Motor stator temperature measurement method, device and vehicle

Abstract

The present disclosure relates to a motor stator temperature measurement method and device and a vehicle, comprising: obtaining a motor rotor speed and a motor phase current; determining a first temperature and an impedance of the motor stator according to the speed and the phase current, wherein the first temperature and the impedance of the motor stator are calibration values; calculating a temperature error caused by heat loss of the motor stator as a temperature correction value through the first temperature and the impedance of the motor stator; determining a second temperature according to the temperature correction value and motor stator temperature sensor measurement data, and taking the second temperature as an actual temperature of the motor stator. In this way, the measurement data obtained by the temperature sensor of the motor stator can be corrected through the measurement of the motor speed and the phase current, so that the actual temperature obtained can more accurately reflect the temperature of the driving motor, avoiding the problem of inaccurate measurement of the motor stator temperature caused by the motor speed and the position of the temperature sensor.

Description

Technical Field

[0001] This disclosure relates to the field of vehicle motors, and more specifically, to a method, apparatus, and vehicle for measuring the stator temperature of a motor. Background Technology

[0002] In pure electric / hybrid vehicles, motor temperature is a crucial parameter during operation. Only when the motor operates within a reasonable range can it properly provide power to the vehicle. Motor temperature is typically used as the basis for control commands; therefore, the reported motor temperature value needs to accurately reflect the actual motor temperature to ensure the effectiveness of thermal management control strategies.

[0003] In a typical electric motor, the stationary part is called the stator, and the rotating part is usually called the rotor. Currently, electric vehicles on the market determine the drive motor temperature directly by reading the temperature sensor readings from the stator. However, in reality, as vehicle conditions change, the drive motor speed also changes in real time. Furthermore, as the vehicle speed, i.e., the rotor speed, increases, the cooling effect of surrounding media such as coolant on the motor stator becomes increasingly uneven, potentially leading to different temperatures in different areas of the stator. Therefore, due to limitations in controller structure, cooling pipe layout, temperature sensor location, and changes in vehicle speed, the temperature measured at a certain location on the stator by the temperature sensor deviates significantly from the actual overall temperature of the stator. Summary of the Invention

[0004] The purpose of this disclosure is to provide a method, apparatus, and vehicle for measuring the temperature of a motor stator, which corrects the measurement data obtained by the temperature sensor of the motor stator, so that the actual temperature obtained can more accurately reflect the temperature of the drive motor. This avoids the problem of inaccurate temperature measurement caused by the uneven cooling effect of the surrounding medium on the motor stator when the motor rotor speed is higher, and also avoids the problem that the accurate temperature of the motor stator cannot be measured due to the location of the temperature sensor.

[0005] To achieve the above objectives, this disclosure provides a method for measuring the stator temperature of an electric motor, the method comprising:

[0006] Obtain the rotor speed and phase current of the motor;

[0007] The first temperature and the impedance of the motor stator are determined based on the rotational speed and phase current, wherein the first temperature and the impedance of the motor stator are calibration values;

[0008] The temperature error caused by the heat loss of the motor stator is calculated using the first temperature and the impedance of the motor stator as the temperature correction value;

[0009] The second temperature is determined based on the temperature correction value and the temperature sensor measurement data of the motor stator, and the second temperature is used as the actual temperature of the motor stator.

[0010] Optionally, the calibration value is determined by finite element simulation.

[0011] Optionally, the step of calculating the temperature error caused by the heat loss of the motor stator using the first temperature and the impedance of the motor stator as a temperature correction value includes:

[0012] The time constant for the complete filling of the motor's heat capacity is determined based on the impedance of the motor stator.

[0013] The first temperature and the time constant are input into a preset filtering model to calculate the temperature error caused by the heat loss of the motor stator.

[0014] Optionally, the preset filtering model is set according to the following calculation formula:

[0015]

[0016] Wherein, ΔT is the first temperature, t is the preset sampling period, n represents the current value, n-1 represents the previous value, τ is the time constant for the motor to fill its heat capacity, and T_offset is the temperature error.

[0017] Optionally, determining the first temperature and the motor stator impedance based on the rotational speed and phase current includes:

[0018] The corresponding first temperature and impedance are found in a preset correspondence table by using the rotational speed and the phase current. The preset correspondence table includes the correspondence between the rotational speed, the phase current and the first temperature, as well as the correspondence between the rotational speed, the phase current and the impedance.

[0019] Optionally, the method further includes:

[0020] Obtain the fault status of the temperature sensor;

[0021] Determining the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator includes: determining the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator when the temperature sensor is not faulty.

[0022] Optionally, the method further includes:

[0023] In the event of a malfunction of the temperature sensor, a third temperature is determined based on the first temperature and the temperature correction value, and the third temperature is used as the actual temperature of the motor stator.

[0024] This disclosure also provides a motor stator temperature measuring device, the device comprising:

[0025] The first acquisition module is used to acquire the rotor speed and phase current of the motor.

[0026] The determination module is used to determine the first temperature and the impedance of the motor stator based on the rotational speed and phase current, wherein the first temperature and the impedance of the motor stator are calibration values;

[0027] The first calculation module is used to calculate the temperature error caused by the heat loss of the motor stator as a temperature correction value based on the first temperature and the impedance of the motor stator.

[0028] The second calculation module is used to determine a second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator, and to use the second temperature as the actual temperature of the motor stator.

[0029] Optionally, the calibration value is determined by finite element simulation.

[0030] Optionally, the first computing module includes:

[0031] The first calculation submodule is used to determine the time constant for the full filling of the heat capacity of the motor based on the impedance of the motor stator.

[0032] The second calculation submodule is used to input the first temperature and the time constant into a preset filtering model to calculate the temperature error caused by the heat loss of the motor stator.

[0033] Optionally, the preset filtering model is set according to the following calculation formula:

[0034]

[0035] Wherein, ΔT is the first temperature, t is the preset sampling period, n represents the current value, n-1 represents the previous value, τ is the time constant for the motor to fill its heat capacity, and T_offset is the temperature error.

[0036] Optionally, the determining module is further configured to:

[0037] The corresponding first temperature and impedance are found in a preset correspondence table by using the rotational speed and the phase current. The preset correspondence table includes the correspondence between the rotational speed, the phase current and the first temperature, as well as the correspondence between the rotational speed, the phase current and the impedance.

[0038] Optionally, the device further includes:

[0039] The second acquisition module is used to acquire the fault status of the temperature sensor;

[0040] The second calculation module is further configured to include: determining the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator, provided that the temperature sensor is not malfunctioning.

[0041] Optionally, the device further includes:

[0042] The third calculation module is used to determine a third temperature based on the first temperature and the temperature correction value in the event of a malfunction of the temperature sensor, and to use the third temperature as the actual temperature of the motor stator.

[0043] This disclosure also provides a vehicle including the motor stator temperature measuring device described above.

[0044] The above technical solution can correct the measurement data obtained by the temperature sensor of the motor stator by measuring the motor speed and phase current, so that the actual temperature can more accurately reflect the temperature of the drive motor. This avoids the problem of inaccurate temperature measurement caused by the uneven cooling effect of the surrounding medium on the motor stator when the motor rotor speed is higher, and also avoids the problem that the temperature sensor cannot measure the accurate temperature of the motor stator due to its location.

[0045] Other features and advantages of this disclosure will be described in detail in the following detailed description section. Attached Figure Description

[0046] The accompanying drawings are provided to further illustrate the present disclosure and form part of the specification. They are used together with the following detailed description to explain the present disclosure, but do not constitute a limitation thereof. In the drawings:

[0047] Figure 1 This is a flowchart illustrating a method for measuring the temperature of a motor stator according to an exemplary embodiment of the present disclosure.

[0048] Figure 2 This is a flowchart illustrating a method for measuring the temperature of a motor stator according to yet another exemplary embodiment of this disclosure.

[0049] Figure 3 This is a schematic diagram of the logic operation structure of a filter module in a motor stator temperature measurement method according to an exemplary embodiment of the present disclosure.

[0050] Figure 4 This is a flowchart illustrating a method for measuring the temperature of a motor stator according to yet another exemplary embodiment of this disclosure.

[0051] Figure 5 This is a structural block diagram of a motor stator temperature measuring device according to an exemplary embodiment of the present disclosure.

[0052] Figure 6 This is a structural block diagram of a motor stator temperature measuring device according to yet another exemplary embodiment of the present disclosure.

[0053] Explanation of reference numerals in the attached figures

[0054] 1. Time constant for heat capacity to be filled 2. First temperature

[0055] 3. Preset sampling period 4. Temperature correction value

[0056] 5. Filtering Model Detailed Implementation

[0057] The specific embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustration and explanation only and are not intended to limit this disclosure.

[0058] Figure 1 This is a flowchart illustrating a method for measuring the stator temperature of an electric motor according to an exemplary embodiment of this disclosure. Figure 1 As shown, the method includes steps 101 to 104.

[0059] In step 101, the rotor speed and phase current of the motor are acquired. This speed and phase current can be obtained directly from the motor via appropriate sensors, or they can be acquired from the vehicle via a controller area network (CAN network).

[0060] In step 102, the first temperature and the impedance of the motor stator are determined based on the rotational speed and phase current, wherein the first temperature and the impedance of the motor stator are calibration values.

[0061] The calibration value can be determined by finite element simulation. This finite element simulation can be performed in advance, simulating various operating conditions and recording the simulated temperature and impedance of the motor stator under different motor speeds and phase currents.

[0062] The simulated temperature of the motor stator determined during the simulation can be the highest temperature value at each location within the motor stator. By using this highest simulated temperature, the actual temperature determined according to this embodiment can be as close as possible to the highest temperature within the entire motor stator, thereby avoiding more high-temperature failures.

[0063] In one possible implementation, the simulated temperature obtained from the finite element simulation can be directly used as the first temperature. In another possible implementation, the actual temperature of the motor stator under the same operating conditions as in the simulation can be measured using high-precision equipment, and the difference between the measured temperature and the simulated temperature obtained from the simulation can be used as the first temperature.

[0064] Since the impedance calculation formulas for different motors are different, the impedance of each motor under different operating conditions can be obtained in advance through simulation calculations, which can reduce the amount of calculation in the temperature measurement process, save computing resources, improve the measurement speed of motor stator temperature in this application to a certain extent, and reduce the hardware's computing power requirements, thus saving hardware costs.

[0065] In step 103, the temperature error caused by the heat loss of the motor stator is calculated using the first temperature and the impedance of the motor stator as a temperature correction value.

[0066] Since the first temperature is obtained through simulation, it corresponds to the current real temperature of the motor stator. Therefore, based on the first temperature and the impedance of the motor stator, a more accurate heat loss can be calculated, thus making the calculated temperature error more accurate.

[0067] There are several ways to calculate this temperature error. For example, the temperature rise caused by internal losses of components in the motor can be calculated directly based on the corresponding motor thermal equivalent circuit and the impedance of the motor stator. The specific calculation method is given below.

[0068] In step 104, a second temperature is determined based on the temperature correction value and the temperature sensor measurement data of the motor stator, and the second temperature is used as the actual temperature of the motor stator.

[0069] After determining the temperature correction value, the second temperature can be obtained by making corresponding corrections based on the temperature sensor measurement data. Specifically, the second temperature can be obtained by adding the temperature correction value to the temperature sensor measurement data.

[0070] The above technical solution can correct the measurement data obtained by the temperature sensor of the motor stator by measuring the motor speed and phase current, so that the actual temperature can more accurately reflect the temperature of the drive motor. This avoids the problem of inaccurate temperature measurement caused by the uneven cooling effect of the surrounding medium on the motor stator when the motor rotor speed is higher, and also avoids the problem that the temperature sensor cannot measure the accurate temperature of the motor stator due to its location.

[0071] Figure 2 This is a flowchart illustrating a method for measuring the stator temperature of an electric motor according to yet another exemplary embodiment of this disclosure. Figure 2 As shown, the method further includes steps 201 and 202.

[0072] In step 201, the time constant for the thermal capacity of the motor to be fully charged is determined based on the impedance of the motor stator. This time constant is calculated using the following formula:

[0073] τ=R×C,

[0074] Where τ is the time constant for the heat capacity to be fully filled. R is the impedance of the motor stator, and C is the capacitive reactance of the motor stator. C can be considered a constant value when the stator material of the motor remains unchanged, and can be calibrated in advance according to different motors.

[0075] In step 202, the first temperature and the time constant are input into a preset filtering model to calculate the temperature error caused by the heat loss of the motor stator as a temperature correction value.

[0076] The preset filtering model is set according to the following calculation formula:

[0077]

[0078] Wherein, ΔT is the first temperature, t is the preset sampling period, n represents the current value, n-1 represents the previous value, τ is the time constant for the motor to fill its heat capacity, and T_offset is the temperature error.

[0079] The derivation process of the above calculation formula (1) is shown below.

[0080] First, the formula for calculating the temperature error caused by the heat loss of the motor stator can be:

[0081] T_offset = P loss ×Z(t),

[0082]

[0083] Where Z is the thermal resistance, which includes thermal resistance and thermal capacity, and Ploss This refers to the power loss of components, including the power loss of resistors and the power loss of capacitors.

[0084] However, when calculating this temperature error using software, the calculation needs to start from the initial sampling time point. That is, if the first temperature determined based on the motor speed and phase current, and the stator impedance, change, the function... It is necessary to recalculate for each step size. Therefore, for each step time period, the calculation can be performed in segments, and the calculation process for each segment can be considered a filtering process. Therefore, the calculation formula based on the above preset filtering model is derived as follows:

[0085] P loss =P R +P C ,

[0086]

[0087] P C =C×ΔT,

[0088]

[0089]

[0090]

[0091] Among them, P R P is the power loss due to thermal resistance of the motor stator. C Let be the heat capacity loss power of the motor stator, and s be the complex variable in the Laplace transform formula.

[0092] Discretizing the above differential equation yields:

[0093] Simplified, we get:

[0094]

[0095] Furthermore, since there is no heat capacity loss in the stator of the vehicle motor, P C If the value is 0, substitute it into the simplified formula above, and combine it with the above formula to obtain the above formula (1).

[0096] In one possible implementation, the logical operations in the filtering model set according to the above formula can be as follows: Figure 3 The filtering model shown in Figure 5 is illustrated. In this model, the Z-logic operation... -1This indicates a delay of one cycle. The inputs to the filtering model 5 include the time constant 1 for the heat capacity to fill, the first temperature 2, and the preset sampling period 3 in the filtering module. The output during one sampling period is the temperature correction value 4. When one cycle ends and the next cycle begins, the output can be recalculated based on the above two inputs and the logic operation module Z. -1 The temperature correction value of 4 output from the previous cycle is used as the ΔT(n-1) to calculate the temperature correction value for the current cycle.

[0097] In one possible implementation, determining the first temperature and the motor stator impedance based on the rotational speed and phase current can be achieved by searching for the corresponding first temperature and impedance in a preset correspondence table using the rotational speed and phase current. This preset correspondence table includes both the correspondence between the rotational speed, phase current, and first temperature, and the correspondence between the rotational speed, phase current, and impedance. Furthermore, this preset correspondence table can include two tables: one corresponding to the first temperature and another corresponding to the impedance.

[0098] Figure 4 This is a flowchart illustrating a method for measuring the stator temperature of an electric motor according to yet another exemplary embodiment of this disclosure. Figure 4 As shown, the method further includes steps 401 to 403.

[0099] In step 401, the fault status of the temperature sensor is obtained.

[0100] In step 402, it is determined whether the temperature sensor is faulty based on the fault status of the temperature sensor. If yes, proceed to step 403; otherwise, proceed to step 104.

[0101] In step 403, i.e., when the temperature sensor of the motor stator malfunctions, a third temperature is determined based on the first temperature and the temperature correction value, and this third temperature is used as the actual temperature of the motor stator. The third temperature can be determined by adding the temperature correction value to the first temperature. Thus, when the temperature sensor of the motor stator malfunctions and the current reference temperature of the motor stator cannot be obtained, the first temperature obtained through simulation can be used as the reference temperature for temperature correction. This allows for accurate determination of the motor stator temperature even when the temperature sensor fails or the temperature data measured due to the malfunction differs significantly from the actual temperature, ensuring vehicle driving safety.

[0102] In step 104, if the temperature sensor of the motor stator is not faulty, the third temperature can be determined directly based on the first temperature and the temperature correction value, and the third temperature can be used as the actual temperature of the motor stator.

[0103] Figure 5 This is a structural block diagram of a motor stator temperature measuring device according to an exemplary embodiment of the present disclosure. Figure 5 As shown, the device includes: a first acquisition module 10, used to acquire the rotational speed of the motor rotor and the phase current of the motor; a determination module 20, used to determine a first temperature and the impedance of the motor stator based on the rotational speed and the phase current, wherein the first temperature and the impedance of the motor stator are calibration values; a first calculation module 30, used to calculate the temperature error caused by the heat loss of the motor stator as a temperature correction value based on the first temperature and the impedance of the motor stator; and a second calculation module 40, used to determine a second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator, and use the second temperature as the actual temperature of the motor stator.

[0104] The above technical solution can correct the measurement data obtained by the temperature sensor of the motor stator by measuring the motor speed and phase current, so that the actual temperature can more accurately reflect the temperature of the drive motor. This avoids the problem of inaccurate temperature measurement caused by the uneven cooling effect of the surrounding medium on the motor stator when the motor rotor speed is higher, and also avoids the problem that the temperature sensor cannot measure the accurate temperature of the motor stator due to its location.

[0105] In one possible implementation, the calibration value is determined by finite element simulation.

[0106] In one possible implementation, the first calculation module 30 includes: a first calculation submodule, configured to determine the time constant for filling the heat capacity of the motor based on the impedance of the motor stator; and a second calculation submodule, configured to input the first temperature and the time constant into a preset filtering model to calculate the temperature error caused by the heat loss of the motor stator.

[0107] In one possible implementation, the preset filtering model is set according to the following calculation formula:

[0108]

[0109] Wherein, ΔT is the first temperature, t is the preset sampling period, n represents the current value, n-1 represents the previous value, τ is the time constant for the motor to fill its heat capacity, and T_offset is the temperature error.

[0110] In one possible implementation, the determining module 20 is further configured to: look up the corresponding first temperature and the impedance in a preset correspondence table using the rotational speed and the phase current, wherein the preset correspondence table includes the correspondence between the rotational speed, the phase current and the first temperature, and also includes the correspondence between the rotational speed, the phase current and the impedance.

[0111] Figure 6 This is a structural block diagram of a motor stator temperature measuring device according to yet another exemplary embodiment of this disclosure. For example... Figure 5 As shown, the device further includes: a second acquisition module 50, used to acquire the fault status of the temperature sensor; the second calculation module 40 is also used to: determine the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator when the temperature sensor is not faulty.

[0112] In one possible implementation, such as Figure 6 As shown, the device further includes a third calculation module 60, which is used to determine a third temperature based on the first temperature and the temperature correction value when the temperature sensor malfunctions, and to use the third temperature as the actual temperature of the motor stator.

[0113] Regarding the apparatus in the above embodiments, the specific manner in which each module performs its operation has been described in detail in the embodiments related to the method, and will not be elaborated upon here.

[0114] This disclosure also provides a vehicle including the motor stator temperature measuring device described above.

[0115] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and all such simple modifications fall within the protection scope of this disclosure.

[0116] It should also be noted that the various specific technical features described in the above embodiments can be combined in any suitable manner without contradiction. To avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0117] Furthermore, various different embodiments of this disclosure can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content disclosed in this disclosure.

Claims

1. A method for measuring the temperature of a motor stator, characterized in that, The method includes: Obtain the rotor speed and phase current of the motor; The first temperature and the impedance of the motor stator are determined based on the rotational speed and phase current, wherein the first temperature and the impedance of the motor stator are calibration values; The temperature error caused by the heat loss of the motor stator is calculated using the first temperature and the impedance of the motor stator as the temperature correction value; The second temperature is determined based on the temperature correction value and the temperature sensor measurement data of the motor stator, and the second temperature is taken as the actual temperature of the motor stator; the step of using the temperature error caused by the heat loss of the motor stator calculated through the first temperature and the impedance of the motor stator as the temperature correction value includes: The time constant for the complete filling of the motor's heat capacity is determined based on the impedance of the motor stator. The first temperature and the time constant are input into a preset filtering model to calculate the temperature error caused by the heat loss of the motor stator; The step of determining the first temperature and the motor stator impedance based on the rotational speed and phase current includes: The corresponding first temperature and impedance are found in a preset correspondence table by using the rotational speed and the phase current. The preset correspondence table includes the correspondence between the rotational speed, the phase current and the first temperature, as well as the correspondence between the rotational speed, the phase current and the impedance.

2. The method according to claim 1, characterized in that, The calibration value is determined by finite element simulation.

3. The method according to claim 2, characterized in that, The preset filtering model is set according to the following calculation formula: ， in, The first temperature, For the preset sampling period, Indicates the current value. This represents the previous value. The time constant for the thermal capacity of the motor to be fully filled. The temperature error is mentioned above.

4. The method according to claim 1, characterized in that, The method further includes: Obtain the fault status of the temperature sensor; Determining the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator includes: determining the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator when the temperature sensor is not faulty.

5. The method according to claim 4, characterized in that, The method further includes: In the event of a malfunction of the temperature sensor, a third temperature is determined based on the first temperature and the temperature correction value, and the third temperature is used as the actual temperature of the motor stator.

6. A motor stator temperature measuring device, characterized in that, The device includes: The first acquisition module is used to acquire the rotor speed and phase current of the motor. The determination module is used to determine the first temperature and the impedance of the motor stator based on the rotational speed and phase current, wherein the first temperature and the impedance of the motor stator are calibration values; The first calculation module is used to calculate the temperature error caused by the heat loss of the motor stator as a temperature correction value based on the first temperature and the impedance of the motor stator. The second calculation module is used to determine the second temperature based on the temperature correction value and the temperature sensor measurement data of the motor stator, and to use the second temperature as the actual temperature of the motor stator. The first computing module includes: The first calculation submodule is used to determine the time constant for the full filling of the heat capacity of the motor based on the impedance of the motor stator. The second calculation submodule is used to input the first temperature and the time constant into a preset filtering model to calculate the temperature error caused by the heat loss of the motor stator; The determining module is further configured to: The corresponding first temperature and impedance are found in a preset correspondence table by using the rotational speed and the phase current. The preset correspondence table includes the correspondence between the rotational speed, the phase current and the first temperature, as well as the correspondence between the rotational speed, the phase current and the impedance.

7. The apparatus according to claim 6, characterized in that, The calibration value is determined by finite element simulation.

8. A vehicle, characterized in that, Includes the motor stator temperature measuring device as described in any one of claims 6-7.

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