Control system and method for permanent magnet synchronous motor

Abstract

A control system for a permanent magnet synchronous motor comprises: a permanent magnet synchronous motor; a first coordinate transformation unit, performing Clarke transformation on a three-phase stator current to obtain a stator current in a two-phase stationary coordinate system; a second coordinate transformation unit, combining the motor angle of the permanent magnet synchronous motor in the previous cycle, performing Park transformation on the stator current in the two-phase stationary coordinate system to obtain the stator current of the dq axes in the dq coordinate system; a control unit, calculating and outputting the stator voltage of the dq axes based on the stator current of the dq axes; a calculation unit, calculating the current motor angle of the motor based on the stator current and the stator voltage of the dq axes; a third coordinate transformation unit, performing Park inverse transformation on the current motor angle to obtain a first AC voltage and a second AC voltage in the two-phase stationary coordinate system; and a drive unit, outputting a three-phase sinusoidal AC power to the stator end of the motor based on the first AC voltage and the second AC voltage, thereby realizing the position positioning of the motor during sensorless operation and completing the control of the permanent magnet synchronous motor.

Description

Technical Field

[0001] The present invention relates to the technical field of control of permanent magnet synchronous motors, and in particular to a control system and method for a permanent magnet synchronous motor. Background Art

[0002] With the maturity of motor manufacturing technology and the widespread availability of permanent magnet materials, permanent magnet synchronous motors (PMSMs) have begun to be used in various motor control applications. Compared to asynchronous motors, PMSMs offer advantages such as high torque, low noise, long service life, and the absence of brushless sparks. Based on their structure, PMSMs can be further categorized as permanent magnet synchronous motors (PMSMs) and brushless DC motors (BLDCs). BLDCs utilize square wave control, offering advantages such as high torque and simple control. However, they are noisier and experience greater wear than PMSMs. As more high-performance motor products demand higher performance indicators, PMSMs are becoming increasingly mainstream. This present invention is based on a modeling design based on PMSMs. In recent years, continuous advancements in PMSM drive control technology have significantly improved motor performance, leading to widespread application of PMSM control in various fields, including home appliances, robotics, industrial CNC, and aerospace medicine.

[0003] Traditional asynchronous motors and brushless DC motors both generate a certain amount of noise, which limits their application in many situations. Therefore, a stable permanent magnet synchronous motor system is needed that is relatively easy to control. Considering that many permanent magnet synchronous motors currently do not have built-in sensors, how to achieve stable and efficient control has become an urgent problem that needs to be solved. Summary of the Invention

[0004] The object of the present invention is to provide a control system and method for a permanent magnet synchronous motor, which can solve the above problems.

[0005] One aspect of an embodiment of the present invention provides a control system for a permanent magnet synchronous motor, including:

[0006] A permanent magnet synchronous motor including a three-phase stator;

[0007] a first coordinate transformation unit, electrically connected to the permanent magnet synchronous motor, configured to perform Clarke transformation on the stator current of the three-phase stator to obtain the stator current in a two-phase stationary coordinate system;

[0008] a second coordinate transformation unit, electrically connected to the first coordinate transformation unit, for performing a Park transformation on the stator current in the two-phase stationary coordinate system in combination with the motor angle of the permanent magnet synchronous motor in the previous cycle to obtain a d-axis stator current and a q-axis stator current in a synchronous rotating coordinate system;

[0009] a control unit, electrically connected to the second coordinate transformation unit, configured to calculate and output a d-axis stator voltage and a q-axis stator voltage according to the d-axis stator current and the q-axis stator current;

[0010] a calculation unit, electrically connected to the second coordinate transformation unit and the control unit, for calculating a current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage;

[0011] a third coordinate transformation unit, electrically connected to the calculation unit and the control unit, configured to perform a Park inverse transformation using the current motor angle to obtain a first AC voltage and a second AC voltage in a two-phase stationary coordinate system;

[0012] The drive unit is electrically connected to the third coordinate transformation unit and the permanent magnet synchronous motor, and is used to output three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor according to the first alternating voltage and the second alternating voltage.

[0013] Optionally, the control unit includes:

[0014] a first subtractor, electrically connected to the calculation unit, for calculating an angular velocity difference between a given motor angular velocity and an actual angular velocity;

[0015] a speed loop controller, electrically connected to the first subtractor, and configured to calculate a q-axis reference current according to the angular velocity difference;

[0016] a second subtractor, electrically connected to the speed loop controller and the second coordinate transformation unit, for calculating a difference between the q-axis stator current and the q-axis reference current;

[0017] a q-axis current loop controller, electrically connected to the second subtractor, and configured to calculate the q-axis stator voltage according to a difference between the q-axis stator current and the q-axis reference current;

[0018] a third subtractor, electrically connected to the second coordinate transformation unit, for calculating a difference between the d-axis stator current and the d-axis reference current;

[0019] A d-axis current loop controller is electrically connected to the second subtractor and is used to calculate the d-axis stator voltage according to a difference between the d-axis stator current and the d-axis reference current.

[0020] Substitute the d-axis stator current, q-axis stator current, d-axis stator voltage, and q-axis stator voltage into the first formula:

[0021] di d / dt=[u d -Rs*i d +ω e*Lqi q ] / Ld;

[0022] di q / dt=[u q -Rs*i q -ω e *Ld i d -ω e *ψ f ] / Lq; (1)

[0023] Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψ f is the q-axis magnetic flux, ω e is the rotor angular velocity;

[0024] Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula:

[0025] [i d (k+1)-i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lqi q (k)] / Ld;

[0026] [i q (k+1)-i q (k)] / T=[u q (k)-Rs*i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2)

[0027] when i d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1;

[0028] when i q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2;

[0029] Substituting the angular velocities ω1 and ω2 into the third formula:

[0030] ω e 1=ω1*Pd+ω2*PI; (3)

[0031] Where ωe1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain;

[0032] The final angular velocity ω is obtained from the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

[0033] Optionally, the driving unit includes:

[0034] a space vector pulse width modulation unit, electrically connected to the third coordinate transformation unit, and configured to output a digital driving signal according to the first alternating current voltage and the second alternating current voltage;

[0035] A three-phase inverter is electrically connected to the space vector pulse width modulation unit and the permanent magnet synchronous motor, and is turned on or off according to the digital drive signal to generate the three-phase sinusoidal alternating current.

[0036] An aspect of an embodiment of the present invention further provides a method for controlling a permanent magnet synchronous motor, including:

[0037] The stator current of the three-phase stator of the permanent magnet synchronous motor is subjected to Clarke transformation to obtain the stator current in the two-phase stationary coordinate system;

[0038] Combined with the motor angle of the permanent magnet synchronous motor in the previous cycle, the stator current in the two-phase stationary coordinate system is subjected to Park transformation to obtain the d-axis stator current and the q-axis stator current in the synchronous rotating coordinate system;

[0039] Calculating and outputting a d-axis stator voltage and a q-axis stator voltage according to the d-axis stator current and the q-axis stator current;

[0040] Calculating a current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage;

[0041] Performing a Park inverse transform according to the current motor angle to obtain a first AC voltage and a second AC voltage in a two-phase stationary coordinate system;

[0042] A three-phase sinusoidal alternating current is output to a stator end of the permanent magnet synchronous motor according to the first alternating current voltage and the second alternating current voltage.

[0043] Optionally, the step of calculating and outputting a d-axis stator voltage and a q-axis stator voltage based on the d-axis stator current and the q-axis stator current specifically includes:

[0044] Calculate the angular velocity difference between the given motor angular velocity and the actual angular velocity;

[0045] Calculating the q-axis reference current according to the angular velocity difference by a speed loop controller;

[0046] Calculating a difference between the q-axis stator current and the q-axis reference current;

[0047] Calculating the q-axis stator voltage according to the difference between the q-axis stator current and the q-axis reference current by a q-axis current loop controller;

[0048] Calculating a difference between the d-axis stator current and the d-axis reference current;

[0049] The d-axis stator voltage is calculated by a d-axis current loop controller according to the difference between the d-axis stator current and the d-axis reference current.

[0050] Optionally, calculating the current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage specifically includes:

[0051] Substitute the d-axis stator current, q-axis stator current, d-axis stator voltage, and q-axis stator voltage into the first formula:

[0052] di d / dt=[u d -Rs*i d +ω e *Lqi q ] / Ld;

[0053] di q / dt=[u q -Rs*i q -ω e *Ld i d -ω e *ψ f ] / Lq; (1)

[0054] Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψf is the q-axis magnetic flux, ω e is the rotor angular velocity;

[0055] Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula:

[0056] [i d (k+1)-i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lqi q (k)] / Ld;

[0057] [i q (k+1)-i q (k)] / T=[u q (k)-Rs*i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2)

[0058] when i d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1;

[0059] when i q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2;

[0060] Substituting the angular velocities ω1 and ω2 into the third formula:

[0061] ω e 1=ω1*Pd+ω2*PI; (3)

[0062] Where ωe1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain;

[0063] The final angular velocity ω is obtained from the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

[0064] Optionally, the step of outputting three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor according to the first alternating current voltage and the second alternating current voltage specifically includes:

[0065] outputting a digital driving signal according to the first AC voltage and the second AC voltage;

[0066] The three-phase inverter is controlled to be turned on and off by the digital drive signal to generate the three-phase sinusoidal alternating current.

[0067] An aspect of an embodiment of the present invention further provides a method for controlling a permanent magnet synchronous motor, including:

[0068] When the permanent magnet synchronous motor is running, collecting the three-phase stator current of the permanent magnet synchronous motor;

[0069] The three-phase stator voltage is obtained according to the PWM control signal output by the space vector pulse width modulation unit in the previous cycle;

[0070] Performing Clarke transformation on the three-phase stator current and the three-phase stator voltage to obtain the stator current and stator voltage in a two-phase stationary coordinate system;

[0071] Performing a Park transformation on the stator current and stator voltage in the two-phase stationary coordinate system to obtain a d-axis stator current, a q-axis stator current, a d-axis stator voltage, and a q-axis stator voltage in a synchronous rotating coordinate system;

[0072] Calculating a current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage;

[0073] Performing a Park inverse transform on the current motor angle and the d-axis stator voltage and the q-axis stator voltage to obtain a first AC voltage and a second AC voltage in a two-phase stationary coordinate system;

[0074] A three-phase sinusoidal alternating current is output to a stator end of the permanent magnet synchronous motor according to the first feedback voltage and the second feedback voltage.

[0075] Optionally, the step of outputting three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor according to the first feedback voltage and the second feedback voltage specifically includes:

[0076] Outputting a digital driving signal according to the first feedback voltage and the second feedback voltage;

[0077] The three-phase inverter is controlled to be turned on and off by the digital drive signal to generate the three-phase sinusoidal alternating current.

[0078] In the control system of the permanent magnet synchronous motor provided by the present invention, the stator current of the three-phase stator is Clarke transformed by a first coordinate transformation unit to obtain the stator current in a two-phase stationary coordinate system, and then the stator current in the two-phase stationary coordinate system is Park transformed by a second coordinate transformation unit to obtain the d-axis stator current and the q-axis stator current in a synchronous rotating coordinate system; then the d-axis stator voltage and the q-axis stator voltage are calculated and output according to the d-axis stator current and the q-axis stator current, thereby calculating the current motor angle of the permanent magnet synchronous motor, realizing the position positioning of the motor during sensorless operation, and finally performing a Park inverse transformation according to the current motor angle to obtain the first AC voltage and the second AC voltage in the two-phase stationary coordinate system, realizing the output of three-phase sinusoidal AC to the stator end of the permanent magnet synchronous motor according to the first AC voltage and the second AC voltage, thereby completing the control of the permanent magnet synchronous motor.

[0079] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, preferred embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0080] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for use in the embodiments. It should be understood that the following drawings only illustrate certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without paying any creative work.

[0081] Figure 1 The following schematically shows a system structure diagram of a control system of a permanent magnet synchronous motor according to the first embodiment of the present invention.

[0082] Figure 2 The equivalent circuit diagram of the permanent magnet synchronous motor 10 according to the first embodiment of the present invention is schematically shown.

[0083] Figure 3 The figure schematically shows a system block diagram of a ring controller according to the first embodiment of the present invention.

[0084] Figure 4 The diagram schematically shows a block diagram of a d-axis current loop system according to the first embodiment of the present invention.

[0085] Figure 5 The system block diagram of the speed loop controller according to the first embodiment of the present invention is schematically shown.

[0086] Figure 6 The flowchart of the control method of the permanent magnet synchronous motor according to the second embodiment of the present invention is schematically shown.

[0087] Figure 7The flowchart of the control method of the permanent magnet synchronous motor according to the third embodiment of the present invention is schematically shown.

[0088] Description of main component symbols:

[0089] Control system of permanent magnet synchronous motor1;

[0090] Permanent magnet synchronous motor 10;

[0091] a first coordinate transformation unit 20;

[0092] A second coordinate transformation unit 30;

[0093] a control unit 40;

[0094] a computing unit 50;

[0095] A third coordinate transformation unit 60;

[0096] Drive unit 70;

[0097] Three-phase stators 10a, 10b, 10c;

[0098] Stator current i a 、i b 、i c、 i α 、i β ;

[0099] d-axis stator current i d ;

[0100] q-axis stator current i q ;

[0101] d-axis stator voltage u d ;

[0102] q-axis stator voltage u q ;

[0103] A first subtractor S1;

[0104] Speed ​​loop controller PI1;

[0105] A second subtractor S2;

[0106] q-axis current loop controller PI2;

[0107] a third subtractor S3;

[0108] d-axis current loop controller PI3;

[0109] Given the motor angular velocity ω * e ;

[0110] Actual angular velocity ωe ;

[0111] Angular velocity difference Δω e ;

[0112] q-axis reference current i * q ;

[0113] d-axis reference current i * d ;

[0114] Motor angle θ e ;

[0115] Space vector pulse width modulation unit 701;

[0116] Three-phase inverter 702. DETAILED DESCRIPTION

[0117] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The components of the embodiments of the present invention generally described and shown in the drawings here can be arranged and designed in various different configurations. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thorough and comprehensive. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. The embodiments of the present invention, and all other embodiments obtained by those skilled in the art without making creative work, are within the scope of protection of the present invention.

[0118] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, it does not need to be further defined or explained in subsequent drawings.

[0119] In the description of the present invention, it should also be noted that, unless otherwise expressly specified or limited, the terms "disposed," "connected," and "electrically connected" should be understood in a broad sense. For example, they may refer to direct connection, indirect connection through an intermediary, or internal communication between two elements. It should be noted that when an element is considered to be "connected" to another element, it may be directly connected to the other element or there may be an intervening element.

[0120] The following embodiments of the present invention are described in detail with reference to the accompanying drawings. In the absence of conflict, the following embodiments and features in the embodiments may be combined with each other.

[0121] Explanation of terms involved in the present invention:

[0122] SVPWM: Space Vector Pulse Width Modulation, space vector pulse width modulation.

[0123] PMSM: permanent-magnet synchronous motor.

[0124] Clarke transformation: transform the variables in the abc coordinate system with three phases stationary and 120 degrees apart to the αβ coordinate system with two phases stationary and 90 degrees apart.

[0125] Park transformation: transforms the variables of the two-phase stationary αβ coordinate system with a 90-degree difference between them into the synchronously rotating dq coordinate system.

[0126] Park inverse transform: The opposite of Park transform, transforms the variables in the synchronously rotating dq coordinate system into the two-phase stationary αβ coordinate system with an angle difference of 90.

[0127] Example 1

[0128] Figure 1 The following schematically shows a system structure diagram of a control system 1 of a permanent magnet synchronous motor according to the first embodiment of the present invention. Figure 1 As shown, the control system 1 of the permanent magnet synchronous motor described in the present invention may include: a permanent magnet synchronous motor 10, a first coordinate transformation unit 20, a second coordinate transformation unit 30, a control unit 40, a calculation unit 50, a third coordinate transformation unit 60 and a drive unit 70.

[0129] In this embodiment, the permanent magnet synchronous motor 10 has no internal sensor and includes three-phase stators 10a, 10b and 10c. The first coordinate transformation unit 20 is electrically connected to the permanent magnet synchronous motor 10 and is used to transform the stator current i of the three-phase stators 10a, 10b and 10c into the coordinate transformation unit 20. a 、i b 、i c Perform Clarke transformation to obtain the stator current i in the two-phase stationary coordinate system (α-β) α 、i β .

[0130] Specifically, the two-phase stationary coordinate system (α-β) is fixed on the stator so that the α axis coincides with the a axis and the β axis rotates counterclockwise 90 degrees ahead of the α axis. The variables on the three-phase abc axis are projected onto the two-phase (α-β) axis. The coordinate system abc corresponds to the axis of the three-phase stator. The control process starts with the motor three-phase current i a 、i b 、i cIn practical applications, the three-phase stator current i a 、i b 、i c The instantaneous sum of the three current values ​​is zero, and the transformation formula is as follows:

[0131] i α =i a ;

[0132] i β =(i a +2i b ) / √3;

[0133] The second coordinate transformation unit 30 is electrically connected to the first coordinate transformation unit 20 and is used to combine the motor angle θ of the permanent magnet synchronous motor 10 in the previous cycle e , the stator current i in the two-phase stationary coordinate system α 、i β Perform Park transformation to obtain the d-axis stator current i in the synchronous rotating coordinate system d and the q-axis stator current i q .i d and i q They are used to control the rotor flux component and torque component respectively.

[0134] Specifically, the synchronous rotating coordinate system is fixed on the rotor, the position of the permanent magnet N pole is selected as the d-axis, and the angle between it and the α(a) axis is θ e (rotor angle, i.e. motor angle), the q-axis rotates counterclockwise ahead of the d-axis by 90°, resulting in a synchronously rotating (dq) coordinate system, which is used to achieve decoupling control of flux and torque. The transformation is as follows:

[0135] i d = i α *cosθ+i β *sinθ;

[0136] i q = -i α *sinθ+ i β *cosθ.

[0137] The control unit 40 is electrically connected to the second coordinate transformation unit 30 and is used to determine the coordinates of the stator according to the d-axis stator current i d and the q-axis stator current i q Calculate the output d-axis stator voltage u d and q-axis stator voltage u q .

[0138] In this embodiment, the control unit 40 may include a first subtractor S1 , a speed loop controller PI1 , a second subtractor S2 , a q-axis current loop controller PI2 , a third subtractor S3 , and a d-axis current loop controller PI3 .

[0139] like Figure 1 As shown, the first subtractor S1 is electrically connected to the calculation unit 50, and is used to calculate the given motor angular velocity ω * e and the actual angular velocity ω e Calculate the angular velocity difference Δω e The speed loop controller PI1 is electrically connected to the first subtractor S1 and is used to calculate the angular velocity difference Δω. e Calculate the q-axis reference current i * q。 The second subtractor S2 is electrically connected to the speed loop controller PI1 and the second coordinate transformation unit 30, and is used to calculate the q-axis stator current i q With the q-axis reference current i * q The difference Δi * q The q-axis current loop controller PI2 is electrically connected to the second subtractor S2 and is used to calculate the q-axis stator current i q With the q-axis reference current i * q The difference Δi * q Calculate the q-axis stator voltage u q The third subtractor S3 is electrically connected to the second coordinate transformation unit 30 and is used to calculate the d-axis stator current i d With the d-axis reference current i * d The difference Δi * d。 In this embodiment, the reference value i of the d-axis current is * d The d-axis current loop controller PI3 is electrically connected to the second subtractor S2 and is used to generate the d-axis stator current i d With the d-axis reference current i * d The d-axis stator voltage u is calculated from the difference d .

[0140] The calculation unit 50 is electrically connected to the second coordinate transformation unit 30 and the control unit 40, and is used to calculate the stator current i according to the d-axis stator current i d , q-axis stator current i q , d-axis stator voltage u d and q-axis stator voltage u qCalculate the current motor angle θ of the permanent magnet synchronous motor 10 e .

[0141] In this embodiment, the calculation unit 50 calculates the current motor angle θ of the permanent magnet synchronous motor 10 e The process is:

[0142] The d-axis stator current i d , q-axis stator current i q , d-axis stator voltage u d and q-axis stator voltage u q Substituting into the first formula:

[0143] di d / dt=[u d -Rs*i d +ω e *Lqi q ] / Ld;

[0144] di q / dt=[u q -Rs*i q -ω e *Ld i d -ω e *ψ f ] / Lq; (1)

[0145] Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψ f is the q-axis magnetic flux, ω e is the rotor angular velocity;

[0146] Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula:

[0147] [i d (k+1)-i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lqi q (k)] / Ld;

[0148] [i q (k+1)-i q(k)] / T=[u q (k)-Rs*i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2)

[0149] When I d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1. Specifically, when there is no error between the estimated motor angle and the actual motor angle, the left-hand rule shows that the torque force is perpendicular to the rotor, that is, the torque generated is provided by the q-axis, while the d-axis only has magnetic excitation torque, I d =0; so the final control method requires I d Converges to 0; when I d When the convergence is 0, substitute the d-axis current equation of the second formula because I d (k+1), I d (k), T, u d (k), Rs, I d (k), Lq, I q (k), Ld and other parameters have been determined, so the d-axis angular velocity ω1 can be calculated.

[0150] When I q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2. Specifically, the q-axis current is related to the actual speed and power. When constant speed and constant power are required, I q It will eventually converge to a fixed value. q (k+1), I q (k), T, u q (k), Rs, I q (k), Lq, I d (k), ψ f ,Ld and other parameters have been determined, so the q-axis angular velocity ω2 can be calculated;

[0151] Substituting the angular velocities ω1 and ω2 into the third formula:

[0152] ω e 1=ω1*Pd+ω2*PI; (3)

[0153] Among them, ω e 1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain; the proportional gain ensures that the d-axis always keeps consistent with the motor angle, and the integral gain ensures that the angular velocity eventually converges to the target velocity value.

[0154] The final angular velocity ω is obtained from the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

[0155] The third coordinate transformation unit 60 is electrically connected to the calculation unit 50 and the control unit 40 and is used to use the current motor angle θ e Perform Park inverse transform to obtain the first AC voltage u in the two-phase stationary coordinate system α and the second AC voltage u β .

[0156] Specifically, the inverse Park transform is the opposite of the Park transform, which transforms the variables from the synchronous rotating coordinate system to the two-phase stationary coordinate system. The transformation formula is as follows:

[0157] i α = i d *cosθ- i q *sinθ;

[0158] i β = i d *sinθ+ i q *cosθ.

[0159] The driving unit 70 is electrically connected to the third coordinate transformation unit 60 and the permanent magnet synchronous motor 10, and is used to generate a first AC voltage u α and the second AC voltage u β Output three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor 10.

[0160] Specifically, the driving unit 70 includes a space vector pulse width modulation unit (SVPWM) 701 and a three-phase inverter 702. The space vector pulse width modulation unit 701 is electrically connected to the third coordinate transformation unit 60 and is used to generate a voltage according to the first AC voltage u α and the second AC voltage u β Outputting a digital drive signal. The three-phase inverter 702 is electrically connected to the space vector pulse width modulation unit 701 and the permanent magnet synchronous motor 10, and is configured to be turned on or off according to the digital drive signal to generate the three-phase sinusoidal alternating current. This three-phase sinusoidal alternating current, with its frequency and amplitude constantly varying, is input to the stator of the permanent magnet synchronous motor 10, generating a circular rotating magnetic field that interacts with the permanent magnets, driving the motor to rotate and thereby achieving motor vector control.

[0161] Further, combined with Figure 2 , Figure 2The equivalent circuit diagram of the permanent magnet synchronous motor 10 of the present invention is shown in FIG. In a synchronous rotating coordinate system, according to Kirchhoff's voltage and current law, the voltage equation in the synchronous rotating coordinate system is obtained to achieve torque decoupling control:

[0162] u d =R*i d +Ld*(di d / dt)-ω e *Lq*i q ;

[0163] u q =R*i q +Lq*(di q / dt)+ω e *Ld*i d +ωe*Ψ f ;

[0164] Among them, f represents the magnetic flux, R is the equivalent resistance, Ld is the d-axis equivalent inductance, and Lq is the q-axis equivalent inductance. q Component control flux Ψf, d-axis current i d Component control motor electromagnetic torque Te.

[0165] Field-oriented control has three interrelated PI control loops: speed loop controller PI1, q-axis current loop controller PI2, and d-axis current loop controller PI3. They control three variables that affect each other, namely rotor speed, rotor flux, and rotor torque, which are controlled by separate PI control loops. Among them, speed loop controller PI1 controls the motor speed, q-axis current loop controller PI2, and d-axis current loop controller PI3 control the decoupled i d 、i q .like Figure 3 As shown, Figure 3 This is a system block diagram of the loop controller of the present invention. The PI control loop serves as a correction step in the loop, bringing the actual feedback value of the closed-loop system closer to a given reference value. The proportional parameter Kp is used to accelerate response, and the integral parameter Ki is used to eliminate the steady-state error e.

[0166] U= Kp* e+Ki*∫ed.

[0167] The mathematical model of the PMSM in the fully decoupled state in the synchronous rotating coordinate system can be equivalent to a resistor-inductor (RL) model, because the back electromotive force interference of the motor system can be perfectly offset by the feedforward compensation. Figure 4 As shown, Figure 4This is the block diagram of the d-axis current loop system of the present invention. The zero pole of the d-axis current loop controller PI3 cancels out a system pole. Therefore, the closed-loop transfer function of the current loop can be designed as a low-pass filter. The proportional coefficient Kip and integral coefficient Kii of the current loop are:

[0168] Kip= La*ωi;

[0169] Kii= Ra*ωi.

[0170] The speed loop controller PI1 is designed to output the target control value Iq for current loop control, such as Figure 5 As shown, Figure 5 This is the system block diagram of the speed loop controller PI1 of the present invention. Estimated speed value ω e and target speed ω e *Calculate the difference and output i through the speed loop controller PI1 q *, feeds back to the q-axis current loop controller PI2, and then the q-axis current loop controller PI2 controls the three-phase stator of the motor to achieve complete control of the system.

[0171] In an embodiment of the present invention, the stator current of the three-phase stator is Clarke-transformed by the first coordinate transformation unit 20 to obtain the stator current in the two-phase stationary coordinate system, and then the stator current in the two-phase stationary coordinate system is Park-transformed by the second coordinate transformation unit 30 to obtain the d-axis stator current and the q-axis stator current in the synchronous rotating coordinate system; then, the d-axis stator voltage and the q-axis stator voltage are calculated and output according to the d-axis stator current and the q-axis stator current, so as to calculate the current motor angle of the permanent magnet synchronous motor 10, thereby realizing the position positioning of the motor during sensorless operation; finally, the Park inverse transformation is performed according to the current motor angle to obtain the first AC voltage and the second AC voltage in the two-phase stationary coordinate system, and the three-phase sinusoidal AC is output to the stator end of the permanent magnet synchronous motor 10 according to the first AC voltage and the second AC voltage, thereby completing the control of the permanent magnet synchronous motor.

[0172] Example 2

[0173] Figure 6 The flow chart of the control method of the permanent magnet synchronous motor according to the second embodiment of the present invention is schematically shown. The method is applied to the control system of the permanent magnet synchronous motor according to the first embodiment. Figure 6 As shown, the method includes the following steps:

[0174] S600, the stator current i of the three-phase stator of the permanent magnet synchronous motor a 、i b 、i c Perform Clarke transformation to obtain the stator current i in the two-phase stationary coordinate system α、i β .

[0175] Specifically, the two-phase stationary coordinate system (α-β) is fixed on the stator so that the α axis coincides with the a axis and the β axis rotates counterclockwise 90 degrees ahead of the α axis. The variables on the three-phase abc axis are projected onto the two-phase (α-β) axis. The coordinate system abc corresponds to the axis of the three-phase stator. The control process starts with the motor three-phase current i a 、i b 、i c In practical applications, the three-phase current i a 、i b 、i c The instantaneous sum of the three current values ​​is zero, and the transformation formula is as follows:

[0176] i α =i a ;

[0177] i β =(i a +2i b ) / √3.

[0178] S602, combining the motor angle of the permanent magnet synchronous motor in the previous cycle, performing Park transformation on the stator current in the two-phase stationary coordinate system to obtain the d-axis stator current i in the synchronous rotating coordinate system d and the q-axis stator current i q .

[0179] Specifically, the synchronous rotating coordinate system is fixed on the rotor, the position of the permanent magnet N pole is selected as the d-axis, and the angle between it and the α(a) axis is θ e (rotor angle, i.e. motor angle), the q-axis rotates counterclockwise ahead of the d-axis by 90°, resulting in a synchronously rotating (dq) coordinate system, which is used to achieve decoupling control of flux and torque. The transformation is as follows:

[0180] i d = i α *cosθ+i β *sinθ;

[0181] i q = -i α *sinθ+ i β *cosθ.

[0182] S604: According to the d-axis stator current i q and the q-axis stator current i q Calculate the output d-axis stator voltage u d and q-axis stator voltage u q .

[0183] Specifically, the calculation process may include: calculating a given motor angular velocity ω * e and the actual angular velocity ω e Calculate the angular velocity difference Δω e ; According to the angular velocity difference Δω through the speed loop controller e Calculate the q-axis reference current i * q ; Calculate the q-axis stator current i q With the q-axis reference current i * q The difference Δi * q ; Through the q-axis current loop controller according to the q-axis stator current i q With the q-axis reference current i * q The difference Δi * q Calculate the q-axis stator voltage u q ; Calculate the d-axis stator current i d With the d-axis reference current i * d The difference Δi * d ; Through the d-axis current loop controller according to the d-axis stator current i d With the d-axis reference current i * d The d-axis stator voltage u is calculated from the difference d .

[0184] S606: Calculate the current motor angle θ of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage. e .

[0185] Specifically, the current motor angle θ of the permanent magnet synchronous motor 10 is calculated as follows: e The process is:

[0186] The d-axis stator current i d , q-axis stator current i q , d-axis stator voltage u d and q-axis stator voltage u q Substituting into the first formula:

[0187] di d / dt=[u d -Rs*i d +ω e *Lqi q ] / Ld;

[0188] di q / dt=[u q -Rs*i q -ω e *Ld i d -ω e *ψ f ] / Lq; (1)

[0189] Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψ f is the q-axis magnetic flux, ω e is the rotor angular velocity;

[0190] Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula:

[0191] [i d (k+1)-i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lqi q (k)] / Ld;

[0192] [i q (k+1)-i q (k)] / T=[u q (k)-Rs*i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2)

[0193] When I d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1. Specifically, when there is no error between the estimated motor angle and the actual motor angle, the left-hand rule shows that the torque force is perpendicular to the rotor, that is, the torque generated is provided by the q-axis, while the d-axis only has magnetic excitation torque, I d =0; so the final control method requires I d Converges to 0; when I d When the convergence is 0, substitute the d-axis current equation of the second formula because I d (k+1), Id (k), T, u d (k), Rs, I d (k), Lq, I q (k), Ld and other parameters have been determined, so the d-axis angular velocity ω1 can be calculated.

[0194] When I q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2. Specifically, the q-axis current is related to the actual speed and power. When constant speed and constant power are required, I q It will eventually converge to a fixed value. q (k+1), I q (k), T, u q (k), Rs, I q (k), Lq, I d (k), ψ f ,Ld and other parameters have been determined, so the q-axis angular velocity ω2 can be calculated;

[0195] Substituting the angular velocities ω1 and ω2 into the third formula:

[0196] ω e 1=ω1*Pd+ω2*PI; (3)

[0197] Among them, ω e 1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain; the proportional gain ensures that the d-axis always keeps consistent with the motor angle, and the integral gain ensures that the angular velocity eventually converges to the target velocity value.

[0198] The final angular velocity ω is obtained from the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

[0199] S608, according to the current motor angle θ e Perform Park inverse transform to obtain the first AC voltage u in the two-phase stationary coordinate system α and the second AC voltage u β .

[0200] Specifically, the inverse Park transform is the opposite of the Park transform, which transforms the variables from the synchronous rotating coordinate system to the two-phase stationary coordinate system. The transformation formula is as follows:

[0201] i α = i d *cosθ- i q *sinθ;

[0202] i β = i d *sinθ+ i q *cosθ.

[0203] S610: Output three-phase sinusoidal alternating current to a stator terminal of the permanent magnet synchronous motor according to the first alternating current voltage and the second alternating current voltage.

[0204] Specifically, a digital drive signal is output based on the first and second AC voltages; the digital drive signal controls the on and off switching of the three-phase inverter to generate the three-phase sinusoidal AC power. The three-phase sinusoidal AC power, with its continuously varying frequency and amplitude, is input to the stator of the permanent magnet synchronous motor 10, generating a circular rotating magnetic field that interacts with the permanent magnets, driving the motor to rotate and thereby achieving motor vector control.

[0205] Example 3

[0206] Figure 7 The flowchart of a control method for a permanent magnet synchronous motor according to the third embodiment of the present invention is shown schematically. Figure 7 As shown, the method includes the following steps:

[0207] S700: When the permanent magnet synchronous motor is running, the three-phase stator current i of the permanent magnet synchronous motor 10 is collected. a 、i b 、i c ;

[0208] S702, obtain the three-phase stator voltage u according to the PWM control signal output by the space vector pulse width modulation unit 701 in the previous cycle a 、u b 、u c ;

[0209] S704: The three-phase stator current i a 、i b 、i c and the three-phase stator voltage u a 、u b 、u c Perform Clarke transformation to obtain the stator current i in the two-phase stationary coordinate system α 、i β and stator voltage u α 、u β ;

[0210] S706: The stator current i in the two-phase stationary coordinate system is α 、i β and stator voltage u α 、uβ Perform Park transformation to obtain the d-axis stator current i in the synchronous rotating coordinate system d , q-axis stator current i q , d-axis stator voltage u d and q-axis stator voltage u q ;

[0211] S708: According to the d-axis stator current i d , q-axis stator current i q , d-axis stator voltage u d and q-axis stator voltage u q Calculate the current motor angle θ of the permanent magnet synchronous motor 10 e ;

[0212] S710, the current motor angle θ e and the d-axis stator voltage u d and q-axis stator voltage u q Perform Park inverse transform to obtain the first feedback voltage u in the two-phase stationary coordinate system α1 And the second feedback voltage u β1 ;

[0213] S712, according to the first feedback voltage u α1 And the second feedback voltage u β1 Output three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor 10.

[0214] Specifically, according to the first feedback voltage u α1 And the second feedback voltage u β1 Outputting a digital drive signal; using this digital drive signal to control the on and off of the three-phase inverter 702 to generate the three-phase sinusoidal AC power. This three-phase sinusoidal AC power, with its varying frequency and amplitude, is input to the stator of the permanent magnet synchronous motor 10, generating a circular rotating magnetic field that interacts with the permanent magnets, driving the motor to rotate and thereby achieving motor vector control.

[0215] The transformation process of Clarke transformation, Park transformation, and Park inverse transformation in the above method and the calculation principle of the motor angle are similar to the control method of the permanent magnet synchronous motor in Example 2. The specific process and effect can be referred to Example 2 and will not be repeated here.

[0216] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A control system for a permanent magnet synchronous motor, characterized in that: include: A permanent magnet synchronous motor including a three-phase stator; a first coordinate transformation unit, electrically connected to the permanent magnet synchronous motor, configured to perform Clarke transformation on the stator current of the three-phase stator to obtain the stator current in a two-phase stationary coordinate system; a second coordinate transformation unit, electrically connected to the first coordinate transformation unit, for performing a Park transformation on the stator current in the two-phase stationary coordinate system in combination with the motor angle of the permanent magnet synchronous motor in the previous cycle to obtain a d-axis stator current and a q-axis stator current in a synchronous rotating coordinate system; a control unit, electrically connected to the second coordinate transformation unit, configured to calculate and output a d-axis stator voltage and a q-axis stator voltage according to the d-axis stator current and the q-axis stator current; a calculation unit, electrically connected to the second coordinate transformation unit and the control unit, for calculating a current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage; a third coordinate transformation unit, electrically connected to the calculation unit and the control unit, configured to perform a Park inverse transformation using the current motor angle to obtain a first AC voltage and a second AC voltage in a two-phase stationary coordinate system; a drive unit, electrically connected to the third coordinate transformation unit and the permanent magnet synchronous motor, configured to output three-phase sinusoidal alternating current to a stator terminal of the permanent magnet synchronous motor according to the first alternating voltage and the second alternating voltage; The process of the calculation unit calculating the current motor angle of the permanent magnet synchronous motor is as follows: Substitute the d-axis stator current, q-axis stator current, d-axis stator voltage, and q-axis stator voltage into the first formula: di d / dt=[u d -Rs*i d +ω e *Lqi q ] / Ld; yes q / dt=[u q -Rs*i q -oh e *Ld i d -oh e *ψ f ] / Lq; (1) Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψ f is the q-axis magnetic flux, ω e is the rotor angular velocity; Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula: [i d (k+1)- i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lq i q (k)] / Ld; [i q (k+1)- i q (k)] / T=[ u q (k)-Rs* i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2) when i d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1; when i q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2; Substituting the angular velocities ω1 and ω2 into the third formula: oh e 1=ω1*Pd+ω2*PI; (3) Where ωe1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain; The final angular velocity ω of the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

2. The control system of the permanent magnet synchronous motor according to claim 1, characterized in that: The control unit comprises: a first subtractor, electrically connected to the calculation unit, for calculating an angular velocity difference according to a given motor angular velocity and an actual angular velocity; a speed loop controller, electrically connected to the first subtractor, and configured to calculate a q-axis reference current according to the angular velocity difference; a second subtractor, electrically connected to the speed loop controller and the second coordinate transformation unit, for calculating a difference between the q-axis stator current and the q-axis reference current; a q-axis current loop controller, electrically connected to the second subtractor, and configured to calculate the q-axis stator voltage according to a difference between the q-axis stator current and the q-axis reference current; a third subtractor, electrically connected to the second coordinate transformation unit, for calculating a difference between the d-axis stator current and the d-axis reference current; A d-axis current loop controller is electrically connected to the third subtractor and is configured to calculate the d-axis stator voltage according to a difference between the d-axis stator current and the d-axis reference current.

3. The control system of the permanent magnet synchronous motor according to claim 1, characterized in that: The driving unit includes: a space vector pulse width modulation unit, electrically connected to the third coordinate transformation unit, and configured to output a digital driving signal according to the first alternating current voltage and the second alternating current voltage; A three-phase inverter is electrically connected to the space vector pulse width modulation unit and the permanent magnet synchronous motor, and is turned on or off according to the digital drive signal to generate the three-phase sinusoidal alternating current.

4. A control method for a permanent magnet synchronous motor, characterized in that: include: The stator current of the three-phase stator of the permanent magnet synchronous motor is subjected to Clarke transformation to obtain the stator current in the two-phase stationary coordinate system; Combined with the motor angle of the permanent magnet synchronous motor in the previous cycle, the stator current in the two-phase stationary coordinate system is subjected to Park transformation to obtain the d-axis stator current and the q-axis stator current in the synchronous rotating coordinate system; Calculating and outputting a d-axis stator voltage and a q-axis stator voltage according to the d-axis stator current and the q-axis stator current; Calculating a current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage; Performing a Park inverse transform according to the current motor angle to obtain a first AC voltage and a second AC voltage in a two-phase stationary coordinate system; outputting three-phase sinusoidal alternating current to a stator terminal of the permanent magnet synchronous motor according to the first alternating current voltage and the second alternating current voltage; Calculating the current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage specifically includes: Substitute the d-axis stator current, q-axis stator current, d-axis stator voltage, and q-axis stator voltage into the first formula: di d / dt=[u d -Rs*i d +ω e *Lqi q ] / Ld; yes q / dt=[u q -Rs*i q -oh e *Ld i d -oh e *ψ f ] / Lq; (1) Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψ f is the q-axis magnetic flux, ω e is the rotor angular velocity; Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula: [i d (k+1)- i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lq i q (k)] / Ld; [i q (k+1)- i q (k)] / T=[ u q (k)-Rs* i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2) when i d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1; when i q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2; Substituting the angular velocities ω1 and ω2 into the third formula: oh e 1=ω1*Pd+ω2*PI; (3) Where ωe1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain; The final angular velocity ω of the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

5. The control method of the permanent magnet synchronous motor according to claim 4, characterized in that: The step of calculating and outputting the d-axis stator voltage and the q-axis stator voltage according to the d-axis stator current and the q-axis stator current specifically includes: Calculate the angular velocity difference based on the given motor angular velocity and the actual angular velocity; Calculating the q-axis reference current according to the angular velocity difference by a speed loop controller; Calculating a difference between the q-axis stator current and the q-axis reference current; Calculating the q-axis stator voltage according to the difference between the q-axis stator current and the q-axis reference current by a q-axis current loop controller; Calculating a difference between the d-axis stator current and the d-axis reference current; The d-axis stator voltage is calculated by a d-axis current loop controller according to the difference between the d-axis stator current and the d-axis reference current.

6. The control method of the permanent magnet synchronous motor according to claim 4, characterized in that: The step of outputting three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor according to the first alternating current voltage and the second alternating current voltage specifically includes: outputting a digital driving signal according to the first AC voltage and the second AC voltage; The three-phase inverter is controlled to be turned on and off by the digital drive signal to generate the three-phase sinusoidal alternating current.

7. A control method for a permanent magnet synchronous motor, characterized in that: include: When the permanent magnet synchronous motor is running, collecting the three-phase stator current of the permanent magnet synchronous motor; The three-phase stator voltage is obtained according to the PWM control signal output by the space vector pulse width modulation unit in the previous cycle; Performing Clarke transformation on the three-phase stator current and the three-phase stator voltage to obtain the stator current and stator voltage in a two-phase stationary coordinate system; Performing a Park transformation on the stator current and stator voltage in the two-phase stationary coordinate system to obtain a d-axis stator current, a q-axis stator current, a d-axis stator voltage, and a q-axis stator voltage in a synchronous rotating coordinate system; Calculating a current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage; Performing a Park inverse transform on the current motor angle and the d-axis stator voltage and the q-axis stator voltage to obtain a first feedback voltage and a second feedback voltage in a two-phase stationary coordinate system; outputting a three-phase sinusoidal alternating current to a stator terminal of the permanent magnet synchronous motor according to the first feedback voltage and the second feedback voltage; Calculating the current motor angle of the permanent magnet synchronous motor according to the d-axis stator current, the q-axis stator current, the d-axis stator voltage, and the q-axis stator voltage specifically includes: Substitute the d-axis stator current, q-axis stator current, d-axis stator voltage, and q-axis stator voltage into the first formula: di d / dt=[u d -Rs*i d +ω e *Lqi q ] / Ld; yes q / dt=[u q -Rs*i q -oh e *Ld i d -oh e *ψ f ] / Lq; (1) Among them, dt is the unit time, di d and di q is the d-axis stator current i per unit time d and the q-axis stator current i q The change value of u d is the d-axis stator voltage and u q is the q-axis stator voltage, Rs is the stator winding resistance, Ld and Lq are the equivalent inductances of the d-axis and q-axis, ψ f is the q-axis magnetic flux, ω e is the rotor angular velocity; Assume that the sampling period is T and the sampling time is kT. Discretize the first formula to obtain the second formula: [i d (k+1)- i d (k)] / T=[u d (k)-Rs* i d (k)+ω e *Lq i q (k)] / Ld; [i q (k+1)- i q (k)] / T=[ u q (k)-Rs* i q (k)-ω e *Ld i d (k)-ω e *ψ f ] / Lq;(2) when i d When the convergence is 0, the d-axis angular velocity ω is calculated according to the d-axis current equation of the second formula e =ω1; when i q When it converges to a fixed value, the q-axis angular velocity ω is calculated according to the q-axis current equation of the second formula e =ω2; Substituting the angular velocities ω1 and ω2 into the third formula: oh e 1=ω1*Pd+ω2*PI; (3) Where ωe1 is the final angular velocity, Pd is the proportional gain, and PI is the integral gain; The final angular velocity ω is obtained from the third formula e 1Integrate to get the motor angle: θ e =ω e 1* T, where T is the sampling period.

8. The control method of the permanent magnet synchronous motor according to claim 7, characterized in that: The step of outputting three-phase sinusoidal alternating current to the stator end of the permanent magnet synchronous motor according to the first feedback voltage and the second feedback voltage specifically includes: outputting a digital driving signal according to the first feedback voltage and the second feedback voltage; The three-phase inverter is controlled to be turned on and off by the digital drive signal to generate the three-phase sinusoidal alternating current.

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