Temperature prediction method of bus capacitor and related equipment
By using the motor controller to query the calibration table and gray box model to predict the bus capacitor temperature, the problem of inaccurate temperature prediction under complex operating conditions with multiple motors is solved, the difficulty of parameter acquisition and hardware cost are reduced, and accurate prediction of bus capacitor temperature is achieved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-30
- Publication Date
- 2026-03-31
AI Technical Summary
Traditional bus capacitor temperature prediction methods are not accurate enough under complex operating conditions with multiple motors, and require accurate acquisition of multiple difficult-to-measure physical parameters, which reduces the feasibility of the method and increases hardware costs.
By querying the calibration table obtained from the pre-experiment by the motor controller, the thermal characteristic parameters of the bus capacitor are obtained based on the operating status of multiple motors. The temperature is predicted using the gray box model, which reduces the dependence on parameters that are difficult to measure and reduces the amount of hardware equipment.
It enables accurate prediction of bus capacitor temperature under multi-motor operation conditions, reduces the difficulty of parameter acquisition and hardware cost, and improves the feasibility and real-time detection capability of the method.
Smart Images
Figure CN121763082A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of motor control, and in particular to a method for predicting the temperature of a bus capacitor, a device for predicting the temperature of a bus capacitor, a controller, and a computer-readable storage medium. Background Technology
[0002] With the development of automotive and energy technologies, consumers are increasingly favoring the purchase of new energy vehicles. New energy vehicles refer to vehicles that use unconventional fuels as their power source, including battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and hybrid electric vehicles (HEVs). New energy vehicles can reduce dependence on fossil fuels such as petroleum and lower the pollution caused by vehicle emissions.
[0003] The electric motor is a core drive component of new energy vehicles, especially multi-motor drive systems, which can improve power performance and efficiency. The performance of the motor's bus capacitor directly affects the motor's operational stability and efficiency. Because multi-motor drive systems draw large currents during operation, the bus capacitor may overheat, affecting its lifespan, potentially causing motor instability, and even safety issues. Therefore, it is necessary to predict the capacitor temperature and achieve real-time monitoring.
[0004] However, traditional methods for predicting the temperature of bus capacitors are not accurate enough under complex operating conditions with multiple motors running. Summary of the Invention
[0005] In view of this, this application provides a method and related equipment for predicting the temperature of bus capacitors, in order to solve the problem that traditional methods for predicting the temperature of bus capacitors are not accurate enough under complex operating conditions with multiple motors.
[0006] In a first aspect, this application provides a method for predicting the temperature of a bus capacitor, applied to a motor controller of a multi-motor driven vehicle, the method comprising:
[0007] The motor controller acquires the operating status of the first and second motors, including at least one of speed or torque. Then, based on the operating status of the first motor, the motor controller queries a first calibration table to obtain the first thermal characteristic parameter of the motor controller's bus capacitor under the current operating condition. The first calibration table includes a mapping relationship between the operating status of the first motor operating alone and its thermal characteristic parameters, determined based on multiple sets of experimental conditions. The thermal characteristic parameters include at least one of heat capacity, thermal resistance, or loss coefficient. The motor controller can also query a second calibration table based on the operating status of the second motor to obtain the second thermal characteristic parameter of the motor controller's bus capacitor under the current operating condition. The second calibration table includes a mapping relationship between the operating status of the second motor operating alone and its thermal characteristic parameters, determined based on multiple sets of experimental conditions. Next, the motor controller inputs the first and second thermal characteristic parameters of the bus capacitor under the current operating condition, along with the temperature of the bus capacitor in the previous operating cycle, into a temperature prediction model to obtain the first and second temperature changes of the bus capacitor in the current operating cycle. Finally, the motor controller predicts the temperature of the bus capacitor in the current operating cycle based on the first and second temperature changes.
[0008] In some possible implementations, the first calibration table can be obtained as follows: the motor controller acquires electrical and temperature parameters under multiple experimental conditions, including multiple operating states under which the first motor operates alone. Then, the motor controller identifies the first thermal characteristic parameters of the bus capacitor based on the electrical and temperature parameters to obtain the first calibration table.
[0009] In some possible implementations, the parameter identification of the first thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters can be performed as follows: The motor controller obtains the first loss coefficient of the bus capacitor under the first operating condition based on the electrical parameters and the speed of the first motor. Then, the motor controller obtains the first thermal capacitance and first thermal resistance of the bus capacitor under the first operating condition based on the first loss coefficient and temperature parameters.
[0010] Specifically, the motor controller can identify the first thermal capacity and first thermal resistance of the bus capacitor under the first operating condition based on the first loss coefficient and temperature parameters using an optimization algorithm. Specifically, the motor controller determines the theoretical temperature, predicted thermal capacity, and predicted thermal resistance of the bus capacitor under the first operating condition based on the first loss coefficient and temperature parameters. When the error between the theoretical temperature and the actual temperature of the bus capacitor is less than a threshold, the motor controller obtains the first thermal capacity and first thermal resistance of the bus capacitor under the first operating condition based on the predicted thermal capacity and predicted thermal resistance values.
[0011] In some possible implementations, the electrical parameters of the motor controller include at least one of the following: bus voltage and current, motor controller direct-axis voltage and current, motor controller quadrature-axis voltage and current, and motor controller line voltage amplitude. The temperature parameters of the motor controller include at least one of the following: bus capacitor core temperature, upper copper busbar temperature, lower copper busbar temperature, and cooling water temperature, wherein the capacitor core temperature indicates the actual temperature of the bus capacitor.
[0012] In some possible implementations, the core temperature of the bus capacitor can be obtained as follows: the motor controller determines the hottest region of the bus capacitor based on the thermal simulation results of the bus capacitor, and then obtains the core temperature based on the temperature of the thermocouples arranged in the hottest region.
[0013] Before performing temperature prediction, the method further includes: establishing a temperature prediction model for the bus capacitor based on the thermal network model of the bus capacitor of the motor controller, wherein the thermal network model is used to reflect the thermal characteristics of the bus capacitor.
[0014] Secondly, this application provides a temperature prediction device for a bus capacitor, the device comprising modules for performing the temperature prediction method for the bus capacitor in the first aspect or any possible implementation of the first aspect, specifically including:
[0015] The communication module is used to acquire the operating status of the first motor and the second motor controlled by the motor controller, and the operating status includes at least one of speed or torque;
[0016] The query module is used to query the first calibration table according to the operating status of the first motor to obtain the first thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The first calibration table includes the mapping relationship between the operating status of the first motor working alone and the thermal characteristic parameters determined based on multiple sets of experimental conditions. The thermal characteristic parameters include at least one of heat capacity, thermal resistance or loss coefficient.
[0017] The query module is also used to query the second calibration table according to the operating status of the second motor to obtain the second thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The second calibration table includes the mapping relationship between the operating status of the second motor working alone and the thermal characteristic parameters determined based on multiple sets of experimental conditions.
[0018] The prediction module is used to input the first thermal characteristic parameter and the second thermal characteristic parameter of the bus capacitor under the current operating condition and the temperature of the bus capacitor in the previous operating cycle into the temperature prediction model to obtain the first temperature change and the second temperature change of the bus capacitor in the current operating cycle.
[0019] The prediction module is also used to predict the temperature of the bus capacitor in the current operating cycle based on the first and second temperature changes of the bus capacitor in the current operating cycle.
[0020] In some possible implementations, the device further includes a calibration module for establishing a calibration table of the operating states and thermal characteristic parameters of multiple motors operating individually. Specifically, when establishing a first calibration table of the operating states and first thermal characteristic parameters of the first motor operating individually, this module is used for:
[0021] The electrical and temperature parameters of the motor controller under multiple experimental operating conditions of the first motor are obtained. The multiple experimental operating conditions of the first motor include multiple operating states under the condition that the first motor works alone. Then, the first thermal characteristic parameters of the bus capacitor are identified according to the electrical and temperature parameters to obtain the first calibration table.
[0022] In some possible implementations, when identifying the first thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters, the calibration module is specifically used for:
[0023] Based on the electrical parameters and the speed of the first motor, the first loss coefficient of the bus capacitor under the first operating condition is obtained. Then, based on the first loss coefficient of the bus capacitor and the temperature parameters, parameter identification is performed to obtain the first thermal capacitance and first thermal resistance of the bus capacitor under the first operating condition.
[0024] Specifically, based on the first loss coefficient and temperature parameters of the bus capacitor, parameter identification is performed to obtain the first thermal capacitance and first thermal resistance of the bus capacitor under the first operating condition. The calibration module is then used for:
[0025] Based on the first loss coefficient and temperature parameters, the theoretical temperature, predicted thermal capacity, and predicted thermal resistance of the bus capacitor under the first operating condition are determined. When the error between the theoretical temperature and the actual temperature of the bus capacitor is less than the threshold, the first thermal capacity and first thermal resistance of the bus capacitor under the first operating condition are obtained based on the predicted thermal capacity and predicted thermal resistance.
[0026] Thirdly, this application provides a controller. The controller includes a processor and a memory. The memory stores computer instructions; the processor executes the methods described in the first aspect of this application or any possible implementation thereof, according to the computer instructions.
[0027] Fourthly, this application provides a computer-readable medium storing instructions that, when executed on a computer device, cause the computer device to perform the method described in the first aspect of this application or any possible implementation thereof.
[0028] Fifthly, this application provides a computer program product containing instructions that, when run on a computer, cause the computer to perform the method described in the first aspect of this application or any possible implementation thereof.
[0029] Based on the implementation methods provided in the above aspects, this application can be further combined to provide more implementation methods.
[0030] As can be seen from the above technical solutions, this application has at least the following advantages:
[0031] On the one hand, this method obtains the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions by querying a calibration table obtained from pre-experiments based on the operating status of multiple motors, and then predicts the temperature of the bus capacitor, thus achieving the prediction of the bus capacitor temperature under the operating conditions of multiple motors. On the other hand, the operating status of multiple motors and the temperature of the capacitor in the previous operating cycle are readily available in the method provided in this application, eliminating the need to accurately obtain multiple difficult-to-measure physical parameters of the capacitor, reducing the difficulty of parameter acquisition and improving the feasibility of the method. At the same time, the method provided in this application does not require additional hardware equipment to obtain the temperature of the bus capacitor, reducing hardware costs. Attached Figure Description
[0032] Figure 1 This is a flowchart of a method for predicting the temperature of a bus capacitor disclosed in an embodiment of this application;
[0033] Figure 2 This is a schematic diagram of a thermal network model of a bus capacitor disclosed in an embodiment of this application;
[0034] Figure 3 This is a flowchart illustrating a method for constructing a first calibration table as disclosed in an embodiment of this application;
[0035] Figure 4 This is a schematic diagram of an experimental operating condition range disclosed in an embodiment of this application;
[0036] Figure 5 This is a schematic diagram of a gray box model verification method disclosed in an embodiment of this application;
[0037] Figure 6 This is a schematic diagram of the structure of a bus capacitor temperature prediction device disclosed in an embodiment of this application. Detailed Implementation
[0038] 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.
[0039] The terminology used in the following embodiments is for the purpose of describing specific embodiments only and is not intended to be a limitation of this application. The terms "first" and "second" in the embodiments of this application are for descriptive purposes only and should not be construed as indicating or implying relative importance, chronological order of operations, or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.
[0040] First, some technical terms involved in the embodiments of this application will be introduced.
[0041] New energy vehicles refer to vehicles that use unconventional vehicle fuels as their power source, including battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and hybrid electric vehicles (HEVs). New energy vehicles can reduce dependence on fossil fuels such as oil and reduce pollution from vehicle emissions.
[0042] The electric motor is the core drive component of new energy vehicles, especially multi-motor drive systems which can improve power performance and efficiency. The motor controller is a device used to control the motor's state and performance, such as receiving and processing various command signals to achieve precise control of parameters like motor speed, direction, and torque. In the motor controller, the DC power from the power supply serves as the input and needs to be connected to the motor controller via a DC bus; this method is called DC support. Because the motor controller receives a high effective value or peak value of pulse current from the power supply, it generates a high pulse voltage on the DC support, which the motor controller may find difficult to withstand. Therefore, a capacitor is needed for connection. This capacitor is called the bus capacitor or support capacitor.
[0043] Because multi-motor drive systems operate at high currents, the bus capacitors may overheat, which not only affects the lifespan of the capacitors but may also lead to unstable motor operation and even safety issues. Therefore, it is necessary to predict the capacitor temperature to achieve real-time monitoring.
[0044] However, current methods for predicting bus capacitor temperature often only consider the simple case of a single motor and cannot provide sufficiently accurate predictions for the complex operating conditions of multiple motors. Furthermore, existing methods require accurate acquisition of many difficult-to-measure physical parameters of the bus capacitor, such as package type, capacitance, tolerance, dielectric material, and insulation resistance, thus reducing the feasibility of the method. In addition, existing solutions include temperature detection by placing temperature sensors inside the capacitor; however, this method requires high hardware costs and has limited effectiveness.
[0045] In view of this, this application provides a method for predicting the temperature of a bus capacitor, which can be applied to the motor controller of a multi-motor driven vehicle. The method includes:
[0046] The motor controller queries a first calibration table based on the operating status of the first motor to obtain the first thermal characteristic parameters of the bus capacitor under the current operating conditions. It then queries a second calibration table based on the operating status of the second motor to obtain the second thermal characteristic parameters of the bus capacitor under the current operating conditions. Next, the motor controller inputs the first and second thermal characteristic parameters of the bus capacitor under the current operating conditions, along with the temperature of the bus capacitor in the previous operating cycle, into a temperature prediction model to obtain the first and second temperature changes of the bus capacitor in the current operating cycle, and predicts the temperature of the bus capacitor in the current operating cycle.
[0047] On the one hand, this method obtains the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions by querying a calibration table obtained from pre-experiments based on the operating status of multiple motors, and then predicts the temperature of the bus capacitor, thus achieving the prediction of the bus capacitor temperature under the operating conditions of multiple motors. On the other hand, the operating status of multiple motors and the temperature of the capacitor in the previous operating cycle are readily available in the method provided in this application, eliminating the need to accurately obtain multiple difficult-to-measure physical parameters of the capacitor, reducing the difficulty of parameter acquisition and improving the feasibility of the method. At the same time, the method provided in this application does not require additional hardware equipment to obtain the temperature of the bus capacitor, reducing hardware costs.
[0048] To make the technical solution of this application clearer and easier to understand, the method provided in this application will be described below with reference to specific embodiments.
[0049] It should be noted that the method provided in this application can be applied to the motor controller of a multi-motor driven vehicle. For ease of discussion, the following description uses the case of the motor controller controlling two motors as an example. In actual application, relevant technicians should make adaptive adjustments to the method provided in this application according to the actual number of motors.
[0050] Figure 1This application discloses a method for predicting the temperature of a bus capacitor. The method includes:
[0051] S102: The motor controller acquires the operating status of the first and second motors it controls.
[0052] The first motor and the second motor are two motors that jointly drive the vehicle. The first motor and the second motor can be the same type of motor; for example, both can be permanent magnet synchronous motors, which simplifies the configuration and maintenance process. Alternatively, the first motor and the second motor can be different types of motors; for example, the first motor can be a permanent magnet synchronous motor, and the second motor can be an induction motor, thus fully utilizing the high efficiency of the permanent magnet synchronous motor and the stability of the induction motor at high speeds.
[0053] The operating state of an electric motor refers to at least one of its speed or torque. Speed refers to the number of revolutions the motor's rotor makes per unit time, while torque refers to the force generated by the motor during rotation. Because components undergo torsional deformation under torque, torque is sometimes also called torque torque.
[0054] The sign of the speed and torque is determined by the reference direction. Generally, the direction of the motor's rotation when it is in driving mode, converting electrical energy into mechanical energy to provide driving force for the vehicle, is taken as the positive direction of the speed, and the direction of the torque generated by the motor is taken as the positive direction of the torque. When the direction of the motor's speed or torque is opposite to the reference direction, the speed or torque of the motor is taken as negative.
[0055] It should be noted that the operating status of the motor can be obtained by the motor controller periodically sending requests to the motor, or by the motor periodically reporting to the motor controller, or it can come from external input. This application does not limit this.
[0056] S104: The motor controller queries the first calibration table based on the operating status of the first motor to obtain the first thermal characteristic parameters of the motor controller's bus capacitor under the current operating conditions.
[0057] The thermal characteristic parameters of the bus capacitor refer to at least one of the following: thermal capacitance, thermal resistance, or loss coefficient. The motor controller can obtain the first thermal characteristic parameters of the bus capacitor corresponding to the current operating state of the first motor by looking up the mapping relationship between the operating state of the first motor and the first thermal characteristic parameters of the bus capacitor in the first calibration table.
[0058] It should be noted that the operating state of a motor can be divided into different intervals based on the magnitude of its speed and torque. Each interval corresponds to a set of thermal characteristic parameters. In other words, the thermal characteristic parameters corresponding to the operating states in the same interval can be the same.
[0059] In some possible implementations, the first calibration table can be determined through multiple sets of experimental conditions of motor operation, the detailed process of which will be explained later.
[0060] S106: The motor controller queries the second calibration table based on the operating status of the second motor to obtain the second thermal characteristic parameters of the motor controller's bus capacitor under the current operating conditions.
[0061] The motor controller can obtain the second thermal characteristic parameters of the bus capacitor corresponding to the current operating state of the second motor by looking up the table according to the mapping relationship between the operating state of the second motor and the second thermal characteristic parameters of the bus capacitor in the second calibration table.
[0062] It should be noted that the operating states of the first motor and the second motor are independent of each other. That is, the process of the motor controller querying the second calibration table based on the operating state of the second motor is unrelated to the first motor. Therefore, S104 and S106 can be executed simultaneously, or S104 can be executed first and then S106, or S106 can be executed first and then S104. This application embodiment does not limit this.
[0063] S108: The motor controller inputs the first thermal characteristic parameter, the second thermal characteristic parameter, and the temperature of the bus capacitor in the previous operating cycle into the temperature prediction model to obtain the first temperature change and the second temperature change of the bus capacitor in the current operating cycle.
[0064] The temperature prediction model is a gray box model used to determine the temperature change of the bus capacitor. A gray box model is a model in which only part of the system's internal structure and operating principle is known, balancing interpretability and predictability. Establishing a gray box model typically involves steps such as model identification, parameter identification, and validation.
[0065] In some possible implementations, the temperature prediction model is established based on the thermal network model of the bus capacitor. The thermal network model of the bus capacitor is an equivalent model used to reflect the thermal characteristics of the bus capacitor. By simulating the heat propagation path in the system, it uses electrical components such as resistors and capacitors to equivalently represent thermal resistance and thermal capacity, thereby enabling the analysis of the temperature field.
[0066] See Figure 2 The diagram shows a thermal network model for a bus capacitor, which is a 4-node thermal network model established for the operation of a single motor. That is, corresponding thermal network models of the same form can be established for both the first motor and the second motor operating independently.
[0067] In the figure, x1, x2, and x3 represent the temperatures of the upper copper busbar, the capacitor core of the busbar capacitor, and the lower copper busbar, respectively. Twater For cooling water temperature, x1 and T water The thermal resistance R1 and the upper copper busbar loss P are connected in parallel. copP And heat capacity C1, x2 and T water The thermal resistance R2 and capacitor core loss P are connected in parallel. cap And heat capacity C2, x3 and T water The thermal resistance R3 and the lower copper busbar loss P are connected in parallel. copN And heat capacity C3. A thermal resistance R4 is connected in series between x1 and x3, a thermal resistance R5 is connected in series between x2 and x3, and a thermal resistance R6 is connected in series between x1 and x3.
[0068] Based on this heat network model, the following mathematical model can be established:
[0069]
[0070] The unknown parameters, heat capacity, thermal resistance, and loss, are the thermal characteristic parameters of the bus capacitor.
[0071] In this embodiment, the temperature prediction model is a gray-box model that has been updated based on parameter identification and verification. The motor controller only needs to input the first and second thermal characteristic parameters of the bus capacitor under the current operating conditions and the temperature of the bus capacitor in the previous operating cycle into the temperature prediction model. Based on the updated gray-box model, the first and second temperature changes of the bus capacitor in the current operating cycle can be obtained. The parameter identification and verification process requires multiple sets of experimental operating conditions based on the motor's operating state, and a calibration table for the motor's operating state and the thermal characteristic parameters of the bus capacitor is established accordingly. This part will be described later in the section on the establishment of the calibration table.
[0072] S110: The motor controller predicts the temperature of the bus capacitor in the current operating cycle based on the first temperature change and the second temperature change.
[0073] After obtaining the first and second temperature changes of the bus capacitor in the current operating cycle based on the temperature prediction model, the motor controller can determine the total temperature change of the bus capacitor in the current operating cycle based on the operating characteristics of the two motors. The specific formula is as follows:
[0074] δT=δT1*K1+δT2*K2
[0075] Where δT is the total temperature change of the bus capacitor in the current operating cycle, δT1 is the first temperature change of the bus capacitor in the current operating cycle, δT2 is the second temperature change of the bus capacitor in the current operating cycle, and K1 and K2 are weighting coefficients.
[0076] In some possible implementations, when the motor torque is 0, the weighting coefficient for that motor is 0, and the total temperature change is related to the temperature change of the remaining motors. When the torques of all motors are not 0, the contribution rate of each motor to the temperature change can be determined through pre-calibration. This application does not impose limitations on how the calibration is performed.
[0077] The motor controller can predict the temperature of the bus capacitor in the current operating cycle based on the cumulative total temperature change over time and the temperature of the bus capacitor in the previous operating cycle. The specific formula is as follows:
[0078] T = T0 + ∫0 t δTdt
[0079] Where T0 represents the temperature of the previous operating cycle, δT represents the total temperature change of the bus capacitor in the current operating cycle, and T represents the temperature of the bus capacitor in the current operating cycle. In this way, the temperature of the bus capacitor can be predicted in real time, thereby achieving continuous monitoring of the bus capacitor temperature.
[0080] In some possible implementations, the motor controller can also deduce the temperature of the bus capacitor in the previous operating cycle from the temperature of the bus capacitor in the current operating cycle and the temperature change of the bus capacitor in the current operating cycle, making the relevant methods more flexible.
[0081] Based on the above description, this application provides a method for predicting the temperature of a capacitor bus. On one hand, this method obtains the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions by querying a calibration table obtained from a pre-experiment based on the operating status of multiple motors, and then predicts the temperature of the bus capacitor, thus achieving the prediction of the bus capacitor temperature under the operating conditions of multiple motors. On the other hand, the operating status of multiple motors and the temperature of the capacitor in the previous operating cycle are readily available in the method provided by this application, eliminating the need to accurately obtain multiple difficult-to-measure physical parameters of the capacitor, reducing the difficulty of parameter acquisition and improving the feasibility of the method. At the same time, the method provided by this application does not require additional hardware equipment to obtain the temperature of the bus capacitor, reducing hardware costs.
[0082] Figure 1 The illustrated embodiment primarily describes in detail the process of obtaining the thermal characteristic parameters of the bus capacitor by querying a calibration table based on the operating status of multiple motors, and predicting the temperature of the bus capacitor. In some possible implementations, the motor controller can also establish a complete gray box model and calibration table based on multiple sets of experimental conditions.
[0083] Figure 3 This application discloses a method for establishing a first calibration table, the method comprising:
[0084] S302: The motor controller acquires the electrical and temperature parameters of the motor controller under multiple experimental operating conditions of the first motor.
[0085] The establishment of calibration tables requires a large amount of data under experimental conditions. In one possible implementation, different experimental conditions can be determined as follows: starting from a speed of 0, the speed is recorded in 2000 rpm increments until the motor's maximum speed is reached. Within each speed value, the torque is recorded starting from 0, in 30 Nm increments until the external characteristic torque is reached. In this way, different combinations of speed and torque values can be used to define different experimental conditions. The external characteristic torque refers to the maximum torque the motor can produce at a specific speed, typically determined by the motor's design parameters, such as magnetic flux, current limits, and mechanical structure. During the experiment, the motor reaching its external characteristic torque can be determined by the motor temperature or the capacitor core temperature of the capacitor bus reaching a threshold.
[0086] like Figure 4 As shown, the multiple experimental operating conditions of the motor can be divided into different ranges based on the magnitude of speed and torque, and combinations that cannot be achieved due to speed limitations have been eliminated based on actual conditions. The division of different ranges is not simply based on the magnitude of speed or torque, but rather on the results of parameter identification. Within the same range, the experimental operating conditions correspond to the same set of thermal characteristic parameters.
[0087] The electrical parameters of a motor controller reflect its electrical performance and are important factors affecting its performance and applicability. For example, the electrical parameters of a motor controller may include at least one of the following: bus voltage and current, direct-axis voltage and current, quadrature-axis voltage and current, and line voltage amplitude.
[0088] Temperature parameters of a motor controller can reflect its thermal performance. For example, temperature parameters may include at least one of the following: the temperature of the bus capacitor core, the temperature of the upper copper busbar, the temperature of the lower copper busbar, and the cooling water temperature.
[0089] Based on complete electrical and temperature parameters, the working status of the motor controller can be better displayed, which in turn facilitates parameter identification.
[0090] S304: The motor controller identifies the first thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters, and obtains the first calibration table.
[0091] After determining multiple sets of experimental operating conditions for multiple motors, the motor controller can identify and verify the thermal characteristic parameters of the bus capacitor based on the electrical and temperature parameters of the motor controller under each set of experimental operating conditions, thereby obtaining a calibration table and a complete gray box model.
[0092] In some possible implementations, the motor controller can first determine the initial loss coefficient of the bus capacitor. Specifically, the motor controller can obtain the loss coefficient of the bus capacitor based on the bus voltage and current, the voltage and current of the motor controller's direct axis, the voltage and current of the motor controller's quadrature axis, the line voltage amplitude of the motor controller, and the speeds of multiple motors. It should be noted that the embodiments of this application do not limit the specific algorithm for obtaining the loss coefficient.
[0093] Then, the motor controller can identify parameters based on the thermal network model of the bus capacitor, the first loss coefficient of the bus capacitor, the core temperature of the bus capacitor, the temperature of the upper copper busbar, the temperature of the lower copper busbar, and the cooling water temperature to obtain the thermal capacitance and thermal resistance of the bus capacitor. In some possible implementations, the motor controller can use optimization algorithms to obtain the thermal capacitance and thermal resistance of the bus capacitor, such as the trust region reflection algorithm, particle swarm optimization algorithm, and genetic algorithm. Among these, the trust region reflection algorithm has the characteristics of high robustness, high computational efficiency, and insensitivity to the selection of the initial temperature point, and therefore has been widely used.
[0094] In one possible implementation, the process by which the motor controller identifies parameters based on a first loss coefficient and temperature parameters to obtain the first thermal capacity and first thermal resistance of the bus capacitor under the first operating condition can be performed as follows: The motor controller determines the theoretical temperature, predicted thermal capacity, and predicted thermal resistance of the bus capacitor under the first operating condition based on the first loss coefficient and temperature parameters. When the error between the theoretical temperature and the actual temperature of the bus capacitor is less than a threshold, the motor controller obtains the first thermal capacity and first thermal resistance of the bus capacitor under the first operating condition based on the predicted thermal capacity and predicted thermal resistance values.
[0095] like Figure 5 As shown, the dashed line represents the theoretical temperature, and the solid line represents the actual capacitor core temperature. The greater the overlap between the two in the image, the smaller the difference between the predicted and actual values, and the more accurate the corresponding thermal characteristic parameters. This allows verification of the accuracy of the obtained thermal characteristic parameters, thereby determining the mapping relationship between the operating state and the thermal characteristic parameters.
[0096] The capacitor core temperature can be obtained using thermocouples. Specifically, the motor controller can determine the hottest region of the bus capacitor based on simulation results, and then obtain the capacitor core temperature based on the temperature of the thermocouples located in the hottest region. This facilitates more accurate verification of the thermal characteristic parameters, thereby improving the accuracy of bus capacitor temperature prediction.
[0097] The motor controller can select the highest temperature among the acquired thermocouple temperatures as the capacitor core temperature. This allows for a more accurate determination of the capacitor's actual maximum temperature, which in turn facilitates the determination of the motor's external characteristic torque, thus making the calibration process more accurate.
[0098] In addition, the motor controller can update the gray box model based on the results of parameter identification and verification to obtain a complete model. This allows the motor controller to input only the first thermal characteristic parameters of the bus capacitor under the current operating conditions and the temperature of the bus capacitor in the previous operating cycle into the gray box model, and output the first temperature change of the bus capacitor in the current operating cycle.
[0099] Based on the above description, this application discloses a method for establishing a first calibration table. Pre-calibration is performed under experimental conditions, so that the motor controller can query the first calibration table through the operating status of the first motor to directly obtain the first thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions, and thus obtain the first temperature change of the bus capacitor, reducing the complexity of the temperature prediction method.
[0100] It should be noted that this application uses a first calibration table as an example to describe the calibration method and process in detail. Those skilled in the art can construct a second calibration table and other calibration tables based on this method.
[0101] This application also provides a temperature prediction device for bus capacitors. The device of this application will be described in detail below with reference to the accompanying drawings.
[0102] See Figure 6 The diagram shows a structural schematic of a bus capacitor temperature prediction device 600, which may include:
[0103] The communication module 602 is used to acquire the operating status of the first motor and the second motor controlled by the motor controller, and the operating status includes at least one of speed or torque;
[0104] The query module 604 is used to query the first calibration table according to the operating status of the first motor to obtain the first thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The first calibration table includes the mapping relationship between the operating status of the first motor working alone and the thermal characteristic parameters determined based on multiple sets of experimental conditions. The thermal characteristic parameters include at least one of heat capacity, thermal resistance or loss coefficient.
[0105] The query module 604 is also used to query the second calibration table according to the operating status of the second motor to obtain the second thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The second calibration table includes the mapping relationship between the operating status of the second motor working alone and the thermal characteristic parameters determined based on multiple sets of experimental conditions.
[0106] Prediction module 606 is used to input the first thermal characteristic parameter and the second thermal characteristic parameter of the bus capacitor under the current operating condition and the temperature of the bus capacitor in the previous operating cycle into the temperature prediction model to obtain the first temperature change and the second temperature change of the bus capacitor in the current operating cycle.
[0107] The prediction module 606 is also used to predict the temperature of the bus capacitor in the current operating cycle based on the first temperature change and the second temperature change of the bus capacitor in the current operating cycle.
[0108] In some possible implementations, the device further includes a calibration module for establishing a calibration table of the operating states and thermal characteristic parameters of multiple motors operating individually. Specifically, when establishing a first calibration table of the operating states and first thermal characteristic parameters of the first motor operating individually, this module is used for:
[0109] The electrical and temperature parameters of the motor controller under multiple experimental operating conditions of the first motor are obtained. The multiple experimental operating conditions of the first motor include multiple operating states under the condition that the first motor works alone. Then, the first thermal characteristic parameters of the bus capacitor are identified according to the electrical and temperature parameters to obtain the first calibration table.
[0110] In some possible implementations, when identifying the first thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters, the calibration module is specifically used for:
[0111] Based on the electrical parameters and the speed of the first motor, the first loss coefficient of the bus capacitor under the first operating condition is obtained. Then, based on the first loss coefficient of the bus capacitor under the first operating condition and the temperature parameters, parameter identification is performed to obtain the first thermal capacitance and the first thermal resistance of the bus capacitor.
[0112] In some possible implementations, when parameter identification is performed based on the first loss coefficient and temperature parameters of the bus capacitor under the first operating condition to obtain the first thermal capacitance and first thermal resistance of the bus capacitor under the first operating condition, the calibration module is used for:
[0113] Based on the first loss coefficient and temperature parameters, the theoretical temperature, predicted thermal capacity, and predicted thermal resistance of the bus capacitor under the first operating condition are determined. When the error between the theoretical temperature and the actual temperature of the bus capacitor is less than the threshold, the first thermal capacity and first thermal resistance of the bus capacitor under the first operating condition are obtained based on the predicted thermal capacity and predicted thermal resistance.
[0114] Based on the aforementioned method and device for predicting the temperature of the bus capacitor, this application also provides a controller. This controller may be, for example, a vehicle control unit (VCU) or an electronic control unit (ECU). The controller includes a processor and a memory. The memory stores computer-readable instructions, and the processor executes these instructions to perform the aforementioned method for predicting the temperature of the bus capacitor. In some examples, the controller is used to implement the functions of the aforementioned device for predicting the temperature of the bus capacitor.
[0115] The modules described above as separate components may or may not be physically separate. Similarly, the components shown as modules may or may not be physical modules; they may be located in one place or distributed across multiple virtual modules. Some or all of the modules can be selected to achieve the purpose of this embodiment, depending on actual needs.
[0116] Furthermore, the functional modules in the various embodiments of this application can be integrated into one processing module, or each module can exist physically separately, or two or more modules can be integrated into one module. The integrated modules described above can be implemented in hardware or as software functional modules.
[0117] If the integrated module is implemented as a software functional module and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the essential contribution of the technical solution of this application, or all or part of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the processes of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory, random access memory, magnetic disks, or optical disks.
[0118] 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 temperature prediction method of a bus capacitor, characterized by, A motor controller applied to a vehicle driven by multiple motors, the method comprising: obtaining operating states of a first motor and a second motor controlled by the motor controller, the operating states comprising at least one of a rotational speed or a torque; querying a first calibration table according to the operating state of the first motor to obtain a first thermal characteristic parameter of a bus capacitor of the motor controller under a current working condition, the first calibration table comprising a mapping relationship between an operating state and a thermal characteristic parameter of the first motor working alone determined based on multiple sets of experimental working conditions, the thermal characteristic parameter comprising at least one of a thermal capacity, a thermal resistance or a loss coefficient; querying a second calibration table according to the operating state of the second motor to obtain a second thermal characteristic parameter of the bus capacitor of the motor controller under the current working condition, the second calibration table comprising a mapping relationship between an operating state and a thermal characteristic parameter of the second motor working alone determined based on multiple sets of experimental working conditions; inputting the first thermal characteristic parameter, the second thermal characteristic parameter and a temperature of the bus capacitor in a previous operating period into a temperature prediction model to obtain a first temperature change and a second temperature change of the bus capacitor in a current operating period; predicting a temperature of the bus capacitor in the current operating period according to the first temperature change and the second temperature change.
2. The method of claim 1, wherein, The first calibration table is obtained by: obtaining electrical parameters and temperature parameters of the motor controller under multiple sets of experimental working conditions of the first motor, the multiple sets of experimental working conditions of the first motor comprising multiple sets of operating states of the first motor working alone; performing parameter identification on the first thermal characteristic parameter of the bus capacitor according to the electrical parameters and the temperature parameters to obtain the first calibration table.
3. The method of claim 2, wherein, The parameter identification on the first thermal characteristic parameter of the bus capacitor according to the electrical parameters and the temperature parameters comprises: determining a first loss coefficient of the bus capacitor in a first working condition according to the electrical parameters and the rotational speed of the first motor; performing parameter identification according to the first loss coefficient and the temperature parameters to obtain a first thermal capacity and a first thermal resistance of the bus capacitor in the first working condition.
4. The method of claim 3, wherein, The parameter identification according to the first loss coefficient and the temperature parameters to obtain the first thermal capacity and the first thermal resistance of the bus capacitor in the first working condition comprises: determining a theoretical temperature, a thermal capacity prediction value and a thermal resistance prediction value of the bus capacitor in the first working condition according to the first loss coefficient and the temperature parameters; when an error between the theoretical temperature and an actual temperature of the bus capacitor is less than a threshold value, obtaining the first thermal capacity and the first thermal resistance of the bus capacitor in the first working condition according to the thermal capacity prediction value and the thermal resistance prediction value.
5. The method according to any one of claims 2 to 4, characterized in that, The electrical parameters of the motor controller comprise at least one of a voltage and a current of the bus, a voltage and a current of a direct-axis of the motor controller, a voltage and a current of a quadrature-axis of the motor controller, and a line voltage amplitude of the motor controller. The temperature parameter of the motor controller comprises at least one of a capacitor core temperature of the bus capacitor, an upper copper bar temperature, a lower copper bar temperature and a cooling water temperature, wherein the capacitor core temperature indicates the actual temperature of the bus capacitor.
6. The method of claim 5, wherein, The capacitor core temperature is obtained by: determining a hottest region of the bus capacitor according to a thermal simulation result of the bus capacitor; collecting a temperature of a thermocouple of the hottest region to obtain the capacitor core temperature.
7. The method of claim 1, wherein, The method further comprises: establishing a temperature prediction model of the bus capacitor according to a thermal network model of the bus capacitor of the motor controller, the thermal network model being used to reflect thermal characteristics of the bus capacitor.
8. A temperature prediction device for a bus capacitor, characterized by The motor controller applied to a vehicle driven by multiple motors, the device comprising: a communication module configured to obtain operating states of first and second motors controlled by the motor controller, the operating states comprising at least one of a rotational speed or a torque; a query module configured to query a first calibration table according to the operating state of the first motor to obtain first thermal characteristic parameters of the bus capacitor of the motor controller under a current operating condition, the first calibration table comprising a mapping relationship between operating states and thermal characteristic parameters under operation of the first motor alone, the thermal characteristic parameters comprising at least one of a thermal capacity, a thermal resistance or a loss coefficient; the query module is further configured to query a second calibration table according to the operating state of the second motor to obtain second thermal characteristic parameters of the bus capacitor of the motor controller under the current operating condition, the second calibration table comprising a mapping relationship between operating states and thermal characteristic parameters under operation of the second motor alone; a prediction module configured to input the first and second thermal characteristic parameters of the bus capacitor under the current operating condition and a temperature of the bus capacitor in a previous operating cycle into a temperature prediction model to obtain first and second temperature change amounts of the bus capacitor in a current operating cycle; the prediction module is further configured to predict a temperature of the bus capacitor in the current operating cycle according to the first and second temperature change amounts of the bus capacitor in the current operating cycle.
9. A controller characterized by comprising: The controller comprises: a memory configured to store computer programs or computer instructions; a processor configured to execute the computer programs or computer instructions stored in the memory, so that the motor controller performs the method according to any one of claims 1 to 7.
10. A computer storage medium, characterized in that, The computer storage medium is configured to store computer programs, which are executed to implement the method according to any one of claims 1 to 7.