Motor thermal model acquisition method, device and equipment
By obtaining test data and operating parameters from the motors of new energy vehicles and adjusting the parameters to be identified in the motor thermal model, the problem of lack of parameters in the establishment of the motor thermal model is solved, and accurate estimation and protection of stator and rotor temperatures are achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- SAIC MOTOR
- Filing Date
- 2024-10-31
- Publication Date
- 2026-05-01
AI Technical Summary
In existing technologies, the establishment of thermal models for new energy vehicle motors depends on the structural parameters of the motor itself, which are often difficult to obtain completely, leading to inaccurate stator and rotor temperature estimations and affecting the protection effect of the control system.
By acquiring test data and operating parameters of the motor under different operating conditions, the parameters are adjusted using the motor thermal model until the error between the test data and the estimated data meets the preset conditions, and the values of the parameters to be identified are determined in order to establish an accurate motor thermal model.
It enables accurate estimation of stator and rotor temperatures under offline conditions, ensuring effective protection of the motor and avoiding measurement errors caused by sensor aging or improper installation.
Smart Images
Figure CN121966404A_ABST
Abstract
Description
A method, apparatus and equipment for obtaining a thermal model of an electric motor Technical Field
[0001] This application relates to the field of new energy vehicle technology, specifically to a method, apparatus, and equipment for obtaining a thermal model of an electric motor. Background Technology
[0002] Most current new energy vehicles use permanent magnet synchronous motors as their drive components, which mainly consist of a stator and a rotor. Temperature sensors are typically embedded in the stator windings to provide real-time feedback of the winding temperature to the controller for protection. However, these sensors can age, or experience power supply or installation malfunctions, leading to abnormal measurement data and potentially causing false protection activation by the control system. The operating temperature of the rotor's permanent magnets also needs to be controlled within a certain range, but due to the high speed of the rotor, installing temperature sensors is extremely difficult and costly.
[0003] Currently, software estimation methods are commonly used to obtain the stator and rotor temperatures. These stator and rotor temperature estimation algorithms are typically based on motor thermal models, and the calculations of capacitance, resistance, and heat loss in these models rely heavily on the motor's structural parameters. However, software developers cannot obtain all motor structural parameters, which affects the establishment of the motor thermal model. Summary of the Invention
[0004] In view of this, this application provides a method, apparatus and equipment for obtaining a motor thermal model, so as to obtain a motor thermal model and provide a basis for estimating the stator and rotor temperatures.
[0005] To solve the above problems, the technical solution provided in this application is as follows:
[0006] In a first aspect of this application, a method for obtaining a thermal model of an electric motor is provided, the method comprising:
[0007] Acquire test data of the motor under different operating conditions, including stator temperature and rotor temperature;
[0008] Obtain the motor's operating parameters under the target operating conditions, including speed, torque, water temperature, and motor efficiency;
[0009] The initial values of the operating parameters and the parameters to be identified are input into the motor thermal model to obtain estimated data. The estimated data includes the estimated stator temperature and the estimated rotor temperature. The motor thermal model includes the parameters to be identified.
[0010] The test data corresponding to the target working condition is compared with the estimated data. The value of the parameter to be identified is adjusted according to the comparison result until the error between the test data and the estimated data meets the preset condition, and the value of the parameter to be identified is obtained.
[0011] In one possible implementation, adjusting the data of the parameter to be identified based on the comparison result until the error between the test data and the estimated data meets a preset condition to obtain the value of the parameter to be identified includes:
[0012] Based on the prediction error minimization algorithm, the value of the parameter to be identified is adjusted according to the comparison results until the error between the test data and the estimated data is minimized, thereby obtaining the value of the parameter to be identified.
[0013] In one possible implementation, the parameters to be identified include thermal resistance, thermal capacity, and loss ratio, wherein the loss ratio refers to the ratio of rotor iron loss to sub-iron loss.
[0014] In one possible implementation, the step of inputting the initial values of the operating parameters and the parameters to be identified into the motor thermal model to obtain estimation data includes:
[0015] The total motor loss is determined based on the speed, torque, and motor efficiency in the operating parameters.
[0016] Calculate the stator winding losses based on the motor's current;
[0017] The stator iron loss and the rotor iron loss are obtained by multiplying the difference between the total motor loss and the stator winding loss by the loss ratio.
[0018] The initial values of thermal resistance, thermal capacity, stator iron loss, and rotor iron loss are input into the motor thermal model to obtain estimated data.
[0019] In one possible implementation, acquiring test data of the motor under different operating conditions includes:
[0020] The stator temperature is obtained based on the stator temperature sensor;
[0021] The rotor temperature is determined based on the back electromotive force generated by the rotor under the stated operating conditions.
[0022] In one possible implementation, the number of nodes in the motor thermal model is determined by the motor's body structure, and the nodes include auxiliary stator nodes, stator nodes, stator iron nodes, auxiliary rotor nodes, rotor nodes, and water temperature nodes.
[0023] In one possible implementation, a first thermal resistance is provided between the auxiliary stator node and the stator node; a second thermal resistance is provided between the stator node and the stator iron node; a third thermal resistance is provided between the stator iron node and the rotor node; a fourth thermal resistance is provided between the rotor node and the auxiliary rotor node; a first thermal capacity is provided between the auxiliary stator node and the water temperature node; a fifth thermal resistance and a second thermal capacity are provided between the stator node and the water temperature node; a sixth thermal resistance and a third thermal capacity are provided between the stator iron node and the water temperature node; a fourth thermal capacity is provided between the rotor node and the water temperature node; a fifth thermal capacity is provided between the auxiliary rotor node and the water temperature node; and the water temperature node is grounded.
[0024] In one possible implementation, the stator winding losses are equivalent to a first current source connected to the auxiliary stator nodes, the temperature of each node is equivalent to an electric potential, the stator iron losses are equivalent to a second current source connected to the stator iron nodes, and the rotor iron losses are equivalent to a third current source connected to the auxiliary rotor nodes.
[0025] In a second aspect of this application, a device for obtaining a thermal model of an electric motor is provided, the device comprising:
[0026] The first acquisition unit is used to acquire test data of the motor under different operating conditions, including stator temperature and rotor temperature.
[0027] The second acquisition unit is used to acquire the operating parameters of the motor under the target operating conditions, including speed, torque, water temperature and motor efficiency.
[0028] The third acquisition unit is used to input the initial values of the operating parameters and the parameters to be identified into the motor thermal model to obtain estimated data. The estimated data includes the stator estimated temperature and the rotor estimated temperature. The motor thermal model includes the parameters to be identified.
[0029] The fourth acquisition unit is used to compare the test data corresponding to the target working condition with the estimated data, adjust the value of the parameter to be identified according to the comparison result, until the error between the test data and the estimated data meets the preset condition, and obtain the value of the parameter to be identified.
[0030] In one possible implementation, the fourth acquisition unit is used to adjust the value of the parameter to be identified based on the comparison result according to the prediction error minimization algorithm until the error between the test data and the estimated data is minimized, thereby obtaining the value of the parameter to be identified.
[0031] In one possible implementation, the parameters to be identified include thermal resistance, thermal capacity, and loss ratio, wherein the loss ratio refers to the ratio of rotor iron loss to sub-iron loss.
[0032] In one possible implementation, the third acquisition unit is used to determine the total motor loss based on the operating parameters, such as the speed, torque, and motor efficiency; calculate the stator winding loss based on the motor current; multiply the difference between the total motor loss and the stator winding loss by the loss ratio to obtain the stator iron loss and the rotor iron loss; and input the initial values of the thermal resistance, thermal capacity, stator iron loss, and rotor iron loss into the motor thermal model to obtain estimated data.
[0033] In one possible implementation, the first acquisition unit is specifically used to acquire the stator temperature based on a stator temperature sensor; and to determine the rotor temperature based on the back electromotive force generated by the rotor under the operating condition.
[0034] In one possible implementation, the number of nodes in the motor thermal model is determined by the motor's body structure, and the nodes include auxiliary stator nodes, stator nodes, stator iron nodes, auxiliary rotor nodes, rotor nodes, and water temperature nodes.
[0035] In one possible implementation, a first thermal resistance is provided between the auxiliary stator node and the stator node; a second thermal resistance is provided between the stator node and the stator iron node; a third thermal resistance is provided between the stator iron node and the rotor node; a fourth thermal resistance is provided between the rotor node and the auxiliary rotor node; a first thermal capacity is provided between the auxiliary stator node and the water temperature node; a fifth thermal resistance and a second thermal capacity are provided between the stator node and the water temperature node; a sixth thermal resistance and a third thermal capacity are provided between the stator iron node and the water temperature node; a fourth thermal capacity is provided between the rotor node and the water temperature node; a fifth thermal capacity is provided between the auxiliary rotor node and the water temperature node; and the water temperature node is grounded.
[0036] In one possible implementation, the stator winding losses are equivalent to a first current source connected to the auxiliary stator nodes, the temperature of each node is equivalent to an electric potential, the stator iron losses are equivalent to a second current source connected to the stator iron nodes, and the rotor iron losses are equivalent to a third current source connected to the auxiliary rotor nodes.
[0037] In a third aspect of this application, an electronic device is provided, comprising: a processor and a memory;
[0038] The memory is used to store computer-readable instructions or computer programs;
[0039] The processor is configured to read the computer-readable instructions or the computer program to enable the electronic device to implement the motor thermal model acquisition method as described in the first aspect.
[0040] Therefore, this application has the following beneficial effects:
[0041] This application first acquires test data of the motor under different operating conditions in offline mode, including stator and rotor temperatures. For a specific operating condition, the corresponding operating parameters of the motor are acquired, such as motor speed, motor torque, water temperature, and motor efficiency. The initial values of these operating parameters and the parameters to be identified are input into a motor thermal model to obtain estimated data, including estimated stator and rotor temperatures. The test data and estimated data under the same operating condition are compared to obtain a comparison result. Based on this comparison result, the values of the parameters to be identified are adjusted until the error between the test data and the estimated data meets a preset condition. The values of the parameters to be identified are then obtained, and the motor thermal model is determined. This model is then used to predict stator and rotor temperatures, thereby providing protection for the stator and rotor. Attached Figure Description
[0042] Figure 1 is a schematic flowchart of a method for obtaining a motor thermal model according to an embodiment of this application;
[0043] Figure 2 is an equivalent circuit diagram of a motor thermal model provided in an embodiment of this application;
[0044] Figure 3 shows a state equation based on a motor thermal model provided in an embodiment of this application;
[0045] Figure 4 is a framework diagram for obtaining parameters to be identified provided in an embodiment of this application;
[0046] Figure 5 is a comparison diagram of test data and estimated data provided in an embodiment of this application;
[0047] Figure 6 is a structural diagram of a motor thermal model acquisition device provided in an embodiment of this application. Detailed Implementation
[0048] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, the embodiments of this application will be further described in detail below with reference to the accompanying drawings and specific implementation methods.
[0049] In practical applications, to obtain stator and rotor temperatures in a timely manner, software is typically used to estimate these temperatures. However, stator and rotor temperature estimation algorithms are usually based on motor thermal models, but the calculation of the parameters to be identified in the motor thermal model (such as capacitance, resistance, and heat loss) is inseparable from the structural parameters of the motor itself. In reality, not all motor structural parameters are available. Motors are often treated as black boxes, and their performance can only be analyzed through input and output measurement data. Furthermore, even if all motor design parameters are known, the resulting motor thermal model may not perfectly match the actual test data, and its inherent deviations need to be corrected based on actual data.
[0050] Based on this, this application provides a method for obtaining a motor thermal model. Under test conditions, test data corresponding to different operating conditions of the motor are acquired, including stator and rotor temperatures. Then, the initial values of the motor's operating parameters under the target conditions and the parameters to be identified are input into the motor thermal model to obtain the stator and rotor temperatures predicted by the model. The errors between the predicted stator and rotor temperatures and those in the test data are compared, and the values of the parameters to be identified in the motor thermal model are adjusted according to the comparison results until the errors meet preset conditions, thereby obtaining the final values of the parameters to be identified and thus obtaining the motor thermal model. This allows for the estimation of stator and rotor temperatures in practical applications, enabling protection of the stator and rotor.
[0051] For ease of understanding, the technical solution of this application will be described below with reference to the accompanying drawings.
[0052] Referring to Figure 1, which is a flowchart of a method for obtaining a motor thermal model provided in this application, the method includes:
[0053] S101: Obtain test data for the motor under different operating conditions.
[0054] In this embodiment, to determine the values of the parameters to be identified in the motor thermal model, the stator and rotor temperatures corresponding to the actual operation of the motor will first be obtained. That is, test data corresponding to the motor under different operating conditions will be obtained, including stator and rotor temperatures. Specifically, under a fixed voltage, the stator and rotor temperatures of the motor can be tested at different speeds and torques with a fixed step size.
[0055] Under the test conditions, the stator temperature can be obtained using a stator temperature sensor, and the rotor temperature can be obtained using a rotor temperature sensor. If a rotor temperature sensor is unavailable, the back electromotive force (EMF) generated by the rotor at zero torque can be measured at fixed time steps (e.g., 1 minute), and the rotor temperature can then be determined based on this back EMF value. In specific testing, when the torque is below the rated capacity, the motor needs to run for 40 minutes to allow the stator temperature to stabilize; when the torque is above the rated capacity, the running time of the motor under this condition decreases as the torque and speed increase, in order to reach the maximum safe temperature that the motor's stator and rotor can withstand.
[0056] When acquiring test data, it is also necessary to obtain the corresponding test conditions, such as speed and torque. Specifically, during the test, data such as speed, torque, stator temperature, rotor temperature, motor efficiency, input DC current, input voltage, and cooling water temperature will be recorded.
[0057] S102: Obtain the operating parameters of the motor under the target operating conditions, including speed, torque, water temperature and motor efficiency.
[0058] S103: Input the initial values of the operating parameters and the parameters to be identified into the motor thermal model to obtain estimated data.
[0059] The target operating condition is a specific operating condition under which the motor operates during the test. The operating parameters of the motor under the target operating condition are obtained, such as speed, torque, water temperature (cooling water temperature), and motor efficiency. These operating parameters, along with the initial values of the parameters to be identified, are input into the motor thermal model to obtain temperature estimates for the stator and rotor, i.e., estimated data.
[0060] To facilitate understanding, the motor thermal model will be explained below. In this embodiment, the number of nodes included in the motor thermal model is determined by the motor's body structure. Specifically, the nodes in the motor thermal model may include auxiliary stator node x1, stator node x2, stator iron node x3, auxiliary rotor node x4, rotor node x5, and water temperature node T. water Please refer to Figure 2 for the equivalent circuit diagram of the motor thermal model. Specifically, a first thermal resistance R6 is provided between auxiliary stator node x1 and stator node x2; a second thermal resistance R4 is provided between stator node x2 and stator iron node x3; a third thermal resistance R5 is provided between stator iron node x3 and rotor node x5; a fourth thermal resistance R7 is provided between rotor node x5 and auxiliary rotor node x4; and a fourth thermal resistance R7 is provided between auxiliary stator node x1 and water temperature node T. water A first heat capacity C is provided between them. NTCT Stator node x2 and water temperature node T water A fifth thermal resistance R1 and a second thermal capacity C are provided between them. NTC Stator iron node x3 and water temperature node T water A sixth thermal resistance R2 and a third thermal capacity C are provided between them. sta Rotor node x5 and water temperature node T water A fourth heat capacity C is provided between them. rotT The fifth heat capacity C of the equipment between auxiliary rotor node x4 and water temperature node x6 rot Water temperature node T water Grounding.
[0061] In this method, the stator winding loss is equivalent to the first current source Pwinding connected to the auxiliary stator node, the temperature of each node is equivalent to the potential, the stator iron loss is equivalent to the second current source Psta connected to the stator iron node x3, and the rotor iron loss is equivalent to the third current source Prot connected to the auxiliary rotor node x4.
[0062] The state equations for the motor thermal model based on the nodal method are shown in Figure 3. G1, G2, G3, G4, G5, G6, and G7 are the reciprocals of R1, R2, R3, R4, R5, R6, and R7, respectively. These state equations describe the relationship between the temperature of each node and its thermal resistance, heat capacity, heat loss, and water temperature. Given the thermal resistance, heat capacity, heat loss, and water temperature under different operating conditions, the temperature of each node can be calculated.
[0063] For electric motors, water temperature is a known quantity, acquired through sensors; thermal resistance, thermal capacity, and heat loss are parameters to be identified. Typically, heat loss is not directly used as the parameter to be identified. Instead, the total motor loss is calculated from the speed and torque, and the stator winding loss is calculated from the input current. Subtracting the stator winding loss from the total motor loss yields the sum of stator iron loss and rotor iron loss. The ratio of these two losses is then used as the parameter to be identified. In other words, the parameters to be identified include thermal resistance, thermal capacity, and the loss ratio, which refers to the ratio of stator iron loss to rotor iron loss.
[0064] Specifically, the total motor loss is determined based on the operating parameters such as speed, torque, and motor efficiency; the stator winding loss is calculated based on the motor current; the difference between the total motor loss and the stator winding loss is multiplied by the loss ratio to obtain the stator iron loss and the rotor iron loss; the initial values of thermal resistance, thermal capacity, stator iron loss, and rotor iron loss are input into the motor thermal model to obtain estimated data.
[0065] It should be noted that when determining the value of the parameter to be identified, the input voltage value will be collected. The purpose of collecting the input voltage is to determine the voltage level at which the operation is performed, because the value of the parameter to be identified will be different under different voltage levels.
[0066] S104: Compare the test data and estimated data corresponding to the target working condition, and adjust the value of the parameter to be identified according to the comparison result until the error between the test data and the estimated data meets the preset condition, and obtain the value of the parameter to be identified.
[0067] After obtaining estimated data through the motor thermal model, the test data under the same operating conditions is compared with the estimated data to obtain the comparison result (the error between the test data and the estimated data). If the comparison result meets the preset conditions, the value of the parameter to be identified under the current condition is determined as the final value; if the comparison result does not meet the preset conditions, the value of the parameter to be identified is adjusted according to the comparison result until the error between the test data and the estimated data meets the preset conditions. The value of the parameter to be identified when the preset conditions are met is determined as the final value, thus obtaining the motor thermal model. Specifically, based on the prediction error minimization algorithm, the data of the parameter to be identified is adjusted according to the comparison result until the error between the test data and the estimated data is minimized, thus obtaining the value of the parameter to be identified.
[0068] In practical implementation, the range and initial values of the parameters to be identified can be given based on experience. Under these conditions, combined with a set of test data and estimated data from the motor thermal model, the values of the parameters to be identified that meet the conditions for each operating condition are determined. After each iteration, the values of the parameters to be identified are obtained and substituted into the motor thermal model to calculate the stator node temperature x2 and rotor node temperature x5 under the corresponding operating condition as predicted values. The termination condition is that the error between the predicted value and the test data is less than a preset threshold. If the error of a single prediction cannot meet the requirements, the values of the parameters to be identified are adjusted within the range until the accuracy requirements are met.
[0069] As can be seen, to determine the motor thermal model, the first step is to acquire offline test data of the motor under different operating conditions, including stator and rotor temperatures. For a specific operating condition, the corresponding operating parameters of the motor are acquired, such as motor speed, motor torque, water temperature, and motor efficiency. These operating parameters, along with the initial values of the parameters to be identified, are input into the motor thermal model to obtain estimated data, including estimated stator and rotor temperatures. The test data and estimated data under the same operating condition are compared to obtain the comparison results. Based on these results, the values of the parameters to be identified are adjusted until the error between the test data and the estimated data meets a preset condition. This process yields the values of the parameters to be identified, thus determining the motor thermal model. This model can then be used to predict stator and rotor temperatures, thereby providing protection for the stator and rotor.
[0070] For ease of understanding, refer to the framework diagram shown in Figure 4. In the first iteration, the initial values of the operating parameters and the parameters to be identified under a certain working condition are obtained. These initial values are then input into the motor thermal model to obtain a set of estimated data. Test data under the same working condition is obtained and compared with the estimated data. The comparison result is then determined to meet the preset conditions. If not, the values of the parameters to be identified are adjusted and input into the motor thermal model again for comparison, until the preset conditions are met. Finally, the values of the parameters to be identified are output.
[0071] Referring to Figure 5, which shows the identification results under a certain working condition, when the error between the fitted temperature value and the measured value is less than the preset threshold, the value of the parameter to be identified corresponding to this condition is taken as the final value of the parameter to be identified.
[0072] Based on the above method embodiments, this application also provides a device for obtaining a motor thermal model, which will be described below with reference to the accompanying drawings.
[0073] Referring to Figure 6, which is a structural diagram of a motor thermal model acquisition device provided in an embodiment of this application, as shown in Figure 6, the device 600 includes:
[0074] The first acquisition unit 601 is used to acquire test data of the motor under different operating conditions, the test data including stator temperature and rotor temperature;
[0075] The second acquisition unit 602 is used to acquire the operating parameters of the motor under the target operating conditions, including speed, torque, water temperature and motor efficiency.
[0076] The third acquisition unit 603 is used to input the initial values of the operating parameters and the parameters to be identified into the motor thermal model to obtain estimated data. The estimated data includes the stator estimated temperature and the rotor estimated temperature. The motor thermal model includes the parameters to be identified.
[0077] The fourth acquisition unit 604 is used to compare the test data corresponding to the target working condition with the estimated data, adjust the value of the parameter to be identified according to the comparison result, until the error between the test data and the estimated data meets the preset condition, and obtain the value of the parameter to be identified.
[0078] In one possible implementation, the fourth acquisition unit 604 is used to adjust the value of the parameter to be identified based on the comparison result according to the prediction error minimization algorithm until the error between the test data and the estimated data is minimized, thereby obtaining the value of the parameter to be identified.
[0079] In one possible implementation, the parameters to be identified include thermal resistance, thermal capacity, and loss ratio, wherein the loss ratio refers to the ratio of rotor iron loss to sub-iron loss.
[0080] In one possible implementation, the third acquisition unit 603 is used to determine the total motor loss based on the operating parameters, such as the speed, torque, and motor efficiency; calculate the stator winding loss based on the motor current; multiply the difference between the total motor loss and the stator winding loss by the loss ratio to obtain the stator iron loss and the rotor iron loss; and input the initial values of the thermal resistance, thermal capacity, stator iron loss, and rotor iron loss into the motor thermal model to obtain estimated data.
[0081] In one possible implementation, the first acquisition unit 601 is specifically used to acquire the stator temperature based on the stator temperature sensor; and to determine the rotor temperature based on the back electromotive force value generated by the rotor under the operating condition.
[0082] In one possible implementation, the number of nodes in the motor thermal model is determined by the motor's body structure, and the nodes include auxiliary stator nodes, stator nodes, stator iron nodes, auxiliary rotor nodes, rotor nodes, and water temperature nodes.
[0083] In one possible implementation, a first thermal resistance is provided between the auxiliary stator node and the stator node; a second thermal resistance is provided between the stator node and the stator iron node; a third thermal resistance is provided between the stator iron node and the rotor node; a fourth thermal resistance is provided between the rotor node and the auxiliary rotor node; a first thermal capacity is provided between the auxiliary stator node and the water temperature node; a fifth thermal resistance and a second thermal capacity are provided between the stator node and the water temperature node; a sixth thermal resistance and a third thermal capacity are provided between the stator iron node and the water temperature node; a fourth thermal capacity is provided between the rotor node and the water temperature node; a fifth thermal capacity is provided between the auxiliary rotor node and the water temperature node; and the water temperature node is grounded.
[0084] In one possible implementation, the stator winding losses are equivalent to a first current source connected to the auxiliary stator nodes, the temperature of each node is equivalent to an electric potential, the stator iron losses are equivalent to a second current source connected to the stator iron nodes, and the rotor iron losses are equivalent to a third current source connected to the auxiliary rotor nodes.
[0085] It should be noted that the specific implementation of each unit in this embodiment can be found in the relevant descriptions in the above method embodiments, and will not be repeated here.
[0086] Additionally, embodiments of this application provide an electronic device, including: a processor and a memory;
[0087] The memory is used to store computer-readable instructions or computer programs;
[0088] The processor is configured to read the computer-readable instructions or the computer program so that the device implements the motor thermal model acquisition method.
[0089] This application provides a computer-readable storage medium, including instructions or a computer program, which, when run on a computer, causes the computer to execute the above-described method for obtaining a motor thermal model.
[0090] It should be noted that the various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the systems or apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the descriptions are relatively simple, and relevant parts can be referred to the method section.
[0091] It should be understood that in this application, "at least one (item)" means one or more, and "more than" means two or more. "And / or" is used to describe the relationship between related objects, indicating that three relationships can exist. For example, "A and / or B" can represent three cases: only A exists, only B exists, and both A and B exist simultaneously, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects are in an "or" relationship. "At least one (item) of the following" or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one (item) of a, b, or c can represent: a, b, c, "a and b", "a and c", "b and c", or "a and b and c", where a, b, and c can be single or multiple.
[0092] It should also be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0093] The steps of the methods or algorithms described in conjunction with the embodiments disclosed herein can be implemented directly by hardware, a software module executed by a processor, or a combination of both. The software module can be located in random access memory (RAM), main memory, read-only memory (ROM), electrically programmable ROM, electrically erasable programmable ROM, registers, hard disk, removable disk, CD-ROM, or any other form of storage medium known in the art.
[0094] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.
Claims
1. A method for obtaining a thermal model of an electric motor, characterized in that, The method includes: acquiring test data of the motor under different operating conditions, the test data including stator temperature and rotor temperature; acquiring operating parameters of the motor under a target operating condition, the operating parameters including speed, torque, water temperature, and motor efficiency; inputting the operating parameters and the initial values of the parameter to be identified into a motor thermal model to obtain estimated data, the estimated data including stator estimated temperature and rotor estimated temperature, the motor thermal model including the parameter to be identified; comparing the test data corresponding to the target operating condition with the estimated data, adjusting the value of the parameter to be identified according to the comparison result until the error between the test data and the estimated data meets a preset condition, and obtaining the value of the parameter to be identified.
2. The method according to claim 1, characterized in that, The step of adjusting the data of the parameter to be identified based on the comparison results until the error between the test data and the estimated data meets the preset condition to obtain the value of the parameter to be identified includes: adjusting the value of the parameter to be identified based on the comparison results using a prediction error minimization algorithm until the error between the test data and the estimated data is minimized to obtain the value of the parameter to be identified.
3. The method according to claim 1, characterized in that, The parameters to be identified include thermal resistance, thermal capacity, and loss ratio, wherein the loss ratio refers to the ratio of rotor iron loss to sub-rotor iron loss.
4. The method according to claim 3, characterized in that, The step of inputting the initial values of the operating parameters and the parameters to be identified into the motor thermal model to obtain estimated data includes: determining the total motor loss based on the speed, torque and motor efficiency in the operating parameters; calculating the stator winding loss based on the motor current; multiplying the difference between the total motor loss and the stator winding loss by the loss ratio to obtain the stator iron loss and the rotor iron loss; and inputting the initial values of the thermal resistance, thermal capacity, stator iron loss and rotor iron loss into the motor thermal model to obtain estimated data.
5. The method according to claim 1, characterized in that, The acquisition of test data corresponding to the motor under different operating conditions includes: acquiring the stator temperature based on the stator temperature sensor; and determining the rotor temperature based on the back electromotive force value generated by the rotor under the operating conditions.
6. The method according to claim 1, characterized in that, The number of nodes in the motor thermal model is determined by the motor's body structure. The nodes include auxiliary stator nodes, stator nodes, stator iron nodes, auxiliary rotor nodes, rotor nodes, and water temperature nodes.
7. The method according to claim 6, characterized in that, A first thermal resistance is provided between the auxiliary stator node and the stator node; a second thermal resistance is provided between the stator node and the stator iron node; a third thermal resistance is provided between the stator iron node and the rotor node; a fourth thermal resistance is provided between the rotor node and the auxiliary rotor node; a first thermal capacity is provided between the auxiliary stator node and the water temperature node; a fifth thermal resistance and a second thermal capacity are provided between the stator node and the water temperature node; a sixth thermal resistance and a third thermal capacity are provided between the stator iron node and the water temperature node; a fourth thermal capacity is provided between the rotor node and the water temperature node; a fifth thermal capacity is provided between the auxiliary rotor node and the water temperature node; and the water temperature node is grounded.
8. The method according to claim 6 or 7, characterized in that, The stator winding losses are equivalent to a first current source connected to the auxiliary stator nodes, the temperature of each node is equivalent to an electric potential, the stator iron losses are equivalent to a second current source connected to the stator iron nodes, and the rotor iron losses are equivalent to a third current source connected to the auxiliary rotor nodes.
9. A device for acquiring a thermal model of an electric motor, characterized in that, The device includes: a first acquisition unit for acquiring test data of the motor under different operating conditions, the test data including stator temperature and rotor temperature; a second acquisition unit for acquiring operating parameters of the motor under a target operating condition, the operating parameters including speed, torque, water temperature, and motor efficiency; a third acquisition unit for inputting the operating parameters and the initial values of the parameter to be identified into a motor thermal model to obtain estimated data, the estimated data including stator estimated temperature and rotor estimated temperature, the motor thermal model including the parameter to be identified; and a fourth acquisition unit for comparing the test data corresponding to the target operating condition with the estimated data, adjusting the value of the parameter to be identified according to the comparison result until the error between the test data and the estimated data meets a preset condition, thereby obtaining the value of the parameter to be identified.
10. An electronic device, characterized in that, Includes: processor, memory; The memory is used to store computer-readable instructions or computer programs; the processor is used to read the computer-readable instructions or computer programs so that the electronic device implements the motor thermal model acquisition method as described in any one of claims 1-8.