Permanent magnet synchronous motor field weakening control method and device and motor control system

Abstract

The invention provides a field weakening control method and device for a permanent magnet synchronous motor and a motor control system, and relates to the technical field of motor control, and the method comprises the steps: obtaining the output voltage of the permanent magnet synchronous motor and the d-axis limit maximum output voltage; determining an MTPV curve of the permanent magnet synchronous motor in the current state in real time according to the rotating speed and the bus voltage; when the output voltage exceeds the maximum output voltage, a d-axis weak magnetic controller is adopted to output a d-axis current regulation value as a d-axis current increment until the output voltage is within a voltage limit ellipse; after the d-axis weak magnetic controller is determined to be saturated according to the curve of the permanent magnet synchronous motor, a q-axis current proportional regulator is adopted to calculate a q-axis current regulation value as a q-axis current reduction value until the output voltage Us is within a voltage limit ellipse, so that the output voltage is controlled to be limited within the voltage limit circle all the time, and the output voltage of the permanent magnet synchronous motor is controlled to be smaller than the voltage limit ellipse. The problem that multiple controllers are adopted for the d axis and the q axis in existing motor control, and the dynamic adjustment time is long due to mutual influence of the functions of the controllers is 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 control system. 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. Most existing controls use multiple controllers to control the d-axis and q-axis in closed loops respectively. The mutual influence of the integral action of multiple controllers will result in a longer dynamic adjustment time for motor control. 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 control system to solve the problem that the existing motor control uses multiple controllers for the d-axis and q-axis respectively, and their functions affect each other, resulting in a long dynamic adjustment time.

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

[0006] Get the output voltage Us of the permanent magnet synchronous motor and the maximum output voltage U of the d-axis limit max *coeff;

[0007] Obtain the speed and bus voltage of the permanent magnet synchronous motor in real time, and determine the MTPV curve of the permanent magnet synchronous motor in the current state according to the speed and bus voltage;

[0008] When the output voltage U s Exceeding the maximum output voltage U max *coeff, using the d-axis weak magnetic controller to output the d-axis current adjustment value ΔI d , ΔI d As the d-axis current increases, the output voltage U s within the voltage limit ellipse;

[0009] When the d-axis weak magnetic controller is saturated according to the MTPV curve of the permanent magnet synchronous motor, the q-axis current proportional regulator is used to calculate the q-axis current adjustment value ΔI q , ΔI q As the q-axis current decreases, the output voltage Us Within the voltage limit ellipse, the output voltage Us is controlled to always be limited within the voltage limit circle.

[0010] Preferably, the d-axis limit coefficient coeff is preset to obtain the maximum output limit voltage U of the inverter of the permanent magnet synchronous motor. max , wherein the d-axis restriction coefficient is 0 to 1;

[0011] According to the maximum output limit voltage U max The product of the d-axis limit coefficient coeff is used to obtain the d-axis limit maximum output voltage U max *coeff.

[0012] Preferably, the maximum allowable output value I of the d-axis current is determined according to the MTPV curve of the permanent magnet synchronous motor. dmax ;

[0013] When the d-axis weak magnetic controller adjusts the d-axis current to reach the maximum value of the d-axis current output I dmax , at this time the d-axis weak magnetic controller is saturated.

[0014] Preferably, after the d-axis field weakening controller is saturated, the portion where the motor operates beyond the MTPV curve is appended to the q-axis to determine the regulation of the q-axis current.

[0015] Preferably, the maximum allowable output value I of the d-axis current is determined according to the MTPV curve of the permanent magnet synchronous motor. dmax ;

[0016] When the d-axis weak magnetic field controller is saturated, obtain the d-axis current adjusted by the d-axis weak magnetic field controller and the maximum allowable d-axis current I dmax The difference is input into the q-axis proportional regulator to determine the q-axis current adjustment value ΔI q .

[0017] Preferably, the preset q-axis proportional regulator gain coefficient K is obtained p , according to the proportional regulator gain coefficient K p The product of the difference is used to determine the q-axis current adjustment value ΔI q .

[0018] Preferably, the d-axis voltage is output according to the d-axis current base value and the d-axis current loop control;

[0019] Output q-axis voltage according to q-axis current base value and q-axis current loop control;

[0020] The output voltage Us is determined by calculation according to the d-axis voltage and the q-axis voltage.

[0021] Preferably, the d-axis controller is a PI controller.

[0022] The present invention also provides a permanent magnet synchronous motor weak magnetic field control device, comprising:

[0023] The acquisition module is used to obtain the output voltage Us of the permanent magnet synchronous motor and the maximum output voltage U of the d-axis limit max *coeff; obtain the speed and bus voltage of the permanent magnet synchronous motor in real time, and determine the MTPV curve of the permanent magnet synchronous motor in the current state according to the speed and bus voltage;

[0024] The first regulating module is used for s Exceeding the maximum output voltage U max *coeff, using the d-axis weak magnetic controller to output the d-axis current adjustment value ΔI d , ΔI d As the d-axis current increases, until the output voltage Us is within the voltage limit ellipse;

[0025] The second regulation module is used to calculate the q-axis current regulation value ΔI using the q-axis current proportional regulator after determining that the d-axis weak magnetic controller is saturated according to the MTPV curve of the permanent magnet synchronous motor. q , ΔI q As the q-axis current decreases, the output voltage U s Within the voltage limit ellipse, the output voltage U s Always confined within the voltage limit circle.

[0026] The present invention also provides a motor control system, which acts on the control of a permanent magnet synchronous motor and applies the above-mentioned permanent magnet synchronous motor weak magnetic field control device.

[0027] Compared with the prior art, the above technical solution has the following beneficial effects:

[0028] The permanent magnet synchronous motor weak magnetic control method, device and control system provided in the present application determine whether the motor is running beyond the MTPV curve based on the output voltage. When the output voltage is lower than the maximum voltage limit of the d-axis, the output voltage can be reduced through q-axis control. When the d-axis control is limited, the part exceeding the MTPV curve is output through q-axis control, so that the output voltage is always kept within the voltage limit circle, reducing the situation where the motor exceeds the voltage limit and causing the system to lose control. Only one PI regulator acting on the d-axis is used to solve the problem of long dynamic adjustment time caused by the mutual influence of the integral action of each controller in the existing use of multiple PI regulators for motor control. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1Schematic diagram of the MTPA curve, MTPV curve voltage limit ellipse and current limit circle of the permanent magnet synchronous motor in the first embodiment of the permanent magnet synchronous motor weak magnetic control method, device and motor control system of the present invention

[0030] Figure 2 This is a flow chart of Embodiment 1 of a permanent magnet synchronous motor weak magnetic control method, device and motor control system according to the present invention;

[0031] FIG3( a ) is a reference diagram of the results of applying the existing control method in Embodiment 1 of a permanent magnet synchronous motor weak magnetic field control method, device and motor control system according to the present invention;

[0032] FIG3( b ) is a reference diagram of the results of applying the control method of this embodiment in Example 1 of a permanent magnet synchronous motor weak magnetic control method, device and motor control system according to the present invention;

[0033] Figure 4 This is a module schematic diagram of a second embodiment of a permanent magnet synchronous motor weak magnetic control method, device and motor control system according to the present invention.

[0034] Reference numerals:

[0035] 1-permanent magnet synchronous motor weak magnetic field control device; 11-acquisition module; 12-first regulation module; 13-second regulation module. DETAILED DESCRIPTION

[0036] The advantages of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0037] 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.

[0038] 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.

[0039] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0040] 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.

[0041] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0042] 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.

[0043] Embodiment 1: This embodiment discloses a method for weakening magnetic field of a permanent magnet synchronous motor, which solves the problem that the existing motor control uses multiple controllers for the d-axis and the q-axis respectively, and their actions affect each other, resulting in a long dynamic adjustment time. Specifically, a single controller acting on the d-axis is used to control the motor, and preferably, the single controller is a PI controller.

[0044] As an explanation, the control of the motor in this embodiment is mainly for, as shown in the schematic diagram Figure 1 As shown, the motor runs Us and gradually reaches the voltage output capacity limit U max , it is necessary to ensure that it is limited to the voltage limit circle and current limit circle, MTPV curve and MTPA curve. The following situations may occur, including but not limited to: 1. When the output voltage exceeds U max When limiting, the voltage feedback loop is used to increase the command voltage I d0The output voltage is reduced, but when the motor runs on the MTPV curve, increase I d0 The output voltage will run in the direction of increasing voltage, causing the motor to lose control, as shown in the figure below: 1→4; 2. When the output voltage exceeds U max When limiting, the voltage feedback closed loop is used to increase the command voltage I along the equal moment line. d0 Reduce I q0 , the output voltage is reduced. However, when the motor runs on the MTPV curve, Id0 is increased and I is reduced along the equal torque line. q0 The output voltage will run in the direction of increasing voltage, causing the motor to lose control; as shown in the figure point 1→2; 3. When the output voltage exceeds U max When limiting, the voltage feedback loop is closed to reduce I q0 , resulting in a decrease in output voltage.

[0045] However, the above controls are not limited to Id0, I q0 Or torque, all need to use multiple controllers, and the control method provided in this embodiment uses a single controller to achieve the following Figure 1 Midpoint 1→5, the torque at point 5 is greater than that at point 3, and the maximum torque output can be achieved in this case. Figure 2 ,include:

[0046] When the motor is running normally, obtain the d-axis current basic value I of the permanent magnet synchronous motor d0 and the q-axis current base value I q0 , determine the output voltage U according to the current loop s Specifically, according to the d-axis current base value I d0 and the d-axis current loop controls the output d-axis voltage U d ; According to the q-axis current base value I q0 And the q-axis current loop controls the output q-axis voltage U q Calculate and determine the output voltage U according to the d-axis voltage and the q-axis voltage s .

[0047] The motor control in the above normal state is similar to the motor control in the prior art, which operates through the d-axis current loop and the q-axis current loop respectively, and outputs the d-axis voltage U d and the q-axis voltage U q After that, according to the d-axis voltage U d and the q-axis voltage U q Calculate the final output voltage U s Specifically, according to the d-axis voltage U d and the q-axis voltage U q Add the squares and take the square root, that is

[0048] Among them U max is the maximum output current of the permanent magnet synchronous motor (i.e. the maximum output limit voltage of the inverter of the permanent magnet synchronous motor), and the output voltage U is determined accordingly s Real-time monitoring and control are performed as described below.

[0049] In this embodiment, in order to overcome the influence of mutual interference of multiple controllers on the control time, only one controller (PI) (i.e., a single controller, i.e., a d-axis weak magnetic controller) is used to perform control on the d-axis, thereby shortening the dynamic control time of the motor. The dynamic control time is the time required to control the motor when it runs on the MTPV curve as mentioned above to prevent the motor from losing control, that is, the time corresponding to dynamic control to control the motor to keep running within the voltage limit circle and the current limit circle, the MTPV curve and the MTPA curve.

[0050] First, obtain the d-axis limit maximum output voltage Umax*coeff. When the output voltage exceeds the d-axis limit maximum output voltage U max *coeff, output current regulation value ΔI using d-axis field weakening controller (single PI controller) d , to the d-axis current base value I d0 To adjust; specifically, ΔI d As the d-axis current increases, the d-axis current is continuously increased so that the output voltage U s Decrease until the output voltage U s As mentioned above, this embodiment uses a single controller to control the d-axis, so a control threshold needs to be preset. When the threshold is reached, the single controller works. The control threshold is the d-axis limit maximum output maximum voltage U max *coeff, specifically, preset the d-axis limit coefficient Coeff to obtain the maximum output voltage U of the permanent magnet synchronous motor max , wherein the d-axis limit coefficient is 0 to 1; obtaining the d-axis limit maximum output voltage according to the product of the maximum output voltage and the d-axis limit coefficient, that is, U max *Coeff. You can choose to set a parameter close to 1, such as 0.95, 0.98, etc., so that the motor is controlled when the motor runs close to or on the MTPV curve.

[0051] Based on the above, the output voltage is less than U max *Coeff, only the voltage feedback d-axis current closed loop works, by increasing I d0 The output voltage decreases, that is, the motor does not run on the MTPV curve at this time. The voltage feedback d-axis current closed-loop strategy is used to increase I d0 Even if the output voltage U sReduce the trend and achieve constant torque stable operation.

[0052] When the output voltage exceeds U max *Coeff, when the motor runs to the MTPV curve, increase I d0 The output voltage will increase. At this time, the q-axis current limiting makes the output voltage decrease, so as to avoid the motor exceeding the voltage limit and causing the system to lose control. In this embodiment, since a single controller is used and only the d-axis is controlled and output, in this case, the d-axis control output makes the part of the motor exceeding the MTPV curve be added to the q-axis for control.

[0053] Specifically, the speed and bus voltage of the permanent magnet synchronous motor are obtained in real time, and the MTPV curve of the permanent magnet synchronous motor in the current state is determined according to the speed and bus voltage. The corresponding d-axis current point on the MTPV curve is the maximum allowable output value of the d-axis current in the current state. dmax ; When the d-axis current is adjusted and runs, it exceeds the maximum value I allowed by the d-axis current output dmax At this time, the d-axis weak magnetic controller is saturated, and the d-axis weak magnetic controller is kept to continue to adjust, but the actual d-axis current output is limited to the maximum d-axis current output allowed on the MTPV curve I dmax , such as output voltage U s If the voltage continues to increase and still cannot be confined within the voltage limit ellipse, the q-axis needs to be adjusted to control the output voltage to be confined within the voltage limit circle.

[0054] As an explanation, according to the rotation speed S pd and bus voltage U dc Calculate the maximum torque voltage ratio curve (MTPV curve) of the permanent magnet synchronous motor and determine the given current point of the permanent magnet synchronous motor (such as I d0 ) under the maximum output capacity (i.e. the maximum output value of the d-axis current allowed I dmax ,), at this time, the d-axis weak magnetic controller is saturated, and after that, the motor operation beyond the MTPV curve is added to the q-axis to determine the adjustment of the q-axis current. Specifically, the q-axis current proportional regulator is used to calculate the q-axis current adjustment value ΔI q , the output of the d-axis current after adjustment is subtracted from the maximum torque voltage ratio curve (MTPV curve), and input into the proportional regulator to calculate the corresponding current adjustment value ΔI q .

[0055] In this embodiment, the part of the permanent magnet synchronous motor running beyond the MTPV curve after the d-axis adjustment is applied to the q-axis control, and the adjustment of the q-axis according to the difference output includes: obtaining a preset q-axis proportional regulator gain coefficient K p , according to the q-axis proportional regulator gain coefficient Kp The product of the difference is used to determine the q-axis current adjustment value ΔI q As an illustration, the adjustment coefficient k can be specifically set according to the parameters of the specific permanent magnet synchronous motor, working scene parameters, etc., and can also be adjusted by control instructions, etc.

[0056] In this embodiment, when a PI controller is used for d-axis control in the entire motor control, the portion of the permanent magnet synchronous motor that exceeds the MTPV curve can be added to the q-axis proportional regulator for q-axis control, which can be achieved through a single P controller. The q-axis proportional regulator is different from the PI controller for the d-axis control, and will not produce mutual influence of integral action. It is only convenient for realizing the assignment adjustment of the q-axis, and other achievable means in the prior art can also be used as an alternative.

[0057] The permanent magnet synchronous motor weak magnetic control method provided in this embodiment can still reduce the output voltage through q-axis control when the motor runs on the MTPV curve (that is, after the above-mentioned d-axis weak magnetic controller is saturated), thereby reducing the situation where the motor exceeds the voltage limit and causes the system to lose control. In this embodiment, only one PI regulator is used to make the output voltage not exceed the d-axis maximum output voltage U max *Coeff, and solve the problem of long dynamic adjustment time caused by the mutual influence of the integral action of each controller when multiple PI regulators are used for motor control.

[0058] Refer to Figure 3, where Figure 3(a) is a reference diagram of the results of applying the existing control method; Figure 3(b) is a reference diagram of the results of applying the weak magnetic control method provided by this embodiment. By comparison, it can be seen that: the modulation of the existing method lasts for more than 0.5 seconds when it is 1.01, while the control method of this embodiment can be set to less than 0.5 seconds, and the control accuracy is more accurate.

[0059] Embodiment 2: The present invention also provides a permanent magnet synchronous motor weak magnetic control device 1, see Figure 4 ,include:

[0060] The acquisition module 11 is used to obtain the d-axis current basic value and the q-axis current basic value of the permanent magnet synchronous motor, and obtain the output voltage U in real time according to the current loop. s ; Get the maximum output voltage U of the d-axis limit max *coeff; obtain the speed and bus voltage of the permanent magnet synchronous motor in real time, and determine the MTPV curve of the permanent magnet synchronous motor in the current state according to the speed and bus voltage;

[0061] Specifically, in this acquisition module, according to the d-axis voltage U d and the q-axis voltage U q The output voltage U is determined by adding the squares of the two respectively and then taking the square root.s , and then the output voltage U s Feedback is given to the first regulating module and the second regulating module described below to control the d-axis and / or q-axis.

[0062] The first regulating module 12 is used to calculate the q-axis current regulating value ΔI by using the q-axis current proportional regulator after determining that the d-axis weak magnetic controller is saturated according to the MTPV curve of the permanent magnet synchronous motor. q , ΔI q As the q-axis current decreases, the output voltage U s Within the voltage limit ellipse, the output voltage U s Always confined within the voltage limit circle;

[0063] Specifically, set the d-axis limit maximum output voltage U max *Coeff, output voltage is less than U max *Coeff, only the voltage feedback d-axis current closed loop works, by increasing I d0 The output voltage has a decreasing trend so that the output voltage is limited within the voltage limit circle.

[0064] The second regulating module 13 is used to calculate the q-axis current regulating value ΔI by using the q-axis current proportional regulator after determining that the d-axis weak magnetic controller is saturated according to the MTPV curve of the permanent magnet synchronous motor. q , ΔI q As the q-axis current decreases, the output voltage U s Within the voltage limit ellipse, the output voltage U s Always confined within the voltage limit circle.

[0065] Specifically, when the d-axis PI regulator is saturated, the d-axis current will run on the MTPV curve. At this time, the d-axis weak magnetic controller is saturated, and the d-axis weak magnetic controller continues to adjust, but the actual d-axis current output is limited to the maximum value of the d-axis current allowed to output I on the MTPV curve. dmax If the output voltage Us continues to increase and still cannot be limited within the voltage limit ellipse, the voltage feedback q-axis current closed loop is increased, that is, the part of the d-axis current running beyond the MTPV curve (using the q-axis current proportional regulator) is adjusted through the q-axis output to reduce the risk of motor loss of control, and the q-axis is adjusted by the product output of the preset proportional regulator gain coefficient, that is, it can be regarded as a parameter assignment method for adjustment, without setting multiple PI regulators. Therefore, the motor is controlled only by the controller acting on the d-axis (d-axis weak magnetic controller), which can effectively reduce the situation in which the existing application of multiple regulators affects each other's integral action and causes a long dynamic adjustment time.

[0066] Embodiment three: The present invention also provides a motor control system, which acts on the control of a permanent magnet synchronous motor. The above-mentioned permanent magnet synchronous motor weak magnetic field control device is applied to new energy vehicles. Furthermore, it can also include or connect other modules or devices for motor control or vehicle operation, so as to adapt to different implementation scenarios and realize fast and accurate control of the motor.

[0067] 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: Get the output voltage U of the permanent magnet synchronous motor s , d-axis limit maximum output voltage U max *coeff; Obtain the speed and bus voltage of the permanent magnet synchronous motor in real time, and determine the MTPV curve of the permanent magnet synchronous motor in the current state according to the speed and bus voltage; When the output voltage U s Exceeding the maximum output voltage U max *coeff, using the d-axis weak magnetic controller to output the d-axis current adjustment value ΔI d , ΔI d As the d-axis current increases, the output voltage U s Within the voltage limit ellipse; when the d-axis weak magnetic controller is determined to be saturated according to the MTPV curve of the permanent magnet synchronous motor, the q-axis current proportional regulator is used to calculate the q-axis current adjustment value ΔI q , ΔI q As the q-axis current decreases, the output voltage U s Within the voltage limit ellipse, the output voltage Us is thus controlled to always be limited within the voltage limit circle.

2. The weak magnetic field control method according to claim 1, characterized in that: Preset the d-axis limit coefficient coeff to obtain the maximum output limit voltage U of the inverter of the permanent magnet synchronous motor max , wherein the d-axis restriction coefficient is 0 to 1; According to the maximum output limit voltage U max The product of the d-axis limit coefficient coeff is used to obtain the d-axis limit maximum output voltage U max *coeff.

3. The weak magnetic field control method according to claim 1, characterized in that: According to the MTPV curve of the permanent magnet synchronous motor, the maximum allowable output value of the d-axis current I is determined. dmax ; When the d-axis weak magnetic controller adjusts the d-axis current to reach the maximum value of the d-axis current output I dmax , at this time the d-axis weak magnetic controller is saturated.

4. The weak magnetic field control method according to claim 1, characterized in that: After the d-axis field weakening controller is saturated, the portion of the motor operating beyond the MTPV curve is appended to the q-axis to determine the regulation of the q-axis current.

5. The weak magnetic field control method according to claim 1 or 4, characterized in that: According to the MTPV curve of the permanent magnet synchronous motor, the maximum allowable output value of the d-axis current I is determined. dmax ; When the d-axis field weakening controller is saturated, Get the d-axis current adjusted by the d-axis weak magnetic controller and the maximum allowable d-axis current I dmax The difference is input into the q-axis proportional regulator to determine the q-axis current adjustment value ΔI q .

6. The magnetic field weakening control method according to claim 5, characterized in that: Get the preset q-axis proportional regulator gain coefficient K p , according to the proportional regulator gain coefficient K p The product of the difference is used to determine the q-axis current adjustment value ΔI q .

7. The magnetic field weakening control method according to claim 1, characterized in that: Output d-axis voltage according to d-axis current base value and d-axis current loop control; Output q-axis voltage according to q-axis current base value and q-axis current loop control; The output voltage Us is determined by calculation according to the d-axis voltage and the q-axis voltage.

8. The magnetic field weakening control method according to claim 1, characterized in that: The d-axis controller is a PI controller.

9. A permanent magnet synchronous motor weak magnetic control device, characterized in that: include: The acquisition module is used to obtain the output voltage Us of the permanent magnet synchronous motor and the maximum output voltage Umax*coeff limited by the d-axis; Obtain the speed and bus voltage of the permanent magnet synchronous motor in real time, and determine the MTPV curve of the permanent magnet synchronous motor in the current state according to the speed and bus voltage; The first regulating module is used for s Exceeding the maximum output voltage U max *coeff, using the d-axis weak magnetic controller to output the d-axis current adjustment value ΔI d , ΔI d As the d-axis current increases, until the output voltage Us is within the voltage limit ellipse; The second regulation module is used to calculate the q-axis current regulation value ΔI using the q-axis current proportional regulator after determining that the d-axis weak magnetic controller is saturated according to the MTPV curve of the permanent magnet synchronous motor. q , ΔI q As the q-axis current decreases, the output voltage U s Within the voltage limit ellipse, the output voltage U s Always confined within the voltage limit circle.

10. A motor control system, characterized in that: The control of the permanent magnet synchronous motor is performed by applying the permanent magnet synchronous motor weak magnetic field control device described in claim 9 above.

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