Permanent magnet synchronous motor vector control rotor position angle compensation method and system

Abstract

The invention provides a permanent magnet synchronous motor vector control rotor position angle compensation method and system, and the method comprises the steps: dragging a tested motor to run at a plurality of rotating speed test points through a dragging motor, controlling a tested motor controller to apply a current to the tested motor at each rotating speed test point through a current instruction, and enabling the initial current angle to be 0 degree; the torque of the tested motor approaches the mechanical loss torque by adjusting the current angle of the current applied to the tested motor, and when the two are equal, the current angle is obtained by reading the current instruction, so that the rotor position compensation angle is determined. And fitting the rotating speed of each rotating speed test point and the rotor position compensation angle. During compensation, the current rotor position compensation angle can be obtained from the fitted curve according to the real-time rotating speed, and the rotor position angle in vector control is compensated. By using the method, the sampled vector transformation angle can be compensated on the basis of not increasing the hardware cost.

Description

Technical Field

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

[0002] The method of controlling torque and flux independently of each other in a permanent magnet synchronous motor is called decoupling control or vector control. For AC motor drives, the key to achieving independent control of flux and torque is: 1) Simplifying the three-phase motor into a motor with only one winding on the stator and rotor, so it can be equivalent to a DC motor. 2) The inverter can control the amplitude, frequency and phase of the current phasor. Using these characteristics, the permanent magnet synchronous motor drive system can be called a high-performance drive system by separately controlling the common flux and electromagnetic torque.

[0003] The most basic idea of ​​vector control technology is to decouple the stator current into a current component that controls the magnetic field and a current component that controls the torque. Figure 1 As shown, after decoupling, the two current components are controlled independently and do not interfere with each other, so the control of the AC motor is as simple as the control of the separately excited DC motor.

[0004] According to the mathematical model of permanent magnet synchronous motor, in order to realize vector control, the following steps are required:

[0005] Detect motor physical quantities (phase voltage, phase current);

[0006] Calculate rotor phase angle and speed;

[0007] Use Park transformation to transform the three-phase stator current into the dq coordinate system;

[0008] Independently control the torque current (iq) component and the excitation current (id) component;

[0009] The stator voltage space vector is transformed from the dq coordinate system to the αβ two-phase coordinate system through the inverse Park transformation (IPark);

[0010] Use space vector modulation to generate three-phase voltage output;

[0011] Coordinate transformation is the key to realize vector control. In order to perform coordinate transformation, it is necessary to know the position angle of the motor rotor. Common methods for obtaining the rotor position angle include sensor measurement method and position sensorless identification method.

[0012] Sensor measurement methods include resolvers, photoelectric encoders, and other methods. However, there is an angle error in the sensor measurement method to obtain the vector control angle. The sources of error include the sampling delay of the position sensor, the delay caused by the current filter, and the delay of the processor program. The traditional method analyzes the delay caused by various factors in the calculation process of the rotor position angle, and multiplies the speed by the delay time to obtain the compensation angle. This method requires knowing the sensor delay index, current filter parameters, and processor program running time, which are often difficult to obtain.

[0013] The sensorless identification method collects the voltage and current information of the motor and uses an observer to observe the motor's magnetic flux or back EMF online, thereby identifying the rotor's position information. However, this method requires online observation of the motor's magnetic flux or back EMF, which requires high processor computing power and increases the cost of the controller. Summary of the invention

[0014] In view of this, the present invention provides a permanent magnet synchronous motor vector control rotor position angle compensation method and system, which can compensate the sampled vector transformation angle, improve the accuracy of the transformation angle without increasing the hardware cost, thereby improving the performance of the motor vector control.

[0015] In order to solve the above technical problems, the present invention is implemented as follows.

[0016] A method for compensating a rotor position angle of a permanent magnet synchronous motor vector control, comprising:

[0017] Step 1: Use a drag motor to drag the tested motor to run at multiple speed test points;

[0018] Step 2: At each speed test point, the motor controller is controlled by the current command to apply current to the motor under test, and the current angle is initially 0 degrees; the torque on the motor shaft under test is read, and the current angle of the motor under test is adjusted to make the motor torque approach the mechanical loss torque. When the difference between the two is less than the set threshold, the current angle θ is obtained by reading the current command. i ; According to the current current angle θ i Determine the rotor position compensation angle θ d ;

[0019] Step 3: Use the rotor position compensation angle θ corresponding to each speed test point d , determine the corresponding relationship between the rotor position compensation angle and the speed;

[0020] Step 4: During compensation, the corresponding rotor position compensation angle θ is obtained according to the real-time speed and the corresponding relationship. d , using the rotor position compensation angle θ dCompensate the rotor position angle in vector control.

[0021] Preferably, the step 2 specifically includes:

[0022] Step 201: Control the traction motor to drive the tested motor to run at the lowest speed test point;

[0023] Step 202: After the speed is stabilized at a given speed, the torque on the shaft of the motor under test is read, which is the mechanical loss torque and is recorded as Tor0;

[0024] Step 203: The controller of the motor under test is powered on and, under the control of the host computer, the controller gives a current command to the motor under test, and the current angle is 0 degrees; after the current of the motor under test is stable, the torque on the shaft of the motor under test is read and recorded as Tor1;

[0025] Step 204: If |Tor1-Tor0|≤ξ, where ξ is the set approach threshold, the current angle θ of the current motor under test is obtained through the current command. i Otherwise, the current angle is gradually reduced by adjusting the current command, and the torque on the motor shaft is read until the judgment condition of |Tor1-Tor0|≤ξ is met. The current angle θ of the motor under test is obtained through the current command. i ;

[0026] Step 205: According to the current angle θ i Calculate the rotor position compensation angle θ at the speed test point d :

[0027]

[0028] Step 206: Control the traction motor to drive the tested motor to run at different speed test points, repeat steps 202 to 205, and obtain the rotor position compensation angle corresponding to each speed test point.

[0029] Preferably, the step 3 is: performing polynomial fitting using the rotational speed of each rotational speed test point and the corresponding rotor position compensation angle to obtain a fitting relationship between the rotor position compensation angle and the rotational speed.

[0030] Preferably, the polynomial fitting adopts linear fitting or quadratic fitting.

[0031] Preferably, in step 4, the rotor position compensation angle θ is used d The compensation for the rotor position angle in vector control is:

[0032] When the motor under test rotates forward, the compensation formula is θ'=θ+θ d ;

[0033] When the tested motor reverses, the compensation formula is θ'=θ-θ d ;

[0034] Among them, θ' is the compensated rotor position angle, and θ is the original angle collected by the position sensor.

[0035] Preferably, in step 1, the method of controlling the tested motor controller to apply current to the tested motor with the current angle initially being 0 degrees is:

[0036] Given the tested motor i d The current command is part of the rated current, i q The current command is 0;

[0037] Then the current angle of the current applied to the tested motor is adjusted so that the torque of the tested motor approaches the mechanical loss torque: Keep i d The current command remains unchanged, adjust i q Current command;

[0038] The current angle θ is obtained i The method is: record the current i d Current command and i q Current command, calculate the current angle corresponding to the current command

[0039] Preferably, in step 1, the method of controlling the tested motor controller to apply current to the tested motor with the current angle initially being 0 degrees is:

[0040] Given the motor current I s The current amplitude command is part of the rated current, and the current angle command is 0 degrees;

[0041] Then, the method of adjusting the current angle of the current applied to the tested motor so that the torque of the tested motor approaches the mechanical loss torque is as follows: adjusting the current angle command;

[0042] The current angle θ is obtained i The method is: directly record the current angle command.

[0043] Preferably, the speed test points are evenly distributed from 0 speed to maximum speed.

[0044] The present invention also provides a permanent magnet synchronous motor vector control rotor position angle compensation system, the system includes a compensation control unit, a DC power supply, a host computer, a test motor controller, a test motor, a speed torque measuring instrument, a traction motor, and a traction motor power supply and controller;

[0045] The DC power supply provides DC voltage to the busbar of the motor controller under test;

[0046] The controller of the motor under test converts the DC voltage into the three-phase AC power required for motor movement and supplies it to the motor under test;

[0047] The controller of the motor under test is connected to the host computer through communication, and the host computer controls the current command input to the motor;

[0048] The motor under test is connected to the driving motor through a mechanical shaft, and a speed and torque measuring instrument is installed on the shaft to monitor the speed and torque on the shaft;

[0049] The drag motor is controlled by the drag motor power supply and controller to drag the tested motor to a specified speed;

[0050] The compensation control unit is connected to the host computer, the speed torque measuring instrument, the traction motor power supply and controller; the traction motor is controlled to rotate through the traction motor power supply and controller, and the tested motor is driven to run at multiple speed test points; at each speed test point, the host computer sends a current instruction to control the tested motor controller to apply current to the tested motor, and the current angle is initially 0 degrees; the torque of the mechanical shaft is read through the speed torque measuring instrument, and the host computer sends a new current instruction to adjust the current angle of the current applied to the tested motor, so that the torque of the tested motor approaches the mechanical loss torque. When the difference between the two is less than the set threshold, the current angle indicated by the current instruction is obtained and recorded as θ i ; According to the current current angle θ i Determine the rotor position compensation angle θ d ; Use the rotor position compensation angle θ corresponding to each speed test point d , the corresponding relationship between the rotor position compensation angle and the speed is obtained, which is used to compensate the rotor position angle in actual vector control.

[0051] Preferably, the mechanical loss torque is determined as follows: the compensation control unit uses the traction motor power supply and controller to control the rotation of the traction motor, driving the test motor to run at the lowest speed test point, and after the speed stabilizes at a given speed, the torque data is read through the speed torque measuring instrument, which is the mechanical loss torque.

[0052] Beneficial effects:

[0053] (1) The present invention utilizes the vector control d Current and i q The current can control the torque and magnetic field of the motor respectively. If the coordinate transformation angle in vector control is accurate, then when only i is injected into the motor dWhen the current is on, the motor under test should not generate electromagnetic torque, and the torque value monitored on the drag table should be equal to the mechanical loss torque, thus setting the judgment condition. At this time, it is only necessary to calculate or record the current angle corresponding to the current current command to calculate the supplementary angle. This solution solves the problem of large angle error measured by the position sensor and poor torque control effect when the motor is vector controlled.

[0054] (2) This solution only needs to detect and judge the torque, and obtain the angle through control instructions. It does not require too many sensors, and has low requirements on the type, accuracy, delay and current filter delay of the position sensor.

[0055] (3) By using offline testing and online compensation methods, the computing power requirements of the processor are reduced.

[0056] (4) This method can compensate for the rotor position angle during forward and reverse rotation of the motor respectively, and can compensate for the full speed within the working range of the motor, thus adapting to various operating conditions of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 This is the vector control principle of permanent magnet synchronous motor.

[0058] Figure 2 Schematic diagram of the rotor position angle compensation test system of the present invention.

[0059] Figure 3 Schematic diagram of the deviation when the rotor position angle lags behind the real d-axis

[0060] Figure 4 This is a schematic diagram of rotor position angle compensation when the motor rotates forward.

[0061] Figure 5 This is a schematic diagram of rotor position angle compensation when the motor reverses. DETAILED DESCRIPTION

[0062] The present invention is described in detail below with reference to the accompanying drawings and embodiments.

[0063] In order to realize vector control, the position information of the motor rotor is needed for coordinate transformation. In order to obtain the rotor position angle information, position sensors such as resolvers and photoelectric encoders are usually used for collection. However, due to the delay caused by sensor sampling, current filtering, processor calculation, etc., the collected position angle will deviate from the actual rotor position, resulting in deviation in coordinate transformation and poor motor current and torque control effects. In order to ensure the effect of motor vector control, the rotor position angle needs to be compensated.

[0064] The present invention proposes a rotor position angle compensation method based on experimental measurement. The schematic diagram of the rotor position angle compensation test system is as follows: Figure 2 To test the rotor position compensation angle, you need to build Figure 2 The test system shown in the figure. The DC power supply provides DC voltage to the controller bus, and the controller converts the DC voltage into the three-phase AC power required for the motor movement. At the same time, the controller is connected to the host computer through CAN communication or serial communication, and the host computer controls the input to the motor current instruction, which can be I s Current command, can also be i d and i q Current command. The motor under test is connected to the drive motor through a mechanical shaft, and a speed torque measuring instrument is installed on the shaft to monitor the speed and torque on the shaft. The drive motor is controlled by a power supply and a frequency converter, and can drive the motor under test to a specified speed.

[0065] The basic principles of the present invention are as follows:

[0066] ① The present invention utilizes the vector control d Current and i q The current can control the torque and magnetic field of the motor respectively. If the coordinate transformation angle in vector control is accurate, then when only i is injected into the motor d When the current is on, the motor under test should not generate electromagnetic torque, and the torque value monitored on the drag table should be equal to the mechanical loss torque, which can trigger the judgment condition of step 4) in the following process, that is, calculate or record the current angle corresponding to the current current command at this time.

[0067] ② If there is an error in the coordinate transformation angle in the vector control, the d-axis obtained by the coordinate transformation of the controller will deviate from the real d-axis. d When the current flows, the current will be projected on the real q-axis q', and the motor will generate positive or negative electromagnetic torque, such as Figure 3 As shown. In the figure, the d-axis is the d-axis calculated after the controller coordinate transformation, and d is the real d-axis. Since the motor current has a current component on the real q-axis, the motor will generate electromagnetic torque at this time, and the torque value measured on the drag table will become larger, which is not equal to the mechanical loss torque, thereby triggering the judgment condition of step 5) in the following process.

[0068] ③ When the torque value measured on the dragging platform is not equal to the mechanical loss torque, the controller gives a negative i q And gradually increase i q The absolute value of the current command can gradually pull the angle of the synthetic current vector to the real d-axis, such as Figure 4 shown.

[0069] ④ In the process of ③, since the projection of the synthetic current on the real q-axis gradually decreases, the torque value can be observed to gradually decrease from the speed torque measuring instrument. When the torque value drops to equal the mechanical loss torque, that is, the judgment condition of step 4) in the following process is met, it means that the current angle of the controller coincides with the real d-axis. Record or calculate the current angle θ at this time i , so the rotor position compensation angle θ can be obtained d As shown in formula (1). Using the rotor position compensation angle θ d The compensation of the rotor position angle in vector control can be completed.

[0070]

[0071] When the motor is reversed, the measured d-axis will lead the real d-axis. When the difference between the torque value and the mechanical loss torque is greater than the set threshold, a positive i is given. q That is, the electromagnetic torque generated by the motor can be gradually reduced to 0, and the current angle θ at this time is used i The rotor position angle can be obtained, and then the motor reversal can be used to compensate for the rotor position angle.

[0072] Based on the above principles, the first embodiment of the present invention describes the specific process of the motor rotor position angle compensation method of vector control, including the following steps:

[0073] Step 1: Assume that the maximum operating speed of the motor under test is n max The speed interval n of the tested motor is set between 0 speed and the maximum speed. d Divided into m speed test points, n1 = n d , n2=2n d , ..., n m =n max Among them, the speed interval n d The smaller it is, the higher the final fitting accuracy will be, but the experimental cycle will be longer.

[0074] Step 2: Control the drag motor to drive the test motor to run to the lowest speed test point, that is, n1 speed. After the speed stabilizes at the given speed, read the torque on the shaft at this time from the speed torque meter. This torque is the mechanical loss torque on the test bench shaft, recorded as Tor0.

[0075] Step 3: Turn on the DC power supply, and the controller of the tested motor will start working. d and i q One way is to give the motor under test i d The current command is part of the rated current, for example, 80% of the rated current. q The current command is 0. Another way is to give the motor current Is , which includes amplitude command and current angle command, the amplitude command is 80% of the rated current, and the current angle command is 0 degrees. After the current of the motor under test is stable, the torque on the shaft is read from the speed torque measuring instrument and recorded as Tor1.

[0076] Step 4: If |Tor1-Tor0|≤ξ, where ξ is the set approach threshold, which is a very small positive number. The threshold defines the degree to which Tor1 approaches Tor0. At this time, the current angle θ of the current motor under test is obtained through the current command. i If the current command is i d and i q Current command, you need to calculate the current angle corresponding to the current command The current angle corresponding to the speed n1 is recorded as θ i1 If the command given by the host computer is current I s , including current amplitude and angle command, then directly record the current angle command as θ i1 .

[0077] Step 5: If |Tor1-Tor0|>ξ, gradually increase i q The current command absolute value or the current angle command is adjusted until the judgment condition in step 4) is met, and the corresponding current angle command θ is calculated or recorded. i1 .

[0078] In this step, when the host computer gives i d and i q When the current command is on, increase or decrease the current angle command. The specific method is to keep i d The current command remains unchanged, i q The absolute value of the current command gradually increases, causing the current angle value to gradually increase. Figure 4 As shown, when the motor rotates forward, the d-axis lags behind the real d-axis, giving a negative i q Current command, i q The sign of is negative; Figure 5 As shown in the figure, when the motor reverses, the d-axis of the current command leads the real d-axis, giving a positive i q Current command, i q The sign is positive. s When current command is given, adjust the current angle command.

[0079] Step 6: Control the drag motor to run at each speed test point, namely n2, n3, ..., n m Repeat steps 3) to 5) at the same speed to obtain the current angle θ corresponding to each speed test point. i2 ,θ i3 ,…,θim .

[0080] Step 7: Calculate the rotor position compensation angle at each speed based on the current angle, as shown in formula (1)

[0081]

[0082] The current angle θ i2 ,θ i3 ,…,θ im As θ i Substitute into the above formula (1) to obtain n2, n3, ..., n m Rotor position compensation angle θ corresponding to the speed d =[θ d1 θ d2 … θ dm ].

[0083] Step 8: Motor speed n = [n1 n2 … n m ] and rotor position compensation angle θ d =[θ d1 θ d2 … θ dm ] data for polynomial fitting. Formula (2) is the linear fitting formula, k1 and k2 are fitting coefficients:

[0084] θ d =k1·n+k2 (2)

[0085] Usually the linear fit of the above formula can satisfy the correlation coefficient R greater than 0.99. If the linear fit does not meet the requirements, a quadratic fit is used.

[0086] Step 9: During actual compensation, the corresponding rotor position compensation angle is obtained from the fitting curve according to the rotation speed, and the compensated angle is calculated according to formula (3), so that the rotor position angle compensation of the motor during forward rotation can be completed.

[0087] θ'=θ+θ d (3)

[0088] Where θ′ is the compensated angle, and θ is the original angle collected by the position sensor.

[0089] Control the drag motor to drive the tested motor to rotate in the opposite direction, repeat steps 1) to 8), and the actual compensation formula is changed to formula (4), which can complete the position angle compensation when the motor is reversed.

[0090] θ'=θ-θ d (4)

[0091] This is the end of the process.

[0092] Based on the above method, the permanent magnet synchronous motor vector control rotor position angle compensation system provided by the present invention is as follows: Figure 2 The system includes a DC power supply, a host computer, a test motor controller, a test motor, a speed torque measuring instrument, a drive motor, and a drive motor power supply and controller. In order to realize the control of each component and data reading, a compensation control unit (not shown in the figure) is also required to be set, and the compensation control unit is connected to the host computer, the speed torque measuring instrument, the drive motor power supply and controller.

[0093] The working of the compensation control unit is as follows: the rotation of the traction motor is controlled by the traction motor power supply and controller, and the tested motor is driven to run at multiple speed test points; at each speed test point, the current command is sent by the host computer to control the tested motor controller to apply current to the tested motor, and the current angle is initially 0 degrees; the torque of the mechanical shaft is read by the speed torque measuring instrument, and the current angle of the current applied to the tested motor is adjusted by the host computer sending a new current command, so that the torque of the tested motor approaches the mechanical loss torque. When the difference between the two is less than the set threshold, the current angle indicated by the current current command is obtained, which is recorded as θ i ; According to the current current angle θ i Determine the rotor position compensation angle θ d ; Use the rotor position compensation angle θ corresponding to each speed test point d , the corresponding relationship between the rotor position compensation angle and the speed is obtained, which is used to compensate the rotor position angle in actual vector control.

[0094] Among them, the mechanical loss torque is determined as follows: the compensation control unit uses the traction motor power supply and controller to control the rotation of the traction motor, driving the tested motor to run at the lowest speed test point, and after the speed stabilizes at a given speed, the torque data is read through the speed torque measuring instrument, which is the mechanical loss torque.

[0095] The above specific embodiments only describe the design principle of the present invention. The shapes and names of the components in the description may be different and are not limited. Therefore, those skilled in the art in the field of the present invention may modify or replace the technical solutions recorded in the above embodiments; and these modifications and replacements do not deviate from the creative purpose and technical solutions of the present invention and should all fall within the protection scope of the present invention.

Claims

1. A method for compensating the rotor position angle of a permanent magnet synchronous motor vector control, characterized in that: include: Step 1: Use a drag motor to drag the tested motor to run at multiple speed test points; Step 2: At each speed test point, the motor controller is controlled by the current command to apply current to the motor under test, and the current angle is initially 0 degrees; the torque on the motor shaft under test is read, and the current angle of the motor under test is adjusted to make the motor torque approach the mechanical loss torque. When the difference between the two is less than the set threshold, the current angle θ is obtained by reading the current command. i ; According to the current current angle θ i Determine the rotor position compensation angle θ d ; Step 3: Use the rotor position compensation angle θ corresponding to each speed test point d , determine the corresponding relationship between the rotor position compensation angle and the speed; Step 4: During compensation, the corresponding rotor position compensation angle θ is obtained according to the real-time speed and the corresponding relationship. d , using the rotor position compensation angle θ d Compensate the rotor position angle in vector control.

2. The method according to claim 1, characterized in that The step 2 specifically includes: Step 201: Control the traction motor to drive the tested motor to run at the lowest speed test point; Step 202: After the speed is stabilized at a given speed, the torque on the shaft of the motor under test is read, which is the mechanical loss torque and is recorded as Tor0; Step 203: The controller of the motor under test is powered on and, under the control of the host computer, the controller gives a current command to the motor under test, and the current angle is 0 degrees; after the current of the motor under test is stable, the torque on the shaft of the motor under test is read and recorded as Tor1; Step 204: If |Tor1-Tor0|≤ξ, where ξ is the set approach threshold, the current angle θ of the current motor under test is obtained through the current command. i Otherwise, the current angle is gradually reduced by adjusting the current command, and the torque on the motor shaft is read until the judgment condition of |Tor1-Tor0|≤ξ is met. The current angle θ of the motor under test is obtained through the current command. i ; Step 205: According to the current angle θ i Calculate the rotor position compensation angle θ at the speed test point d : Step 206: Control the traction motor to drive the tested motor to run at different speed test points, repeat steps 202 to 205, and obtain the rotor position compensation angle corresponding to each speed test point.

3. The method according to claim 1 or 2, characterized in that The step 3 is: performing polynomial fitting using the rotation speed of each rotation speed test point and the corresponding rotor position compensation angle to obtain a fitting relationship between the rotor position compensation angle and the rotation speed.

4. The method according to claim 3, characterized in that The polynomial fitting adopts linear fitting or quadratic fitting.

5. The method according to claim 1, characterized in that In step 4, the rotor position compensation angle θ is used d The compensation for the rotor position angle in vector control is: When the motor under test rotates forward, the compensation formula is θ'=θ+θ d ; When the tested motor reverses, the compensation formula is θ'=θ-θ d ; Among them, θ' is the compensated rotor position angle, and θ is the original angle collected by the position sensor.

6. The method according to claim 1, characterized in that In step 1, the method of controlling the motor controller to apply current to the motor, with the current angle initially being 0 degrees, is as follows: Given the tested motor i d The current command is part of the rated current, i q The current command is 0; Then the current angle of the current applied to the tested motor is adjusted so that the torque of the tested motor approaches the mechanical loss torque: Keep i d The current command remains unchanged, adjust i q Current command; The current angle θ is obtained i The method is: record the current i d Current command and i q Current command, calculate the current angle corresponding to the current command 7. The method according to claim 1, characterized in that In step 1, the method of controlling the motor controller to apply current to the motor, with the current angle initially being 0 degrees, is as follows: Given the motor current I s The current amplitude command is part of the rated current, and the current angle command is 0 degrees; Then, the method of adjusting the current angle of the current applied to the tested motor so that the torque of the tested motor approaches the mechanical loss torque is as follows: adjusting the current angle command; The current angle θ is obtained i The method is: directly record the current angle command.

8. The method according to claim 1, characterized in that The speed test points are evenly distributed from 0 speed to the maximum speed.

9. A permanent magnet synchronous motor vector control rotor position angle compensation system, characterized in that: The system includes a compensation control unit, a DC power supply, a host computer, a test motor controller, a test motor, a speed torque measuring instrument, a traction motor, and a traction motor power supply and controller; The DC power supply provides DC voltage to the busbar of the motor controller under test; The controller of the motor under test converts the DC voltage into the three-phase AC power required for motor movement and supplies it to the motor under test; The controller of the motor under test is connected to the host computer through communication, and the host computer controls the current command input to the motor; The motor under test is connected to the driving motor through a mechanical shaft, and a speed and torque measuring instrument is installed on the shaft to monitor the speed and torque on the shaft; The drag motor is controlled by the drag motor power supply and controller to drag the tested motor to a specified speed; The compensation control unit is connected to the host computer, the speed torque measuring instrument, the traction motor power supply and controller; the traction motor is controlled to rotate through the traction motor power supply and controller, and the tested motor is driven to run at multiple speed test points; at each speed test point, the host computer sends a current instruction to control the tested motor controller to apply current to the tested motor, and the current angle is initially 0 degrees; the torque of the mechanical shaft is read through the speed torque measuring instrument, and the host computer sends a new current instruction to adjust the current angle of the current applied to the tested motor, so that the torque of the tested motor approaches the mechanical loss torque. When the difference between the two is less than the set threshold, the current angle indicated by the current instruction is obtained and recorded as θ i ; According to the current current angle θ i Determine the rotor position compensation angle θ d ; Use the rotor position compensation angle θ corresponding to each speed test point d , the corresponding relationship between the rotor position compensation angle and the speed is obtained, which is used to compensate the rotor position angle in actual vector control.

10. The system according to claim 9, characterized in that The mechanical loss torque is determined as follows: the compensation control unit uses the traction motor power supply and controller to control the rotation of the traction motor, driving the tested motor to run at the lowest speed test point. After the speed stabilizes at a given speed, the torque data is read through the speed torque measuring instrument, which is the mechanical loss torque.

Images