Temperature prediction method of bus capacitor and related equipment

Abstract

The invention discloses a motor controller applied to a multi-motor-driven vehicle, and the method comprises the steps that the motor controller obtains the operation states of a plurality of motors controlled by the motor controller, and the operation states comprise at least one of the rotating speed or the torque of the motors. Then, the motor controller inquires the calibration table according to the running states of the multiple motors, and thermal characteristic parameters of a bus capacitor of the motor controller under the current working condition are obtained; thirdly, the motor controller inputs the thermal characteristic parameters of the bus capacitor under the current working condition and the temperature of the bus capacitor in the previous operation cycle into the temperature prediction model, and the temperature variation of the bus capacitor in the current operation cycle is obtained; and predicting the temperature of the bus capacitor in the current operation cycle. The method achieves the prediction of the temperature of the bus capacitor under the complex working condition of multi-motor operation, and improves the accuracy of the temperature prediction of the bus capacitor.

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). Among these, hybrid electric vehicles hold an important position in the market due to their high stability.

[0003] Hybrid electric vehicles typically employ two or more power sources in their drive systems, such as an integrated starter generator (ISG) and a traction motor (TM). When both motors operate at high power for extended periods, the bus capacitor of the motor controller may overheat. Therefore, it is necessary to predict the temperature of the bus capacitor and monitor it in real time.

[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 the traditional method for predicting the temperature of bus capacitors has low accuracy under complex operating conditions with multiple motors.

[0006] In a first aspect, this application provides a method for determining capacitor temperature, applied to a motor controller of a multi-motor driven vehicle, the method comprising:

[0007] The motor controller acquires the operating status of multiple motors it controls, whereby the operating status includes at least one of the motor speeds or torques. Then, based on the operating status of the multiple motors, it consults a calibration table to obtain the thermal characteristic parameters of the motor controller's bus capacitor under the current operating conditions. The calibration table includes a mapping relationship between operating status and 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. Next, the thermal characteristic parameters of the bus capacitor under the current operating conditions and the temperature of the bus capacitor in the previous operating cycle are input into a temperature prediction model to obtain the temperature change of the bus capacitor in the current operating cycle. Finally, based on the temperature change of the bus capacitor in the current operating cycle, the temperature of the bus capacitor in the current operating cycle is predicted.

[0008] In some possible implementations, the calibration table can be obtained as follows: The motor controller acquires electrical and temperature parameters under multiple sets of experimental conditions, where the multiple sets of experimental conditions include multiple operating states of multiple motors. Then, the motor controller identifies the thermal characteristic parameters of the bus capacitor based on the electrical and temperature parameters to obtain the calibration table.

[0009] Among them, multiple sets of experimental conditions can be determined in the following way: multiple sets of experimental conditions for multiple motors are determined based on the orthogonal experimental method. The multiple sets of experimental conditions include multiple sets of operating states for multiple motors, and the operating state includes at least one of speed or torque.

[0010] When multiple motors include an integrated starter generator and a traction motor, the motor controller can determine multiple sets of experimental operating conditions for the integrated starter generator and the traction motor based on the orthogonal experimental method. In each experimental operating condition, the torque and speed of the integrated starter generator are different from the torque and speed of the traction motor.

[0011] In some possible implementations, parameter identification of the thermal characteristics of the bus capacitor based on electrical and temperature parameters can be performed as follows: The motor controller obtains the loss coefficient of the bus capacitor under the first operating condition based on the electrical parameters and the speeds of multiple motors. Then, the motor controller performs parameter identification based on the loss coefficient and temperature parameters to obtain the thermal capacitance and thermal resistance of the bus capacitor under the first operating condition.

[0012] 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, cooling water temperature, bus capacitor input port temperature, and each motor-side output port temperature.

[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] In some possible implementations, when multiple motors include an integrated starter generator and a traction motor, the method further includes: when the temperature of the bus capacitor is greater than a first threshold at a first moment, if the traction motor is in a generating state, the motor controller instructs the traction motor to stop generating power; when the temperature of the bus capacitor is greater than a second threshold at a second moment or the traction motor is not in a generating state, if the integrated starter generator is in a generating state at the second moment, the motor controller instructs the integrated starter generator to stop generating power, wherein the second threshold is less than the first threshold and the second moment is later than the first moment; when the temperature of the bus capacitor is greater than the second threshold at a third moment or the integrated starter generator is not in a generating state at the second moment, the traction motor is instructed to reduce its maximum torque until the temperature of the bus capacitor is less than the second threshold, the third moment being later than the second moment.

[0015] 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:

[0016] A communication module is used to acquire the operating status of multiple motors controlled by the motor controller, wherein the operating status includes at least one of speed or torque;

[0017] The query module is used to query the calibration table according to the operating status of the multiple motors to obtain the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The calibration table includes the mapping relationship between the operating status and the thermal characteristic parameters determined based on multiple sets of experimental operating conditions. The thermal characteristic parameters include at least one of heat capacity, thermal resistance or loss coefficient.

[0018] The prediction module is used to input the 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 to obtain the 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 temperature change of the bus capacitor in the current operating cycle.

[0020] In some possible implementations, the device also includes a calibration module for establishing calibration tables of the operating states and thermal characteristic parameters of multiple motors. This module is specifically used for:

[0021] The electrical and temperature parameters of the motor controller under multiple experimental conditions are obtained. These multiple experimental conditions include multiple operating states of multiple motors. Then, the thermal characteristic parameters of the bus capacitor are identified based on the electrical and temperature parameters to obtain a calibration table.

[0022] In some possible implementations, when determining multiple sets of experimental conditions, the calibration module is specifically used for:

[0023] Multiple sets of experimental operating conditions for multiple motors are determined based on the orthogonal experimental method. The multiple sets of experimental operating conditions include multiple sets of operating states for multiple motors, and the operating states include at least one of speed or torque.

[0024] In some possible implementations, when identifying the thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters, this module is specifically used for:

[0025] Based on electrical parameters and the speeds of multiple motors, the loss coefficient of the bus capacitor under the first operating condition is obtained. Then, based on the loss coefficient of the bus capacitor and temperature parameters, parameter identification is performed to obtain the thermal capacitance and thermal resistance of the bus capacitor under the first operating condition.

[0026] In some possible implementations, the bus capacitor temperature prediction device also includes an over-temperature protection module, used to limit the operating status of multiple motors and reduce the temperature of the bus capacitor when the temperature is too high. When the multiple motors include an integrated starter generator and a traction motor, this module is specifically used for:

[0027] When the temperature of the bus capacitor exceeds the first threshold at the first moment, if the traction motor is in the power generation state, the traction motor is instructed to stop generating electricity.

[0028] When the temperature of the bus capacitor is greater than the second threshold at the second moment or the traction motor is not in the power generation state, if the integrated starter generator is in the power generation state at the second moment, it is instructed to stop the integrated starter generator from generating power. The second threshold is less than the first threshold and the second moment is later than the first moment.

[0029] When the temperature of the bus capacitor is greater than the second threshold at the third moment or the integrated starter generator is not generating power at the second moment, the traction motor is instructed to reduce the maximum torque until the temperature of the bus capacitor is less than the second threshold. The third moment is later than the second moment.

[0030] 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.

[0031] 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.

[0032] 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.

[0033] Based on the implementation methods provided in the above aspects, this application can be further combined to provide more implementation methods.

[0034] As can be seen from the above technical solutions, this application has at least the following advantages:

[0035] 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 realizing the prediction of the bus capacitor temperature under complex operating conditions with 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. In addition, this application also provides a protection method for the bus capacitor when it over-temperatures, improving the safety and reliability of the system. Attached Figure Description

[0036] Figure 1 This is a flowchart of a method for predicting the temperature of a bus capacitor disclosed in an embodiment of this application;

[0037] Figure 2 This is a schematic diagram of a thermal network model of a bus capacitor disclosed in an embodiment of this application;

[0038] Figure 3 This is a flowchart illustrating a method for constructing a calibration table as disclosed in an embodiment of this application;

[0039] Figure 4 This is a schematic diagram of a gray box model verification method disclosed in an embodiment of this application;

[0040] Figure 5 This is a flowchart of a method for protecting a bus capacitor from over-temperature according to an embodiment of this application;

[0041] 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

[0042] 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.

[0043] 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.

[0044] First, some technical terms involved in the embodiments of this application will be introduced.

[0045] 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). Among them, hybrid electric vehicles occupy an important position in the market due to their high stability.

[0046] Hybrid electric vehicles (HEVs) typically employ two or more power sources in their drive systems, such as an integrated starter generator (ISG) and a traction motor (TM). These two motors work together efficiently through a motor controller. The motor controller is responsible for controlling the motor's state and performance, such as receiving and processing various command signals to precisely control parameters like speed, direction, and torque. In the motor controller, the direct current (DC) from the power supply serves as the input and needs to be connected to the controller via a DC bus; this connection 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 controller may find difficult to withstand. Therefore, a capacitor is required for this connection. This capacitor is called the bus capacitor or support capacitor.

[0047] In the drive system of hybrid vehicles, the ISG (Integrated Gas Generator) is generally directly connected to the engine, operating in two modes: unidirectional power generation and driving. The TM (Motor Motor), as the main drive motor, is one of the core components of the vehicle's powertrain, operating in four modes: forward drive, reverse drive, forward power generation, and reverse power generation. The two motors can combine to form at least eight operating scenarios. Considering the speeds of the two motors, even more complex operating conditions arise. Such complex operating conditions lead to complex variations in the ripple current of the motor controller's bus capacitor. Furthermore, when both motors operate simultaneously at high torque for extended periods, the bus capacitor temperature can easily become excessively high, resulting in a safety hazard. Therefore, it is necessary to predict the bus capacitor temperature for real-time monitoring.

[0048] However, current methods for predicting bus capacitor temperature often only consider the simple case of a single motor and cannot make 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 its package, capacitance, tolerance, dielectric properties, and insulation resistance, which reduces the feasibility of the method.

[0049] In view of this, this application provides a method for predicting the temperature of a bus capacitor. This method can be applied to the motor controller of a multi-motor driven vehicle. The method includes: the motor controller acquiring the operating status of multiple motors it controls, wherein the operating status includes at least one of the motor speed or torque. Then, the motor controller queries a calibration table based on the operating status of the multiple motors to obtain the thermal characteristic parameters of the bus capacitor under the current operating condition. The calibration table includes a mapping relationship between the operating status and the thermal characteristic parameters determined based on multiple sets of experimental conditions, wherein the thermal characteristic parameters include at least one of heat capacity, thermal resistance, or loss coefficient. Next, the motor controller inputs the thermal characteristic parameters of the bus capacitor under the current operating condition and the temperature of the bus capacitor in the previous operating cycle into a temperature prediction model to obtain the temperature change 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 temperature change of the bus capacitor in the current operating cycle.

[0050] 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 realizing the prediction of the temperature of the bus capacitor under complex operating conditions of multiple motors. On the other hand, in the method provided by this application, the operating status of multiple motors and the temperature of the capacitor in the previous operating cycle are readily available, 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.

[0051] 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.

[0052] Figure 1 This application discloses a method for predicting the temperature of a bus capacitor. The method includes:

[0053] S102: The motor controller acquires the operating status of multiple motors under its control.

[0054] The operating status of multiple motors refers to at least one of the following: speed or torque. Speed ​​refers to the number of revolutions the motor 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.

[0055] 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.

[0056] For example, multiple motors may include an Integrated Starter Generator (ISG) and a Traction Motor (TM). The ISG is typically directly connected to the engine and operates in two modes: unidirectional power generation and driving. The ISG's speed is a positive value, while its torque can be positive or negative. For instance, during deceleration, the ISG converts the vehicle's kinetic energy into electrical energy and stores it in the battery, outputting torque in the opposite direction of motion, i.e., generating negative torque. The TM includes various operating scenarios such as forward drive, reverse drive, forward power generation, and reverse power generation, with four corresponding positive and negative values ​​for speed and torque.

[0057] It should be noted that the operating status of multiple motors can be obtained by the motor controller periodically sending requests to multiple motors, or by multiple motors periodically and actively reporting to the motor controller, or it can come from external input. This application does not limit this.

[0058] S104: The motor controller queries the calibration table based on the operating status of multiple motors to obtain the thermal characteristic parameters of the motor controller's bus capacitor under the current operating conditions.

[0059] 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 corresponding thermal characteristic parameters of the bus capacitor for the current operating states of multiple motors by looking up the mapping relationship between motor operating states and the thermal characteristic parameters of the bus capacitor in the calibration table. It should be noted that the motor operating states can be divided into different intervals based on the magnitude and direction of speed and torque. Each interval corresponds to a set of thermal characteristic parameters; that is, operating states within the same interval can have the same thermal characteristic parameters.

[0060] In some possible implementations, the calibration table can be determined through multiple sets of experimental conditions of motor operation, the detailed process of which will be explained later.

[0061] S106: The motor controller inputs the 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 to obtain the temperature change of the bus capacitor in the current operating cycle.

[0062] 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.

[0063] 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.

[0064] See Figure 2 The figure shows a thermal network model of a bus capacitor used in the motor controller of an ISG and TM dual-motor system. In the figure, x1, x2, and x3 represent the temperatures of the upper copper bus, the capacitor core, and the lower copper bus, respectively, and T1, T2, T3, and T... water These are the capacitor input port temperature, capacitor ISG side output port temperature, capacitor TM side output port temperature, and cooling water temperature, respectively, 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. copNAnd 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; a thermal resistance R6 is connected in series between x1 and x3; a thermal resistance R7 is connected in series between T1 and x1; a thermal resistance R8 is connected in series between T2 and x1; a thermal resistance R9 is connected in series between T3 and x1; and a thermal resistance R... 10 A thermal resistance R is connected in series between T2 and x3. 11 A thermal resistance R is connected in series between T3 and x3. 12 .

[0065] Based on this heat network model, the following mathematical model can be established:

[0066]

[0067] The unknown parameters, heat capacity, thermal resistance, and loss, are the thermal characteristic parameters of the bus capacitor.

[0068] 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 thermal characteristic parameters 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 temperature change of the bus capacitor in the current operating cycle based on the updated gray-box model. 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 based on this. This part will be described later in the process of establishing the calibration table.

[0069] S108: The motor controller predicts the temperature of the bus capacitor in the current operating cycle based on the temperature change of the bus capacitor in the current operating cycle.

[0070] After obtaining the temperature change of the bus capacitor in the current operating cycle based on the temperature prediction model, the motor controller predicts the temperature of the bus capacitor in the current operating cycle based on the cumulative effect of this temperature change over time and the temperature of the bus capacitor in the previous operating cycle. The specific formula is as follows:

[0071] T = T0 + ∫0 t δTdt

[0072] Where T0 represents the temperature of the previous operating cycle, δT represents the 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.

[0073] 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.

[0074] Based on the above description, this application provides a method for predicting the temperature of a capacitor bus. On the one hand, this method obtains the thermal characteristic parameters of the bus capacitor under the current operating conditions by querying a calibration table obtained from a pre-experimental study based on the operating status of multiple motors, and then predicts the temperature of the bus capacitor, thus realizing the prediction of the bus capacitor temperature under complex operating conditions with 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 this method, 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.

[0075] 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.

[0076] Figure 3 This application discloses a method for establishing a calibration table, the method comprising:

[0077] S302: The motor controller acquires electrical and temperature parameters under multiple experimental conditions.

[0078] 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.

[0079] 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 bus, the temperature of the lower copper bus, the cooling water temperature, the temperature of the input port of the bus capacitor, and the temperature of the output port of each motor side.

[0080] The establishment of a calibration table requires a large amount of data from experimental operating conditions. As described above, the combination of multiple operating conditions for multiple motors is extremely complex. To obtain a more accurate calibration table, the experimental operating conditions need to cover as many combinations of operating conditions as possible for multiple motors. However, it is impractical to traverse all combinations of speed and torque values ​​for multiple motors. In order to establish a calibration table with limited experimental operating conditions, while saving time and manpower costs while maintaining accuracy, this application proposes an experimental operating condition design method based on orthogonal experimental design.

[0081] Orthogonal experimental design is a scientific method that utilizes mathematical statistics and the principle of orthogonality to select representative data from a large amount of experimental data and rationally arrange the experiments. See Table 1, which is an orthogonal experimental design table disclosed in an embodiment of this application. The multiple motors controlled by the motor controller are ISG and TM.

[0082] Table 1 Orthogonal Experimental Design Table

[0083]

[0084] In this orthogonal experiment, the factors are the speed and torque of multiple motors. The number of levels for each factor can be determined based on the actual operating speed and torque range of the motors. In the example shown in Table 1, the orthogonal experiment table contains four factors: the speed and torque of the ISG and the speed and torque of the TM. Each speed and torque has four different values, with negative values ​​indicating that the direction of the corresponding speed or torque is opposite to the reference direction. It should be noted that due to the limitations imposed by the motor's external characteristics on its torque and speed, some speed and torque combinations in the experimental conditions may not be achievable in practice. Relevant technical personnel need to remove the experimental data corresponding to these conditions based on the actual situation.

[0085] S304: The motor controller identifies the thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters, and obtains a calibration table.

[0086] 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.

[0087] In some possible implementations, the motor controller can first determine the loss factor of the bus capacitor. Specifically, the motor controller can obtain the loss factor 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. The formula is as follows:

[0088]

[0089] Among them, I d and I q V represents the d-axis and q-axis currents of the motor controller. d and V q U represents the d-axis and q-axis voltages of the motor controller. dc V is the bus voltage. dq I is the line voltage amplitude. s P is the bus current. copP For copper busbar losses, P copN For the lower copper busbar loss, P cap The capacitor core loss of the bus capacitor is given, and spd is the sum of the absolute values ​​of the speeds of multiple motors. ka and k are also mentioned. b k c k d k e k f and k s The parameter is unknown.

[0090] Then, the motor controller can identify parameters based on the thermal network model of the bus capacitor, the 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, the cooling water temperature, the input port temperature of the bus capacitor, and the output port temperature of each motor side, to obtain the thermal capacitance and thermal resistance of the bus capacitor.

[0091] 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.

[0092] like Figure 4 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.

[0093] 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 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 temperature change of the bus capacitor in the current operating cycle.

[0094] It should be noted that the embodiments of this application do not limit how to obtain the capacitor core temperature of the bus capacitor. Those skilled in the art can use infrared thermal imaging, thermistors, temperature sensors and other methods to obtain the capacitor core temperature of the bus capacitor.

[0095] Based on the above description, this application discloses a method for establishing a calibration table. Pre-calibration is performed under experimental conditions, allowing the motor controller to query the calibration table through the operating status of multiple motors and directly obtain the thermal characteristic parameters of the motor controller's bus capacitor under the current operating conditions. This enables the determination of the temperature change of the bus capacitor and the prediction of the bus capacitor's temperature, thereby reducing the complexity of the temperature prediction method.

[0096] In some possible implementations, the motor controller can also provide a protection method for when the bus capacitor temperature is too high, based on the motor operating status.

[0097] See Figure 5 A flowchart of a method for protecting a bus capacitor from over-temperature is disclosed, applicable when multiple motors are traction motors and an integrated starter generator. The method includes:

[0098] When the temperature of the bus capacitor exceeds the first threshold at the first moment, if the traction motor is in the power generation state, the motor controller instructs the traction motor to stop generating electricity.

[0099] When the temperature of the bus capacitor is greater than the second threshold at the second moment or the traction motor is not in the power generation state, if the integrated starter generator is in the power generation state at the second moment, the motor controller instructs the integrated starter generator to stop power generation. Here, the second threshold is less than the first threshold and the second moment is later than the first moment.

[0100] If the temperature of the bus capacitor exceeds the second threshold at the third time point, or if the integrated starter generator is not in generating mode at the second time point, the motor controller instructs the traction motor to reduce its maximum torque until the temperature of the bus capacitor is below the second threshold. The third time point is later than the second time point. When the temperature of the bus capacitor is below the second threshold, the motor controller can instruct the integrated starter generator and traction motor to resume generating mode and release the torque limit on the traction motor.

[0101] In some possible implementations, the motor controller can also issue an alarm when instructing the motor to stop generating electricity, such as by sending a fault code or triggering a buzzer alarm. This can alert the driver or relevant technicians to intervene in the motor's operating status, thereby quickly and manually reducing the temperature of the bus capacitor.

[0102] Based on the above description, this application provides a protection method for when the bus capacitor temperature is too high, which can automatically limit the operation of the motor and reduce the temperature of the bus capacitor, thereby improving the safety and reliability of the system.

[0103] 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.

[0104] See Figure 6 The diagram shows a structural schematic of a bus capacitor temperature prediction device 600, which may include:

[0105] The communication module 602 is used to acquire the operating status of multiple motors controlled by the motor controller, and the operating status includes at least one of speed or torque;

[0106] The query module 604 is used to query the calibration table based on the operating status of multiple motors to obtain the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The calibration table includes the mapping relationship between the operating status and the thermal characteristic parameters determined based on multiple sets of experimental operating conditions. The thermal characteristic parameters include at least one of heat capacity, thermal resistance or loss coefficient.

[0107] Prediction module 606 is used to input the 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 to obtain the temperature change of the bus capacitor in the current operating cycle.

[0108] The prediction module 606 is also used to predict the temperature of the bus capacitor in the current operating cycle based on the temperature change of the bus capacitor in the current operating cycle.

[0109] In some possible implementations, the device also includes a calibration module for establishing calibration tables of the operating states and thermal characteristic parameters of multiple motors. This module is specifically used for:

[0110] The electrical and temperature parameters of the motor controller under multiple experimental conditions are obtained. Each experimental condition includes multiple operating states of multiple motors. Then, the thermal characteristic parameters of the bus capacitor are identified based on the electrical and temperature parameters to obtain a calibration table.

[0111] In some possible implementations, when determining multiple sets of experimental conditions, this module is specifically used for:

[0112] Multiple sets of experimental operating conditions for multiple motors are determined based on the orthogonal experimental method. The multiple sets of experimental operating conditions include multiple sets of operating states for multiple motors, and the operating states include at least one of speed or torque.

[0113] In some possible implementations, when identifying the thermal characteristic parameters of the bus capacitor based on electrical and temperature parameters, the calibration module is specifically used for:

[0114] Based on electrical parameters and the speeds of multiple motors, the loss coefficient of the bus capacitor under the first operating condition is obtained. Then, based on the loss coefficient of the bus capacitor and temperature parameters, parameter identification is performed to obtain the thermal capacitance and thermal resistance of the bus capacitor under the first operating condition.

[0115] In some possible implementations, the bus capacitor temperature prediction device also includes an over-temperature protection module, used to limit the operating status of multiple motors and reduce the temperature of the bus capacitor when the temperature is too high. When the multiple motors include an integrated starter generator and a traction motor, this module is specifically used for:

[0116] When the temperature of the bus capacitor exceeds the first threshold at the first moment, if the traction motor is in the power generation state, the traction motor is instructed to stop generating electricity.

[0117] When the temperature of the bus capacitor is greater than the second threshold at the second moment or the traction motor is not in the power generation state, if the integrated starter generator is in the power generation state at the second moment, it is instructed to stop the integrated starter generator from generating power. The second threshold is less than the first threshold and the second moment is later than the first moment.

[0118] When the temperature of the bus capacitor is greater than the second threshold at the third moment or the integrated starter generator is not generating power at the second moment, the traction motor is instructed to reduce the maximum torque until the temperature of the bus capacitor is less than the second threshold. The third moment is later than the second moment.

[0119] 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), a motor controller, 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.

[0120] 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.

[0121] 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.

[0122] 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.

[0123] 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 predicting the temperature of a bus capacitor, characterized in that, A motor controller for a multi-motor driven vehicle, the method comprising: The operating status of multiple motors controlled by the motor controller is obtained, and the operating status includes at least one of speed or torque; According to the operating status of the multiple motors, the calibration table is consulted to obtain the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The calibration table includes the mapping relationship between the operating status 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. The thermal characteristic parameters of the bus capacitor under the current operating conditions and the temperature of the bus capacitor in the previous operating cycle are input into the temperature prediction model to obtain the temperature change of the bus capacitor in the current operating cycle. The temperature of the bus capacitor in the current operating cycle is predicted based on the temperature change of the bus capacitor in the current operating cycle.

2. The method according to claim 1, characterized in that, The calibration table is obtained in the following way: The electrical and temperature parameters of the motor controller are obtained under the multiple sets of experimental conditions, which include multiple operating states of the multiple motors. The thermal characteristic parameters of the bus capacitor are identified based on the electrical parameters and the temperature parameters to obtain the calibration table.

3. The method according to claim 2, characterized in that, The multiple sets of experimental conditions were determined as follows: The multiple sets of experimental conditions for the multiple motors are determined based on the orthogonal experimental method. Each set of experimental conditions includes multiple operating states of the multiple motors, and the operating state includes at least one of speed or torque.

4. The method according to claim 3, characterized in that, The multiple motors include an integrated starter generator and a traction motor; The determination of the multiple sets of experimental conditions for the multiple motors based on the orthogonal experimental method includes: Multiple sets of experimental conditions for the integrated starter generator and the traction motor are determined based on the orthogonal experimental method, wherein, under each experimental condition, the torque and speed of the integrated starter generator are different from the torque and speed of the traction motor, at least one of which is different.

5. The method according to claim 2, characterized in that, The step of identifying the thermal characteristic parameters of the bus capacitor based on the electrical parameters and the temperature parameters includes: Based on the electrical parameters and the rotational speeds of the plurality of motors, the loss coefficient of the bus capacitor under the first operating condition is obtained; Based on the loss coefficient of the bus capacitor and the temperature parameter, parameter identification is performed to obtain the thermal capacitance and thermal resistance of the bus capacitor under the first operating condition.

6. The method according to any one of claims 2 to 5, characterized in that, The electrical parameters include at least one of the following: the voltage and current of the busbar, the voltage and current of the direct axis of the motor controller, the voltage and current of the quadrature axis of the motor controller, and the line voltage amplitude of the motor controller; The temperature parameters include at least one of the following: the temperature of the capacitor core of the bus capacitor, the temperature of the upper copper busbar, the temperature of the lower copper busbar, the cooling water temperature, the temperature of the input port of the bus capacitor, and the temperature of the output port on each motor side.

7. The method according to claim 1, characterized in that, The method further includes: A temperature prediction model for the bus capacitor is established based on the thermal network model of the bus capacitor of the motor controller. The thermal network model is used to reflect the thermal characteristics of the bus capacitor.

8. The method according to any one of claims 1 to 4, characterized in that, The plurality of motors includes an integrated starter generator and a traction motor, and the method further includes: When the temperature of the bus capacitor is greater than the first threshold at the first moment, if the traction motor is in the power generation state, the traction motor is instructed to stop generating electricity. When the temperature of the bus capacitor is greater than the second threshold at the second moment or the traction motor is not in the power generation state, if the integrated starter generator is in the power generation state at the second moment, the integrated starter generator is instructed to stop power generation, the second threshold is less than the first threshold, and the second moment is later than the first moment; When the temperature of the bus capacitor is greater than the second threshold at the third moment or the integrated starter generator is not generating power at the second moment, the traction motor is instructed to reduce the maximum torque until the temperature of the bus capacitor is less than the second threshold. The third moment is later than the second moment.

9. A temperature prediction device for bus capacitors, characterized in that, A motor controller for use in a multi-motor driven vehicle, the device comprising: A communication module is used to acquire the operating status of multiple motors controlled by the motor controller, wherein the operating status includes at least one of speed or torque; The query module is used to query the calibration table according to the operating status of the multiple motors to obtain the thermal characteristic parameters of the bus capacitor of the motor controller under the current operating conditions. The calibration table includes the mapping relationship between the operating status and the thermal characteristic parameters determined based on multiple sets of experimental operating conditions. The thermal characteristic parameters include at least one of heat capacity, thermal resistance or loss coefficient. The prediction module is used to input the 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 to obtain the temperature change of the bus capacitor in the current operating cycle. The prediction module is also used to predict the temperature of the bus capacitor in the current operating cycle based on the temperature change of the bus capacitor in the current operating cycle.

10. A controller, characterized in that, The controller includes: Memory is used to store computer programs or computer instructions; A processor for executing a computer program or computer instructions stored in the memory, causing the motor controller to perform the method as described in any one of claims 1 to 8.

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