Permanent magnet synchronous motor rotor position locking method

Abstract

The invention discloses a permanent magnet synchronous motor rotor position locking method, a vector control mode and a servo control mode are designed in electric drive, the vector control mode is used for motor rotation speed adjustment, and the servo control mode is used for motor rotor position adjustment; switching the vector control mode to the servo control mode according to the switching criterion and the transition scheme; after switching to a servo control mode, performing closed-loop rotor position adjustment based on rotating speed open-loop current; after position adjustment is completed, a constant current vector rotor position locking scheme or a stator winding short circuit rotor position locking scheme is adopted to realize reliable locking of the rotor position; and finally, switching the servo control mode to the vector control mode according to the switching criterion and the transition scheme. The motor can be adjusted to the target rotating speed through the vector control mode, the rotor position can be adjusted to the target position and locked through the servo control mode, and the two operation modes of motor speed regulation and rotor position locking can be flexibly switched.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of permanent magnet synchronous motor control, and particularly relates to a permanent magnet synchronous motor rotor position locking method. BACKGROUND

[0002] Permanent magnet synchronous motors are widely used in all-electric aircrafts due to high power density, excellent efficiency and control performance. A typical all-electric aircraft propulsion system usually comprises driving inverters, permanent magnet synchronous motors, transmission shafts, propellers and other components, forming a direct-drive permanent magnet electric drive system to provide power for the aircraft.

[0003] In actual applications, the propeller needs to be locked at a specific position under certain special working conditions. For example, when the all-electric aircraft lands on the ground and slides, in order to avoid the propeller moving without power and colliding with the ground or other components, the rotor position of the permanent magnet synchronous motor usually needs to be locked at a specified angle, so that the propeller remains stationary.

[0004] However, under the above working conditions, the driving system is usually in a non-working state, and the motor does not provide output torque. In this state, if no special control strategy is adopted, the rotor position is difficult to maintain at the predetermined position, which poses a safety risk. In order to meet the requirements of the aircraft for static stability and system safety, it is necessary to develop a permanent magnet synchronous motor rotor position locking method. SUMMARY

[0005] The application aims to solve the above problems, and provides a permanent magnet synchronous motor rotor position locking method, which is suitable for application scenarios such as safe positioning of the propeller after the landing of the aircraft. The method designs two motor control modes in the electric drive system, namely a vector control mode and a servo control mode. The vector control mode is used for motor speed regulation, and the servo control mode is used for motor rotor position regulation. A switching criterion and a transition scheme from the vector control mode to the servo control mode are designed to avoid speed fluctuations and current surges during the switching process. After switching to the servo control mode, a rotor position regulation scheme based on speed open-loop current closed-loop is designed to regulate the rotor position to any target position. After completing the position regulation, a constant current vector rotor position locking scheme and a stator winding short-circuit rotor position locking scheme are designed, both of which can achieve reliable locking of the rotor position. At the same time, a switching criterion and a transition scheme from the servo control mode to the vector control mode are designed, so that the motor can return to the vector control mode for conventional speed control.

[0006] The design of the method can adjust the motor to the target speed by using the vector control mode,

[0007] The servo control mode allows the rotor position to be adjusted to the target position and locked. The two operating modes—motor speed regulation and rotor position locking—can be flexibly switched. To achieve the above objectives, the present invention includes the following steps:

[0008] Step A) Design two motor control modes in the electric drive system: design a vector control mode and a servo control mode in the electric drive system. The vector control mode is used for motor speed regulation, and the servo control mode is used for motor rotor position regulation.

[0009] Step B) Design the switching criteria and transition scheme from vector control mode to servo control mode: Design the switching criteria for switching from vector control mode to servo control mode in the electric drive system to complete the control mode switching. At the same time, design a smooth transition scheme for speed and current during the switching to avoid speed fluctuations and current surges.

[0010] Step C) Rotor position adjustment is achieved using a speed-based open-loop and current-based closed-loop method: In servo control mode, the speed loop is eliminated, and a rotor position adjustment scheme based solely on the current loop is used. By utilizing the interaction between the stator current vector and the rotor permanent magnet, the rotor position is gradually adjusted to any target position.

[0011] Step D) Design two schemes to achieve rotor position locking: After completing the rotor position adjustment, design a constant current vector rotor position locking scheme and a stator winding short-circuit rotor position locking scheme to achieve reliable rotor position locking;

[0012] Step E) Design the switching criteria and transition scheme from servo control mode to vector control mode: When it is necessary to exit rotor position locking and return to normal speed regulation mode, design the switching criteria for switching back from servo control mode to vector control mode, as well as the smooth transition scheme for speed and current during the switching. At this time, the motor returns to the normal speed regulation mode.

[0013] Preferably, in step A), the specific implementation of designing two motor control modes in the electric drive is as follows: one is a dual closed-loop vector control mode for motor speed regulation using both speed and current, and the other is a servo control mode for motor rotor position regulation. Simultaneously, three types of position information are defined: current vector position θ. eref Rotor position θ of the resolver e (i.e., the rotor position detected by the rotary transformer), target locking position θ edest .

[0014] In vector control mode, the current vector position θ eref The rotor position θ of the resolver is used. e During the motor speed regulation process, the rotor position θ of the resolver is adjusted accordingly. e Achieving the current vector position θeref Control.

[0015] In servo control mode, the speed loop is eliminated and only the current loop is retained, with the current vector position θ... eref The given angle information is used. During the motor position adjustment process, the target locked position θ is used. edest With the position θ of the resolver rotor e The deviation gradually changes the position θ of the current vector. eref .

[0016] Preferably, in step B), the specific implementation of the switching criterion and transition scheme from vector control mode to servo control mode is as follows: A switching criterion is set such that when the given speed is no greater than 0.5 rpm and the actual speed is no greater than 5 rpm, the system enters servo control mode. The transition scheme involves the host computer issuing a 0-speed command or a rotor position lock command when the motor drive system is in vector control mode, causing the motor to execute a speed adjustment command. The servo control mode is automatically enabled when the switching criterion is met. The d-axis current, q-axis current, and resolver rotor position θ at the last moment of the vector control mode are recorded. e When servo control mode is enabled, the recorded d-axis current and q-axis current are used as the initial values ​​of the servo control mode current, and the recorded resolver rotor position θ is used as the initial values. e As the position of the current vector θ eref The initial value.

[0017] Then, the speed loop control is cancelled, leaving only the current loop with a constant current vector applied. The speed is set to 0 rpm; the current is set to 0A for the q-axis and T% of the rated current for the d-axis, where T can be set according to actual conditions, such as 50%, thus generating a constant stator current vector I. s The angle transformation information is: current vector position θ eref Use the given angle information.

[0018] The current vector is applied along the d-axis of the dq coordinate system, with a step size of Δi. The current vector is applied in the following manner:

[0019] I qref =0

[0020] When I dref <I s At that time, I dref =I dref +Δi

[0021] When I dref ≥I s At that time, I dref =I s

[0022] wherein I qref represents the q-axis current given value, I dref represents the d-axis current given value.

[0023] Preferably, in the step C), the rotor position adjustment is achieved by using a speed open-loop current closed-loop based method, which is specifically implemented as follows: the permanent magnet synchronous motor rotor position, i.e. the resolver rotor position θ e , is detected in real time by means of a resolver, and the current vector position θ eref is adjusted so that the resolver rotor position θ e is constantly approaching the target locking position θ edest . In operation, the deviation between the target locking position θ edest and the resolver rotor position θ e is compared in real time, and the current vector position θ set is adjusted by a designed step Δθ eref according to the polarity of the deviation, so as to gradually guide the resolver rotor position θ e to the target locking position θ edest , and achieve flexible adjustment of the rotor position.

[0024] The adjustment of the current vector position θ eref is as follows:

[0025] when θ edest - θ e ≤ 0, θ eref = θ eref - Δθ set

[0026] when θ edest - θ e > 0, θ eref = θ eref + Δθ set

[0027] The above current vector position θ eref is used for current Park transformation and pulse width modulation inverse Park transformation of the permanent magnet synchronous motor vector control system, and the transformation matrices are as follows:

[0028] Park transformation matrix:

[0029]

[0030] Inverse Park transformation matrix:

[0031]

[0032] Preferably, in the step D), the rotor position locking is achieved by two schemes, which are specifically implemented as follows:

[0033] Scheme one is a constant current vector rotor position locking method. When the rotor position θ e of the resolver is within a design threshold value Δθ edest from the target locking position θ set , the rotor position closed loop comparison is turned off. The current vector position θ eref is set to the target locking position θ edest , and a constant stator current vector I s is applied to the d-axis by means of the current closed loop. The electromagnetic force between the stator current vector I s and the rotor permanent magnet is used to achieve rotor position locking.

[0034] At this time, the angle information adopted by the current vector position θ eref is

[0035] θ eref = θ edest

[0036] The d-axis and q-axis current application method is

[0037] I qref = 0

[0038] I dref = I s

[0039] Scheme two is a stator winding short circuit rotor position locking method. When the rotor target locking position θ edest is within a design threshold value Δθ e from the resolver rotor position θ set , the motor speed loop and current loop for motor control are canceled, and the motor is stopped. Then, the short circuit pulse generation module is enabled alone, a pulse signal is outputted to make the lower three transistors of the inverter simultaneously open, and the stator winding is short circuited to achieve rotor position locking.

[0040] It is assumed that the inverter switch tube is open when the drive pulse is 1, and the inverter switch tube is closed when the drive pulse is 0. The pulse signal application method for making the lower three transistors of the inverter simultaneously and continuously open is as follows:

[0041] PWM A_L = 1 PWM A_H = 0

[0042] PWM B_L = 1, PWM B_H = 0

[0043] PWM C_L = 1 PWM C_H = 0

[0044] In the formula, PWM A_L , PWMB_L PWM C_L PWM A_H PWM B_H PWM C_H PWM

[0045] Preferably, in the step E), the switching criterion of the servo control mode to the vector control mode and the specific implementation of the transition scheme are: setting the switching criterion, that is, when the given speed is greater than 0.5 rpm, the system enters the vector control mode. The speed and current smooth transition scheme at the switching time is introduced as follows according to the rotor position locking scheme adopted in step D).

[0046] When the constant current vector rotor position locking method is used for rotor position locking, when the vector control mode is enabled, the speed given mode is derived from the upper layer control instruction; the current given mode is that the q-axis current given is derived from the speed regulator output, and the d-axis current given is derived from the MTPA curve and the field weakening regulator; the angle transformation information is the resolver rotor position θ e . At this time, the transition from the servo control mode to the vector control mode is completed, and then the normal motor speed regulation operation control is started.

[0047] When the stator winding short circuit rotor position locking method is used for rotor position locking, when the vector control mode is enabled, the short circuit pulse generation module is shielded, the motor is started, and the motor speed regulation function is normally executed. The speed given mode is derived from the upper layer control instruction; the current given mode is that the q-axis current given is derived from the speed regulator output; the d-axis current given is derived from the MTPA curve and the field weakening regulator; the angle transformation information is the resolver rotor position θ e .

[0048] The beneficial effects of the present application at least include:

[0049] 1. The two motor control modes and transition schemes proposed by the present application have the beneficial effect that the flexible switching of the motor speed regulation and the rotor position locking two operation modes can be realized, and there is no speed and current impact in the switching process.

[0050] 2. The constant current vector rotor position locking scheme proposed by the present application has the beneficial effect that the rotor position locking under the load working condition of the motor output shaft can be realized, and the locking position can be arbitrarily set.

[0051] 3. The stator winding short circuit rotor position locking scheme proposed by the present application has the beneficial effect that the stator current does not need to be applied, which effectively reduces the power loss during the rotor position locking, and the locking position can be arbitrarily set. BRIEF DESCRIPTION OF DRAWINGS

[0052] Figure 1 Switching criterion for two motor control modes of the present application;

[0053] Figure 2 Principle structure diagram for realizing rotor position regulation based on the open-loop speed and closed-loop current of the present application;

[0054] Figure 3 Schematic diagram of the rotor position change law of the resolver during the implementation of the rotor position regulation process of the present application, Figure 3 (a) represents the working condition that the resolver rotor position leads the target locking position, Figure 3 (b) represents the working condition that the resolver rotor position lags behind the target locking position;

[0055] Figure 4 Schematic diagram of the inverter pulse application during the implementation of the stator winding short circuit of the present application;

[0056] Figure 5 Test waveforms for entering the servo control mode from the vector control mode to lock the rotor position, from top to bottom are speed, rotor position, current, control mode (the target locking position is 180°, and the actual locking position is 179.6°);

[0057] Figure 6 Test waveforms for entering the servo control mode from the vector control mode to regulate the rotor position at any position, and finally execute the position locking, from top to bottom are speed, rotor position, current, control mode (the target locking positions are 180°, 135°, and 90° in sequence, and the actual locking positions are 179.5°, 135.3°, and 89.8° in sequence);

[0058] Figure 7 Test waveforms for entering the servo control mode from the vector control mode to lock the rotor position, and then entering the speed modulation mode to regulate the speed, from top to bottom are speed, rotor position, current, control mode (the motor speed instruction is 800 rpm to 0 rpm and then to 800 rpm). DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present application will be described clearly and completely below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments of the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0060] To facilitate understanding of the embodiments of the present invention, further explanations and descriptions will be provided below with reference to the accompanying drawings and specific embodiments. These embodiments do not constitute a limitation on the embodiments of the present invention.

[0061] like Figure 1 As shown, this invention sets two motor control modes in the motor control system: a vector control mode for motor speed regulation and a servo control mode for motor rotor position regulation. The switching criteria for the two control modes are also described. When the given speed is no greater than 0.5 rpm and the actual speed is no greater than 5 rpm, the system enters the servo control mode. When the motor drive system is in vector control mode, the host computer sends a 0-speed command to cause the motor to execute a speed adjustment command. The servo control mode is automatically enabled when the switching criteria are met.

[0062] Figure 2 This is a schematic diagram illustrating the principle and structure of the rotor position adjustment based on an open-loop speed control and a closed-loop current control method according to the present invention. As shown in the diagram, in servo control mode, the speed loop control is eliminated, and only the current loop is retained with a constant current vector applied. The given speed is set to 0 rpm, the q-axis current is set to 0 A, and the d-axis current is set to 50% of the rated current, thereby generating a constant stator current vector I. s Current vector position θ eref The given angle information is used.

[0063] The current vector is applied along the d-axis of the dq coordinate system, with a step size of Δi. The current vector is applied in the following manner:

[0064] I qref =0

[0065] When I dref <I s At that time, I dref =I dref +Δi

[0066] When I dref ≥I s At that time, I dref =I s

[0067] I qref I represents the q-axis current setpoint. dref This represents the given value of the d-axis current.

[0068] Figure 3 This is a schematic diagram illustrating the change in resolver rotor position during rotor position adjustment in this invention. The rotor position θ of the permanent magnet synchronous motor, i.e., the resolver rotor position, is detected in real time using a resolver. e Adjust the current vector position θ eref To make the resolver rotor position θe Approaching target lock position θ edest . Operationally, real-time comparison of target lock position θ edest and the deviation of the rotary variable transducer rotor position θ e , according to the deviation polarity to design step Δθ set adjust the current vector position θ eref , and then gradually guide the rotary variable transducer rotor position θ e to the target lock position θ edest , achieve flexible adjustment of rotor position.

[0069] Adjustment of current vector position θ eref The adjustment method is as follows:

[0070] When θ edest - θ e ≤ 0, θ eref = θ eref - Δθ set

[0071] When θ edest - θ e > 0, θ eref = θ eref + Δθ set

[0072] The above-mentioned current vector position θ eref is used for current Park transformation and pulse width modulation inverse Park transformation of the permanent magnet synchronous motor vector control system, and the transformation matrices are as follows.

[0073] Park transformation matrix:

[0074]

[0075] Inverse Park transformation matrix:

[0076]

[0077] When the difference between the rotary variable transducer rotor position θ e and the target lock position θ edest is within the design threshold value Δθ set , the constant current vector rotor position lock scheme or the stator winding short circuit rotor position lock scheme can be selected to perform rotor position lock.

[0078] For the constant current vector rotor position lock method. When the difference between the rotary variable transducer rotor position θ e and the target lock position θ edest is within the design threshold value Δθ set , the rotor position closed-loop comparison is closed. Set the current vector position θ eref to the target lock position θedest And with this as the d-axis, a constant stator current vector I is applied to the d-axis by means of current closed loop s . The stator current vector I s Interacts with the rotor permanent magnet to achieve rotor position locking.

[0079] At this time, the current vector position θ eref The angle information adopted is:

[0080] θ eref = θ edest

[0081] The d-axis and q-axis current application method is:

[0082] I qref = 0

[0083] I dref = I s

[0084] For the rotor position locking method of stator winding short circuit, when the difference between the rotor target locking position θ edest And the resolver rotor position θ e Is within the design threshold value Δθ set Cancel the motor control speed loop and current loop, and the motor stops. Then, enable the short circuit pulse generation module alone, output the pulse signal that makes the lower three tubes of the inverter open at the same time, and then make the stator winding short circuit, realizing rotor position locking. Figure 4 It is an inverter pulse application schematic diagram for the stator winding short circuit of the embodiment of the application.

[0085] Assuming that the inverter switching tube is open when the driving pulse is 1, and the inverter switching tube is closed when the driving pulse is 0, the pulse signal application method that makes the lower three tubes of the inverter open at the same time is:

[0086] PWM A_L = 1 PWM A_H = 0

[0087] PWM B_L = 1, PWM B_H = 0

[0088] PWM C_L = 1 PWM C_H = 0

[0089] In the formula, PWM A_L , PWM B_L , PWM C_L Respectively represent the driving pulse of the lower bridge arm switching tube of the three-phase inverter A, B, and C phase. PWM A_H , PWM B_H , PWMC_H These represent the drive pulses of the upper bridge arm switching transistors of phases A, B, and C, respectively.

[0090] Figure 5 The waveforms represent the test waveforms for rotor position locking during the transition from vector control mode to servo control mode. From top to bottom, they represent rotational speed, rotor position, current, and control mode. During the test, the target locked position θ... edest The actual locked position is 179.6°, with a position locking error of 0.4°. As shown in the figure, in vector control mode, the motor speed is 800 rpm. The host computer issues a 0-speed command to cause the motor to execute a speed adjustment command. When the switching criterion is met, the servo control mode is automatically enabled, and the control mode jumps from 0 to 1. Afterward, the d-axis current rapidly increases to the set 30A and begins to adjust the rotor position to the target position of 180°. When the resolver rotor position θ... e Target lock position θ edest The difference lies in the design threshold Δθ set Within a certain value (in this example, Δθ is set). set =2°), shut down the rotor position closed-loop comparison. A constant current vector rotor position locking method is used to lock the target position θ. edest Using the d-axis as an example, a constant stator current vector of 30A is applied to the d-axis through a current closed-loop method to achieve rotor position locking.

[0091] Figure 6 The waveforms represent the test waveforms from vector control mode to servo control mode, performing arbitrary rotor position adjustments, and finally locking the position. From top to bottom, they represent speed, rotor position, current, and control mode. During the test, the target locked positions were 180°, 135°, and 90°, respectively, and the actual locked positions were 179.5°, 135.3°, and 89.8°, respectively, with position adjustment errors all within 0.5°. The test results demonstrate that the proposed rotor position adjustment method based on open-loop speed control and closed-loop current control can adjust the motor rotor position to any target position.

[0092] Figure 7 The test waveforms, from top to bottom, show the rotor position locking during the transition from vector control mode to servo control mode, and then to speed modulation mode for speed adjustment. During the test, the motor speed was initially set to 800 rpm. Then, the host computer issued a 0 rpm command to instruct the motor to execute the speed adjustment command. Once the switching criteria were met, the servo control mode was automatically enabled, and the control mode transitioned from 0 to 1. Subsequently, the d-axis current rapidly increased to the set 30A, and the rotor position began to adjust to the target position of 180°, before position locking was performed.

[0093] When the given speed is greater than 0.5 rpm, the control mode jumps from 1 to 0, and the system enters the vector control mode. At this time, the q-axis current given is derived from the speed regulator output, the d-axis current given is derived from the MTPA curve and the field weakening regulator, the angle transformation information uses the angle information detected by the resolver, and the motor starts to normally execute the conventional motor speed regulation operation control. The test results prove that the two motor control modes and the transition scheme proposed in the application can realize the flexible switching of the motor speed regulation and the rotor position locking two operation modes, and there is no speed and current impact in the switching process.

[0094] The technical features of the above embodiments can be combined in any manner. In order to make the description simple, all possible combinations of the technical features in the above embodiments are not described, only the preferred embodiments of the application are expressed, and the description is more specific and detailed, but it should not be understood as limiting the scope of the application. As long as the combination of these technical features does not exist, it should be considered as the scope of the description.

[0095] It should be pointed out that for those skilled in the art, without departing from the concept of the application, several modifications and improvements can be made, which are within the scope of the application. Therefore, the protection scope of the application should be subject to the appended claims.

Claims

1. A method of permanent magnet synchronous motor rotor position locking, characterized by, The method comprises the following steps: Step A) designing a vector control mode and a servo control mode in the electric drive system, the vector control mode being used for speed regulation of the motor, and the servo control mode being used for rotor position regulation of the motor; Step B) completing switching from the vector control mode to the servo control mode according to a switching criterion and a transition scheme; Step C) realizing rotor position regulation by using a speed open-loop current closed-loop based mode; Step D) after completing the rotor position regulation, adopting a constant current vector rotor position locking scheme or a stator winding short circuit rotor position locking scheme to realize locking of the rotor position; Step E) when exiting the rotor position locking to return to the normal speed regulation mode, completing switching from the servo control mode back to the vector control mode according to a switching criterion and a transition scheme.

2. The method of claim 1, wherein In the vector control mode, the current vector position θ eref The rotor position θ of the resolver is used. e During the motor speed regulation process, according to the resolver rotor position θ e To control the position θ of the current vector eref ; In the servo control mode, the speed loop is eliminated and only the current loop is retained, and the current vector position θ eref The given angle information is used; during the motor position adjustment process, the current vector position θ edest is gradually changed according to the deviation of the resolver rotor position θ e from the target locking position θ eref .

3. The method of claim 2, wherein the step of locking the rotor position of the permanent magnet synchronous motor is characterized by, The switching criterion of switching from the vector control mode to the servo control mode in the step B) is: given speed ≤ 0.5 rpm and actual speed ≤ 5 rpm; the speed and current smooth transition scheme is: when the motor driving system is in the vector control mode, the host computer issues a 0 speed instruction or a rotor position locking instruction to make the motor execute the speed regulation command, and when the switching criterion is met, the servo control mode is automatically enabled; the d-axis current, the q-axis current and the resolver rotor position θ of the last moment of the vector control mode are recorded e When the servo control mode is enabled, the recorded d-axis current and q-axis current are taken as the initial values of the servo control mode current, and the recorded resolver rotor position θ e is taken as the initial value of the current vector position θ eref . The speed given mode is that the given speed is set to 0 rpm; the current given mode is that the q-axis current given is set to 0 A, and the d-axis current given is T% of the rated current, T is set according to the actual situation, and then a constant stator current vector I is generated s ; the angle transformation information is that the current vector position θ eref The given angle information is used.

4. The method of claim 3, wherein, The current vector position θ eref The current Park transformation and the pulse width modulation inverse Park transformation used in the permanent magnet synchronous motor vector control system, the transformation matrix is as follows: Park transformation matrix: Inverse Park transformation matrix: 。 5. The method of claim 3, wherein, In the step C), when switching to the servo control mode, the rotor position regulation is realized by using a speed open-loop current closed-loop based mode; The rotor position adjusting process is: the rotor position of the permanent magnet synchronous motor is detected in real time by means of the resolver, that is, the resolver rotor position θ e , the current vector position θ eref is adjusted, the resolver rotor position is constantly close to the target locking position θ edest ; in operation, the deviation between the target locking position θ edest and the resolver rotor position θ e is compared in real time, the current vector position θ set is adjusted step by step according to the deviation polarity and the design step Δθ eref , and then the resolver rotor position θ e is gradually guided to the target locking position θ edest , so that the rotor position is flexibly adjusted. Current vector position θ eref The adjustment mode is: when θ edest - θ e ≤ 0, θ eref = θ eref - Δθ set When θ edest - θ e > 0, θ eref = θ eref + Δθ set .

6. The method of claim 5, wherein, The step D) is adopted after the rotor position adjustment is completed, a constant current vector rotor position locking scheme is adopted; specifically, when the rotor position θ e is within the design threshold value Δθ edest from the target locking position θ set , the rotor position closed-loop comparison is closed; the current vector position θ eref is set as the target locking position θ edest , and the d-axis is taken as the d-axis, and a constant stator current vector I s is applied to the d-axis by means of the current closed loop; the electromagnetic force between the stator current vector I s and the rotor permanent magnet is used to realize the rotor position locking; At this time, the current vector position θ eref The angle information used is: θ eref =θ edest The d-axis and q-axis current application mode is: I qref =0 I dref =I s where I qref represents a q-axis current command value, I dref represents a d-axis current command value.

7. The method of claim 5, wherein, In the step D), after the completion of the rotor position adjustment, a stator winding short-circuit rotor position locking scheme is adopted; specifically, when the difference between the rotor target locking position θ edest and the resolver rotor position θ e is within a design threshold value Δθ set , the motor control speed loop and current loop are cancelled, and the motor is stopped; then, the short-circuit pulse generation module is enabled alone, a pulse signal is output to make the lower three tubes of the inverter simultaneously open, and the stator winding is short-circuited to realize rotor position locking; Supposing that the inverter switch tube is turned on when the driving pulse is 1, and the inverter switch tube is turned off when the driving pulse is 0, the pulse signal application mode in which the lower three tubes of the inverter are simultaneously and continuously turned on is: PWM A_L =1 PWM A_H =0 PWM B_L = 1, PWM B_H = 0 PWM C_L =1 PWM C_H =0.

8. The method of claim 6 or 7, wherein In the step E), the criterion for returning the servo control mode to the vector control mode after completing the locking is that the given speed is greater than 0.5 rpm.

9. The method of claim 8, wherein, After the completion of the locking in step E), when the rotor position locking is completed by using the constant current vector rotor position locking scheme, it is necessary to realize the return of the servo control mode to the vector control mode, and the transition scheme is as follows: when the vector control mode is enabled, the speed given mode is as follows: the source is the upper layer control instruction; the current given mode is as follows: the q-axis current given is sourced from the output of the speed regulator, and the d-axis current given is sourced from the MTPA curve and the field weakening regulator; the angle transformation information is as follows: the resolver rotor position θ e At this time, the transition from the servo control mode to the vector control mode is completed, and then the normal motor speed regulation operation control is started to be executed.

10. The method of claim 8, wherein, After the completion of the locking in step E), when the rotor position locking is completed by using the stator winding short-circuit rotor position locking scheme, it is necessary to return the vector control mode from the servo control mode, and the transition scheme is as follows: when the vector control mode is enabled, the short-circuit pulse generation module is shielded, the motor is started, and the motor speed regulation function is normally executed; the speed given mode is: derived from the upper layer control instruction; the current given mode is: the q-axis current given is derived from the speed regulator output; the d-axis current given is derived from the MTPA curve and the field weakening regulator; the angle transformation information is: the resolver rotor position θ e At this time, the transition from the servo control mode to the vector control mode is completed, and then the normal motor speed regulation operation control is started.

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