achieve the maximum torque output under the DC voltage / speed condition and is prone to cause the motor to lose control, posing a high safety risk. Summary of the invention

[0004] In order to overcome the above technical defects, the purpose of the present invention is to provide a permanent magnet synchronous motor weak magnetic control method, device and motor controller to solve the problem that the existing motor control cannot achieve maximum torque output and easily causes motor loss of control and high safety risks.

[0005] The present invention discloses a magnetic field weakening control method of a permanent magnet synchronous motor, comprising:

[0006] Obtaining a d-axis current reference value and a torque reference value of the permanent magnet synchronous motor to determine an output voltage;

[0007] Obtaining the maximum output voltage of the permanent magnet synchronous motor, and predetermining the d-axis limit coefficient and the torque limit coefficient of the permanent magnet synchronous motor to determine the d-axis limit maximum output voltage and the torque limit maximum output voltage, wherein the d-axis limit coefficient and the torque limit coefficient are both 0 to 1, and wherein the d-axis limit coefficient is less than the torque limit coefficient;

[0008] When the output voltage is greater than the maximum output voltage of the d-axis limit and less than the maximum output voltage of the torque limit, the d-axis current closed-loop control is fed back to control the output voltage to be limited within the voltage limit circle through the d-axis regulator;

[0009] When the output voltage is greater than the torque-limited maximum output voltage, the torque closed-loop control is increased, and the starting torque regulator controls the output voltage to be limited within the voltage limit circle.

[0010] Preferably, controlling the output voltage to be limited within a voltage limit circle by a d-axis regulator comprises:

[0011] The output voltage is obtained, and the d-axis regulator is used to output a d-axis current adjustment value according to the output voltage and the d-axis maximum output voltage limit;

[0012] The d-axis voltage output is increased according to the d-axis current reference value and the d-axis current adjustment value to control the output voltage to decrease so that the output voltage is limited within the voltage limit circle.

[0013] Preferably, the d-axis regulator controls the d-axis current adjustment value to be between a maximum torque / current curve and a maximum torque-to-voltage ratio curve of the permanent magnet synchronous motor.

[0014] Preferably, the starting torque regulator controls the output voltage to be limited within a voltage limit circle, including:

[0015] The torque regulator is used to output a torque adjustment value according to the output voltage and the torque limit maximum output voltage;

[0016] The q-axis voltage output is determined according to the conversion of the torque reference value and the torque adjustment value, and the torque is reduced to control the output voltage to decrease, so that the output voltage is limited within the voltage limit circle.

[0017] Preferably, the torque regulator controls the torque adjustment value to act on the torque reference value without changing the torque direction.

[0018] Preferably, the converting and determining the q-axis voltage output according to the torque reference value and the torque adjustment value comprises:

[0019] determining a target torque according to the torque reference value and the torque adjustment value, and determining a target d-axis current based on the d-axis current reference value and the d-axis current adjustment value;

[0020] The target q-axis current is determined according to the target torque and the target d-axis current using a preset torque-current conversion relationship table to determine the q-axis voltage output.

[0021] Preferably, the d-axis voltage output is determined by a d-axis current control loop according to the d-axis current reference value;

[0022] Determine the q-axis voltage output by converting to the q-axis current control loop according to the torque reference value;

[0023] An output voltage is determined according to the d-axis voltage output and the q-axis voltage output.

[0024] Preferably, the d-axis regulator and the torque regulator are both PI regulators.

[0025] The present invention also provides a magnetic field weakening control device for a permanent magnet synchronous motor, comprising:

[0026] An acquisition module is used to obtain a d-axis current reference value and a torque reference value of the permanent magnet synchronous motor to determine an output voltage;

[0027] A preprocessing module, used for obtaining the maximum output voltage of the permanent magnet synchronous motor, and presetting the d-axis limit coefficient and the torque limit coefficient of the permanent magnet synchronous motor to determine the d-axis limit maximum output voltage and the torque limit maximum output voltage, wherein the d-axis limit coefficient and the torque limit coefficient are both 0 to 1, and wherein the d-axis limit coefficient is less than the torque limit coefficient;

[0028] The first control module is used for feeding back the d-axis current closed-loop control when the output voltage is greater than the d-axis maximum output voltage limit and less than the torque maximum output voltage limit, and controlling the output voltage to be limited within the voltage limit circle through the d-axis regulator;

[0029] The second control module is used to increase the torque closed-loop control when the output voltage is greater than the torque limit maximum output voltage, and start the torque regulator to control the output voltage to be limited within the voltage limit circle.

[0030] The present invention also provides a motor controller, which applies the above-mentioned permanent magnet synchronous motor weak magnetic field control device.

[0031] Compared with the prior art, the above technical solution has the following beneficial effects:

[0032] The present invention provides a magnetic field weakening control method, device and motor controller for a permanent magnet synchronous motor, which set the d-axis limit maximum voltage and torque limit maximum voltage of the permanent magnet synchronous motor. When the output voltage exceeds the d-axis limit maximum voltage, the d-axis voltage is increased by d-axis regulation to reduce the output voltage. When the output voltage exceeds the torque limit maximum voltage, the output voltage is reduced by reducing the torque. This solves the problem that the existing motor control cannot achieve maximum torque output and is prone to cause motor loss of control, resulting in a high safety risk. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a flow chart of Embodiment 1 of a magnetic field weakening control method, device and motor controller for a permanent magnet synchronous motor according to the present invention;

[0034] Figure 2 A schematic diagram of a MTPA curve, a voltage limit ellipse and a current limit circle of a permanent magnet synchronous motor, including a method and device for weakening magnetic field control of a permanent magnet synchronous motor and a motor controller according to Embodiment 1 of the present invention;

[0035] Figure 3 A control schematic diagram of a first embodiment of a magnetic field weakening control method, device and motor controller for a permanent magnet synchronous motor according to the present invention;

[0036] Figure 4 It is a module schematic diagram of a second embodiment of a magnetic field weakening control method, device and motor controller for a permanent magnet synchronous motor described in the present invention.

[0037] Reference numerals:

[0038] 5-weak magnetic field control device of magnetic synchronous motor; 51-acquisition module; 52-preprocessing module; 53-first control module; 54-second control module. DETAILED DESCRIPTION

[0039] The advantages of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0040] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0041] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0042] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0043] In the following description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings. Therefore, "module" and "component" can be used interchangeably.

[0044] Embodiment 1: This embodiment discloses a permanent magnet synchronous motor weak magnetic control method. In the existing motor control, as shown in FIG. Figure 1As shown, the motor operation needs to be limited within the voltage limit circle and current limit circle, MTPV curve and MTPA curve. In the existing weak magnetic control, the following situations may occur: 1. When the output voltage exceeds the Umax limit, the voltage feedback closed loop is used to increase the command voltage Id0 to reduce the output voltage. However, when the motor runs on the MTPV curve, increasing Id0 will cause the output voltage to run in the direction of increasing voltage, resulting in motor loss of control, as shown in the figure point 1→4; 2. When the output voltage exceeds the Umax limit, the voltage feedback closed loop is used to increase the command voltage Id0 and reduce Iq0 along the equal torque line to reduce the output voltage. However, when the motor runs on the MTPV curve, increasing Id0 and reducing Iq0 along the equal torque line will cause the output voltage to run in the direction of increasing voltage, resulting in motor loss of control; as shown in the figure point 1→2; 3. When the output voltage exceeds the Umax limit, the voltage feedback closed loop is used to reduce Iq0 to reduce the output voltage. However, when the motor runs on the MTPV curve, the maximum torque output at this voltage cannot be achieved; as shown in the figure point 1→3.

[0045] Based on the above, as the speed of the permanent magnet synchronous motor increases, the output voltage Us gradually reaches the voltage output capacity limit Umax. However, when the motor runs on the MTPV curve, controlling the d-axis current Id0 or the q-axis current Iq0 can easily cause the motor to lose control and fail to achieve maximum torque output.

[0046] In this embodiment, when the motor runs on the MTPV curve, the output voltage is reduced by reducing the torque to avoid the system out of control due to the motor exceeding the voltage limit. At the same time, the maximum torque output can be achieved autonomously, solving the problem that the existing motor control cannot achieve the maximum torque output and is prone to cause the motor to lose control, resulting in a high safety risk. Figure 1 The midpoint 1→5, the torque at point 5 is greater than that at point 3, and the maximum torque output in this case can be achieved. Figure 2-Figure 3 , including the following steps:

[0047] S10: Obtain a d-axis current reference value Id0 and a torque reference value Trq of the permanent magnet synchronous motor to determine an output voltage Us;

[0048] Specifically, the d-axis voltage output Ud is determined through the d-axis current control loop according to the d-axis current reference value Id0; the q-axis voltage output Uq is determined by converting to the q-axis current control loop according to the torque reference value Trq; and the output voltage Us is determined according to the d-axis voltage output Ud and the q-axis voltage output Uq.

[0049] It should be noted that the torque can be converted to the q-axis voltage output by calculating the q-axis current Iq0 through the torque reference value Trq and the d-axis current reference value Id0 using a preset (or existing) torque formula, and then input into the q-axis current control loop to determine the q-axis voltage output Uq. A torque-current conversion relationship table can also be preset, and the q-axis current Iq0 can be obtained by looking up the table according to the torque reference value Trq and the d-axis current reference value Id0 to improve control efficiency.

[0050] The output voltage Us is determined according to the d-axis voltage output Ud and the q-axis voltage output Uq, specifically, according to the following formula: That is, it is calculated by adding the squares of the d-axis voltage output Ud and the q-axis voltage output Uq and taking the square root. The feedback based on the output voltage is used for the weak magnetic control in the following steps.

[0051] S20: Acquire the maximum output voltage Umax of the permanent magnet synchronous motor, and predetermine the d-axis limit coefficient Coeff_d and the torque limit coefficient Coeff_trq of the permanent magnet synchronous motor to determine the d-axis limit maximum output voltage and the torque limit maximum output voltage, wherein the d-axis limit coefficient Coeff_d and the torque limit coefficient Coeff_trq are both 0 to 1, and wherein the d-axis limit coefficient Coeff_d is less than the torque limit coefficient Coeff_trq;

[0052] As an illustration, Umax is the maximum voltage output limit of the inverter driving the motor limited by the bus voltage. The d-axis limited maximum output voltage is the product of the maximum output voltage and the d-axis limit coefficient, that is, Umax×Coeff_d; the torque limited maximum output voltage is the product of the maximum output voltage and the torque limit parameter, that is, Umax×Coeff_trq; Coeff_Trq>Coeff_d is set. It can be understood that when the d-axis limited maximum output voltage is slightly lower than the torque limited maximum output voltage, when the d-axis limited maximum output voltage is reached, the output voltage is reduced through d-axis control, and when the torque limited maximum output voltage is reached, the torque control is increased to reduce the output voltage. The d-axis control and torque control cooperate with each other, which is different from the existing method of increasing Id0 and reducing Iq0. Torque control is increased to avoid the situation where the motor is out of control, and the maximum torque is output according to the output voltage.

[0053] As a supplement, Coeff_Trq>Coeff_d is set, that is, the stable operation of the motor is achieved by the d-axis current closed-loop strategy first. The d-axis limit coefficient Coeff_d and the torque limit coefficient Coeff_trq can be set according to the actual application scenario, and can be set to any parameter close to 1, that is, it is understood to be close to the maximum output voltage Umax, that is, the d-axis current control is performed when the motor runs close to the MTPV curve. The command can be set to set the parameters, and the command adjustment can also be triggered in a specific scenario.

[0054] S30: When the output voltage Us is greater than the d-axis maximum output voltage Umax×Coeff_d and less than the torque-limited maximum output voltage Umax×Coeff_trq, the d-axis current closed-loop control is fed back to control the output voltage Us to be limited within the voltage limit circle through the d-axis regulator;

[0055] In this embodiment, the output voltage is less than the maximum output voltage of the torque limit, that is, the motor is not running / running close to the MTPV curve, and the voltage feedback d-axis current closed-loop strategy is used to increase Id0 even if the output voltage decreases, so as to achieve constant torque stable operation. Specifically, the output voltage is controlled to be limited within the voltage limit circle by the d-axis regulator, including: obtaining the output voltage Us, using the d-axis regulator to output the d-axis current adjustment value ΔId according to the output voltage Us and the d-axis limit maximum output voltage Umax×Coeff_d; according to the d-axis current reference value Id0 and the d-axis current adjustment value ΔId, using ΔId as the increment of the d-axis current, and continuously increasing the d-axis current to reduce the output voltage Us of the inverter until the output voltage Us is within the voltage limit ellipse.

[0056] In this embodiment, it is further necessary to explain that the d-axis regulator controls the d-axis current adjustment value to be between the maximum torque / current MPTA curve and the maximum torque-to-voltage ratio MPTV curve of the permanent magnet synchronous motor, that is, Id satisfies limitMPTA~MPTV, that is, the minimum limit value of the d-axis current command value after compensation obtained by the above-mentioned d-axis reference value based on the above-mentioned d-axis adjustment value is the MTPA curve, and the maximum limit value is the MTPV curve, thereby realizing the steady-state operation of the motor and reducing the possibility of the motor system losing control.

[0057] S40: When the output voltage Us is greater than the torque limited maximum output voltage Umax×Coeff_trq, the torque closed-loop control is increased, and the starting torque regulator controls the output voltage Us to be limited within the voltage limit circle.

[0058] In this embodiment, when the motor is running or close to running on the MTPV curve, increasing Id0 will increase the output voltage. At this time, the torque Trq is controlled to reduce the torque to reduce the output voltage, so as to avoid the motor exceeding the voltage limit and causing the system to lose control. Specifically, the starting torque regulator controls the output voltage to be limited within the voltage limit circle, including: using the torque regulator to output the torque adjustment value ΔTrq according to the output voltage Us and the torque limit maximum output voltage Umax×Coeff_trq; according to the torque reference value ΔTrq and the torque adjustment value conversion, determine the q-axis voltage output Uq, reduce the torque to control the output voltage to decrease, so that the output voltage is limited within the voltage limit circle.

[0059] In the above steps, the q-axis voltage output is determined according to the conversion of the torque reference value and the torque adjustment value, including: determining the target torque according to the torque reference value ΔTrq and the torque adjustment value Trq (i.e., the sum of the torque reference value ΔTrq and the torque adjustment value Trq), determining the target d-axis current based on the d-axis current reference value Id0 and the d-axis current adjustment value ΔId (i.e., the sum of the d-axis current reference value Id0 and the d-axis current adjustment value ΔId); determining the target q-axis current according to the target torque and the target d-axis current with a preset torque-current conversion relationship table to determine the q-axis voltage output Uq.

[0060] It should also be noted that the torque regulator controls the torque adjustment value ΔTrq to act on the torque reference value Trq without changing the torque direction, that is, the torque adjustment value output by the torque regulator is controlled within a maximum limit value of 0 and a minimum limit value of -Trq, thereby reducing the damage to the motor caused by torque reversal.

[0061] In this embodiment, for illustration, the d-axis regulator and the torque regulator are both PI regulators. Two PI regulators are respectively provided to respectively adjust the d-axis current and torque. The two regulators have similar functions and can be replaced by regulators of the same type. Other regulators can be used according to the specific implementation scenario to ensure that the motor control is achieved.

[0062] In this embodiment, as an example, Coeff_Trq is set to 0.98 and Coeff_d is set to 0.9;

[0063] When the output voltage Us is 0.8Umax, when compared with the d-axis limit maximum voltage, a value less than 0 will be obtained. This value does not belong to the preset range MTPA to MTPV of the d-axis regulator, so the d-axis regulator will not perform regulation at this time.

[0064] When the output voltage Us is 0.95Umax, when compared with the d-axis maximum limit voltage, a value greater than 0 will be obtained, and the d-axis voltage feedback closed loop will work; at this time, the torque regulator will not perform regulation work.

[0065] When the output voltage Us is 0.99Umax, it exceeds the maximum torque limit voltage and the motor operating voltage exceeds MTPV. At this time, the torque regulator starts and performs adjustment work simultaneously with the d-axis regulator.

[0066] Id0 is obtained through torque command and MTPA, and Iq0 is obtained through torque command, Idref\ and other torque curve parameter tables. The motor does not run on the MTPV curve. Through the voltage feedback d-axis current closed-loop strategy, Id0 is increased. When the MTPV exceeds the voltage limit, the motor is re-controlled to run within the voltage limit. As shown in the figure, the torque is reduced from point 1 to point 5, thereby reducing the risk of motor loss of control and automatically outputting the maximum torque at the voltage according to the output voltage setting value.

[0067] Embodiment 2: This embodiment also provides a permanent magnet synchronous motor weak magnetic control device 5, see Figure 4 ,include:

[0068] The acquisition module 51 is used to obtain the d-axis current reference value and the torque reference value of the permanent magnet synchronous motor to determine the output voltage;

[0069] In the acquisition module, the d-axis voltage output Ud is determined according to the d-axis current reference value Id0; the q-axis voltage output Uq is determined according to the torque reference value Trq, and the output voltage is obtained by square-adding the d-axis voltage output Ud and the q-axis voltage output Uq and then taking the square root of the square.

[0070] A preprocessing module 52 is used to obtain the maximum output voltage of the permanent magnet synchronous motor, and to predetermine the d-axis limit coefficient and the torque limit coefficient of the permanent magnet synchronous motor to determine the d-axis limit maximum output voltage and the torque limit maximum output voltage, wherein the d-axis limit coefficient and the torque limit coefficient are both 0 to 1, and wherein the d-axis limit coefficient is less than the torque limit coefficient;

[0071] In the preprocessing module, the predetermined d-axis limit coefficient and the torque limit coefficient can be fed back through instructions to facilitate the control response of the subsequent first control module or the second control module.

[0072] The first control module 53 is used for feedback d-axis current closed-loop control when the output voltage is greater than the d-axis maximum output voltage limit and less than the torque maximum output voltage limit, and controls the output voltage to be limited within the voltage limit circle through the d-axis regulator;

[0073] The second control module 54 is used to increase the torque closed-loop control when the output voltage is greater than the torque limited maximum output voltage, and start the torque regulator to control the output voltage to be limited within the voltage limit circle.

[0074] In this embodiment, it can be understood that the operation of the first control module and the second control module is started according to the output voltage. When the output voltage is greater than the maximum output voltage limited by the d-axis and less than the maximum output voltage limited by the torque, the output voltage is controlled through the d-axis. When the output voltage is greater than the maximum output voltage limited by the torque, the torque control output voltage is increased to limit it within the voltage limit circle, thereby reducing the risk of motor loss of control and achieving maximum torque output, thereby improving the working efficiency of the motor.

[0075] Embodiment three: The present invention also provides a motor controller, which applies the above-mentioned permanent magnet synchronous motor weak magnetic control device. The output end of the motor controller is connected to the control end of the inverter of the permanent magnet synchronous motor. It can also include or be connected to other modules or devices for realizing motor control. It is applied to new energy vehicles to reduce the risk of motor loss of control, improve control efficiency, and improve vehicle operation safety.

[0076] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. A method for weakening magnetic field of a permanent magnet synchronous motor, characterized in that: include: Obtaining a d-axis current reference value and a torque reference value of the permanent magnet synchronous motor to determine an output voltage; Obtain the maximum output voltage of the permanent magnet synchronous motor, and predetermine the d-axis limit coefficient and the torque limit coefficient of the permanent magnet synchronous motor to determine the d-axis limit maximum output voltage and the torque limit maximum output voltage, wherein the d-axis limit coefficient and the torque limit coefficient are both 0 to 1, and the d-axis limit coefficient is less than the torque limit coefficient; when the output voltage is greater than the d-axis limit maximum output voltage and less than the torque limit maximum output voltage, the d-axis current closed-loop control is fed back, and the output voltage is controlled to be limited within the voltage limit circle through the d-axis regulator; When the output voltage is greater than the torque-limited maximum output voltage, the torque closed-loop control is increased, and the starting torque regulator controls the output voltage to be limited within the voltage limit circle.

2. The weak magnetic field control method according to claim 1, characterized in that: The method of controlling the output voltage to be limited within the voltage limit circle by the d-axis regulator includes: The output voltage is obtained, and the d-axis regulator is used to output a d-axis current adjustment value according to the output voltage and the d-axis maximum output voltage limit; The d-axis voltage output is increased according to the d-axis current reference value and the d-axis current adjustment value to control the output voltage to decrease so that the output voltage is limited within the voltage limit circle.

3. The weak magnetic field control method according to claim 2, characterized in that: The d-axis regulator controls the d-axis current adjustment value to be between a maximum torque / current curve and a maximum torque-voltage ratio curve of the permanent magnet synchronous motor.

4. The weak magnetic field control method according to claim 2, characterized in that: The starting torque regulator controls the output voltage to be limited within the voltage limit circle, including: The torque regulator is used to output a torque adjustment value according to the output voltage and the torque limit maximum output voltage; The q-axis voltage output is determined according to the conversion of the torque reference value and the torque adjustment value, and the torque is reduced to control the output voltage to decrease, so that the output voltage is limited within the voltage limit circle.

5. The weak magnetic field control method according to claim 4, characterized in that: The torque regulator controls the torque adjustment value to act on the torque reference value without changing the torque direction.

6. The weak magnetic field control method according to claim 4, characterized in that: The step of converting and determining the q-axis voltage output according to the torque reference value and the torque adjustment value comprises: determining a target torque according to the torque reference value and the torque adjustment value, and determining a target d-axis current based on the d-axis current reference value and the d-axis current adjustment value; The target q-axis current is determined according to the target torque and the target d-axis current using a preset torque-current conversion relationship table to determine the q-axis voltage output.

7. The magnetic field weakening control method according to claim 1, characterized in that: Determine the d-axis voltage output through the d-axis current control loop according to the d-axis current reference value; Determine the q-axis voltage output by converting to the q-axis current control loop according to the torque reference value; An output voltage is determined according to the d-axis voltage output and the q-axis voltage output.

8. The magnetic field weakening control method according to claim 1, characterized in that: The d-axis regulator and the torque regulator are both PI regulators.

9. A magnetic field weakening control device for a permanent magnet synchronous motor, characterized in that: include: An acquisition module is used to obtain a d-axis current reference value and a torque reference value of the permanent magnet synchronous motor to determine an output voltage; A preprocessing module, used for obtaining the maximum output voltage of the permanent magnet synchronous motor, and presetting the d-axis limit coefficient and the torque limit coefficient of the permanent magnet synchronous motor to determine the d-axis limit maximum output voltage and the torque limit maximum output voltage, wherein the d-axis limit coefficient and the torque limit coefficient are both 0 to 1, and wherein the d-axis limit coefficient is less than the torque limit coefficient; The first control module is used for feeding back the d-axis current closed-loop control when the output voltage is greater than the d-axis maximum output voltage limit and less than the torque maximum output voltage limit, and controlling the output voltage to be limited within the voltage limit circle through the d-axis regulator; The second control module is used to increase the torque closed-loop control when the output voltage is greater than the torque limit maximum output voltage, and start the torque regulator to control the output voltage to be limited within the voltage limit circle.

10. A motor controller, characterized in that: The permanent magnet synchronous motor weakening control device described in claim 9 above is used.

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