Motor stall test method and device and vehicle electric drive system

Abstract

The application provides a motor stall test method and device and a vehicle electric drive system, and belongs to the automobile field. The method comprises the following steps: collecting the current and motor speed of a permanent magnet synchronous motor; obtaining a first reference current of the permanent magnet synchronous motor; keeping the amplitude of the first reference current unchanged, reconstructing the components of the first reference current on the direct axis and the quadrature axis based on the motor speed to obtain a second reference current, so that when the current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0; adjusting the alternating voltage of the permanent magnet synchronous motor based on the current and the second reference current of the permanent magnet synchronous motor; and when it is detected that the motor speed of the permanent magnet synchronous motor is not greater than a preset speed, performing a stall test on the permanent magnet synchronous motor. In the application, an external force does not need to be applied to the permanent magnet synchronous motor, and the stall of the permanent magnet synchronous motor is controlled by the internal logic of the permanent magnet synchronous motor, which is beneficial to reducing the cost of the stall test and improving the convenience.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of automobiles, in particular to a motor locked-rotor test method and device and a vehicle electric drive system. BACKGROUND

[0002] Permanent magnet synchronous motors are widely used in electric drive systems of new energy vehicles due to their high efficiency, high power density, wide speed regulation range and other advantages. The locked-rotor capability of a permanent magnet synchronous motor is an important evaluation index.

[0003] In related technologies, in the locked-rotor test of a permanent magnet synchronous motor, a mechanical locking mechanism in a test bench is used to lock the output shaft of the tested permanent magnet synchronous motor, and the permanent magnet synchronous motor is powered. When the output torque of the permanent magnet synchronous motor reaches the locked-rotor torque, the motor speed of the permanent magnet synchronous motor is 0 because the output shaft of the permanent magnet synchronous motor has been locked, so that the permanent magnet synchronous motor is in a locked-rotor state, and the locked-rotor test of the permanent magnet synchronous motor is performed.

[0004] However, since a test bench mechanical locking mechanism needs to be provided, the cost of the locked-rotor test is high, and the convenience of the motor locked-rotor test is low. SUMMARY

[0005] The embodiments of the present application provide a motor locked-rotor test method, device and vehicle electric drive system, which can reduce the cost of the locked-rotor test and improve the convenience of the motor locked-rotor test. The technical solutions are as follows:

[0006] In one aspect, a motor locked-rotor test method is provided, and the method comprises:

[0007] acquiring the current and motor speed of the permanent magnet synchronous motor;

[0008] acquiring a first reference current of the permanent magnet synchronous motor, the first reference current being the current required when the output torque of the permanent magnet synchronous motor reaches the locked-rotor torque;

[0009] keeping the amplitude of the first reference current unchanged, reconstructing the components of the first reference current on the direct axis and the quadrature axis based on the motor speed to obtain a second reference current, so that when the current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0;

[0010] adjusting the alternating voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current;

[0011] When it is detected that the motor rotating speed of the permanent magnet synchronous motor is not greater than a preset rotating speed, the permanent magnet synchronous motor is tested for locked-rotor, and the motor rotating speed of the permanent magnet synchronous motor not being greater than the preset rotating speed indicates that the permanent magnet synchronous motor is currently in a locked-rotor state.

[0012] In a possible implementation, the collecting the current of the permanent magnet synchronous motor comprises:

[0013] The three-phase alternating current of the permanent magnet synchronous motor is collected.

[0014] The three-phase alternating current is converted into an alpha-axis current and a beta-axis current by using a Clark conversion.

[0015] The alpha-axis current and the beta-axis current are converted into a direct-axis current and a quadrature-axis current based on the rotor position of the permanent magnet synchronous motor by using a Park conversion.

[0016] In a possible implementation, the obtaining the first reference current of the permanent magnet synchronous motor comprises:

[0017] The locked-rotor torque and the bus voltage of the permanent magnet synchronous motor are obtained.

[0018] In a reference current table, the reference current corresponding to the locked-rotor torque, the bus voltage and the motor rotating speed is queried, and the queried reference current is determined as the first reference current.

[0019] The reference current table stores the reference current corresponding to any torque, any bus voltage and any motor rotating speed.

[0020] In a possible implementation, the adjusting the alternating voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor tends to the second reference current, comprises:

[0021] The direct-axis reference voltage and the quadrature-axis reference voltage are determined based on the current of the permanent magnet synchronous motor and the second reference current by using a proportional-integral control algorithm.

[0022] The direct-axis reference voltage and the quadrature-axis reference voltage are converted into an alpha-axis reference voltage and a beta-axis reference voltage by using a Park inverse conversion.

[0023] The three-phase duty cycles are generated based on the alpha-axis reference voltage and the beta-axis reference voltage.

[0024] The bus voltage is converted into the alternating voltage of the permanent magnet synchronous motor according to the three-phase duty cycles, so that the current of the permanent magnet synchronous motor tends to the second reference current.

[0025] In a possible implementation, the first reference current includes a first direct-axis reference current and a first quadrature-axis reference current; the maintaining the amplitude of the first reference current unchanged, reconstructing components of the first reference current on the direct axis and the quadrature axis based on the motor speed, to obtain a second reference current, includes:

[0026] determining a target reference current angle based on the inverse of the first direct-axis reference current, the first quadrature-axis reference current and the motor speed, so that the motor speed of the permanent magnet synchronous motor tends to 0 after the permanent magnet synchronous motor is controlled based on the target reference current angle;

[0027] determining a second direct-axis reference current and a second quadrature-axis reference current based on the amplitude of the first reference current and the target reference current angle, and determining the second direct-axis reference current and the second quadrature-axis reference current as the second reference current.

[0028] In a possible implementation, the determining the target reference current angle based on the inverse of the first direct-axis reference current, the first quadrature-axis reference current and the motor speed includes:

[0029] determining an initial reference current angle based on the inverse of the first direct-axis reference current and the first quadrature-axis reference current;

[0030] determining a current compensation angle based on a difference between the motor speed and a target speed, the target speed being 0;

[0031] determining the sum of the initial reference current angle and the current compensation angle as the target reference current angle.

[0032] In a possible implementation, the current compensation angle is not less than a first angle and not greater than a second angle, the first angle being equal to the inverse of the initial reference current angle, and the second angle being equal to the difference between 90 degrees and the initial reference current angle.

[0033] In a possible implementation, when the current of the permanent magnet synchronous motor is equal to the second reference current, the sum of a permanent magnet torque and a reluctance torque of the permanent magnet synchronous motor is equal to 0, and the permanent magnet torque and the reluctance torque are equal in magnitude and opposite in direction.

[0034] In another aspect, a motor stall test device is provided, and the device includes:

[0035] a collection module configured to collect a current and a motor speed of a permanent magnet synchronous motor;

[0036] The acquisition module is configured to acquire a first reference current of the permanent magnet synchronous motor, the first reference current being a current required when an output torque of the permanent magnet synchronous motor reaches a locked-rotor torque.

[0037] The reconstruction module is configured to keep a magnitude of the first reference current unchanged, reconstruct components of the first reference current on a direct axis and a quadrature axis based on the motor speed, and obtain a second reference current, so that when a current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0.

[0038] The adjustment module is configured to adjust an alternating current voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current.

[0039] The test module is configured to perform a locked-rotor test on the permanent magnet synchronous motor when it is detected that the motor speed of the permanent magnet synchronous motor is not greater than a preset speed, the motor speed of the permanent magnet synchronous motor not being greater than the preset speed indicating that the permanent magnet synchronous motor is currently in a locked-rotor state.

[0040] In a possible implementation, the acquisition module is configured to:

[0041] Acquire a three-phase alternating current of the permanent magnet synchronous motor.

[0042] Convert the three-phase alternating current into an α-axis current and a β-axis current by using a Clark transformation.

[0043] Convert the α-axis current and the β-axis current into a direct-axis current and a quadrature-axis current by using a Park transformation based on a rotor position of the permanent magnet synchronous motor.

[0044] In a possible implementation, the acquisition module is configured to:

[0045] Acquire the locked-rotor torque and a bus voltage of the permanent magnet synchronous motor.

[0046] In a reference current table, query a reference current corresponding to the locked-rotor torque, the bus voltage, and the motor speed, and determine the queried reference current as the first reference current.

[0047] The reference current table stores a reference current corresponding to any torque, any bus voltage, and any click speed.

[0048] In a possible implementation, the adjustment module is configured to:

[0049] determining, by using a proportional-integral control algorithm, a direct-axis reference voltage and a quadrature-axis reference voltage based on the current of the permanent magnet synchronous motor and the second reference current;

[0050] transforming, by using a Park inverse transformation, the direct-axis reference voltage and the quadrature-axis reference voltage into an alpha-axis reference voltage and a beta-axis reference voltage;

[0051] generating a three-phase duty ratio based on the alpha-axis reference voltage and the beta-axis reference voltage;

[0052] transforming, according to the three-phase duty ratio, the bus voltage into an alternating voltage of the permanent magnet synchronous motor, so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current.

[0053] In a possible implementation, the first reference current includes a first direct-axis reference current and a first quadrature-axis reference current; and the reconstruction module is configured to:

[0054] determining a target reference current angle based on an inverse of the first direct-axis reference current, the first quadrature-axis reference current and the motor speed, so that the motor speed of the permanent magnet synchronous motor after control based on the target reference current angle tends to 0;

[0055] determining a second direct-axis reference current and a second quadrature-axis reference current based on a magnitude of the first reference current and the target reference current angle, and determining the second direct-axis reference current and the second quadrature-axis reference current as the second reference current.

[0056] In a possible implementation, the reconstruction module is configured to:

[0057] determining an initial reference current angle based on the inverse of the first direct-axis reference current and the first quadrature-axis reference current;

[0058] determining a current compensation angle based on a difference between the motor speed and a target speed, the target speed being 0;

[0059] determining the target reference current angle as a sum of the initial reference current angle and the current compensation angle.

[0060] In a possible implementation, the current compensation angle is not less than a first angle and not greater than a second angle, the first angle being equal to an inverse of the initial reference current angle, and the second angle being equal to a difference between 90 degrees and the initial reference current angle.

[0061] In a possible implementation, when the current of the permanent magnet synchronous motor is equal to the second reference current, the sum of a permanent magnet torque and a reluctance torque of the permanent magnet synchronous motor is equal to 0, and the magnitudes of the permanent magnet torque and the reluctance torque are equal and the directions thereof are opposite.

[0062] In another aspect, a vehicle electric drive system is provided, which includes a permanent magnet synchronous motor, a motor controller, and a memory. The memory stores at least one computer program, which is run by the motor controller to implement the motor stall test method according to the above aspect.

[0063] In another aspect, a computer readable storage medium is provided, which stores at least one computer program. The at least one computer program, when run, implements the motor stall test method according to the above aspect.

[0064] The technical scheme provided by the embodiments of the present application has at least the following beneficial effects:

[0065] The embodiments of the present application provide a motor stall test method, device and vehicle electric drive system. The first reference current is the current required when the output torque of the permanent magnet synchronous motor reaches the stall torque. In the case of keeping the amplitude of the first reference current unchanged, the second reference current is obtained by reconstructing the components of the first reference current on the direct axis and the quadrature axis. Then, the AC voltage of the permanent magnet synchronous motor is adjusted according to the difference between the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor tends to the second reference current. At this time, the speed of the permanent magnet synchronous motor tends to 0 and the current amplitude of the permanent magnet synchronous motor is equal to the current amplitude required when the stall torque is reached. Therefore, the permanent magnet synchronous motor is ensured to be in the stall state without applying external force to the permanent magnet synchronous motor, and the permanent magnet synchronous motor is tested in the stall state without locking the output shaft of the permanent magnet synchronous motor. The stall of the permanent magnet synchronous motor is controlled by the internal logic of the permanent magnet synchronous motor, which is conducive to reducing the cost of the stall test and improving the convenience of the stall test of the permanent magnet synchronous motor. BRIEF DESCRIPTION OF DRAWINGS

[0066] In order to more clearly illustrate the technical scheme in the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0067] Figure 1 is a flowchart of a motor control method provided by the embodiments of the present application;

[0068] Figure 2 is a direct axis current and a quadrature axis current trajectory diagram provided by an embodiment of the present application;

[0069] Figure 3 is a flowchart of a motor stall test method provided by an embodiment of the present application;

[0070] Figure 4 is a flowchart of a current reconstruction method provided by an embodiment of the present application;

[0071] Figure 5 is a flowchart of another motor control method provided by an embodiment of the present application;

[0072] Figure 6 is a structural schematic diagram of a motor stall test device provided by an embodiment of the present application. DETAILED DESCRIPTION

[0073] In order to make the purpose, technical solutions and advantages of the present application clearer, the embodiments of the present application will be further described in detail below with reference to the drawings.

[0074] The terms "first", "second", "third", and "fourth" and the like in the specification of the present application, the claims and the drawings are used to distinguish different objects, and are not used to describe a particular order. In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but can optionally include steps or units not listed, or can optionally include other steps or units inherent to the process, method, product or device.

[0075] The vehicle electric drive system of a new energy vehicle mainly includes a driving motor and a motor controller. Due to the advantages of high efficiency, high power density, wide speed regulation range, etc. of permanent magnet synchronous motor, the vehicle electric drive system of new energy vehicle is widely used. The control strategy of permanent magnet synchronous motor includes direct torque control strategy and vector control strategy, among which the vector control strategy has the advantages of fast torque response, high control accuracy, small torque ripple, etc. and is widely used in the vehicle electric drive system of new energy vehicle.

[0076] In the related art, the locked-rotor capability of the vehicle electric drive system of a new energy vehicle is a very important evaluation index. In the locked-rotor test of a permanent magnet synchronous motor, a mechanical locking mechanism in a test bench is used to mechanically lock the output shaft of the permanent magnet synchronous motor under test on the test bench, so as to ensure that the rotation speed of the permanent magnet synchronous motor is 0 when the output torque of the permanent magnet synchronous motor reaches the locked-rotor torque, thereby making the permanent magnet synchronous motor in the locked-rotor state, so as to perform the locked-rotor test on the permanent magnet synchronous motor. However, since the test bench mechanical locking mechanism needs to be provided, the cost of the locked-rotor test is relatively high, and the convenience of the locked-rotor test of the motor is relatively low.

[0077] Based on this, the embodiment of the present application proposes a scheme for performing the locked-rotor test on the permanent magnet synchronous motor by using the vector control strategy under the condition that the mechanical locking mechanism of the test bench is cancelled, which can ensure that the locked-rotor test is performed under the condition that the output shaft of the permanent magnet synchronous motor is in the no-load state, that is, the locked-rotor test is performed under the condition that no external force is applied to the output shaft of the permanent magnet synchronous motor. The detailed process can be referred to each of the following embodiments.

[0078] For ease of understanding, the process of controlling the permanent magnet synchronous motor by using the vector control strategy is described first as follows.

[0079] Among them, the vector control of the permanent magnet synchronous motor is also called field-oriented control. The control principle is to establish a synchronous rotating coordinate system of the motor rotor through field orientation, convert the three-phase alternating current of the motor stator into direct-axis current and quadrature-axis current through Clark transformation and Park transformation, the direct-axis is also called d-axis, and the quadrature-axis is also called q-axis. The torque and magnetic field in the current of the motor stator are decoupled, the control of the permanent magnet synchronous motor is simplified, and the advantages of fast torque response, small output torque ripple, high torque accuracy, etc. are achieved.

[0080] Figure 1 is a flowchart of a motor control method provided by the embodiment of the present application, referring to Figure 1 , the method comprises:

[0081] 1. The power module converts the direct-current power supply of the high-voltage battery into alternating-current power supply to provide three-phase alternating-current voltage for the permanent magnet synchronous motor. The power module is also called an inverter.

[0082] 2. In the working process of the permanent magnet synchronous motor, the current sensor collects the three-phase alternating current of the permanent magnet synchronous motor, and the three-phase alternating current is denoted as Iu, Iv and Iw respectively.

[0083] 3. The position sensor collects the rotor position θ and the motor rotation speed Spd of the permanent magnet synchronous motor.

[0084] Where, the rotor position θ refers to the angle between the rotor magnetic pole axis (the axis of N pole or S pole) and the stator A phase winding axis. This angle is fixed in space, but will change with the rotation of the rotor. The rotor position θ is an important parameter in vector control, which determines the distribution of motor current and the size and direction of output torque. By accurately controlling the rotor position, precise control and high performance operation of the motor can be achieved.

[0085] Where, the motor speed Spd usually refers to the number of revolutions per minute (Revolution Per Minute, RPM) of the motor.

[0086] 4. The Clark transformation is used to convert three-phase alternating current into α-axis current Iα and β-axis current Iβ, and the transformation method is shown in formula (1):

[0087]

[0088] 5. The Park transformation is used to convert α-axis current Iα and β-axis current Iβ into d-axis current Id and q-axis current Iq, and the transformation method is shown in formula (2):

[0089]

[0090] Where, the d-axis current is also called direct-axis current, and the q-axis current is also called quadrature-axis current.

[0091] 6. The vehicle controller VCU obtains the target torque, and combines the target torque, bus voltage and motor speed to query the reference current table to obtain the d-axis reference current Idref and the q-axis reference current Iqref, wherein the reference current table is generated offline after data fitting processing of permanent magnet synchronous motor bench calibration.

[0092] Where, the d-axis reference current is also called direct-axis reference current, and the q-axis reference current is also called quadrature-axis reference current.

[0093] 7. The proportional integral control algorithm (PI controller) is used to determine the d-axis reference voltage U d and the q-axis reference voltage U q based on the difference between the actual current values (Id and Iq) of the permanent magnet synchronous motor and the reference current values (Idref and Iqref).

[0094] Where, the d-axis reference voltage is also called direct-axis reference voltage, and the q-axis reference voltage is also called quadrature-axis reference voltage.

[0095] The proportional-integral control algorithm is also known as a PI (Proportional-Integral) controller, which is used to control the feedback loop in a system by adjusting the output signal to make the actual output of the system as close as possible to the desired value. The PI controller is a feedback control strategy that includes a proportional part P and an integral part I. The proportional part P adjusts the control output according to the current error (the difference between the reference value and the actual value), and there may be a steady-state error. The integral part I considers the past error and gradually eliminates the steady-state error to ensure that the system reaches the set target in the long run.

[0096] 8. The d-axis reference voltage U d and the q-axis reference voltage U q are converted into the α-axis reference voltage U α and the β-axis reference voltage U β by using Park inverse transformation. The conversion method is shown in equation (3):

[0097]

[0098] 9. The α-axis reference voltage U α and the β-axis reference voltage U β are used to generate the three-phase duty ratio Uduty, Vduty, Wduty by using the SVPWM algorithm.

[0099] The SVPWM (Space Vector Pulse Width Modulation) algorithm is a modulation technique used to control the output of the power module to generate three-phase alternating current voltage. The SVPWM algorithm uses the position of the voltage vector in space to convert the DC bus voltage into the required three-phase alternating current voltage.

[0100] The three-phase duty ratio refers to the proportion of the effective voltage of each phase output by the power module to the total period.

[0101] 10. The power module converts the DC bus voltage of the high-voltage battery into three-phase alternating current voltage of the motor stator according to the three-phase duty ratio Uduty, Vduty, Wduty, thereby adjusting the three-phase alternating current voltage of the motor stator, so that the actual current value of the permanent magnet synchronous motor approaches the reference current value obtained by looking up the table, and the permanent magnet synchronous motor outputs the target torque.

[0102] The torque output by the permanent magnet synchronous motor is related to the actual current value of the permanent magnet synchronous motor. The output torque equation of the permanent magnet synchronous motor is shown in equation (4).

[0103]

[0104] where T qrepresents the output torque of the permanent magnet synchronous motor, P represents the pole pair number of the motor, λ f represents the flux linkage constant, L d represents the d-axis inductance of the motor, L q represents the q-axis inductance of the motor, I d represents the d-axis current of the motor, I q represents the q-axis current of the motor.

[0105] The output torque of the permanent magnet synchronous motor can be divided into a permanent magnet torque T p and a reluctance torque T r , the expressions of the permanent magnet torque T p and the reluctance torque T r are shown in formulas (5) and (6).

[0106]

[0107]

[0108] Wherein, the d-axis current Id and the q-axis current Iq of the permanent magnet synchronous motor work in the second quadrant and the third quadrant when the permanent magnet synchronous motor works normally. As shown in Figure 2 , the abscissa represents the d-axis current Id, the ordinate represents the q-axis current Iq, and the trajectory of the d-axis current Id and the q-axis current Iq is 0→A1→A2→A3. Wherein, the above λ f > 0, L d < L q Therefore, no matter whether the d-axis current Id and the q-axis current Iq work in the second quadrant or the third quadrant, the permanent magnet torque and the reluctance torque output by the permanent magnet synchronous motor when the permanent magnet synchronous motor works normally are in the same direction.

[0109] In order to make the permanent magnet synchronous motor reach the locked-rotor state without applying external force to the permanent magnet synchronous motor, the current components on the direct axis and the quadrature axis are reconstructed under the condition that the current amplitude is unchanged, so that the permanent magnet torque and the reluctance torque output by the permanent magnet synchronous motor are the same in size and opposite in direction, thereby ensuring that the output torque of the permanent magnet synchronous motor is 0, and then the motor speed of the permanent magnet synchronous motor tends to 0, and the locked-rotor state of the permanent magnet synchronous motor is realized under the condition that the output shaft of the permanent magnet synchronous motor is empty.

[0110] Figure 3 is a flowchart of a motor locked-rotor test method provided by the embodiment of the application, referring to Figure 3 , the method comprises:

[0111] 301, collecting the current and the motor speed of the permanent magnet synchronous motor.

[0112] In a possible implementation manner, the current of the permanent magnet synchronous motor is collected by a current sensor, and the current collected by the current sensor is obtained.

[0113] In a possible implementation, the motor speed of the permanent magnet synchronous motor is collected by the position sensor, and the motor speed collected by the position sensor is obtained.

[0114] In a possible implementation, the three-phase alternating current of the permanent magnet synchronous motor is collected, the three-phase alternating current is converted into the alpha-axis current and the beta-axis current by using the Clark conversion, and the alpha-axis current and the beta-axis current are converted into the direct-axis current and the quadrature-axis current by using the Park conversion based on the rotor position of the permanent magnet synchronous motor.

[0115] In the formula (1), the three-phase alternating current is converted into the alpha-axis current and the beta-axis current, and in the formula (2), the alpha-axis current and the beta-axis current are converted into the direct-axis current and the quadrature-axis current, which are not described herein again.

[0116] It should be noted that the current collected in the step 301 is the actual current of the permanent magnet synchronous motor, and the purpose of the embodiment of the present application is to control the three-phase alternating voltage of the permanent magnet synchronous motor, so that the actual direct-axis current and the actual quadrature-axis current of the permanent magnet synchronous motor approach the required direct-axis current and the required quadrature-axis current, to ensure that the output torque of the permanent magnet synchronous motor is 0, so as to achieve the goal that the speed of the permanent magnet synchronous motor is 0.

[0117] 302, obtaining a first reference current of the permanent magnet synchronous motor, the first reference current being a current required when the output torque of the permanent magnet synchronous motor reaches the locked-rotor torque.

[0118] In a possible implementation, the locked-rotor torque and the bus voltage of the permanent magnet synchronous motor are obtained, the reference current corresponding to the locked-rotor torque, the bus voltage and the motor speed is queried in a reference current table, and the queried reference current is determined as the first reference current.

[0119] In the reference current table, the reference current corresponding to any torque, any bus voltage and any click speed is stored. The reference current table is generated offline after data fitting processing of the permanent magnet synchronous motor bench calibration.

[0120] Optionally, the first reference current includes a first direct-axis reference current and a first quadrature-axis reference current.

[0121] In the embodiment of the present application, in the case that the permanent magnet synchronous motor works normally, there are two cases. In the first case, the output torque of the permanent magnet synchronous motor is a positive torque, the first direct-axis reference current is less than 0, and the first quadrature-axis reference current is greater than 0, that is, the first direct-axis reference current and the first quadrature-axis reference current work in the second quadrant. In the second case, the output torque of the permanent magnet synchronous motor is a negative torque, the first direct-axis reference current is less than 0, and the first quadrature-axis reference current is less than 0, that is, the first direct-axis reference current and the first quadrature-axis reference current work in the third quadrant.

[0122] 303、keeping the amplitude of the first reference current unchanged, reconstructing components of the first reference current on the direct axis and the quadrature axis based on the motor speed to obtain a second reference current, so that when the current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0.

[0123] The first reference current includes a component on the direct axis and a component on the quadrature axis, the component on the direct axis is also referred to as the first direct-axis reference current, and the component on the quadrature axis is also referred to as the first quadrature-axis reference current. The second reference current includes a component on the direct axis and a component on the quadrature axis, the component on the direct axis is also referred to as the second direct-axis reference current, and the component on the quadrature axis is also referred to as the second quadrature-axis reference current. The amplitude of the first reference current is equal to the amplitude of the second reference current, that is, the vector sum of the first direct-axis reference current and the first quadrature-axis reference current is equal to the vector sum of the second direct-axis reference current and the second quadrature-axis reference current. However, the magnitude of the first direct-axis reference current is not necessarily equal to the magnitude of the second direct-axis reference current, and the magnitude of the first quadrature-axis reference current is not necessarily equal to the magnitude of the second quadrature-axis reference current. The second direct-axis reference current and the second quadrature-axis reference current are obtained by reconstructing the first direct-axis reference current and the first quadrature-axis reference current.

[0124] In the embodiments of the present application, the first reference current is reconstructed to obtain the second reference current, so that when the current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0.

[0125] The second reference current includes the second direct-axis reference current and the second quadrature-axis reference current, and when the output torque calculated according to the second direct-axis reference current and the second quadrature-axis reference current according to the above formula (4) is equal to 0, the motor speed of the permanent magnet synchronous motor tends to 0. That is, the permanent magnet torque calculated according to the second direct-axis reference current and the second quadrature-axis reference current according to the above formula (5) and the reluctance torque calculated according to the second direct-axis reference current and the second quadrature-axis reference current according to the above formula (6) are equal in size and opposite in direction.

[0126] In a possible implementation manner, the first reference current includes the first direct-axis reference current and the first quadrature-axis reference current. The step 303 includes the following steps 3031-3032.

[0127] 3031, determining a target reference current angle based on the opposite of the first direct-axis reference current, the first quadrature-axis reference current, and the motor speed, so that the motor speed of the permanent magnet synchronous motor tends to 0 after the permanent magnet synchronous motor is controlled based on the target reference current angle.

[0128] wherein the current angle is an angle between the stator current space vector and the rotor d-axis, i.e. the projection angle of the stator current vector on the q-axis. In motor control, this angle is also referred to as phase lead angle, control angle or current lead angle.

[0129] In the embodiments of the present application, the motor speed of the permanent magnet synchronous motor tends to 0 after the permanent magnet synchronous motor is controlled based on the target reference current angle means that: the second direct-axis reference current and the second quadrature-axis reference current are reconstructed based on the target reference current angle, the permanent magnet torque calculated according to the above formula (5) and the reluctance torque calculated according to the above formula (6) are of the same magnitude and opposite directions according to the second direct-axis reference current and the second quadrature-axis reference current.

[0130] Optionally, the initial reference current angle is determined based on the negative of the first direct-axis reference current and the first quadrature-axis reference current, the current compensation angle is determined based on the difference between the motor speed and the target speed, the target speed is 0, and the sum of the initial reference current angle and the current compensation angle is determined as the target reference current angle.

[0131] For example, the initial reference current angle is determined based on the negative of the first direct-axis reference current and the first quadrature-axis reference current according to the following formula (7).

[0132]

[0133] wherein I qref represents the first quadrature-axis reference current, I dref represents the first direct-axis reference current. γ represents the initial reference current angle.

[0134] For example, the current compensation angle is obtained by adaptive adjustment. For example, when the motor speed is a positive speed (e.g. clockwise rotation), the current compensation angle is adjusted to obtain a new current compensation angle, so that the direct-axis reference current reconstructed based on the new current compensation angle is reduced, and the quadrature-axis reference current reconstructed based on the new current compensation angle is increased, thereby reducing the amplitude of the permanent magnet torque and increasing the amplitude of the reluctance torque, so that the output torque is less than 0, and then the motor speed is reduced to make the motor speed tend to 0. When the motor speed tends to 0, the current compensation angle is adjusted so that the output torque tends to 0, so that the motor speed is stable at a state close to 0. For another example, when the motor speed is a negative speed (e.g. counterclockwise rotation), the current compensation angle is adjusted to obtain a new current compensation angle, so that the direct-axis reference current reconstructed based on the new current compensation angle is increased, and the quadrature-axis reference current reconstructed based on the new current compensation angle is reduced, thereby increasing the amplitude of the permanent magnet torque and reducing the amplitude of the reluctance torque, so that the output torque is greater than 0, and then the motor speed is reduced to make the motor speed tend to 0. When the motor speed tends to 0, the current compensation angle is adjusted so that the output torque tends to 0, so that the motor speed is stable at a state close to 0.

[0135] Optionally, the current compensation angle is adaptively adjusted by using a proportional-integral control algorithm. In the embodiment of the application, the purpose of adjusting the current compensation angle is to dynamically adjust the direct-axis reference current and the quadrature-axis reference current through the current compensation angle, so that the permanent magnet torque and the reluctance torque output by the permanent magnet synchronous motor are equal in size and opposite in direction, so that the motor speed of the permanent magnet synchronous motor is equal to 0, and the locked-rotor state is achieved under the condition that the current amplitude of the permanent magnet synchronous motor is unchanged.

[0136] In the formula, the proportional-integral control algorithm is used to adjust the output control quantity according to the difference between the actual value of the feedback signal and the target value of the reference signal, so that the actual value of the feedback signal is approximately equal to the target value of the reference signal. In the embodiment of the application, the actual value of the feedback signal is the actual motor speed, the target value of the reference signal is the target speed, the target speed is 0, and the output control quantity is the current compensation angle. That is, the purpose of the proportional-integral control algorithm is to control the motor speed to be 0. The input of the proportional-integral control algorithm is the motor speed and the target speed, and the output value is the current compensation angle. The target reference current angle is determined by the initial reference current angle and the current compensation angle, and the second direct-axis reference current and the second quadrature-axis reference current are obtained by reconstruction using the target reference current angle. If the motor speed is a positive speed (that is, the motor speed is greater than the target speed), the current compensation angle is adjusted so that the second direct-axis reference current increases and the second quadrature-axis reference current decreases, thereby reducing the size of the output torque of the motor, and further reducing the motor speed, until the output torque tends to 0 and the speed tends to 0. If the motor speed is a negative speed (that is, the motor speed is less than the target speed), the current compensation angle is adjusted so that the second direct-axis reference current decreases and the second quadrature-axis reference current increases, thereby reducing the size of the output torque of the motor, and further reducing the motor speed, until the output torque tends to 0 and the speed tends to 0.

[0137] Optionally, the current compensation angle is not less than a first angle and not greater than a second angle, the first angle is equal to the opposite of the initial reference current angle, and the second angle is equal to the difference between 90 degrees and the initial reference current angle.

[0138] Taking the case that the first direct-axis reference current and the first quadrature-axis reference current work in the second quadrant as an example, in order to ensure that the second direct-axis reference current and the second quadrature-axis reference current work in the first quadrant, the current compensation angle needs to be limited, and the limitation condition of the current compensation angle is as follows Formula (8).

[0139]

[0140] In the formula, γ represents the current compensation angle, and γ represents the initial reference current angle. comp

[0141] ​3032. Based on the amplitude of the first reference current and the target reference current angle, determine the second direct-axis reference current and the second quadrature-axis reference current, and define the second direct-axis reference current and the second quadrature-axis reference current as the second reference current.

[0142] For example, the magnitude of the first reference current is determined as shown in the following formula (9).

[0143]

[0144] Among them, I amp I represents the amplitude of the first reference current. qref I represents the first quadrature-axis reference current. dref This represents the first direct-axis reference current.

[0145] For example, the second direct-axis reference current and the second quadrature-axis reference current are determined as shown in the following formula (10).

[0146]

[0147] Among them, I drefnew I represents the second direct-axis reference current. qrefnew I represents the second quadrature-axis reference current. amp γ represents the amplitude of the first reference current, and γ represents the initial reference current angle. comp Represents the current compensation angle, γ+γ comp Indicates the target reference current angle.

[0148] In one possible implementation, when the current of the permanent magnet synchronous motor is equal to the second reference current, the sum of the permanent magnet torque and the reluctance torque of the permanent magnet synchronous motor is equal to 0, and the magnitudes of the permanent magnet torque and the reluctance torque are equal and opposite in direction.

[0149] Figure 4 This is a flowchart of a current reconstruction method provided in an embodiment of this application, such as... Figure 4 As shown, by consulting the reference current table based on the stall torque, bus voltage, and motor speed, the first direct-axis reference current and the first quadrature-axis reference current are obtained. Based on the first direct-axis reference current and the first quadrature-axis reference current, the amplitude of the first reference current and the initial reference current angle are calculated. Based on the motor speed, the current compensation angle is calculated. The sum of the initial reference current angle and the current compensation angle is determined as the target reference current angle. Based on the target reference current angle, the components of the first reference current on the direct axis and the quadrature axis are reconstructed to obtain the second direct-axis reference current and the second quadrature-axis reference current.

[0150] 304. Based on the current of the permanent magnet synchronous motor and the second reference current, the AC voltage of the permanent magnet synchronous motor is adjusted so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current.

[0151] Among them, the current of the permanent magnet synchronous motor is the actual current, and the second reference current is the desired current.

[0152] In one possible implementation, a proportional-integral control algorithm is used to determine the direct-axis reference voltage and quadrature-axis reference voltage based on the current of the permanent magnet synchronous motor and the second reference current. The direct-axis reference voltage and quadrature-axis reference voltage are transformed into α-axis reference voltage and β-axis reference voltage using the Park inverse transformation. Based on the α-axis reference voltage and β-axis reference voltage, the three-phase duty cycle is generated. According to the three-phase duty cycle, the bus voltage is transformed into the AC voltage of the permanent magnet synchronous motor so that the current of the adjusted permanent magnet synchronous motor tends to the second reference current.

[0153] The proportional-integral (PI) control algorithm adjusts the output control quantity based on the difference between the actual value of the feedback signal and the target value of the reference signal, so that the actual value of the feedback signal is approximately equal to the target value of the reference signal. In this embodiment, the actual value of the feedback signal is the actual current, the target value of the reference signal is the second reference current, and the output control quantity is the AC voltage of the permanent magnet synchronous motor. That is, the purpose of the PPI control algorithm is to control the current of the permanent magnet synchronous motor to be the second reference current. The inputs of the PPI control algorithm are the current of the permanent magnet synchronous motor and the second reference current, and the output values ​​are the direct-axis reference voltage and the quadrature-axis reference voltage.

[0154] Optionally, the Park inverse transformation is used to transform the direct-axis reference voltage and quadrature-axis reference voltage into the α-axis reference voltage and β-axis reference voltage, as shown in the above formula (3), which will not be repeated here.

[0155] In one possible implementation, when the current of the permanent magnet synchronous motor is equal to the second reference current, the sum of the permanent magnet torque and the reluctance torque of the permanent magnet synchronous motor is equal to 0, and the magnitudes of the permanent magnet torque and the reluctance torque are equal and opposite in direction.

[0156] Figure 5 This is a flowchart of another motor control method provided in the embodiments of this application, such as... Figure 5 As shown, in Figure 1 Based on this, the method for obtaining the reference current is improved. Figure 5 In the process, after obtaining the first direct-axis reference current and the first quadrature-axis reference current by looking up the table, the above-mentioned... Figure 4The current reconstruction method in the paper reconstructs the first direct-axis reference current and the first quadrature-axis reference current to obtain the second direct-axis reference current and the second quadrature-axis reference current. Then, based on the difference between the second direct-axis reference current and the second quadrature-axis reference current and the actual direct-axis reference current and quadrature-axis reference current of the permanent magnet synchronous motor, the AC voltage of the permanent magnet synchronous motor is adjusted so that the current amplitude of the adjusted permanent magnet synchronous motor is equal to the current amplitude required to achieve the stall torque, and the speed of the permanent magnet synchronous motor tends to 0.

[0157] 305. When the motor speed of the permanent magnet synchronous motor is detected to be no greater than the preset speed, a stall test is performed on the permanent magnet synchronous motor. The fact that the motor speed of the permanent magnet synchronous motor is no greater than the preset speed indicates that the permanent magnet synchronous motor is currently in a stall state.

[0158] If the speed of the permanent magnet synchronous motor is not greater than the preset speed, it can be considered that the permanent magnet synchronous motor is currently in a stall state. Therefore, when the permanent magnet synchronous motor is in a stall state, a stall test can be performed. The stall test of the permanent magnet synchronous motor assesses whether the temperature of the permanent magnet synchronous motor and power module exceeds the allowable normal operating range under high torque conditions such as peak torque or 0.7 times the peak torque, while maintaining a water flow rate of 8L / min and a water temperature of 65℃. The test time generally does not exceed 30 seconds.

[0159] In permanent magnet synchronous motors, the rotor heat capacity is much larger than the stator heat capacity. During the test, the rotor temperature rise is negligible compared to the stator temperature rise. Therefore, the stall test primarily assesses whether the stator temperature exceeds the motor's allowable normal operating temperature threshold. The stator temperature rise during stall is determined by motor losses. In stall mode, the motor loss is copper loss, calculated using the formula Q = I. 2 Rt, where I represents the stator current, R represents the stator resistance, and t represents time. Therefore, the stator temperature rise is constant during the test time in the stalled state. Since the stalled test time is no more than 30 seconds, the stator temperature rise under this condition will not exceed the normal operating temperature range, thus preventing motor overheating faults.

[0160] The power module used to control the AC voltage of a permanent magnet synchronous motor also experiences temperature rise under locked-rotor conditions. The junction temperature of the power module typically reaches thermal equilibrium within 3 seconds. This junction temperature is determined by the module's conduction and switching losses. Under fixed vector control bus voltage, three-phase AC voltage, and switching frequency, the conduction and switching losses are constant. Therefore, the goal of the locked-rotor test is to detect whether the junction temperature of the power module exceeds the normal operating temperature range under fixed bus voltage, phase current, and switching frequency conditions.

[0161] The embodiment of the present application provides a motor stall test method, the first reference current is the current required when the output torque of the permanent magnet synchronous motor reaches the stall torque, the second reference current is obtained by reconstructing the components of the first reference current on the direct axis and the quadrature axis under the condition that the amplitude of the first reference current is kept unchanged, and then the AC voltage of the permanent magnet synchronous motor is adjusted according to the difference between the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor tends to the second reference current, then the speed of the permanent magnet synchronous motor tends to 0 and the current amplitude of the permanent magnet synchronous motor is equal to the current amplitude required when the output torque reaches the stall torque, so that the permanent magnet synchronous motor is ensured to be in the stall state without applying external force to the permanent magnet synchronous motor, and then the permanent magnet synchronous motor is tested in the stall state, the output shaft of the permanent magnet synchronous motor does not need to be locked, the stall of the permanent magnet synchronous motor is controlled by the internal logic of the permanent magnet synchronous motor, which is beneficial to reduce the cost of the stall test and improve the convenience of the stall test of the permanent magnet synchronous motor.

[0162] Figure 6 is a structural schematic diagram of a motor stall test device provided by the embodiment of the present application. Referring to Figure 6 , the device comprises:

[0163] The acquisition module 601 is configured to acquire the current and the motor speed of the permanent magnet synchronous motor.

[0164] The acquisition module 602 is configured to acquire the first reference current of the permanent magnet synchronous motor, and the first reference current is the current required when the output torque of the permanent magnet synchronous motor reaches the stall torque.

[0165] The reconstruction module 603 is configured to keep the amplitude of the first reference current unchanged, reconstruct the components of the first reference current on the direct axis and the quadrature axis based on the motor speed, and obtain the second reference current, so that when the current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0.

[0166] The adjustment module 604 is configured to adjust the AC voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the adjusted permanent magnet synchronous motor tends to the second reference current.

[0167] The test module 605 is configured to test the permanent magnet synchronous motor in the stall state when it is detected that the motor speed of the permanent magnet synchronous motor is not greater than a preset speed.

[0168] The motor stall test device provided by the embodiment of the application, the first reference current is the current required when the output torque of the permanent magnet synchronous motor reaches the stall torque, the second reference current is obtained by reconstructing the components of the first reference current on the direct axis and the quadrature axis while keeping the amplitude of the first reference current unchanged, and then the AC voltage of the permanent magnet synchronous motor is adjusted according to the difference between the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor tends to the second reference current, and then the speed of the permanent magnet synchronous motor tends to 0 and the current amplitude of the permanent magnet synchronous motor is equal to the current amplitude required when the output torque reaches the stall torque, thereby realizing that the permanent magnet synchronous motor is in the stall state without applying external force to the permanent magnet synchronous motor, and then the permanent magnet synchronous motor is tested in the stall state, and the output shaft of the permanent magnet synchronous motor does not need to be locked, the stall of the permanent magnet synchronous motor is controlled by the internal logic of the permanent magnet synchronous motor, which is conducive to reducing the cost of the stall test and improving the convenience of the stall test of the permanent magnet synchronous motor.

[0169] Optionally, the acquisition module 601 is configured to:

[0170] acquire three-phase AC currents of the permanent magnet synchronous motor;

[0171] convert the three-phase AC currents into an alpha-axis current and a beta-axis current by using a Clark transformation;

[0172] convert the alpha-axis current and the beta-axis current into a direct-axis current and a quadrature-axis current by using a Park transformation based on the rotor position of the permanent magnet synchronous motor.

[0173] Optionally, the acquisition module 602 is configured to:

[0174] acquire the stall torque and the bus voltage of the permanent magnet synchronous motor;

[0175] query the reference current corresponding to the stall torque, the bus voltage, and the motor speed in a reference current table, and determine the queried reference current as the first reference current;

[0176] The reference current table stores the reference current corresponding to any torque, any bus voltage, and any click speed.

[0177] Optionally, the adjustment module 604 is configured to:

[0178] determine a direct-axis reference voltage and a quadrature-axis reference voltage based on the current of the permanent magnet synchronous motor and the second reference current by using a proportional-integral control algorithm;

[0179] convert the direct-axis reference voltage and the quadrature-axis reference voltage into an alpha-axis reference voltage and a beta-axis reference voltage by using a Park inverse transformation;

[0180] generate the three-phase duty cycle based on the alpha-axis reference voltage and the beta-axis reference voltage;

[0181] transform the bus voltage into the AC voltage of the permanent magnet synchronous motor according to the three-phase duty cycle, so that the current of the adjusted permanent magnet synchronous motor tends to the second reference current.

[0182] Optionally, the first reference current comprises a first direct-axis reference current and a first quadrature-axis reference current; and the reconstruction module 603 is configured to:

[0183] determine a target reference current angle based on the inverse of the first direct-axis reference current, the first quadrature-axis reference current and the motor speed, so that the motor speed of the permanent magnet synchronous motor controlled based on the target reference current angle tends to 0.

[0184] determine a second direct-axis reference current and a second quadrature-axis reference current based on the amplitude of the first reference current and the target reference current angle, and determine the second direct-axis reference current and the second quadrature-axis reference current as the second reference current.

[0185] Optionally, the reconstruction module 603 is configured to:

[0186] determine an initial reference current angle based on the inverse of the first direct-axis reference current and the first quadrature-axis reference current.

[0187] determine a current compensation angle based on the difference between the motor speed and a target speed, the target speed being 0.

[0188] determine the target reference current angle as the sum of the initial reference current angle and the current compensation angle.

[0189] Optionally, the current compensation angle is not less than a first angle and not greater than a second angle, the first angle being equal to the inverse of the initial reference current angle, and the second angle being equal to the difference between 90 degrees and the initial reference current angle.

[0190] It should be noted that the motor stall test device provided in the above embodiments is only exemplified by the division of the above functional modules. In actual application, the above functions can be completed by different functional modules according to needs, i.e., the internal structure of the electronic device is divided into different functional modules to complete all or part of the functions described above. In addition, the motor stall test device and the motor stall test method provided in the above embodiments belong to the same concept, and the specific implementation process is described in the method embodiments, which will not be repeated here.

[0191] In some embodiments, the application also provides a vehicle electric drive system, comprising a permanent magnet synchronous motor, a motor controller and a memory, wherein the memory stores at least one computer program, and the at least one computer program is run by the motor controller to implement the motor stall test method in the above embodiments.

[0192] In some embodiments, a computer readable storage medium is also provided, wherein the storage medium stores a computer program, and the computer program is run to implement the steps of the motor stall test method in the above embodiments. For example, the computer readable storage medium can be a ROM (Read-Only Memory), a RAM (Random Access Memory), a CD-ROM (Compact Disc Read-Only Memory), a magnetic tape, a floppy disk, an optical data storage device, etc. It should be noted that the computer readable storage medium mentioned in the embodiments of the application can be a non-volatile storage medium, in other words, can be a non-transitory storage medium.

[0193] It should be understood that all or part of the steps of the above embodiments can be implemented by software, hardware, firmware or any combination thereof. When implemented by software, it can be implemented in the form of a computer program product entirely or partially. The computer program product includes one or more computer instructions. The computer instructions can be stored in the above computer readable storage medium.

[0194] That is, in some embodiments, a computer program product containing instructions is also provided, which, when run on a computer, causes the computer to perform the steps of the vehicle test method described above.

[0195] It should be noted that the information (including but not limited to user device information, user personal information, etc.), data (including but not limited to data for analysis, stored data, displayed data, etc.) and signals involved in the embodiments of the application are all authorized by the user or fully authorized by all parties, and the collection, use and processing of related data need to comply with relevant laws, regulations and standards of relevant countries and regions.

[0196] The above is only an optional embodiment of the application and does not limit the application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the application shall be included in the protection scope of the application.

Claims

1. A method of testing a motor for locked rotor, the method comprising: The method comprises: collecting the current and the motor speed of the permanent magnet synchronous motor; obtaining a first reference current of the permanent magnet synchronous motor, the first reference current being a current required when the output torque of the permanent magnet synchronous motor reaches the locked-rotor torque; keeping the amplitude of the first reference current unchanged, reconstructing components of the first reference current on the direct axis and the quadrature axis based on the motor speed to obtain a second reference current, so that when the current of the permanent magnet synchronous motor is equal to the second reference current, the motor speed of the permanent magnet synchronous motor tends to 0; adjusting the alternating voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current; when it is detected that the motor speed of the permanent magnet synchronous motor is not greater than a preset speed, performing locked-rotor test on the permanent magnet synchronous motor, and the motor speed of the permanent magnet synchronous motor not being greater than the preset speed indicates that the permanent magnet synchronous motor is currently in a locked-rotor state.

2. The motor stall test method of claim 1, wherein, The collecting of the current of the permanent magnet synchronous motor comprises: collecting three-phase alternating currents of the permanent magnet synchronous motor; using Clark transformation to transform the three-phase alternating currents into α-axis current and β-axis current; using Park transformation to transform the α-axis current and the β-axis current into direct-axis current and quadrature-axis current based on the rotor position of the permanent magnet synchronous motor.

3. The motor stall test method of claim 1, wherein, The obtaining of the first reference current of the permanent magnet synchronous motor comprises: obtaining the locked-rotor torque and the bus voltage of the permanent magnet synchronous motor; in a reference current table, querying the reference current corresponding to the locked-rotor torque, the bus voltage and the motor speed, and determining the queried reference current as the first reference current; wherein the reference current table stores the reference current corresponding to any torque, any bus voltage and any click speed.

4. The motor stall test method of claim 1, wherein, The adjusting of the alternating voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current, comprises: using a proportional-integral control algorithm to determine direct-axis reference voltage and quadrature-axis reference voltage based on the current of the permanent magnet synchronous motor and the second reference current; using Park inverse transformation to transform the direct-axis reference voltage and the quadrature-axis reference voltage into α-axis reference voltage and β-axis reference voltage; generating three-phase duty cycles based on the α-axis reference voltage and the β-axis reference voltage; transforming the bus voltage of the permanent magnet synchronous motor into the alternating voltage of the permanent magnet synchronous motor according to the three-phase duty cycles, so that the current of the permanent magnet synchronous motor after adjustment tends to the second reference current.

5. The motor stall test method of claim 1, wherein, The first reference current comprises a first direct-axis reference current and a first quadrature-axis reference current; and the keeping of the amplitude of the first reference current unchanged and the reconstructing of components of the first reference current on the direct axis and the quadrature axis based on the motor speed to obtain a second reference current comprise: determine a target reference current angle based on the opposite of the first direct-axis reference current, the first quadrature-axis reference current and the motor speed, so that the motor speed of the permanent magnet synchronous motor tends to 0 after the permanent magnet synchronous motor is controlled based on the target reference current angle; determine a second direct-axis reference current and a second quadrature-axis reference current based on the amplitude of the first reference current and the target reference current angle, and determine the second direct-axis reference current and the second quadrature-axis reference current as the second reference current.

6. The motor stall test method of claim 5, wherein, The determination of the target reference current angle based on the opposite of the first direct-axis reference current, the first quadrature-axis reference current and the motor speed comprises: determine an initial reference current angle based on the opposite of the first direct-axis reference current and the first quadrature-axis reference current; determine a current compensation angle based on the difference between the motor speed and a target speed, the target speed being 0; determine the target reference current angle as the sum of the initial reference current angle and the current compensation angle.

7. The motor stall test method of claim 6, wherein, The current compensation angle is not less than a first angle and not greater than a second angle, the first angle being equal to the opposite of the initial reference current angle, and the second angle being equal to the difference between 90 degrees and the initial reference current angle.

8. The motor stall testing method of claim 1, wherein, When the current of the permanent magnet synchronous motor is equal to the second reference current, the sum of the permanent magnet torque and the reluctance torque of the permanent magnet synchronous motor is equal to 0, and the magnitudes of the permanent magnet torque and the reluctance torque are equal and the directions thereof are opposite.

9. A motor stall testing device, characterized by, The device comprises: a collection module configured to collect the current and the motor speed of the permanent magnet synchronous motor; an acquisition module configured to acquire a first reference current of the permanent magnet synchronous motor, the first reference current being the current required when the output torque of the permanent magnet synchronous motor reaches the stall torque; a reconstruction module configured to keep the amplitude of the first reference current unchanged, reconstruct the components of the first reference current on the direct axis and the quadrature axis based on the motor speed, and obtain a second reference current, so that the motor speed of the permanent magnet synchronous motor tends to 0 when the current of the permanent magnet synchronous motor is equal to the second reference current; an adjustment module configured to adjust the alternating voltage of the permanent magnet synchronous motor based on the current of the permanent magnet synchronous motor and the second reference current, so that the current of the permanent magnet synchronous motor tends to the second reference current after the adjustment; a test module configured to perform a stall test on the permanent magnet synchronous motor when it is detected that the motor speed of the permanent magnet synchronous motor is not greater than a preset speed, the motor speed of the permanent magnet synchronous motor not being greater than the preset speed indicating that the permanent magnet synchronous motor is currently in a stall state.

10. A vehicle electric drive system, characterized by, The vehicle electric drive system comprises a permanent magnet synchronous motor, a motor controller and a memory, the memory storing at least one computer program, and the at least one computer program is run by the motor controller to implement the motor stall test method according to any one of claims 1 to 8.

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