Rotor magnetic steel temperature estimation method, device, equipment, medium and product

Abstract

The embodiment of the invention provides a rotor magnetic steel temperature estimation method and device, equipment, a medium and a product. The method comprises the steps that firstly, if a current motor of the vehicle is in a first working state, the current motor rotating speed, a first counter electromotive force peak value and the first stator winding temperature are obtained; then, according to the current motor rotating speed, the first counter electromotive force peak value and the mapping relation, the first rotor magnetic steel temperature of the current motor is obtained; then, calculating a first temperature difference value between a first rotor magnetic steel temperature and a first stator winding temperature of the current motor; and finally, when the current motor is in a second working state, determining a second rotor magnetic steel temperature according to the first temperature difference value and a second stator winding temperature of the current motor. By means of the method, estimation of the temperature of the rotor magnetic steel is achieved, and the accuracy and reliability of calculation of the temperature of the rotor magnetic steel are improved.

Description

Technical Field

[0001] The present application relates to the field of motor temperature detection, and in particular to a rotor magnetic steel temperature estimation method, device, equipment, medium and product. Background Art

[0002] With the rapid development of new energy vehicles, permanent magnet synchronous motors are a common type of motors for new energy vehicles due to their high efficiency, high power density, and fast response speed. However, since permanent magnet synchronous motors increase the temperature of the rotor magnets during operation, the magnetic properties of the magnets will significantly decline when the temperature exceeds a certain threshold, resulting in a decrease in motor efficiency. Therefore, in order to improve the service life and efficiency of the motor, it is particularly important to monitor the temperature of the motor rotor magnets in real time.

[0003] In the prior art, since it is difficult to measure the temperature of the rotating magnetic steel in the rotor by physical devices, a temperature sensor is usually embedded in the stator winding, and the temperature difference between the current stator winding temperature and the current rotor magnetic steel temperature is obtained as a constant value to further estimate the temperature of the rotor magnetic steel under other working conditions. Specifically, assuming that the stator winding temperature obtained by the temperature sensor is 50 degrees Celsius (℃) when the rotor is not working, and the current rotor magnetic steel temperature is 60 degrees using an infrared temperature tester, it is calculated that the temperature difference between the current stator winding temperature and the current rotor magnetic steel temperature is 10℃. Furthermore, if the stator winding temperature measured in the next working condition is 70℃, the corresponding rotor magnetic steel temperature can be estimated to be 80℃.

[0004] However, the accuracy of the method for estimating the temperature of the rotor magnetic steel in the prior art is low. Summary of the invention

[0005] The embodiments of the present application provide a rotor magnetic steel temperature estimation method, device, equipment, medium and product to solve the problem of low accuracy of the rotor magnetic steel temperature estimation method in the prior art.

[0006] In a first aspect, an embodiment of the present application provides a rotor magnetic steel temperature estimation method, comprising:

[0007] If the current motor of the vehicle is in a first working state, the current motor speed, the first back-EMF peak value and the first stator winding temperature are obtained, and the first working state is a working state with speed but no torque;

[0008] Acquire the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value and a mapping relationship, wherein the mapping relationship includes a corresponding relationship between the motor speed, the back-EMF peak value and the rotor magnetic steel temperature;

[0009] Calculating a first temperature difference between a first rotor magnetic steel temperature and a first stator winding temperature of the current motor;

[0010] When the current motor is in the second working state, the second rotor magnetic steel temperature is determined according to the first temperature difference and the second stator winding temperature of the current motor, and the second working state is a working state with speed and torque.

[0011] In a possible implementation, when the current motor is in the second working state, determining the second rotor magnetic steel temperature according to the first temperature difference and the second stator winding temperature of the current motor includes:

[0012] When the current motor is in the second working state, collecting a second stator winding temperature of the current motor;

[0013] The second rotor magnetic steel temperature is determined as the sum of the second stator winding temperature of the current motor and the first temperature difference.

[0014] In a possible implementation manner, acquiring the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value, and the mapping relationship includes:

[0015] Determining a target mapping relationship corresponding to the current motor from at least two mapping relationships;

[0016] The first rotor magnetic steel temperature of the current motor is acquired according to the current motor speed, the first back-electromotive force peak value and the target mapping relationship.

[0017] In a possible implementation manner, acquiring the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value, and the target mapping relationship includes:

[0018] Determine, according to the target mapping relationship, a second temperature difference between a maximum rotor magnetic steel temperature and a minimum rotor magnetic steel temperature included in the target mapping relationship;

[0019] Determining a second back-EMF peak value according to the current motor speed, the maximum rotor magnetic steel temperature and the target mapping relationship;

[0020] Determining a third back-EMF peak value according to the current motor speed, the minimum rotor magnetic steel temperature and the target mapping relationship;

[0021] Calculating a first back-electromotive force peak difference between the second back-electromotive force peak and the third back-electromotive force peak;

[0022] Calculate a second back-electromotive force peak difference between the third back-electromotive force peak and the first back-electromotive force peak;

[0023] Calculating the ratio of the second temperature difference to the first back-electromotive force peak difference;

[0024] The first rotor magnetic steel temperature is determined by multiplying the ratio by the product of the second back-electromotive force peak difference.

[0025] In a possible implementation manner, before acquiring the current motor speed, the first back-EMF peak value, and the first stator winding temperature if the current motor of the vehicle is in the first working state, the method further includes:

[0026] For each test environment temperature, testing each motor of the vehicle at the test environment temperature by using a test bench to obtain the back electromotive force peak value of each motor at different motor speeds;

[0027] Determine the current test environment temperature as the rotor magnetic steel temperature of each motor;

[0028] A mapping relationship corresponding to each motor is established according to the rotor magnetic steel temperature and the back electromotive force peak value of each motor at different motor speeds.

[0029] In a possible implementation, the method further includes:

[0030] If the vehicle is in a dual-motor output mode and the current motor is in a non-operating state, another motor is determined as a new current motor.

[0031] In a second aspect, the present application provides a rotor magnetic steel temperature estimation device, comprising:

[0032] A first acquisition module, configured to acquire a current motor speed, a first back-EMF peak value, and a first stator winding temperature if the current motor of the vehicle is in a first working state, wherein the first working state is a working state with speed but no torque;

[0033] A second acquisition module is used to acquire the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value and a mapping relationship, wherein the mapping relationship includes a corresponding relationship between the motor speed, the back-EMF peak value and the rotor magnetic steel temperature;

[0034] A calculation module, used for calculating a first temperature difference between a first rotor magnetic steel temperature of the current motor and a first stator winding temperature;

[0035] A determination module is used to determine the second rotor magnetic steel temperature according to the first temperature difference and the second stator winding temperature of the current motor when the current motor is in a second working state, and the second working state is a working state with speed and torque.

[0036] In a possible implementation manner, the determining module is specifically configured to:

[0037] When the current motor is in the second working state, collecting a second stator winding temperature of the current motor;

[0038] The second rotor magnetic steel temperature is determined as the sum of the second stator winding temperature of the current motor and the first temperature difference.

[0039] In a possible implementation manner, the second acquisition module is specifically configured to:

[0040] Determining a target mapping relationship corresponding to the current motor from at least two mapping relationships;

[0041] The first rotor magnetic steel temperature of the current motor is acquired according to the current motor speed, the first back-electromotive force peak value and the target mapping relationship.

[0042] In a possible implementation manner, the second acquisition module is specifically configured to:

[0043] Determine, according to the target mapping relationship, a second temperature difference between a maximum rotor magnetic steel temperature and a minimum rotor magnetic steel temperature included in the target mapping relationship;

[0044] Determining a second back-EMF peak value according to the current motor speed, the maximum rotor magnetic steel temperature and the target mapping relationship;

[0045] Determining a third back-EMF peak value according to the current motor speed, the minimum rotor magnetic steel temperature and the target mapping relationship;

[0046] Calculating a first back-electromotive force peak difference between the second back-electromotive force peak and the third back-electromotive force peak;

[0047] Calculate a second back-electromotive force peak difference between the third back-electromotive force peak and the first back-electromotive force peak;

[0048] Calculating the ratio of the second temperature difference to the first back-electromotive force peak difference;

[0049] The first rotor magnetic steel temperature is determined by multiplying the ratio by the product of the second back-electromotive force peak difference.

[0050] In a possible implementation manner, the rotor magnetic steel temperature estimation device further includes a processing module, and before obtaining the current motor speed, the first back-EMF peak value, and the first stator winding temperature if the current motor of the vehicle is in the first working state, the processing module is used to:

[0051] For each test environment temperature, testing each motor of the vehicle at the test environment temperature by using a test bench to obtain the back electromotive force peak value of each motor at different motor speeds;

[0052] Determine the current test environment temperature as the rotor magnetic steel temperature of each motor;

[0053] A mapping relationship corresponding to each motor is established according to the rotor magnetic steel temperature and the back electromotive force peak value of each motor at different motor speeds.

[0054] In a possible implementation manner, the processing module is further used to:

[0055] If the vehicle is in a dual-motor output mode and the current motor is in a non-operating state, another motor is determined as a new current motor.

[0056] In a third aspect, an embodiment of the present application provides an electronic device, including: a memory, a processor;

[0057] The memory stores computer-executable instructions;

[0058] The processor executes the computer-executable instructions stored in the memory, so that the processor executes the above first aspect and / or various possible implementations of the first aspect.

[0059] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, in which computer-executable instructions are stored. When the computer-executable instructions are executed by a processor, they are used to implement the first aspect above and / or various possible implementations of the first aspect.

[0060] In a fifth aspect, an embodiment of the present application provides a computer program product, including a computer program, which, when executed by a processor, implements the above first aspect and / or various possible implementation methods of the first aspect.

[0061] The rotor magnetic steel temperature estimation method, device, equipment, medium and product provided in the embodiments of the present application first obtain the current motor speed, the first back-EMF peak value and the first stator winding temperature when the current motor of the vehicle is in the first working state, so as to provide the necessary data basis for the subsequent calculation of the first rotor magnetic steel temperature of the current motor; then, according to the current motor speed, the first back-EMF peak value and the mapping relationship, the first rotor magnetic steel temperature of the current motor is obtained, so that the inaccuracy of the first rotor magnetic steel temperature of the current motor measured by other methods is reduced by using the mapping relationship; then, by calculating the first rotor magnetic steel temperature of the current motor The first temperature difference between the first temperature and the first stator winding temperature is determined, and when the current motor is in the second working state, the second rotor magnetic steel temperature is determined according to the first temperature difference and the current second stator winding temperature of the motor. In this way, the first temperature difference is used as a correction factor, and combined with the current second stator winding temperature, the second rotor magnetic steel temperature in the second working state is calculated, thereby realizing the dynamic calculation of the temperature difference between the rotor magnetic steel temperature and the stator winding temperature of the motor, thereby improving the accuracy and reliability of the rotor magnetic steel temperature estimation, and further ensuring that the temperature of the rotor magnetic steel is within a suitable range, thereby improving the service life and efficiency of the motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0062] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the present application.

[0063] Figure 1 Schematic diagram of the process of the rotor magnetic steel temperature estimation method provided in the embodiment of the present application Figure 1 ;

[0064] Figure 2 Schematic diagram of the process of the rotor magnetic steel temperature estimation method provided in the embodiment of the present application Figure 2 ;

[0065] Figure 3 A motor mapping relationship diagram provided for an embodiment of the present application;

[0066] Figure 4 Schematic diagram of the process of the rotor magnetic steel temperature estimation method provided in the embodiment of the present application Figure 3 ;

[0067] Figure 5 A schematic diagram of the structure of a rotor magnetic steel temperature estimation device provided in an embodiment of the present application;

[0068] Figure 6 A schematic diagram of the structure of an electronic device provided in an embodiment of the present application.

[0069] The above drawings have shown clear embodiments of the present application, which will be described in more detail later. These drawings and text descriptions are not intended to limit the scope of the present application in any way, but to illustrate the concept of the present application to those skilled in the art by referring to specific embodiments. DETAILED DESCRIPTION

[0070] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The implementations described in the following exemplary embodiments do not represent all implementations consistent with the present application. Instead, they are merely examples of devices and methods consistent with some aspects of the present application as detailed in the appended claims.

[0071] With the rapid development of new energy vehicles, permanent magnet synchronous motors are a common type of motors for new energy vehicles because of their high efficiency, high power density, and fast response speed. However, the high-order harmonic magnetic field of the stator of the permanent magnet synchronous motor will induce eddy current and hysteresis losses in the rotor core and magnetic steel, and the heat energy generated by the stator will also be transmitted to the rotor through the air gap, eventually causing the temperature of the rotor magnetic steel to rise. When the temperature exceeds the maximum operating temperature of 220°C of the rotor magnetic steel of the automotive permanent magnet synchronous motor, the magnetic properties of the magnetic steel will significantly decline, resulting in a decrease in motor efficiency. Therefore, in order to improve the service life and efficiency of the motor, it is particularly important to monitor the temperature of the motor rotor magnetic steel in real time.

[0072] In the prior art, since it is difficult to measure the temperature of the rotating magnetic steel in the rotor by physical devices, a temperature sensor is usually embedded in the stator winding, and the temperature difference between the current stator winding temperature and the current rotor magnetic steel temperature is obtained as a constant value to further estimate the temperature of the rotor magnetic steel under other working conditions. Specifically, assuming that the stator winding temperature obtained by the temperature sensor is 50°C when the rotor is not working, and the current rotor magnetic steel temperature is 60 degrees using an infrared temperature tester, it is calculated that the temperature difference between the current stator winding temperature and the current rotor magnetic steel temperature is 10°C. Furthermore, if the stator winding temperature measured in the next working condition is 70°C, the corresponding rotor magnetic steel temperature can be estimated to be 80°C.

[0073] However, the temperature difference between the stator winding temperature and the rotor magnet temperature will change under different operating conditions, but the rotor magnet temperature estimation method in the prior art cannot modify the temperature difference value according to the operating conditions, resulting in low accuracy of the estimated rotor magnet temperature.

[0074] Based on this, the present application proposes a method for estimating the rotor magnetic steel temperature. In practical applications, the temperature difference between the rotor magnetic steel temperature and the stator winding temperature will change dynamically due to changes in the working conditions of the motor (such as speed, load, electromagnetic parameters, etc.). If only a fixed temperature difference is used to estimate the rotor magnetic steel temperature, significant calculation errors will be caused. However, since the motor's rotor magnets have a certain mapping relationship with the motor's rotor magnet performance at different temperatures, that is, at the same speed, different rotor magnet temperatures are linearly related to the motor's back-electromotive force peak, that is, different rotor magnet temperatures correspond to different line voltage back-electromotive forces, it can be concluded that if the current motor speed and the first back-electromotive force peak can be obtained, the current rotor magnet temperature (that is, the first rotor magnet temperature of the current motor) can be inferred by using the mapping relationship between the motor's rotor magnet temperature and the motor's rotor magnet performance; further, the first stator winding temperature can be used to calculate the temperature difference between the rotor magnet temperature and the stator winding temperature under the current working condition (that is, the first temperature difference); finally, as long as the stator winding temperature under the next working condition is obtained (that is, the second stator winding temperature of the current motor when the current motor is in the second working state), the corresponding rotor magnet temperature (that is, the second rotor magnet temperature) can be calculated in real time; and by analogy, the dynamic temperature difference between the rotor magnet temperature and the stator winding temperature under different working conditions can be obtained, thereby accurately estimating the rotor magnet temperature under all working conditions.

[0075] The technical solution of the present application and how the technical solution of the present application solves the above-mentioned technical problems are described in detail below with specific embodiments. The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be repeated in some embodiments. The embodiments of the present application will be described below in conjunction with the accompanying drawings.

[0076] Figure 1 Schematic diagram of the process of the rotor magnetic steel temperature estimation method provided in the embodiment of the present application Figure 1 ;like Figure 1 As shown, the method includes:

[0077] S101. If the current motor of the vehicle is in a first working state, obtain the current motor speed, the first back-electromotive force peak value, and the first stator winding temperature.

[0078] The first working state is a working state with rotation speed but without torque; the temperature of the stator winding is obtained by embedding a temperature sensor in the stator winding.

[0079] It should be noted that when the vehicle motor is in the first working state, that is, a working state with speed but no torque, the operating state of the motor is relatively simple, that is, no-load operation or standby mode. The current motor speed, the first back-EMF peak and the first stator winding temperature obtained at this time can also better reflect the current thermal state of the motor, and will not cause additional load or risk to the motor.

[0080] It can be understood that obtaining corresponding performance parameters when the vehicle motor is in a working state with speed but without torque can provide a good data basis for the subsequent accurate estimation of the rotor magnetic steel temperature.

[0081] S102, obtaining a first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-electromotive force peak value and the mapping relationship.

[0082] The mapping relationship includes the corresponding relationship between the motor speed, the back electromotive force peak value and the rotor magnetic steel temperature.

[0083] It should be noted that the magnetic field strength of the rotor magnet of the permanent magnet synchronous motor used in new energy vehicles is different at different temperatures (that is, the magnetic field strength of the magnet and the temperature have a negative coefficient relationship); and different rotor magnet magnetic field strengths will produce different air gap magnetic field strengths; further, different air gap magnetic field strengths will produce different no-load back EMFs on the phase windings of the motor stator (that is, the rotor magnet temperature is different, and the back EMF induced in the stator phase coil at the same rotor speed will be different; that is, different rotor magnet temperatures correspond to different line voltage back EMFs). Therefore, by establishing a corresponding relationship between the motor speed, back EMF peak value and rotor magnet temperature, the rotor magnet temperature can be further estimated.

[0084] S103, calculating a first temperature difference between a first rotor magnetic steel temperature and a first stator winding temperature of the current motor.

[0085] It can be understood that the first stator winding temperature can reflect the overall heat dissipation of the motor. By obtaining the first temperature difference between the first rotor magnetic steel temperature and the first stator winding temperature of the current motor, it can further help determine whether the rotor magnetic steel temperature of the motor is overheated.

[0086] S104. When the current motor is in the second working state, determine the second rotor magnetic steel temperature according to the first temperature difference and the current second stator winding temperature of the motor.

[0087] The second working state is a working state with rotation speed and torque, that is, a state in which the motor is running under load.

[0088] In one feasible method, first, when the current motor is in the second working state, the second stator winding temperature of the current motor is collected; then the second rotor magnetic steel temperature is determined as the sum of the second stator winding temperature of the current motor and the first temperature difference.

[0089] It should be understood that when the motor is in a working state with speed and torque, that is, the motor is running under load, the embedded temperature sensor is used to collect the second stator winding temperature of the current motor, and then the second stator winding temperature is added to the first temperature difference calculated previously to obtain the accurate second rotor magnet temperature.

[0090] For example, assuming that in the first working state, the first rotor magnetic steel temperature of the current motor is M1_RotorTemp_NonWorking, and the first stator winding temperature is M1_StatorTemp_NonWorking; in the second working state, the second stator winding temperature of the current motor is M1_StatorTemp_Working, then the first temperature difference can be expressed as:

[0091] Delta_M1Temp = M1_StatorTemp_NonWorking- M1_RotorTemp_NonWorking

[0092] Furthermore, the second rotor magnetic steel temperature can be expressed as:

[0093] M1_RotorTemp_Working= Delta_M1Temp+ M1_StatorTemp_Working

[0094] It should be noted that, in the dual-motor driving state, the relevant operating parameters corresponding to the second motor can be obtained in the same way, and the specific calculation process will not be described in detail in this embodiment of the present application.

[0095] It can be understood that in this way, the first temperature difference under different working conditions can be dynamically obtained, avoiding the ignoring of the thermal behavior difference between the stator and the rotor, and can more accurately evaluate the temperature of the second rotor magnetic steel, ensuring that the temperature of the second rotor magnetic steel is always at an appropriate temperature, thereby improving the service life and operating efficiency of the motor.

[0096] The rotor magnet temperature estimation method provided in the embodiment of the present application first obtains the current motor speed, the first back-EMF peak value and the first stator winding temperature when the current motor of the vehicle is in the first working state, so as to provide the necessary data basis for the subsequent calculation of the first rotor magnet temperature of the current motor; then, the first rotor magnet temperature of the current motor is obtained according to the current motor speed, the first back-EMF peak value and the mapping relationship, so as to reduce the inaccuracy of the first rotor magnet temperature of the current motor measured by other methods by using the mapping relationship; then, by calculating the first temperature difference between the first rotor magnet temperature of the current motor and the first stator winding temperature, and when the current motor is in the second working state, the second rotor magnet temperature is determined according to the first temperature difference and the second stator winding temperature of the current motor. In this way, the first temperature difference is used as a correction factor, and combined with the current second stator winding temperature, the second rotor magnet temperature in the second working state is calculated, so as to realize the dynamic calculation of the temperature difference between the rotor magnet temperature and the stator winding temperature of the motor, thereby improving the accuracy and reliability of the rotor magnet temperature estimation, and further ensuring that the temperature of the rotor magnet is within a suitable range, thereby improving the service life and efficiency of the motor.

[0097] In one achievable manner, if the vehicle is in a dual-motor output mode and the current motor is in a non-operating state, another motor is determined as a new current motor.

[0098] It is understandable that in a dual-motor system, in order to maintain the vehicle's driving ability and not be affected by changes in the state of a single motor, if the current motor is not in a working or driving state, the system will automatically select another motor as the current motor to ensure that the vehicle can continue to operate normally.

[0099] Figure 2 Schematic diagram of the process of the rotor magnetic steel temperature estimation method provided in the embodiment of the present application Figure 2 ; This embodiment is Figure 1 Based on the embodiment, the method is described in detail, and includes:

[0100] S201. Determine a target mapping relationship corresponding to a current motor from at least two mapping relationships.

[0101] It should be noted that in a dual-motor system, among the at least two mapping relationships established, all motors may share the same mapping relationship, or different motors may correspond to different mapping relationships in consideration of the differences between the motors.

[0102] Specifically, if the current motor is similar to another motor in terms of working principle, load type, power output, etc., they can choose to share the same mapping relationship; correspondingly, if the performance or working conditions of the motors are different (for example, motor 1 tends to drive at high speed, while motor 2 is used for low-speed driving), the two motors can use different mapping relationships. In practical applications, the mapping relationship used is determined according to the specific situation, and the embodiments of this application do not make specific restrictions here.

[0103] In one achievable method, the specific method of obtaining the target mapping relationship corresponding to the motor is:

[0104] Firstly, for each test ambient temperature, each motor of the vehicle is tested at the test ambient temperature through a test bench to obtain the back EMF peak value of each motor at different motor speeds; then, the current test ambient temperature is determined as the rotor magnetic steel temperature of each motor; finally, a mapping relationship corresponding to each motor is established based on the rotor magnetic steel temperature and the back EMF peak value of each motor at different motor speeds.

[0105] For example, suppose there are motor 1 and motor 2. Put motor 1 and motor 2 in the test bench, and set the first test environment temperature to 45℃ and keep it still for 2 hours. At this time, it can be determined that the current motor rotor magnetic steel temperature is 45℃. Set the bench dynamometer speed to 1000RPM and 5000RPM, and use an oscilloscope to record the back EMF waveform of motor 1 and motor 2 at this specific speed. The back EMF peak value of motor 1 is recorded as M1_Emf_45_1000 and M1_Emf_45_5000, and the back EMF peak value of motor 2 is recorded as M2_Emf_45_1000 and M2_Emf_45_5000; accordingly, set the second test environment temperature to 45℃ and keep it still for 2 hours. The test environment temperature is 120℃ and it is kept still for 2 hours. At this time, it can be determined that the current motor rotor magnetic steel temperature is 120℃. The bench dynamometer speed is set to 1000RPM and 5000RPM. The back EMF waveform of the motor at this specific speed is recorded with an oscilloscope. The back EMF peak values ​​of motor 2 are recorded as M1_Emf_120_1000 and M1_Emf_120_5000, and the back EMF peak values ​​of motor 2 are recorded as M2_Emf_120_1000 and M2_Emf_120_5000. Based on the linear relationship between the motor back EMF and the speed, the back EMF peak values ​​at 45℃ and 120℃ at 0-10000RPM are plotted. The mapping relationship of the motor is shown in Table 1.

[0106] Table 1 Motor mapping table

[0107]

[0108] It can be understood that by testing the back EMF peak value of the motor at different test environment temperatures and speeds on a test bench to establish a corresponding mapping relationship, an accurate data basis can be provided for the subsequent calculation of the rotor magnetic steel temperature.

[0109] S202, obtaining a first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-electromotive force peak value and the target mapping relationship.

[0110] In one feasible method, first, according to the target mapping relationship, the second temperature difference between the maximum rotor magnetic steel temperature and the minimum rotor magnetic steel temperature included in the target mapping relationship is determined; then, according to the current motor speed, the maximum rotor magnetic steel temperature and the target mapping relationship, the second back EMF peak value is determined; further, according to the current motor speed, the minimum rotor magnetic steel temperature and the target mapping relationship, the third back EMF peak value is determined; then, the first back EMF peak difference between the second back EMF peak value and the third back EMF peak value is calculated; the second back EMF peak difference between the third back EMF peak value and the first back EMF peak value is calculated; and the ratio of the second temperature difference to the first back EMF peak difference is calculated; finally, the ratio is multiplied by the product of the second back EMF peak difference to determine the first rotor magnetic steel temperature.

[0111] For example, during the operation of a vehicle with a dual-motor system, the dual motors will shift gears alternately according to different operating conditions, that is, there will be a gap in which motor 1 or motor 2 does not output torque. Taking the gap in which motor 1 does not output torque as an example, the controller controls the shift mechanism to put motor 1 into gear, that is, at this time motor 1 has speed but no torque output, and the speed of motor 1 is recorded as M1_Spd; the controller detects the first back-electromotive force peak of motor 1 at this speed and records it as M1_Emf, and detects the first stator winding temperature of motor 1 and records it as M1_StatorTemp_NonWorking. After completion, the controller controls motor 1 to complete subsequent work according to the operating conditions. Similarly, in the gap in which motor 2 is not working, the same Detection, respectively recorded as the motor 2 speed M2_Spd and the first back-EMF peak M2_Emf and the first stator winding temperature M2_StatorTemp_NonWorking of the motor 2; further, according to the speed M1_Spd of the motor 1 and the target mapping relationship in the mapping relationship table of the motor in S201, the back-EMF peaks of 120°C and 45°C under the speed M1_Spd are obtained, which are respectively recorded as the second back-EMF peak M1_Emf_120 and the third back-EMF peak M1_Emf_45, so it can be calculated that the second temperature difference between the maximum rotor magnetic steel temperature and the minimum rotor magnetic steel temperature is 120°C-45°C; the first back-EMF peak difference is M1_Emf_120- M1_Emf_45; the second back-EMF peak difference is M1_Emf_45-M1_Emf; then, the ratio of the second temperature difference to the first back-EMF peak difference is calculated, and the ratio is multiplied by the product of the second back-EMF peak difference, and the first rotor magnetic steel temperature M1_RotorTemp_NonWorking is determined as: M1_RotorTemp_NonWorking=((120-45) / (M1_Emf_45-M1_Emf_120))*( M1_Emf_45-M1_Emf). Correspondingly, the first rotor magnetic steel temperature M2_RotorTemp_NonWorking of motor 2 is ((120-45) / (M2_Emf_45-M2_Emf_120))*( M2_Emf_45-M2_Emf).

[0112] It can be understood that when the motor is in the first working state, by calculating the relationship between the back-EMF peak and the temperature, the first rotor magnetic steel temperature of the current motor can be accurately calculated, and then by obtaining the second stator winding temperature of the motor in the second working state, the temperature difference between the stator and the rotor under the current motor operating conditions can be obtained, thereby more accurately obtaining the second rotor magnetic steel temperature in the second working state, and then serving as a basis for torque distribution arbitration, rotor magnetic steel anti-demagnetization over-temperature protection and fault diagnosis information.

[0113] Figure 3 The motor mapping relationship diagram provided in the embodiment of the present application is as follows: Figure 3 As shown in the figure, the circular marked curve represents the linear relationship between the motor speed and the peak value of the motor back-EMF when the rotor magnetic steel temperature is 45°C, and the triangular marked curve represents the linear relationship between the motor speed and the peak value of the motor back-EMF when the rotor magnetic steel temperature is 120°C.

[0114] Figure 4 Schematic diagram of the process of the rotor magnetic steel temperature estimation method provided in the embodiment of the present application Figure 3 ;

[0115] S401 : Acquire the output mode of the vehicle motor.

[0116] S402, determining whether the vehicle motor is in a single-motor switching dual-motor output mode, if so, executing S403, if not, executing S409.

[0117] S403: If the current motor is in a non-working state, another motor is determined as a new current motor, and a target mapping relationship corresponding to the current motor is determined from at least two mapping relationships.

[0118] S404. Determine, according to the target mapping relationship, a second temperature difference between the maximum rotor magnetic steel temperature and the minimum rotor magnetic steel temperature included in the target mapping relationship.

[0119] S405, determining a second back EMF peak value according to the current motor speed, the maximum rotor magnetic steel temperature and the target mapping relationship, and determining a third back EMF peak value according to the current motor speed, the minimum rotor magnetic steel temperature and the target mapping relationship.

[0120] S406, calculating a first back-electromotive force peak difference between the second back-electromotive force peak and the third back-electromotive force peak, and calculating a second back-electromotive force peak difference between the third back-electromotive force peak and the first back-electromotive force peak.

[0121] S407, calculating the ratio of the second temperature difference to the first back-electromotive force peak difference, and multiplying the ratio by the second back-electromotive force peak difference to determine the first rotor magnetic steel temperature.

[0122] S408, calculating a first temperature difference between a first rotor magnetic steel temperature and a first stator winding temperature of the current motor.

[0123] S409: When the current motor is in the second working state, determine the second rotor magnetic steel temperature according to the first temperature difference and the second stator winding temperature of the current motor.

[0124] It should be noted that the specific implementation of the embodiments of the present application has been specifically described in the above embodiments, and the embodiments of the present application will not be repeated here.

[0125] Figure 5 The schematic diagram of the structure of the rotor magnetic steel temperature estimation device provided in the embodiment of the present application is as follows: Figure 5 As shown, the rotor magnetic steel temperature estimation device 50 provided in this embodiment includes: a first acquisition module 501, a second acquisition module 502, a calculation module 503, and a determination module 505.

[0126] A first acquisition module 501 is used to acquire the current motor speed, the first back-EMF peak value and the first stator winding temperature if the current motor of the vehicle is in a first working state, and the first working state is a working state with speed but no torque;

[0127] A second acquisition module 502 is used to acquire the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value and a mapping relationship, wherein the mapping relationship includes a corresponding relationship between the motor speed, the back-EMF peak value and the rotor magnetic steel temperature;

[0128] A calculation module 503 is used to calculate a first temperature difference between a first rotor magnetic steel temperature and a first stator winding temperature of the current motor;

[0129] The determination module 505 is used to determine the second rotor magnetic steel temperature according to the first temperature difference and the second stator winding temperature of the current motor when the current motor is in the second working state, and the second working state is a working state with speed and torque.

[0130] In a possible implementation, the determination module 505 is specifically configured to:

[0131] When the current motor is in the second working state, collecting the second stator winding temperature of the current motor;

[0132] The sum of the current second stator winding temperature of the motor and the first temperature difference is determined as the second rotor magnetic steel temperature.

[0133] In a possible implementation manner, the second acquisition module 502 is specifically configured to:

[0134] Determine a target mapping relationship corresponding to the current motor from at least two mapping relationships;

[0135] The first rotor magnetic steel temperature of the current motor is obtained according to the current motor speed, the first back-EMF peak value and the target mapping relationship.

[0136] In a possible implementation manner, the second acquisition module 502 is specifically configured to:

[0137] Determine, according to the target mapping relationship, a second temperature difference between a maximum rotor magnetic steel temperature and a minimum rotor magnetic steel temperature included in the target mapping relationship;

[0138] Determine the second back-EMF peak value according to the current motor speed, the maximum rotor magnetic steel temperature and the target mapping relationship;

[0139] Determine the third back-EMF peak value according to the current motor speed, the minimum rotor magnetic steel temperature and the target mapping relationship;

[0140] Calculating a first back-electromotive force peak difference between a second back-electromotive force peak and a third back-electromotive force peak;

[0141] Calculate a second back-electromotive force peak difference between the third back-electromotive force peak and the first back-electromotive force peak;

[0142] Calculating the ratio of the second temperature difference to the first back-electromotive force peak difference;

[0143] The first rotor magnetic steel temperature is determined by multiplying the ratio by the product of the second back-electromotive force peak difference.

[0144] In a possible implementation manner, the rotor magnetic steel temperature estimation device further includes a processing module, which is used to: before obtaining the current motor speed, the first back-EMF peak value and the first stator winding temperature if the current motor of the vehicle is in the first working state, the processing module is used to:

[0145] For each test environment temperature, each motor of the vehicle is tested at the test environment temperature through a test bench to obtain the back EMF peak value of each motor at different motor speeds;

[0146] Determine the current test environment temperature as the rotor magnetic steel temperature of each motor;

[0147] According to the rotor magnetic steel temperature and the back electromotive force peak value of each motor at different motor speeds, a mapping relationship corresponding to each motor is established.

[0148] In a possible implementation manner, the processing module is further configured to:

[0149] If the vehicle is in dual-motor output mode and the current motor is not in operation, the other motor is determined as the new current motor.

[0150] The rotor magnetic steel temperature estimation device provided in this embodiment can execute the method provided in the above method embodiment. Its implementation principle and technical effect are similar, and this embodiment will not be described in detail here.

[0151] Figure 6 This is a schematic diagram of the structure of an electronic device provided in an embodiment of the present application. Figure 6 As shown, the electronic device 60 provided in this embodiment includes: at least one processor 601 and a memory 602. Optionally, the device 60 also includes a communication component 603. The processor 601, the memory 602 and the communication component 603 are connected via a bus 604.

[0152] In a specific implementation process, at least one processor 601 executes the computer execution instructions stored in the memory 602, so that at least one processor 601 executes the above method.

[0153] The specific implementation process of the processor 601 can be found in the above method embodiment, and its implementation principle and technical effect are similar, so this embodiment will not be repeated here.

[0154] In the above embodiments, it should be understood that the processor can be a central processing unit (CPU), or other general-purpose processors, digital signal processors (DSP), application-specific integrated circuits (ASIC), etc. A general-purpose processor can be a microprocessor or any conventional processor. The steps of the method disclosed in the invention can be directly implemented as a hardware processor, or can be implemented by a combination of hardware and software modules in the processor.

[0155] The memory may include a high-speed memory (Random Access Memory, RAM), and may also include a non-volatile memory (NVM), such as at least one disk storage.

[0156] The bus can be an Industry Standard Architecture (ISA) bus, a Peripheral Component Interconnect (PCI) bus, or an Extended Industry Standard Architecture (EISA) bus, etc. The bus can be divided into an address bus, a data bus, a control bus, etc. For ease of representation, the bus in the drawings of this application is not limited to only one bus or one type of bus.

[0157] The present application also provides a computer program product, including a computer program, which implements the above method when executed by a processor.

[0158] The present application also provides a computer-readable storage medium, in which computer-executable instructions are stored. When a processor executes the computer-executable instructions, the above method is implemented.

[0159] The above-mentioned readable storage medium can be implemented by any type of volatile or non-volatile storage device or a combination thereof, such as static random access memory (SRAM), electrically erasable programmable read-only memory (EEPROM), erasable programmable read-only memory (EPROM), programmable read-only memory (PROM), read-only memory (ROM), magnetic memory, flash memory, magnetic disk or optical disk. The readable storage medium can be any available medium that can be accessed by a general or special-purpose computer.

[0160] An exemplary readable storage medium is coupled to a processor so that the processor can read information from the readable storage medium and write information to the readable storage medium. Of course, the readable storage medium can also be a component of the processor. The processor and the readable storage medium can be located in an application specific integrated circuit (Application Specific Integrated Circuits, referred to as: ASIC). Of course, the processor and the readable storage medium can also exist in the device as discrete components.

[0161] The division of units is only a logical function division, and there may be other divisions in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interface, device or unit, which can be electrical, mechanical or other forms.

[0162] The units described as separate components may or may not be physically separated, and the components shown as units may or may not be physical units, that is, they may be located in one place or distributed on multiple network units. Some or all of the units may be selected according to actual needs to achieve the purpose of the solution of this embodiment.

[0163] In addition, each functional unit in each embodiment of the present invention may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0164] If the function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, server, or network device, etc.) to perform all or part of the steps of the methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk, etc. Various media that can store program codes.

[0165] Those skilled in the art can understand that all or part of the steps of implementing the above-mentioned method embodiments can be completed by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, the steps of the above-mentioned method embodiments are executed; and the aforementioned storage medium includes: ROM, RAM, disk or optical disk and other media that can store program codes.

[0166] Finally, it should be noted that those skilled in the art will readily conceive of other embodiments of the present invention after considering the specification and practicing the invention disclosed herein. The present invention is intended to cover any variations, uses or adaptations of the present invention, which follow the general principles of the present invention and include common knowledge or customary technical means in the art not disclosed by the present invention, are not limited to the precise structure described above and shown in the drawings, and may be modified and changed in various ways without departing from the scope thereof. The scope of the present invention is limited only by the appended claims.

Claims

1. A method for estimating rotor magnetic steel temperature, characterized in that: include: If the current motor of the vehicle is in a first working state, the current motor speed, the first back-EMF peak value and the first stator winding temperature are obtained, and the first working state is a working state with speed but no torque; Acquire the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value and a mapping relationship, wherein the mapping relationship includes a corresponding relationship between the motor speed, the back-EMF peak value and the rotor magnetic steel temperature; Calculating a first temperature difference between a first rotor magnetic steel temperature and a first stator winding temperature of the current motor; When the current motor is in the second working state, the second rotor magnetic steel temperature is determined according to the first temperature difference and the second stator winding temperature of the current motor, and the second working state is a working state with speed and torque.

2. The method according to claim 1, characterized in that When the current motor is in the second working state, determining the second rotor magnetic steel temperature according to the first temperature difference and the second stator winding temperature of the current motor includes: When the current motor is in the second working state, collecting a second stator winding temperature of the current motor; The second rotor magnetic steel temperature is determined as the sum of the second stator winding temperature of the current motor and the first temperature difference.

3. The method according to claim 1 or 2, characterized in that: The step of obtaining the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back electromotive force peak value and the mapping relationship includes: Determining a target mapping relationship corresponding to the current motor from at least two mapping relationships; The first rotor magnetic steel temperature of the current motor is acquired according to the current motor speed, the first back-electromotive force peak value and the target mapping relationship.

4. The method according to claim 3, characterized in that The obtaining, according to the current motor speed, the first back-EMF peak value and the target mapping relationship, the first rotor magnetic steel temperature of the current motor comprises: Determine, according to the target mapping relationship, a second temperature difference between a maximum rotor magnetic steel temperature and a minimum rotor magnetic steel temperature included in the target mapping relationship; Determining a second back-EMF peak value according to the current motor speed, the maximum rotor magnetic steel temperature and the target mapping relationship; Determining a third back-EMF peak value according to the current motor speed, the minimum rotor magnetic steel temperature and the target mapping relationship; Calculating a first back-electromotive force peak difference between the second back-electromotive force peak and the third back-electromotive force peak; Calculate a second back-electromotive force peak difference between the third back-electromotive force peak and the first back-electromotive force peak; Calculating the ratio of the second temperature difference to the first back-electromotive force peak difference; The first rotor magnetic steel temperature is determined by multiplying the ratio by the product of the second back-electromotive force peak difference.

5. The method according to claim 3, characterized in that: Before obtaining the current motor speed, the first back-EMF peak value and the first stator winding temperature if the current motor of the vehicle is in the first working state, the method further includes: For each test environment temperature, testing each motor of the vehicle at the test environment temperature by using a test bench to obtain the back electromotive force peak value of each motor at different motor speeds; Determine the current test environment temperature as the rotor magnetic steel temperature of each motor; A mapping relationship corresponding to each motor is established according to the rotor magnetic steel temperature and the back electromotive force peak value of each motor at different motor speeds.

6. The method according to claim 1 or 2, characterized in that: The method further comprises: If the vehicle is in a dual-motor output mode and the current motor is in a non-operating state, another motor is determined as a new current motor.

7. A rotor magnetic steel temperature estimation device, characterized in that: include: A first acquisition module, configured to acquire a current motor speed, a first back-EMF peak value, and a first stator winding temperature if the current motor of the vehicle is in a first working state, wherein the first working state is a working state with speed but no torque; A second acquisition module is used to acquire the first rotor magnetic steel temperature of the current motor according to the current motor speed, the first back-EMF peak value and a mapping relationship, wherein the mapping relationship includes a corresponding relationship between the motor speed, the back-EMF peak value and the rotor magnetic steel temperature; A calculation module, used for calculating a first temperature difference between a first rotor magnetic steel temperature of the current motor and a first stator winding temperature; A determination module is used to determine the second rotor magnetic steel temperature according to the first temperature difference and the second stator winding temperature of the current motor when the current motor is in a second working state, and the second working state is a working state with speed and torque.

8. An electronic device, characterized in that: include: Memory, processor; The memory stores computer-executable instructions; The processor executes the computer-executable instructions stored in the memory, so that the processor performs the method according to any one of claims 1 to 6.

9. A computer-readable storage medium, characterized in that: The computer-readable storage medium stores computer-executable instructions, which are used to implement the method according to any one of claims 1 to 6 when executed by a processor.

10. A computer program product, characterized in that The invention comprises a computer program, which implements the method according to any one of claims 1 to 6 when being executed by a processor.

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