Control method and device for vehicle cooling water pump, vehicle and storage medium

Abstract

The embodiment of the invention discloses a control method and device for a vehicle cooling water pump, a vehicle and a storage medium. The method comprises the steps that the current temperature of a motor and the maximum temperature rise of the motor after high-speed emergency power-off of the vehicle are obtained; acquiring a current rotating speed and a weak magnetic rotating speed of the motor; if the current temperature of the motor is larger than or equal to the first over-temperature threshold value and smaller than a preset second over-temperature threshold value, and the current rotating speed is larger than or equal to the flux weakening rotating speed, the cooling water pump is controlled to be started. According to the method, the maximum temperature rise of the motor after high-speed emergency power-off of the vehicle can be understood and predicted, and when the maximum temperature rise of the motor and the rotating speed of the motor meet preset conditions, it is determined that the current backflow phenomenon occurs, a cooling water pump is controlled to be started, and a motor control loop composed of a motor controller, a motor controller node and the motor is cooled. Therefore, the problems of serious heating of a motor control loop, sharp temperature rise of a motor controller node and damage of the motor controller node caused by the current backward flowing phenomenon after the vehicle is powered off emergently at a high speed are avoided.

Description

Technical Field

[0001] The present application relates to the technical field of cooling systems, and in particular to a control method and device for a vehicle cooling water pump, a vehicle and a storage medium. Background Art

[0002] New energy vehicles usually include a motor control loop consisting of a motor, a motor controller, and a motor controller node. Among them, the motor controller node is a circuit composed of power semiconductor devices (Insulated Gate Bipolar Transistor, IGBT). When the motor is running at high speed, the IGBT switching frequency is high. Affected by factors such as load and ambient temperature, the motor and IGBT will heat up. If the temperature continues to rise, the motor power performance will decrease, and even the IGBT will be damaged. Therefore, the temperature of the motor control loop should be controlled within an appropriate range.

[0003] In the related art, the temperature rise of the motor control circuit is generally monitored and the cooling water pump is controlled to dissipate heat and cool the motor control circuit. However, if the cooling water pump is controlled after the temperature rise occurs, the heat dissipation has a delay, causing the motor control circuit to continue to heat up, resulting in a decrease in the motor's power performance and even damage to the IGBT. For example, when the vehicle is powered off at high speed in an emergency, if the motor is running at high speed, a huge back electromotive force will be generated, causing the current to flow back into the motor control circuit, causing severe heating of the motor control circuit in a short period of time, and the temperature rise of the IGBT is particularly obvious. If the cooling water pump is controlled only after the temperature rise is detected, the heat dissipation will not be timely, resulting in damage to the IGBT.

[0004] It should be pointed out that the information disclosed in the background technology section of this application is only intended to deepen the understanding of the general background technology of this application, and should not be regarded as an admission or suggestion in any form that the information constitutes prior art already known to those skilled in the art. Summary of the invention

[0005] In view of this, the present application provides a control method, device, vehicle and storage medium for a vehicle cooling water pump, so as to solve the problem that after the vehicle is urgently powered off at high speed, the high-speed operation of the motor causes current to flow back into the motor control circuit, causing severe heating of the motor control circuit and rapid heating of the IGBT, thereby causing damage to the IGBT.

[0006] In a first aspect, an embodiment of the present application provides a method for controlling a cooling water pump of a vehicle, wherein the vehicle includes a motor controller, a motor controller node, and a motor, and the method includes: Obtain the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency, wherein the maximum temperature rise is used to characterize the difference between the power-off temperature of the motor and the maximum temperature, and the power-off temperature is the temperature of the motor when the vehicle is powered off at high speed in an emergency; Obtaining the current speed and flux weakening speed of the motor; If the current temperature of the motor is greater than or equal to the first over-temperature threshold and less than the preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed, the cooling water pump is controlled to start; The first over-temperature threshold is the difference between the second over-temperature threshold and the maximum temperature rise.

[0007] In a possible implementation, controlling the cooling water pump to start includes: Determine a control signal duty cycle according to a temperature difference of the motor, the temperature difference of the motor being a difference between a current temperature of the motor and the first over-temperature threshold, and the control signal duty cycle being used to control a flow rate of the cooling water pump; The speed of the cooling water pump impeller is controlled according to the duty cycle of the control signal.

[0008] In a possible implementation, determining the duty cycle of the control signal according to the temperature difference of the motor includes: According to the temperature difference of the motor, the duty cycle of the control signal is determined through fuzzy control.

[0009] In a possible implementation, determining the duty cycle of the control signal through fuzzy control according to the temperature difference of the motor includes: The duty cycle of the control signal is determined through fuzzy control according to the temperature difference and the speed difference of the motor, wherein the speed difference is the difference between the current speed and the weak magnetic speed.

[0010] In a possible implementation, obtaining the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency manner includes: Determine the mapping relationship between vehicle speed and maximum temperature rise based on historical data; The maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency is determined according to the current vehicle speed and the mapping relationship between the vehicle speed and the maximum temperature rise.

[0011] In a possible implementation manner, obtaining the magnetic field weakening speed of the motor includes: The weak magnetic rotation speed of the motor is determined according to the parameters of the motor, and the parameters of the motor are inherent parameters of the motor.

[0012] In a possible implementation manner, determining the magnetic weakening speed of the motor according to the parameters of the motor includes: Determining a first flux weakening speed of the motor according to the parameters of the motor; Determining a magnetic field weakening speed of the motor according to the first magnetic field weakening speed and the second magnetic field weakening speed; The second weak magnetic rotation speed is an experimental value obtained through testing.

[0013] In a possible implementation, the method further includes: If the current temperature of the motor is greater than or equal to the second over-temperature threshold, the cooling water pump is controlled to start.

[0014] In a possible implementation, the method further includes: If the current temperature of the motor controller is greater than a preset third over-temperature threshold, the cooling water pump is controlled to start.

[0015] In a possible implementation, the method further includes: If the current temperature of the motor controller node is greater than a preset fourth over-temperature threshold, the cooling water pump is controlled to start.

[0016] In a second aspect, an embodiment of the present application provides a control device for a vehicle cooling water pump, wherein the vehicle includes a motor controller, a motor controller node, and a motor, and the device includes: A maximum temperature rise acquisition module is used to acquire the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency. The maximum temperature rise is used to characterize the difference between the power-off temperature of the motor and the maximum temperature. The power-off temperature is the temperature of the motor when the vehicle is powered off at high speed in an emergency. A magnetic field weakening speed acquisition module, used to acquire the current speed and magnetic field weakening speed of the motor; A cooling water pump control module, configured to control the cooling water pump to start if the current temperature of the motor is greater than or equal to a first over-temperature threshold and less than a preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed; The first over-temperature threshold is the difference between the second over-temperature threshold and the maximum temperature rise.

[0017] In a third aspect, an embodiment of the present application provides a vehicle, including: A vehicle-mounted controller, wherein the controller is configured to execute the method described in any one of the first aspects.

[0018] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium, characterized in that the computer-readable storage medium includes a stored program, wherein when the program is running, the device where the computer-readable storage medium is located is controlled to execute any one of the methods described in the first aspect.

[0019] In the embodiment of the present application, the maximum temperature rise of the motor after the vehicle is powered off at high speed is predicted, and when the maximum temperature rise of the motor and the speed of the motor meet the preset conditions, it is determined that the current backflow phenomenon occurs, and the cooling water pump is controlled to start, and the motor control circuit composed of the motor controller, the motor controller node and the motor is cooled down. This avoids the problem that after the vehicle is powered off at high speed, the motor control circuit is severely heated due to the current backflow phenomenon, the motor controller node is rapidly heated, and the motor controller node is damaged. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0021] Figure 1 A schematic diagram of an application scenario provided for an embodiment of the present application.

[0022] Figure 2 A schematic flow chart of a method for controlling a vehicle cooling water pump provided in an embodiment of the present application.

[0023] Figure 3 A flowchart of a method for obtaining current temperature and maximum temperature rise provided in an embodiment of the present application.

[0024] Figure 4 A flowchart of a method for determining the magnetic weakening speed of a motor provided in an embodiment of the present application.

[0025] Figure 5 A schematic diagram of an electric drive cooling circuit provided in an embodiment of the present application.

[0026] Figure 6 A flow chart of a method for controlling the impeller speed of a cooling water pump provided in an embodiment of the present application.

[0027] Figure 7 A flowchart of a method for determining a duty cycle of a control signal provided in an embodiment of the present application.

[0028] Figure 8 A flowchart of another method for determining a duty cycle of a control signal provided in an embodiment of the present application.

[0029] Fig. 9 A schematic diagram of the structure of a vehicle control device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0030] In order to better understand the technical solution of the present application, the embodiments of the present application are described in detail below with reference to the accompanying drawings.

[0031] It should be clear that the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the present application.

[0032] The terms used in the embodiments of the present application are only for the purpose of describing specific embodiments, and are not intended to limit the present application. The singular forms "a", "said" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

[0033] It should be understood that the term "and / or" used in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0034] To facilitate understanding, the concepts involved in the embodiments of the present application are first briefly described below.

[0035] The motor control loop refers to the closed-loop control circuit of the vehicle motor, which consists of the motor, motor controller and motor controller node.

[0036] The motor controller node refers to the control circuit mainly composed of power semiconductor devices (Insulated Gate Bipolar Transistor, IGBT).

[0037] Emergency power-off at high speed means disconnecting the high-voltage power supply to the vehicle unexpectedly when the vehicle speed is greater than the speed corresponding to the weak magnetic speed of the motor.

[0038] The power-off temperature refers to the temperature of the motor when the vehicle is urgently powered off at high speed.

[0039] The maximum temperature rise refers to the difference between the motor's power-off temperature and its maximum temperature.

[0040] The first over-temperature threshold is the difference between the second over-temperature threshold and the maximum temperature rise.

[0041] The second over-temperature threshold is the motor's over-temperature preset value, which indicates the critical high temperature that the motor can withstand during operation. Exceeding this temperature may cause motor damage or a safety accident.

[0042] The third over-temperature threshold is the over-temperature preset value of the motor controller, which indicates the critical high temperature value that the motor controller can withstand during operation. Exceeding this temperature may cause damage to the motor controller or a safety accident.

[0043] The fourth over-temperature threshold refers to the over-temperature preset value of the motor controller node, which indicates the critical high temperature value that the motor controller node can withstand during operation. Exceeding this temperature may cause damage to the motor controller node or a safety accident.

[0044] For ease of understanding, specific application scenarios are further illustrated below.

[0045] See also Figure 1 , which provides a schematic diagram of an application scenario for the embodiment of the present application. Figure 1 As shown, the vehicle 100 includes: an onboard controller 101, a cooling water pump 102, and a motor control circuit 103. Specifically, the vehicle 100 controls the start and stop of the cooling water pump 102 according to the temperature of the motor control circuit 103 through the onboard controller 101.

[0046] The vehicle 100 is a new energy vehicle, which can be a pure electric vehicle or a hybrid vehicle. A pure electric vehicle has only an electric motor as a power source to provide power to the vehicle; a hybrid vehicle has two power sources, an engine and an electric motor, to provide power to the vehicle. The vehicle 100 can control the start and stop of the cooling water pump 102 according to the temperature of the motor control circuit 103 through the on-board controller 101.

[0047] The vehicle controller 101 can control the start and stop of the cooling water pump 102 according to the temperature of the motor control circuit 103 .

[0048] The cooling water pump 102 can receive the control signal of the vehicle controller 101 to turn on or off, and pressurize the coolant so that the coolant flows along the pipeline to dissipate heat for the motor control circuit 103. The cooling water pump 102 can be a mechanical water pump, an electronic water pump, a centrifugal water pump, etc.

[0049] The motor control loop 103 includes a motor, a motor controller and a motor controller node, and the motor operates under the control of the motor controller and the motor controller node, wherein the motor controller node is a circuit composed of IGBTs.

[0050] in addition, Figure 1 The vehicle structure shown in the figure is merely an exemplary description and should not be regarded as limiting the scope of protection of the present application.

[0051] In the related art, the temperature rise of the motor control circuit is generally monitored and the cooling water pump is controlled to dissipate heat and cool the motor control circuit. However, if the cooling water pump is controlled after the temperature rise occurs, the heat dissipation has a delay, causing the motor control circuit to continue to heat up, resulting in a decrease in the motor's power performance and even damage to the IGBT. For example, when the vehicle is powered off at high speed in an emergency, if the motor is running at high speed, a huge back electromotive force will be generated, causing the current to flow back into the motor control circuit, causing severe heating of the motor control circuit in a short period of time, and the temperature rise of the IGBT is particularly obvious. If the cooling water pump is controlled only after the temperature rise is detected, the heat dissipation will not be timely, resulting in damage to the IGBT.

[0052] In view of the above problems, in the embodiment of the present application, first, the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed are obtained, the maximum temperature rise refers to the difference between the power-off temperature of the motor and the highest temperature, and the power-off temperature is the temperature of the motor when the vehicle is powered off at high speed; secondly, the current speed and weak magnetic speed of the motor are obtained; then, if the current temperature of the motor is greater than or equal to the first over-temperature threshold, less than the preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed, the cooling water pump is controlled to be turned on, wherein the first over-temperature threshold is the difference between the second over-temperature threshold and the maximum temperature rise. It can be understood that the maximum temperature rise of the motor after the vehicle is powered off at high speed is predicted, and when the maximum temperature rise of the motor and the speed of the motor meet the preset conditions, it is determined that the current backflow phenomenon occurs, the cooling water pump is controlled to be turned on, and the motor control circuit composed of the motor controller, the motor controller node and the motor is cooled down. Thereby avoiding the problem that after the vehicle is powered off at high speed, the motor control circuit is seriously heated due to the current backflow phenomenon, the motor controller node is heated sharply, and the motor controller node is damaged.

[0053] Specifically, a detailed description is given below in conjunction with the accompanying drawings and specific embodiments.

[0054] See also Figure 2 , which is a flow chart of a method for controlling a vehicle cooling water pump according to an embodiment of the present application. The method can be applied to Figure 1 The vehicle controller in the application scenario shown is Figure 2 As shown, it mainly includes the following steps.

[0055] Step S201: Acquire the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency.

[0056] In the embodiment of the present application, the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency is a predicted value, not the actual maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency. For example, before the vehicle is powered off at high speed in an emergency, a certain method is used to predict that the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency is 40°C, while after the vehicle is powered off at high speed in an emergency, the actual maximum temperature rise of the motor may be 40.5°C. The predicted value and actual value of the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency may be the same, or there may be a difference.

[0057] In a possible implementation, a temperature sensor may be provided on the vehicle, and the temperature sensor may monitor the temperature of the motor in real time. The vehicle controller may obtain the current temperature of the motor through the temperature sensor. Of course, the vehicle controller may also obtain the current temperature of the motor through other methods, and the embodiments of the present application do not specifically limit this.

[0058] In a possible implementation, the vehicle controller obtains the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency by looking up a table.

[0059] Through experiments, the maximum temperature rise of the motor corresponding to different vehicle speeds after the current vehicle is powered off in an emergency is obtained in advance, and the experimental data is organized into a corresponding relationship table between vehicle speed and maximum temperature rise and stored in the vehicle controller. When the vehicle is powered off at high speed in an emergency, the vehicle controller obtains the maximum temperature rise of the motor based on the vehicle speed at the time of emergency power off and the corresponding relationship table between vehicle speed and maximum temperature rise.

[0060] By looking up the table to obtain the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency, the amount of calculation is greatly reduced, and the on-board controller responds faster. However, the result may not be too accurate. In addition, the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency is used for prediction, and the response sensitivity of the on-board controller is not too high.

[0061] Reference Figure 3 , which is a flow chart of a method for obtaining the current temperature and the maximum temperature rise provided in the embodiment of the present application. Figure 3 As shown, it mainly includes the following steps.

[0062] Step S301: Acquire the current temperature of the motor.

[0063] According to the method described above, the on-board controller can obtain the current temperature of the motor.

[0064] Step S302: Determine the mapping relationship between vehicle speed and maximum temperature rise according to historical data.

[0065] The historical data refers to the historical data of the vehicle speed and the maximum temperature rise of the motor when the vehicle is powered off at high speed in an emergency, including the historical data of the current vehicle and the historical data of the same type of vehicles in the same batch.

[0066] In a possible implementation, the mapping relationship between the vehicle speed and the maximum temperature rise is determined by calculation based on historical data.

[0067] Specifically, after the vehicle is powered on, historical data is obtained through the big data platform, namely the maximum temperature rise of the motors of a certain number of vehicles. These vehicles are from the same batch and model as the current vehicle, and the number is a preset value. The maximum temperature rise is the maximum temperature rise of the motor corresponding to different vehicle speeds after the vehicle is powered off in an unexpected emergency. Therefore, the motor of the same vehicle can obtain many maximum temperature rises, corresponding to different vehicle speeds when the vehicle is powered off in an emergency at high speed.

[0068] The historical data is fitted by the least squares method, that is, the maximum temperature rise of the motor corresponding to different vehicle speeds at the time of emergency power-off of the vehicle at high speed is fitted, and the mapping relationship between vehicle speed and maximum temperature rise is established, as shown in formula (1): (1) in, is the maximum temperature rise, , … is the mapping relationship fitting coefficient, and v is the vehicle speed.

[0069] The least squares method is a fitting method that minimizes the error between the obtained mapping relationship and the actual data by minimizing the sum of squares of the errors between the values ​​on the mapping relationship and the measured data, calculating the optimal coefficient of the mapping relationship.

[0070] For example, when the vehicle speed is 60 km / h and the maximum temperature rise is 30°C, it is expressed as (60,30). Then, if we have a set of historical data (60,30), (50,25), (80,40), the mapping relationship between the vehicle speed to be fitted and the maximum temperature rise is Then, construct the fitting matrix X and fitting vector Y: X= , Y=

[0071] calculate and : ,

[0072] According to the least squares normal equation Calculate the optimal coefficient of the mapping relationship:

[0073] Then, the mapping relationship between the vehicle speed and the maximum temperature rise corresponding to the historical data (60,30), (50,25), (80,40) is: .

[0074] Step S303: Determine the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency according to the mapping relationship between the vehicle speed and the maximum temperature rise and the current vehicle speed.

[0075] Exemplarily, according to the example in step S302, the mapping relationship between vehicle speed and maximum temperature rise is: If the vehicle is powered off urgently at the current moment, if the current vehicle speed is 96km / h, and the current vehicle speed is greater than the speed corresponding to the weak magnetic speed of the motor, the maximum temperature rise is 48℃.

[0076] Step S202: Obtain the current rotation speed and flux weakening rotation speed of the motor.

[0077] In practical applications, the on-board controller can obtain the current speed of the motor through a sensor, or measure the output signal of the motor in real time and calculate the current speed of the motor based on the output signal of the motor.

[0078] In a possible implementation, the current weak magnetic rotation speed of the motor is determined by testing, and the test result is stored in the vehicle controller.

[0079] Specifically, a pair of towing motors is used to drive the motor to run, and the back electromotive force generated by the motor is tested. When the back electromotive force is equal to the motor bus voltage, the motor speed is the weak magnetic speed.

[0080] When the back electromotive force is greater than the motor bus voltage, if the vehicle is powered off at high speed, current will flow back into the motor control circuit, causing severe heating of the motor control circuit in a short period of time, and the IGBT temperature rise is particularly obvious. If the heat dissipation is not timely, the temperature will continue to rise, affecting the motor power performance and may also cause damage to the IGBT.

[0081] The on-board controller can directly read the current weak magnetic speed of the motor from the memory. This implementation method does not require additional calculations, greatly reduces the amount of calculation of the on-board controller, shortens the response time of the on-board controller, and makes the control response more sensitive.

[0082] However, the data obtained through the test is discrete. When the vehicle is urgently powered off at high speed, it is impossible to accurately determine the weak magnetic speed corresponding to the various parameters of the motor.

[0083] In a possible implementation, the on-board controller determines the weak magnetic rotation speed of the motor according to the parameters of the motor.

[0084] The parameters of the motor include the number of motor pole pairs and the strength of the permanent magnet flux of the motor. The on-board controller determines the weak magnetic speed based on the number of motor pole pairs and the strength of the permanent magnet flux of the motor by using the back electromotive force coefficient calculation formula.

[0085] The calculation formula of back electromotive force coefficient is shown in formula (2): (2) in, is the back electromotive force coefficient, in units of ; is the pole pair number; is the flux strength of the permanent magnet of the motor.

[0086] For example, if the number of motor pole pairs is 4, the flux linkage strength of the motor permanent magnet is , then the back EMF coefficient of the motor is 10π If the back electromotive force generated by the motor is 150V, the weak magnetic speed of the motor is about 4775rpm.

[0087] However, there is a difference between the field weakening speed obtained in the test environment and the theoretical value of the field weakening speed calculated based on the motor parameters. In actual applications, the motor bus voltage will fluctuate within the allowable range, and the field weakening speed of the motor will also be affected.

[0088] In practical applications, the weakening speed of the motor is usually calculated in real time based on the weakening speed obtained by testing and the theoretical weakening speed calculated according to the parameters of the motor.

[0089] Reference Figure 4 , which is a flow chart of a method for determining the magnetic field weakening speed of a motor according to an embodiment of the present application. Figure 4 As shown, it mainly includes the following steps.

[0090] Step S401: determining a first field weakening speed of the motor according to the parameters of the motor.

[0091] The first field weakening speed refers to a theoretical field weakening speed obtained by calculating the parameters of the motor. According to the method described above, the first field weakening speed of the motor can be determined, which will not be described in detail here.

[0092] Step S402: Determine the magnetic field weakening speed of the motor according to the first magnetic field weakening speed and the second magnetic field weakening speed.

[0093] The second field weakening speed refers to the field weakening speed obtained by testing. According to the method described above, the second field weakening speed of the motor can be determined, which will not be described in detail here.

[0094] In a possible implementation, a preset correction coefficient is introduced, and the weakening magnetic speed of the motor is determined by weighting the first weakening magnetic speed and the second weakening magnetic speed.

[0095] The correction coefficient K is a preset value, and its value range is .

[0096] The on-board controller determines the motor's weak magnetic speed according to the weak magnetic speed correction formula. The weak magnetic speed correction formula is shown in formula (3): (3) in, is the field weakening speed, K is the correction factor, is the first field weakening speed, It is the second field weakening speed.

[0097] For example, if the correction coefficient K=0.3, the first field weakening speed =4680rpm, second field weakening speed =4775rpm, then the weak magnetic speed of the motor is 4746.5rpm.

[0098] Step S203: If the current temperature of the motor is greater than or equal to the first over-temperature threshold and less than the preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed, the cooling water pump is controlled to start.

[0099] The cooling water pump pressurizes the coolant so that the coolant circulates along the electric drive cooling circuit. The coolant circulation takes away the heat of the motor control circuit, thereby achieving a cooling effect.

[0100] For example, Figure 5 A schematic diagram of an electric drive cooling circuit is provided for an embodiment of the present application. Figure 5 As shown, the heat dissipation execution components in the electric drive cooling circuit include a cooling water pump, a low-temperature radiator and a temperature sensor, and the heat dissipated components include a motor controller, a motor controller node and a motor. The on-board controller obtains the temperature of the heat dissipated component through the temperature sensor, and controls the start and stop of the cooling water pump and the low-temperature radiator according to the temperature of the heat dissipated component to dissipate heat and cool down the heat dissipated component. When any heat dissipated component in the electric drive cooling circuit needs to dissipate heat and cool down, the on-board controller will control the cooling water pump and the low-temperature radiator to start.

[0101] It should be pointed out that Figure 5 The schematic diagram of an electric drive cooling circuit shown is only an exemplary description of the electric drive cooling circuit. In actual applications, those skilled in the art can determine the specific electric drive cooling circuit based on the specific electric drive system.

[0102] When the current temperature of the motor is greater than or equal to the first over-temperature threshold and less than the preset second over-temperature threshold, the current temperature of the motor will not affect the motor control loop. However, if the vehicle is powered off at high speed at this moment, a strong back electromotive force may be generated during the process of the motor sliding from the current speed to stop, causing current to flow back into the motor control loop, thereby causing the motor, motor controller, and motor controller nodes in the motor control loop to generate heat, especially the IGBT in the motor controller node will heat up sharply. If the current temperature of the motor plus the maximum temperature rise of the motor, it will exceed the second over-temperature threshold, resulting in a decrease in the motor's power performance and may also cause damage to the IGBT.

[0103] In practical applications, by judging whether the current speed is greater than or equal to the weak magnetic speed, it is determined whether current backflow will occur when the vehicle is powered off at high speed in an emergency.

[0104] In order to avoid the problem that when the vehicle is shut down at high speed, the current may flow back into the motor control circuit during the process of the motor sliding from high speed to stop, causing the motor to heat up seriously in a short period of time, the IGBT to heat up rapidly, resulting in a decrease in the motor's power performance or even damage to the IGBT, the cooling water pump needs to be turned on in advance for pre-heating.

[0105] In an embodiment of the present application, by judging the relationship between the current speed of the motor and the weak magnetic speed, it is predicted whether, at the current speed of the motor, current backflow into the motor control circuit will occur if the vehicle is urgently powered off at high speed; by judging the relationship between the current temperature of the motor and the first over-temperature threshold and the second over-temperature threshold, it is predicted whether, at the current temperature of the motor, if current backflow into the motor control circuit occurs, the temperature will be within an allowable range.

[0106] By judging the temperature and speed of the motor, it is possible to predict in real time whether the motor control circuit will be affected by overheating after the vehicle's high-speed emergency power-off. By controlling the start and stop of the cooling water pump, the motor control circuit can be pre-cooled, thereby avoiding the problem of motor power performance degradation or even IGBT damage due to overheating.

[0107] As described above, when the current temperature of the motor is greater than or equal to the first over-temperature threshold and less than the preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed, if the vehicle is urgently powered off at high speed at the current speed and current temperature of the motor, current backflow will enter the motor control circuit, and it will cause the motor to overheat and even burn out the IGBT. Therefore, the on-board controller controls the cooling water pump to turn on the motor control circuit to dissipate heat in advance to avoid the problem of motor power performance degradation and IGBT burning due to untimely heat dissipation caused by overheating of the motor.

[0108] In a possible implementation, if the current temperature of the motor is greater than or equal to the second over-temperature threshold, the on-board controller controls the cooling water pump to start.

[0109] Since the second over-temperature threshold represents the critical high temperature value that the motor can withstand during operation, if the current temperature of the motor exceeds the maximum temperature limit that the motor can withstand, the on-board controller controls the cooling water pump to start to dissipate heat and cool the motor control circuit.

[0110] In a possible implementation, if the temperature of the motor controller is greater than a preset third over-temperature threshold, the cooling water pump is controlled to start.

[0111] Since the third over-temperature threshold represents the critical value of the high temperature that the motor controller can withstand during operation, exceeding this temperature may cause damage to the motor controller or a safety accident. If the current temperature of the motor controller exceeds the critical value of the high temperature that the motor controller can withstand, the on-board controller controls the cooling water pump to start, dissipate heat and cool the motor controller, and also dissipate heat and cool the motor control circuit.

[0112] In a possible implementation, if the temperature of the motor controller node is greater than a preset fourth over-temperature threshold, the cooling water pump is controlled to start.

[0113] Since the fourth over-temperature threshold represents the critical value of the high temperature that the motor controller node can withstand during operation, exceeding this temperature may cause damage to the motor controller node or a safety accident. If the current temperature of the motor controller node exceeds the critical value of the high temperature that the motor controller node can withstand, the on-board controller controls the cooling water pump to start, dissipate heat and cool the motor controller node, and also dissipate heat and cool the motor control loop.

[0114] In practical applications, the third over-temperature threshold and the fourth over-temperature threshold are usually equal.

[0115] Since the impeller speed of the cooling water pump determines the flow rate and flow velocity of the coolant, and the flow rate and flow velocity of the coolant determine the speed of heat dissipation, in the embodiment of the present application, the on-board controller not only controls the start and stop of the cooling water pump, but also controls the impeller speed of the cooling water pump.

[0116] See also Figure 6 , is a flow chart of a method for controlling the impeller speed of a cooling water pump provided in an embodiment of the present application. Figure 6 As shown, in Figure 2 Based on the illustrated embodiment, the following steps are also included.

[0117] After step S203 , if the cooling water pump is turned on, the onboard controller also controls the impeller speed of the cooling water pump.

[0118] Step S601: Determine the duty cycle of the control signal according to the temperature difference of the motor.

[0119] The temperature difference of the motor refers to the difference between the current temperature of the motor and the first over-temperature threshold value, and the control signal duty cycle is used to control the flow rate of the cooling water pump.

[0120] In a possible implementation, the on-board controller determines the duty cycle of the control signal as a ratio of the temperature difference and the maximum temperature rise of the motor according to the temperature difference and the maximum temperature rise of the motor.

[0121] The larger the ratio of the motor's temperature difference to the maximum temperature rise, the greater the probability that the motor's current temperature may be overheated. The larger the duty cycle of the control signal, the greater the flow rate of the cooling water pump and the stronger the heat dissipation and cooling ability.

[0122] The on-board controller determines the duty cycle of the control signal as the ratio of the temperature difference and the maximum temperature rise of the motor according to the temperature difference and the maximum temperature rise of the motor. This method is simple and direct, requires little calculation, shortens the response time of the on-board controller to a certain extent, and makes the control response more sensitive.

[0123] However, the temperature difference and maximum temperature rise of the motor are constantly changing, which causes the duty cycle of the control signal to constantly change, thereby causing the impeller speed of the cooling water pump to constantly change, resulting in the impeller speed control of the cooling water pump being too sensitive.

[0124] In a possible implementation, the vehicle controller determines the duty cycle of the control signal through fuzzy control according to the temperature difference of the motor.

[0125] Fuzzy control is an intelligent control technology that achieves effective control of complex systems by simulating human approximate reasoning and comprehensive decision-making processes. Fuzzy control does not rely on the precise mathematical model of the controlled object and has strong resistance to changes and interference in system parameters. Therefore, through fuzzy control, the duty cycle of the control signal is determined, making the impeller speed control of the cooling water pump more robust and reducing the sensitivity of the impeller speed control to a certain extent.

[0126] Reference Figure 7 , which is a flow chart of a method for determining a duty cycle of a control signal provided in an embodiment of the present application. Figure 7 As shown, it mainly includes the following steps.

[0127] Step S701: Obtain the temperature difference of the motor and the fuzzy subset of the control signal duty cycle.

[0128] The temperature difference of the motor and the fuzzy subset of the control signal duty cycle are preset values ​​and can be directly read by the on-board controller.

[0129] The temperature difference of the motor is recorded in the fuzzy operation as , set its fuzzy subset ={large, medium, small}; the duty cycle of the control signal is recorded as P in the fuzzy operation, and its fuzzy subset is set ={Large, Medium, Small}.

[0130] Step S702: performing fuzzy processing on the temperature difference of the motor.

[0131] The actual physical domain of the temperature difference of the motor is the value range from zero to the maximum temperature rise, for example [0,50]. The actual physical domain refers to the actual value range of the fuzzy control input or output.

[0132] According to the fuzzification formula, the actual physical domain of the temperature difference of the motor is converted into a fuzzy value domain described in the form of discrete natural numbers, thereby realizing the fuzzification of the temperature difference of the motor.

[0133] The fuzzification formula is shown in formula (4): (4) Among them, e is the value of the variable converted to the fuzzy value range, and e is a discrete natural number; is the value of the actual physical domain of the variable; is the maximum value of the variable in the actual physical domain; is the minimum value of the variable in the actual physical domain; E is the quantization factor of the fuzzy value range.

[0134] For example, if the actual physical domain of the temperature difference of the motor is [0,50], the quantization factor E of the fuzzy value domain is 1, and the maximum value of the actual physical domain is =50℃, the minimum value in the actual physical domain =0℃, the temperature difference N of the motor = 25℃, then under the said conditions, the fuzzy value of the temperature difference of the motor is 0.

[0135] According to the above method, the fuzzy value of the temperature difference of the motor is calculated ={-1,0,1}.

[0136] Similarly, the fuzzy value of the control signal duty cycle is calculated ={-1,0,1} Step S703: Obtain a fuzzy membership table of the temperature difference and the duty cycle of the control signal.

[0137] The fuzzy membership table of the temperature difference and the fuzzy membership table of the control signal duty cycle are preset values, which are stored in the vehicle controller and can be directly read by the vehicle controller.

[0138] Exemplarily, Table 1 provides a fuzzy membership table of the temperature difference of a motor according to an embodiment of the present application.

[0139] Table 1:

[0140] It should be pointed out that Table 1 is only an exemplary description of the fuzzy membership of the temperature difference of the motor. In practical applications, those skilled in the art can determine the fuzzy membership table of the temperature difference of the motor according to the actual membership of the temperature difference of the motor.

[0141] It can be seen from Table 1 that when the fuzzy value of the temperature difference of the motor is -1, the probability that the corresponding fuzzy language motor temperature difference is small is 1; when the fuzzy value of the temperature difference of the motor is 0, the probability that the corresponding fuzzy language motor temperature difference is small is 0.2; when the fuzzy value of the temperature difference of the motor is 0, the probability that the corresponding fuzzy language motor temperature difference is small is 0.1.

[0142] Then, the membership matrix of the temperature difference of the motor is as follows:

[0143] Illustratively, Table 2 provides a fuzzy membership table of a control signal duty cycle according to an embodiment of the present application.

[0144] Table 2:

[0145] It should be pointed out that Table 2 is only an exemplary description of the fuzzy membership of the control signal duty cycle. In practical applications, those skilled in the art can determine the fuzzy membership table of the control signal duty cycle based on the actual membership of the control signal duty cycle.

[0146] Then, the membership matrix of the control signal duty cycle is as follows:

[0147] Step S704: Obtain a fuzzy control rule table for the duty cycle of the control signal.

[0148] The fuzzy control rule of the duty cycle of the control signal is a preset value table, which is stored in the vehicle controller. The vehicle controller can directly read the fuzzy control rule table of the duty cycle of the control signal.

[0149] Exemplarily, Table 3 provides a control rule table for a duty cycle of a control signal in an embodiment of the present application.

[0150] Table 3:

[0151] It should be pointed out that Table 3 is only an exemplary description of the control signal duty cycle control rule. In practical applications, those skilled in the art can determine the control signal duty cycle control rule table according to the actual control signal duty cycle control rule.

[0152] It can be seen from Table 3 that if the temperature difference rule is large, the control rule of the control signal duty cycle is large.

[0153] Step S705: Establish a fuzzy relationship matrix.

[0154] The control rule table for the duty cycle of the control signal has 3 rules in total, forming a fuzzy relationship matrix R, where R is the submatrix corresponding to each rule. The synthesis of submatrices is the membership vector of the temperature difference in the corresponding sub-rule i , the membership vector of the control signal duty cycle Direct product operation between: (5) Pair Matrix Perform the merging operation to obtain the fuzzy relationship matrix R: (6) For example, if the fuzzy relationship matrix R obtained according to the above algorithm is as follows:

[0155] It should be pointed out that R is only an exemplary description of the fuzzy relationship matrix. In practical applications, those skilled in the art can determine the fuzzy relationship matrix R according to the actual temperature difference and the degree of membership of the duty cycle of the control signal.

[0156] Step S706: Determine the duty cycle of the control signal through fuzzy operation according to the fuzzy relationship matrix.

[0157] According to formula (4) and fuzzy value Determine the membership matrix .

[0158] On this basis, the membership matrix of the control signal duty cycle is calculated .in,

[0159] For example, if the actual physical domain of the temperature difference of the motor is [0,50], the quantization factor E of the fuzzy value domain is 1, and the maximum value of the actual physical domain is =50℃, the minimum value in the actual physical domain =0℃, the temperature difference of the motor N=25℃, then, under the above conditions, the fuzzy value of the temperature difference of the motor is 0. That is: =0 According to Table 1, when e=0, the maximum membership degree corresponds to the fuzzy subset "medium", and the corresponding membership matrix is [0.2,1,0.3].

[0160] Then, the membership matrix of the control signal duty cycle is:

[0161] =

[0162] =

[0163] is a1 3. Among the three elements of the row vector, the element with the largest value, that is, the element with the largest membership, has a corresponding fuzzy value e of 0.

[0164] According to the control signal duty cycle calculation formula, the control signal duty cycle P is calculated.

[0165] The calculation formula of the control signal duty cycle is shown in formula (7): + e (7) Where P is the duty cycle of the control signal, is the maximum value of the duty cycle of the control signal within the value range, is the minimum value of the duty cycle of the control signal within the value range, n is the number of elements of the fuzzy subset corresponding to the temperature difference, and e is the fuzzy value corresponding to the temperature difference.

[0166] If the value range of the control signal duty cycle P is [0,1], the control signal duty cycle P=0.5 can be determined according to formula (7).

[0167] As mentioned above, the temperature rise is the result of heating of the motor control circuit, and one of the causes is the motor speed. Therefore, the duty cycle of the control signal can be determined not only according to the temperature difference, but also according to the temperature difference and speed difference.

[0168] In a possible implementation, the vehicle controller determines the duty cycle of the control signal through fuzzy control according to the temperature difference and the speed difference of the motor.

[0169] Reference Figure 8 , provides a flow chart of another method for determining the duty cycle of a control signal for an embodiment of the present application. Figure 8 As shown, it mainly includes the following steps.

[0170] Step S801: Obtain the temperature difference, speed difference and control signal duty cycle fuzzy subset of the motor.

[0171] The temperature difference of the motor and the fuzzy subset of the control signal duty cycle are preset values ​​and can be directly read by the on-board controller.

[0172] The temperature difference of the motor is recorded in the fuzzy operation as , set its fuzzy subset ={large, medium, small}; the speed difference is recorded as , set its fuzzy subset ={large, medium, small}; the duty cycle of the control signal is recorded as P in the fuzzy operation, and its fuzzy subset is set ={large, somewhat large, medium, somewhat small, small}.

[0173] Step S802: fuzzy processing is performed on the temperature difference and the rotation speed difference.

[0174] According to the fuzzy formula, the actual physical domain of temperature difference and speed difference is converted into a fuzzy value domain described in the form of discrete natural numbers, so as to realize the fuzzification of the temperature difference of the motor.

[0175] For example, if the actual physical domain of the temperature difference of the motor is [0,50], the quantization factor E of the fuzzy value domain is 1, and the maximum value of the actual physical domain is =50℃, the minimum value in the actual physical domain =0℃, the temperature difference N of the motor = 25℃, then under the said conditions, the fuzzy value of the temperature difference of the motor is 0.

[0176] If the actual physical domain of the speed difference is [500,1000], the quantization factor E of the fuzzy value domain is 1, and the actual physical domain maximum value is =1000rpm, the minimum value in the actual physical domain =500rpm, the speed difference N of the motor =600rpm, then, under the said conditions, the fuzzy value of the temperature difference of the motor is 0.

[0177] According to the above method, the fuzzy value of the temperature difference of the motor is calculated ={-1,0,1}, fuzzy value of the speed difference ={-1,0,1}.

[0178] Step S803: Obtain the fuzzy membership table of the temperature difference and the rotation speed difference.

[0179] The fuzzy membership tables of the temperature difference and the rotation speed difference are preset values, stored in the vehicle controller, and can be directly read by the vehicle controller.

[0180] Exemplarily, Table 4 provides a fuzzy membership table of temperature difference for an embodiment of the present application.

[0181] Table 4:

[0182] It should be pointed out that Table 4 is only an exemplary description of the fuzzy membership of the temperature difference. In practical applications, those skilled in the art can determine the fuzzy membership table of the temperature difference according to the actual membership of the temperature difference.

[0183] Then, the membership matrix of the temperature difference of the motor is as follows:

[0184] Exemplarily, Table 5 provides a fuzzy membership table of rotation speed difference for an embodiment of the present application.

[0185] Table 5:

[0186] It should be pointed out that Table 5 is only an exemplary description of the fuzzy membership of the motor speed difference. In practical applications, those skilled in the art can determine the fuzzy membership table of the motor speed difference according to the actual membership of the motor speed difference.

[0187] Then, the membership matrix of the motor speed difference is as follows:

[0188] Exemplarily, Table 6 provides a fuzzy membership table of a control signal duty cycle according to an embodiment of the present application.

[0189] Table 6:

[0190] It should be pointed out that Table 6 is only an exemplary description of the fuzzy membership of the control signal duty cycle. In practical applications, those skilled in the art can determine the fuzzy membership table of the control signal duty cycle based on the actual membership of the control signal duty cycle.

[0191] Then, the membership matrix of the control signal duty cycle is as follows:

[0192] Step S804: Obtain a fuzzy control rule table for the duty cycle of the control signal.

[0193] The fuzzy control rule of the duty cycle of the control signal is a preset value table, which is stored in the vehicle controller. The vehicle controller can directly read the fuzzy control rule table of the duty cycle of the control signal.

[0194] Exemplarily, Table 7 provides a control rule table for a control signal duty cycle in an embodiment of the present application.

[0195] Table 7:

[0196] It should be pointed out that Table 7 is only an exemplary description of the control signal duty cycle control rule. In practical applications, those skilled in the art can determine the control signal duty cycle control rule table according to the actual control signal duty cycle control rule.

[0197] It can be seen from Table 7 that there are 9 control rules for the duty cycle of the control signal. For example, if the rule for the temperature difference is large and the rule for the speed difference is medium, then the control rule for the duty cycle of the control signal is large.

[0198] Step S805: Establish a fuzzy relationship matrix.

[0199] The control rule table for the duty cycle of the control signal has a total of 9 rules, forming a fuzzy relationship matrix R, where R is the submatrix corresponding to each rule. Fuzzy synthesis of . Submatrix is the membership matrix corresponding to the temperature difference rule and speed rule membership matrix Direct product operation: (8) Pair Matrix Perform the merging operation to obtain the fuzzy relationship matrix R:

[0200] That is, any element at any position in the fuzzy relationship matrix R is all 9 sub-matrices The maximum value of the elements at the same position in .

[0201] For example, if the fuzzy relationship matrix R obtained according to the above algorithm is as follows: R=

[0202] It should be pointed out that R is only an exemplary description of the fuzzy relationship matrix. In practical applications, those skilled in the art can determine the fuzzy relationship matrix R according to the actual temperature difference and the degree of membership of the duty cycle of the control signal.

[0203] Step S806: Determine the duty cycle of the control signal through fuzzy operation according to the fuzzy relationship matrix.

[0204] According to formula (4) and fuzzy value , Determine the membership matrix .

[0205] On this basis, the membership matrix of the control signal duty cycle is calculated .in,

[0206] For example, if the actual physical domain of the temperature difference of the motor is [0,50], the quantization factor E of the fuzzy value domain is 1, and the maximum value of the actual physical domain is =50℃, the minimum value in the actual physical domain =0℃, the temperature difference of the motor N=25℃, then, under the above conditions, the fuzzy value of the temperature difference of the motor is 0. That is: =0 According to Table 4, when = 0, the maximum membership degree corresponds to the fuzzy subset "medium", and the corresponding membership matrix is [0.1,0.4,1].

[0207] The actual physical domain of the speed difference is [500,1000], the quantization factor of the fuzzy value domain is E=1, and the actual physical domain maximum value is =1000rpm, the minimum value in the actual physical domain =500rpm, the motor speed difference N=600rpm, then, under the above conditions, the fuzzy value of the motor temperature difference is 0. That is: =0 According to Table 5, when = 0, the maximum membership degree corresponds to the fuzzy subset "medium", and the corresponding membership matrix is [0.1,0.4,0.9].

[0208] Then, the membership matrix of the control signal duty cycle is:

[0209] is a1 5, among the 5 elements of the row vector, compare and obtain the element with the largest value, that is, the element with the largest membership. For example, the fuzzy value corresponding to the element with the largest membership is is 1.

[0210] According to the control signal duty cycle calculation formula, the control signal duty cycle P is calculated.

[0211] If the value range of the control signal duty cycle P is [0,1], the control signal duty cycle P=0.6 can be determined according to formula (7).

[0212] In a possible implementation, the vehicle controller determines the duty cycle of the control signal through fuzzy control according to the temperature difference of the motor, the speed difference, the temperature difference of the motor controller and the temperature difference of the motor control node.

[0213] According to the method described above, the control signal duty ratio P1 controlled by the temperature difference of the motor, the control signal duty ratio P2 controlled by the temperature difference and speed difference of the motor, the control signal duty ratio P3 controlled by the temperature difference of the motor controller, and the control signal duty ratio P4 controlled by the motor controller node can be determined respectively. The final control signal duty ratio adopts the principle of taking the largest one, that is: P=MAX{P1, P2, P3, P4}.

[0214] Step S602: controlling the impeller speed of the cooling water pump according to the duty cycle of the control signal.

[0215] The on-board controller sends the control signal duty cycle to the cooling water pump, and the cooling water pump adjusts the impeller speed according to the control signal duty cycle, thereby adjusting the coolant flow and flow rate, so that the heat dissipation and cooling rate is adjusted.

[0216] Corresponding to the above method embodiment, the present application also provides a vehicle control device. Specifically, see Fig. 9 , is a schematic diagram of the structure of a vehicle control device provided in an embodiment of the present application. Fig. 9 As shown, the figure shows a vehicle control device 901. The vehicle control device 901 includes: a maximum temperature rise acquisition module 902, a weak magnetic speed acquisition module 903, and a cooling water pump control module 904. Specifically, the maximum temperature rise acquisition module 902 is used to obtain the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed; the weak magnetic speed acquisition module 903 is used to obtain the current speed and weak magnetic speed of the motor; the cooling water pump control module 904 is used to control the start and stop of the cooling water pump.

[0217] The specific contents involved in the embodiments of the present application can be found in the description of the above method embodiments. For the sake of brevity, they will not be elaborated on here.

[0218] Corresponding to the above method embodiment, the present application also provides a vehicle. The vehicle specifically includes a controller for executing some or all of the steps in the above method embodiment, which will not be described in detail for the sake of brevity.

[0219] Corresponding to the above method embodiments, the present application also provides a computer storage medium, wherein the computer storage medium may store a program, and when the program is executed, the program may include some or all of the steps in each embodiment of the simulation scene generation method provided by the present invention. The storage medium may be a disk, an optical disk, a read-only memory (ROM) or a random access memory (RAM), etc.

[0220] In the embodiments of the present application, "at least one" refers to one or more, and "plurality" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent the existence of A alone, the existence of A and B at the same time, and the existence of B alone. Among them, A and B can be singular or plural. The character " / " generally indicates that the previous and subsequent associated objects are in an "or" relationship. "At least one of the following" and similar expressions refer to any combination of these items, including any combination of single or plural items. For example, at least one of a, b and c can be represented by: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple.

[0221] Those of ordinary skill in the art will appreciate that the various units and algorithm steps described in the embodiments disclosed herein can be implemented in a combination of electronic hardware, computer software, and electronic hardware. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professional and technical personnel can use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of this application.

[0222] Those skilled in the art can clearly understand that, for the convenience and brevity of description, the specific working processes of the systems, devices and units described above can refer to the corresponding processes in the aforementioned method embodiments and will not be repeated here.

[0223] In several embodiments provided in the present application, if any function is implemented in the form of a software functional unit and sold or used as an independent product, it can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present application is essentially or the part that contributes to the prior art or the part of the technical solution can be embodied in the form of a software product, and the computer software product is stored in a storage medium, including a number of instructions to enable a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the method described in each embodiment of the present application. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM), random access memory (RAM), disk or optical disk, etc., various media that can store program codes.

[0224] In this specification, the same or similar parts between the various embodiments can be referred to each other. In particular, for the device embodiment and the terminal embodiment, since they are basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the description in the method embodiment.

Claims

1. A method for controlling a vehicle cooling water pump, characterized in that: The vehicle includes a motor controller, a motor controller node, and a motor, and the method includes: Obtain the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency, wherein the maximum temperature rise is used to characterize the difference between the power-off temperature of the motor and the maximum temperature, and the power-off temperature is the temperature of the motor when the vehicle is powered off at high speed in an emergency; Obtaining the current speed and flux weakening speed of the motor; If the current temperature of the motor is greater than or equal to the first over-temperature threshold and less than the preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed, the cooling water pump is controlled to start; The first over-temperature threshold is the difference between the second over-temperature threshold and the maximum temperature rise.

2. The method according to claim 1, characterized in that The controlling the cooling water pump to start includes: Determine a control signal duty cycle according to a temperature difference of the motor, the temperature difference of the motor being a difference between a current temperature of the motor and the first over-temperature threshold, and the control signal duty cycle being used to control a flow rate of the cooling water pump; The impeller speed of the cooling water pump is controlled according to the duty cycle of the control signal.

3. The method according to claim 2, characterized in that Determining the duty cycle of the control signal according to the temperature difference of the motor includes: According to the temperature difference of the motor, the duty cycle of the control signal is determined through fuzzy control.

4. The method according to claim 3, characterized in that Determining the duty cycle of the control signal through fuzzy control according to the temperature difference of the motor includes: The duty cycle of the control signal is determined through fuzzy control according to the temperature difference and the speed difference of the motor, wherein the speed difference is the difference between the current speed and the weak magnetic speed.

5. The method according to claim 1, characterized in that Obtain the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency, including: Determine the mapping relationship between vehicle speed and maximum temperature rise based on historical data; The maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency is determined according to the current vehicle speed and the mapping relationship between the vehicle speed and the maximum temperature rise.

6. The method according to claim 1, characterized in that The method obtains the field weakening speed of the motor, comprising: The weak magnetic rotation speed of the motor is determined according to the parameters of the motor, and the parameters of the motor are inherent parameters of the motor.

7. The method according to claim 6, characterized in that Determining the magnetic weakening speed of the motor according to the parameters of the motor includes: Determining a first flux weakening speed of the motor according to the parameters of the motor; Determining a magnetic field weakening speed of the motor according to the first magnetic field weakening speed and the second magnetic field weakening speed; The second weak magnetic rotation speed is an experimental value obtained through testing.

8. The method according to claim 1, characterized in that The method further comprises: If the current temperature of the motor is greater than or equal to the second over-temperature threshold, the cooling water pump is controlled to start.

9. The method according to claim 1, characterized in that: The method further comprises: If the current temperature of the motor controller is greater than a preset third over-temperature threshold, the cooling water pump is controlled to start.

10. The method according to claim 1, characterized in that The method further comprises: If the current temperature of the motor controller node is greater than a preset fourth over-temperature threshold, the cooling water pump is controlled to start.

11. A control device for a vehicle cooling water pump, characterized in that: The vehicle comprises a motor controller, a motor controller node and a motor, and the device comprises: A maximum temperature rise acquisition module is used to acquire the current temperature of the motor and the maximum temperature rise of the motor after the vehicle is powered off at high speed in an emergency. The maximum temperature rise is used to characterize the difference between the power-off temperature of the motor and the maximum temperature. The power-off temperature is the temperature of the motor when the vehicle is powered off at high speed in an emergency. A magnetic field weakening speed acquisition module, used to acquire the current speed and magnetic field weakening speed of the motor; A cooling water pump control module, configured to control the cooling water pump to start if the current temperature of the motor is greater than or equal to a first over-temperature threshold and less than a preset second over-temperature threshold, and the current speed is greater than or equal to the weak magnetic speed; The first over-temperature threshold is the difference between the second over-temperature threshold and the maximum temperature rise.

12. A vehicle, characterized in that: include: An on-vehicle controller, wherein the controller is configured to execute the method according to any one of claims 1 to 10.

13. A computer-readable storage medium, characterized in that: The computer-readable storage medium includes a stored program, wherein when the program is executed, the device where the computer-readable storage medium is located is controlled to execute the method according to any one of claims 1 to 10.

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