Method and device for evaluating over-temperature risk of direct-current bus capacitor of drive motor controller

Abstract

The application provides a kind of driving motor controller DC bus capacitor over-temperature risk assessment method and device, the method comprises: obtaining the temperature rise rate of DC bus capacitor of driving motor controller at each steady state operating point according to bench test, and determining the corresponding target temperature rise rate;When the driving motor controller of target vehicle is powered on, the initial temperature of the capacitor of the DC bus capacitor of the driving motor controller is obtained;According to the initial temperature of the capacitor, the current operating condition of the driving motor controller and the target temperature rise rate, the capacitor temperature rise estimation curve is calculated;When it is judged according to the capacitor temperature rise estimation curve whether the DC bus capacitor exists over-temperature risk, the torque output of the driving motor controller is limited.The method and device can accurately detect over-temperature risk and limit the torque output of the motor without using capacitor sensor, so as to ensure the safety of capacitor while reducing unnecessary power interruption, improve driving safety and continuity of vehicle operation.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of automobile motor, in particular to a driving motor controller DC bus capacitor over-temperature risk assessment method and device. BACKGROUND

[0002] At present, in the driving motor control system of electric vehicles, the temperature monitoring of key components such as capacitors generally relies on temperature sensors directly buried near the capacitors. However, this monitoring method has significant limitations, that is, the temperature sensor itself may fail due to short circuit, open circuit and other faults. Once the temperature sensor is abnormal, the system often cannot accurately assess the actual temperature state of the capacitor, and then triggers an over-protection measure to directly stop the power output of the vehicle to avoid potential over-temperature risks. However, it is found in practice that although this method can effectively prevent the capacitor from overheating and damaging, it inevitably leads to power interruption of the vehicle, making it difficult for the driver to safely transfer the vehicle to a safe area in the case of power loss, thereby increasing the driving risk and the possibility of vehicle damage. SUMMARY

[0003] The purpose of the embodiments of the present application is to provide a driving motor controller DC bus capacitor over-temperature risk assessment method and device, which can assess the over-temperature risk of the driving motor controller DC bus capacitor without the need for sensors, and timely limit the torque output of the motor when the over-temperature risk is assessed, so as to ensure the safety of the capacitor while reducing unnecessary power interruption and improving driving safety and continuity of vehicle operation.

[0004] The first aspect of the present application provides a driving motor controller DC bus capacitor over-temperature risk assessment method, comprising:

[0005] obtaining the temperature rise rate of the DC bus capacitor of the driving motor controller at each steady state operating point according to bench test;

[0006] obtaining the initial temperature of the DC bus capacitor of the driving motor controller when the driving motor controller of the target vehicle is powered on;

[0007] determining the current operating condition of the driving motor controller;

[0008] determining the target temperature rise rate corresponding to the current operating condition according to the temperature rise rate of the DC bus capacitor;

[0009] calculating the capacitor temperature rise estimation curve according to the initial temperature of the capacitor, the current operating condition and the target temperature rise rate;

[0010] judging whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve;

[0011] If yes, limit the torque output of the drive motor controller.

[0012] In the implementation process, the method can evaluate the over-temperature risk of the drive motor controller DC bus capacitor without the need of sensors, and limit the torque output of the motor in time when it is evaluated that there is an over-temperature risk, so as to ensure the safety of the capacitor while reducing unnecessary power interruption and improving driving safety and continuity of vehicle operation.

[0013] Further, the obtaining of the temperature rise rate of the DC bus capacitor of the drive motor controller at each steady state operating point according to the bench test comprises:

[0014] obtaining a preset steady state operating point; wherein the steady state operating point comprises one or more of coolant temperature, motor speed, motor torque, cooling condition reference signal, and power related reference signal;

[0015] obtaining temperature change data of the DC bus capacitor of the drive motor controller at each steady state operating point according to the bench test; wherein in the bench test, the initial temperature of the DC bus capacitor on the test bench is consistent with the preset water temperature;

[0016] calculating the temperature rise rate corresponding to each steady state operating point according to the temperature change data.

[0017] Further, the calculating of the temperature rise rate corresponding to each steady state operating point according to the temperature change data comprises:

[0018] for each steady state operating point, judging whether the DC bus capacitor can rise from the preset water temperature to a preset over-temperature threshold according to the temperature change data;

[0019] if yes, obtaining a first temperature rise time according to the temperature change data, and calculating the temperature rise rate according to the first temperature rise time and the preset over-temperature threshold.

[0020] Further, the method further comprises:

[0021] when it is judged according to the temperature change data that the DC bus capacitor cannot rise from the preset water temperature to the preset over-temperature threshold, calculating the temperature rise rate below the thermal equilibrium point and the temperature rise rate above the thermal equilibrium point according to the temperature change data.

[0022] Further, the calculating of the temperature rise rate below the thermal equilibrium point and the temperature rise rate above the thermal equilibrium point according to the temperature change data comprises:

[0023] determining a current steady state operating point to be calculated and a thermal equilibrium temperature value corresponding to the current steady state operating point;

[0024] obtaining, according to the temperature change data, a second temperature rise time for the capacitor temperature of the DC bus capacitor to rise from the initial temperature to the thermal equilibrium temperature value for the first time;

[0025] calculating, according to the thermal equilibrium temperature value and the second temperature rise time, a temperature rise rate of the current steady state operating point below the thermal equilibrium point;

[0026] after the capacitor temperature of the DC bus capacitor reaches the thermal equilibrium state, and a deviation between the thermal equilibrium temperature value and the preset over-temperature threshold is greater than a preset deviation threshold, determining a new steady state operating point according to the temperature change data and the current steady state operating point;

[0027] obtaining, according to the temperature change data, the current steady state operating point and the new steady state operating point, a duration for the capacitor temperature of the DC bus capacitor to return from the new thermal equilibrium temperature value to the thermal equilibrium temperature value again;

[0028] calculating, according to the thermal equilibrium temperature value, the new thermal equilibrium temperature value and the duration, a temperature rise rate of the current steady state operating point above the thermal equilibrium point;

[0029] wherein the water temperature and the rotating speed of the new steady state operating point are the same as those of the current steady state operating point, and the torque of the new steady state operating point is greater than that of the current steady state operating point, and a deviation between the new thermal equilibrium temperature value of the new steady state operating point and the preset over-temperature threshold is not greater than the deviation threshold.

[0030] Further, the obtaining of the capacitor initial temperature of the DC bus capacitor of the drive motor controller comprises:

[0031] reading a last estimated capacitor temperature value, a last water temperature value and a last absolute time stored when the drive motor controller is last powered off;

[0032] obtaining a current water temperature value and a current absolute time when the drive motor controller is currently powered on;

[0033] calculating, according to the last estimated capacitor temperature value, the last water temperature value, the last absolute time, the current water temperature value and the current absolute time, the capacitor initial temperature of the DC bus capacitor when the drive motor controller is powered on.

[0034] Further, the calculating of the capacitor temperature rise estimation curve according to the capacitor initial temperature, the current operating condition and the target temperature rise rate comprises:

[0035] determining whether the current operating condition is a thermal equilibrium point operating condition;

[0036] If no, calculate a capacitor temperature rise estimation curve according to the capacitor initial temperature and the target temperature rise rate;

[0037] If yes, determine a target thermal equilibrium temperature corresponding to the current operating condition;

[0038] Calculate a capacitor temperature rise estimation curve according to the target thermal equilibrium temperature, the target temperature rise rate and the capacitor initial temperature.

[0039] Further, the judging whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve comprises:

[0040] Judging whether the capacitor temperature exceeds a preset over-temperature threshold according to the capacitor temperature rise estimation curve;

[0041] If yes, judging whether a duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than a preset first over-temperature time threshold according to the capacitor temperature rise estimation curve;

[0042] If yes, determining that the DC bus capacitor has an over-temperature risk.

[0043] Further, the limiting the torque output of the drive motor controller comprises:

[0044] Obtaining a current water temperature and a current rotating speed of the drive motor controller under the current operating condition;

[0045] Determining a maximum torque value corresponding to a thermal equilibrium condition according to the current water temperature and the current rotating speed;

[0046] Determining an upper limit of the torque output of the drive motor controller as the maximum torque value;

[0047] When it is judged according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold and a duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than a preset second over-temperature time threshold, obtaining a target capacitor temperature exceeding the preset over-temperature threshold; wherein the second over-temperature time threshold is greater than the first over-temperature time threshold;

[0048] Calculating a torque value difference according to the target capacitor temperature, the preset over-temperature threshold and the maximum torque value;

[0049] Determining the upper limit of the torque output of the drive motor controller as the torque value difference;

[0050] determining that the capacitor temperature exceeds the preset over-temperature threshold and the duration of exceeding the preset over-temperature threshold is greater than a preset third over-temperature time threshold, determining the upper limit of the output torque of the drive motor controller as 0; wherein the third over-temperature time threshold is greater than the second over-temperature time threshold.

[0051] The second aspect of the present application provides a drive motor controller DC bus capacitor over-temperature risk evaluation device, the drive motor controller DC bus capacitor over-temperature risk evaluation device comprises:

[0052] The first acquisition unit is configured to acquire the DC bus capacitor temperature rise rate of the drive motor controller at each steady state operating point according to the bench test.

[0053] The second acquisition unit is configured to acquire the initial capacitor temperature of the DC bus capacitor of the drive motor controller when the drive motor controller of the target vehicle is powered on.

[0054] The first determination unit is configured to determine the current operating condition of the drive motor controller.

[0055] The second determination unit is configured to determine the target temperature rise rate corresponding to the current operating condition according to the DC bus capacitor temperature rise rate.

[0056] The calculation unit is configured to calculate a capacitor temperature rise estimation curve according to the initial capacitor temperature, the current operating condition, and the target temperature rise rate.

[0057] The judgment unit is configured to determine whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve.

[0058] The limit control unit is configured to limit the torque output of the drive motor controller when it is determined that the DC bus capacitor has an over-temperature risk.

[0059] Further, the first acquisition unit comprises:

[0060] The first acquisition subunit is configured to acquire a preset steady state operating point; wherein the steady state operating point comprises one or more of coolant temperature, motor speed, motor torque, cooling condition reference signal, and power related reference signal.

[0061] The first acquisition subunit is further configured to acquire temperature change data of the DC bus capacitor of the drive motor controller at each steady state operating point according to the bench test; wherein in the bench test, the initial temperature of the DC bus capacitor on the test bench is consistent with the preset water temperature.

[0062] The first calculation subunit is configured to calculate the temperature rise rate corresponding to each steady state operating point according to the temperature change data.

[0063] Further, the first calculation subunit is specifically configured to determine, for each of the steady-state operating points, whether the DC bus capacitor can rise from the preset water temperature to a preset over-temperature threshold according to the temperature change data; and when the DC bus capacitor can rise from the preset water temperature to the preset over-temperature threshold, acquire a first temperature rise time according to the temperature change data, and calculate a temperature rise rate according to the first temperature rise time and the preset over-temperature threshold.

[0064] Further, the first calculation subunit is specifically configured to, when the DC bus capacitor cannot rise from the preset water temperature to the preset over-temperature threshold, calculate a temperature rise rate below the thermal equilibrium point and a temperature rise rate above the thermal equilibrium point according to the temperature change data.

[0065] Further, the first calculation subunit comprises:

[0066] A determination module configured to determine a current steady-state operating point to be calculated and a thermal equilibrium temperature value corresponding to the current steady-state operating point;

[0067] An acquisition module configured to acquire, according to the temperature change data, a second temperature rise time for a capacitor temperature of the DC bus capacitor to rise from an initial temperature to the thermal equilibrium temperature value for the first time;

[0068] A calculation module configured to calculate, according to the thermal equilibrium temperature value and the second temperature rise time, a temperature rise rate below the thermal equilibrium point for the current steady-state operating point;

[0069] The determination module is further configured to, after the capacitor temperature of the DC bus capacitor reaches a thermal equilibrium state, and when a deviation between the thermal equilibrium temperature value and the preset over-temperature threshold is greater than a preset deviation threshold, determine a new steady-state operating point according to the temperature change data and the current steady-state operating point;

[0070] The acquisition module is further configured to acquire, according to the temperature change data, the current steady-state operating point, and the new steady-state operating point, a duration for the capacitor temperature of the DC bus capacitor to return from a new thermal equilibrium temperature value to the thermal equilibrium temperature value again;

[0071] The calculation module is further configured to calculate, according to the thermal equilibrium temperature value, the new thermal equilibrium temperature value, and the duration, a temperature rise rate above the thermal equilibrium point for the current steady-state operating point;

[0072] The water temperature and the rotating speed of the new steady state operating point are same as the water temperature and the rotating speed of the current steady state operating point, and the torque of the new steady state operating point is greater than the torque of the current steady state operating point, and the deviation between the new thermal equilibrium temperature value of the new steady state operating point and the preset over-temperature threshold value is not greater than the deviation threshold value.

[0073] Further, the second obtaining unit comprises:

[0074] The reading sub-unit is configured to read a last estimated capacitor temperature value, a last water temperature value and a last absolute time stored when the drive motor controller was last powered off.

[0075] The second obtaining sub-unit is configured to obtain a current water temperature value and a current absolute time at the current power-on of the drive motor controller.

[0076] The second calculating sub-unit is configured to calculate a capacitor initial temperature of the DC bus capacitor at the power-on of the drive motor controller according to the last estimated capacitor temperature value, the last water temperature value, the last absolute time, the current water temperature value and the current absolute time.

[0077] Further, the calculating unit comprises:

[0078] The first judging sub-unit is configured to judge whether the current operating condition is a thermal equilibrium point condition.

[0079] The third calculating sub-unit is configured to calculate a capacitor temperature rise estimation curve according to the capacitor initial temperature and the target temperature rise rate when the current operating condition is not the thermal equilibrium point condition.

[0080] The first determining sub-unit is configured to determine a target thermal equilibrium temperature corresponding to the current operating condition when the current operating condition is the thermal equilibrium point condition.

[0081] The third calculating sub-unit is further configured to calculate a capacitor temperature rise estimation curve according to the target thermal equilibrium temperature, the target temperature rise rate and the capacitor initial temperature.

[0082] Further, the judging unit comprises:

[0083] The second judging sub-unit is configured to judge whether the capacitor temperature exceeds the preset over-temperature threshold value according to the capacitor temperature rise estimation curve.

[0084] The second judging sub-unit is further configured to judge whether the duration that the capacitor temperature exceeds the preset over-temperature threshold value is greater than a preset first over-temperature time threshold value according to the capacitor temperature rise estimation curve when the capacitor temperature exceeds the preset over-temperature threshold value.

[0085] The second determining sub-unit is configured to determine that the DC bus capacitor is at risk of over-temperature when the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than the first over-temperature time threshold.

[0086] Further, the limiting control unit comprises:

[0087] The third obtaining sub-unit is configured to obtain a current water temperature and a current rotating speed of the drive motor controller under the current operating condition.

[0088] The third determining sub-unit is configured to determine a maximum torque value corresponding to a thermal balance condition according to the current water temperature and the current rotating speed.

[0089] The third determining sub-unit is further configured to determine the upper limit of the output torque of the drive motor controller as the maximum torque value.

[0090] The third obtaining sub-unit is further configured to obtain a target capacitor temperature exceeding the preset over-temperature threshold when it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold and the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than a preset second over-temperature time threshold; and the second over-temperature time threshold is greater than the first over-temperature time threshold.

[0091] The fourth calculating sub-unit is configured to calculate a torque value difference according to the target capacitor temperature, the preset over-temperature threshold, and the maximum torque value.

[0092] The fourth determining sub-unit is configured to determine the upper limit of the output torque of the drive motor controller as the torque value difference.

[0093] The fourth determining sub-unit is further configured to determine the upper limit of the output torque of the drive motor controller as 0 when it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold and the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than a preset third over-temperature time threshold; and the third over-temperature time threshold is greater than the second over-temperature time threshold.

[0094] The third aspect of the present application provides an electronic device comprising a memory and a processor, the memory is configured to store a computer program, and the processor is configured to run the computer program to enable the electronic device to perform the drive motor controller DC bus capacitor over-temperature risk evaluation method according to any one of the first aspect of the present application.

[0095] The fourth aspect of the present application provides a computer readable storage medium storing computer program instructions, which are read and run by a processor to perform the drive motor controller DC bus capacitor over-temperature risk evaluation method according to any one of the first aspect of the present application.

[0096] The beneficial effects of the present application are: the use of a capacitor temperature sensor can be cancelled, the signal-based working condition point can be easily obtained, and the sensor-free drive motor controller DC bus capacitor over-temperature risk assessment can be realized; at the same time, the capacitor temperature rise and fall and the temperature estimation when in thermal equilibrium can be considered, and the scenario that the initial temperature of the capacitor after parking and power-off is inconsistent with the reference temperature can be considered; finally, over-temperature early warning and torque limiting protection can be performed at different levels. BRIEF DESCRIPTION OF DRAWINGS

[0097] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed to be used in the embodiments of the present application will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present application, and therefore should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can also be obtained without creative labor on the basis of these drawings.

[0098] Figure 1 A flowchart of a drive motor controller DC bus capacitor over-temperature risk assessment method provided by an embodiment of the present application is shown in the figure.

[0099] Figure 2 A partial flowchart of another drive motor controller DC bus capacitor over-temperature risk assessment method provided by an embodiment of the present application is shown in the figure.

[0100] Figure 3 A partial flowchart of another drive motor controller DC bus capacitor over-temperature risk assessment method provided by an embodiment of the present application is shown in the figure.

[0101] Figure 4 A structure diagram of a drive motor controller DC bus capacitor over-temperature risk assessment device provided by an embodiment of the present application is shown in the figure.

[0102] Figure 5 A structure diagram of another drive motor controller DC bus capacitor over-temperature risk assessment device provided by an embodiment of the present application is shown in the figure. DETAILED DESCRIPTION

[0103] The technical solutions in the embodiments of the present application will be described below with reference to the drawings in the embodiments of the present application.

[0104] It should be noted that: similar reference numerals and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings. At the same time, in the description of the present application, the terms "first", "second", etc. are only used for differentiation, and cannot be understood as indicating or implying relative importance.

[0105] Embodiment 1

[0106] Referring to Figure 1 , Figure 1 A flowchart of a driving motor controller DC bus capacitor over-temperature risk assessment method provided by the embodiment is shown. The driving motor controller DC bus capacitor over-temperature risk assessment method includes the following steps.

[0107] S101, obtaining the DC bus capacitor temperature rise rate of the driving motor controller at each steady-state operating point according to bench testing.

[0108] S102, obtaining the initial temperature of the driving motor controller DC bus capacitor when the driving motor controller of the target vehicle is powered on.

[0109] S103, determining the current operating condition of the driving motor controller.

[0110] S104, determining the target temperature rise rate corresponding to the current operating condition according to the DC bus capacitor temperature rise rate.

[0111] S105, calculating the capacitor temperature rise estimation curve according to the initial temperature of the capacitor, the current operating condition, and the target temperature rise rate.

[0112] S106, determining whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve, and if so, performing step S107; otherwise, ending the flowchart.

[0113] S107, limiting the torque output of the driving motor controller.

[0114] In the embodiment, the execution subject of the method can be a computer, a server, or other computing devices, which are not limited in the embodiment.

[0115] In the embodiment, the execution subject of the method can also be a smart phone, a tablet computer, or other smart devices, which are not limited in the embodiment.

[0116] It can be seen that the driving motor controller DC bus capacitor over-temperature risk assessment method described in the embodiment can assess the over-temperature risk of the driving motor controller DC bus capacitor without the need for sensors, and limit the torque output of the motor in time when the over-temperature risk is assessed, so as to ensure the safety of the capacitor while reducing unnecessary power interruption and improving driving safety and continuity of vehicle operation.

[0117] Embodiment 2

[0118] Referring to Figure 2 and Figure 3 , Figure 2A part flowchart diagram of a method for evaluating over-temperature risk of a DC bus capacitor of a motor controller is provided in the embodiment, Figure 3 A part flowchart diagram of a method for evaluating over-temperature risk of a DC bus capacitor of a motor controller is provided in the embodiment. The method for evaluating over-temperature risk of the DC bus capacitor of the motor controller comprises:

[0119] S201, obtaining a preset steady-state operating point.

[0120] In the embodiment, the steady-state operating point comprises one or more of coolant temperature, motor speed, motor torque, cooling condition reference signal, and power-related reference signal.

[0121] S202, obtaining temperature change data of the DC bus capacitor of the motor controller at each steady-state operating point according to bench testing.

[0122] In the embodiment, the method can obtain temperature change of the DC bus capacitor of the motor controller (controller for short) at each steady-state operating point of coolant temperature (water temperature for short), motor speed, and motor torque according to bench testing. The initial temperature of the capacitor on the bench is consistent with the set water temperature.

[0123] In the embodiment, the initial temperature of the DC bus capacitor on the bench is consistent with the preset water temperature in the bench testing.

[0124] In the embodiment, the operating point setting can also select an environmental temperature or other cooling condition reference signal as input of the cooling condition, and can also select a bus voltage, bus current, or other power-related reference signal as input of the heating condition.

[0125] S203, for each steady-state operating point, determining whether the DC bus capacitor can rise from the preset water temperature to a preset over-temperature threshold according to the temperature change data, and if yes, performing step S204, and if no, performing step S205.

[0126] S204, obtaining a first temperature rise time according to the temperature change data, and calculating a temperature rise rate according to the first temperature rise time and the preset over-temperature threshold, and performing step S211.

[0127] In the embodiment, when the temperature of the capacitor can rise from the set water temperature to the over-temperature threshold T t , the temperature rise time of the capacitor temperature is recorded as t r(x,y,z) , the subscript x represents water temperature, y represents speed, and z represents torque, and the temperature rise rate of the operating point is calculated as v r(x,y,z) =(T t -x) / t r(x,y,z) .

[0128] S205, determine the current steady state operating point to be calculated and the heat balance temperature value corresponding to the current steady state operating point.

[0129] S206, according to the temperature change data, obtain the second temperature rise time of the capacitor temperature of the DC bus capacitor from the initial temperature to the heat balance temperature value.

[0130] S207, calculate the temperature rise rate of the current steady state operating point below the heat balance point according to the heat balance temperature value and the second temperature rise time.

[0131] In the embodiment, when the capacitor temperature cannot rise from the set water temperature to the over-temperature threshold T t , record the temperature value T b(x,y,z) at which the capacitor temperature reaches the heat balance state, and record the temperature rise time t b(x,y,z) from the set water temperature to the heat balance temperature T b(x,y,z) , and calculate the temperature rise rate v b(x,y,z) = (T b(x,y,z) -x) / t b(x,y,z) of the operating condition below the heat balance point; wherein the heat balance state refers to a state in which the temperature change is less than 2℃ for 15 minutes.

[0132] S208, after the capacitor temperature of the DC bus capacitor reaches the heat balance state, and the deviation between the heat balance temperature value and the preset over-temperature threshold is greater than the preset deviation threshold, determine a new steady state operating point according to the temperature change data and the current steady state operating point.

[0133] In the embodiment, after the new steady state operating point is determined, the current operating condition is set to the new steady state operating point; under the new steady state operating point, after the capacitor temperature of the DC bus capacitor reaches the new heat balance temperature value, the current operating condition is adjusted from the new steady state operating point back to the current steady state operating point. At this time, the duration of the capacitor temperature of the DC bus capacitor from the new heat balance temperature value back to the heat balance temperature value can be obtained from the temperature change data.

[0134] S209, according to the temperature change data, the current steady state operating point and the new steady state operating point, obtain the duration of the capacitor temperature of the DC bus capacitor from the new heat balance temperature value back to the heat balance temperature value.

[0135] S210, calculate the temperature rise rate of the current steady state operating point above the heat balance point according to the heat balance temperature value, the new heat balance temperature value and the duration.

[0136] In the embodiment, the water temperature and the speed of the new steady state operating point are the same as those of the current steady state operating point, and the torque of the new steady state operating point is greater than that of the current steady state operating point, and the deviation between the new heat balance temperature value of the new steady state operating point and the preset over-temperature threshold is not greater than the deviation threshold.

[0137] In this embodiment, in this working condition (hereinafter referred to as working condition a), the capacitor temperature can reach thermal equilibrium, and the thermal equilibrium temperature T b(x,y,z＝a) In the case of a deviation of more than 2°C from the over-temperature threshold, after the working condition a reaches thermal equilibrium, it can be adjusted to another thermal equilibrium working condition point (hereinafter referred to as working condition b). The water temperature and speed settings of working condition b are the same as those of working condition a, but the torque is higher and the thermal equilibrium temperature T b(x,y,z＝b) The deviation from the over-temperature threshold is less than 2°C.

[0138] At this time, the waiting capacitor temperature rises to the thermal equilibrium temperature T b(x,y,z＝b) Then, it is adjusted to working condition a again, and the duration of the capacitor temperature from the thermal equilibrium temperature T b(x,y,z＝b) of working condition b to the thermal equilibrium temperature T b(x,y,z＝a) of working condition a is recorded as t f(x,y,z) .

[0139] Then, the temperature rise rate of this working condition above the thermal equilibrium point is calculated as v f(x,y,z) =(T b(x,y,z＝a) -T b(x,y,z＝b) ) / t f(x,y,z) . If working condition a and working condition b are the same, v f(x,y,z) =0 is set.

[0140] S211, when the target vehicle's drive motor controller is powered on, read the last estimated capacitor temperature value, the last water temperature value and the last absolute time stored when the drive motor controller is last powered off.

[0141] S212, get the current water temperature value and the current absolute time when the drive motor controller is powered on.

[0142] S213, according to the last estimated capacitor temperature value, the last water temperature value, the last absolute time, the current water temperature value and the current absolute time, calculate the initial temperature of the capacitor of the direct current bus capacitor when the drive motor controller is powered on.

[0143] In this embodiment, when considering the initial temperature of the capacitor when the drive motor controller on the actual vehicle is powered on, the initial temperature of the capacitor and the coolant temperature are not necessarily consistent, in order to obtain the initial temperature of the capacitor, the following measures can be taken:

[0144] (1) Store the estimated capacitor temperature value T c0 , the water temperature value T w0 and the absolute time t s0 when the controller is powered off;

[0145] (2) Read the estimated capacitor temperature value T c0 , the water temperature value T w0 and the absolute time ts0 and read the water temperature value T at power-on w1 and absolute time t s1 . Then the initial temperature T of the capacitor at power-on c1 is:

[0146] If t s1 -t s0 <t gap ,T c1 = h x (T w1 -T w0 ) + T c0 ;

[0147] Else, T c1 = T w1

[0148] wherein h is the ratio of the temperature drop rate of the capacitor to the temperature drop rate of the water at power-off;

[0149] t gap is a calibration time threshold, i.e. when the time threshold is exceeded, the capacitor temperature is considered to be consistent with the water temperature.

[0150] In this embodiment, the initial temperature of the capacitor can also be obtained by using the temperatures of the motor, power module, control board and other devices that are not additionally cooled after the controller is powered off to replace the water temperature, or to correct the initial temperature of the capacitor at power-on.

[0151] S214, determine the current operating condition of the drive motor controller.

[0152] S215, determine the target temperature rise rate corresponding to the current operating condition according to the temperature rise rate of the DC bus capacitor.

[0153] S216, determine whether the current operating condition is a thermal equilibrium point condition, if yes, execute step S217; if no, execute step S218.

[0154] S217, determine the target thermal equilibrium temperature corresponding to the current operating condition, and calculate the capacitor temperature rise estimation curve according to the target thermal equilibrium temperature, the target temperature rise rate and the initial temperature of the capacitor, and execute step S219.

[0155] In this embodiment, after the drive motor controller is powered on, the method calculates the capacitor temperature rise estimation curve according to the initial temperature of the capacitor at power-on and the operating condition of the drive motor controller after power-on as follows:

[0156] (1) The current condition is a thermal equilibrium point, and T c,k <T b(x,y,z) : T c,k+1 = T c,k + vb(x,y,z) × Δt;

[0157] (2) the current working condition is a thermal equilibrium point, and T c,k > T b(x,y,z) : T c,k+1 = T c,k + v f(x,y,z) × Δt;

[0158] (3) the current working condition is a thermal equilibrium point, and T c,k = T b(x,y,z) : T c,k+1 = T c,k ;

[0159] wherein, when k = 1, T c,k = T c1 .

[0160] S218, calculate the capacitor temperature rise estimation curve according to the initial temperature of the capacitor and the target temperature rise rate, and perform step S219.

[0161] In the embodiment, if the current working condition is a non-thermal equilibrium point, the capacitor temperature rise estimation curve is:

[0162] T c,k+1 = T c,k + v r(x,y,z) × Δt.

[0163] S219, determine whether the capacitor temperature exceeds the preset over-temperature threshold according to the capacitor temperature rise estimation curve, if yes, perform step S220; if no, end the process.

[0164] S220, determine whether the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than the preset first over-temperature time threshold according to the capacitor temperature rise estimation curve, if yes, perform step S221; if no, end the process.

[0165] S221, determine that the DC bus capacitor has an over-temperature risk.

[0166] S222, obtain the current water temperature and the current rotating speed of the driving motor controller under the current operating condition.

[0167] S223, determine the maximum torque value corresponding to the thermal equilibrium condition according to the current water temperature and the current rotating speed.

[0168] S224, determine the upper limit of the output torque of the driving motor controller as the maximum torque value.

[0169] S225, when it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold, and the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than the preset second over-temperature time threshold, obtain the target capacitor temperature that exceeds the preset over-temperature threshold.

[0170] In this embodiment, the second over-temperature time threshold is greater than the first over-temperature time threshold.

[0171] S226 , calculating a torque value difference according to the target capacitor temperature, a preset over-temperature threshold, and a maximum torque value.

[0172] S227: Determine the upper limit of the output torque of the drive motor controller as the torque value difference.

[0173] S228. When it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold, and the duration of exceeding the preset over-temperature threshold is greater than the preset third over-temperature time threshold, the upper limit of the output torque of the drive motor controller is determined to be 0.

[0174] In this embodiment, the third over-temperature time threshold is greater than the second over-temperature time threshold.

[0175] For example, when estimating the capacitor temperature T c,k Exceeds the overtemperature threshold T t And the duration exceeds t t1 When the capacitor is overheated, the risk is reported and the torque output is limited in three cases:

[0176] (1) First, the upper limit of the output torque is limited to the maximum torque value Q under the thermal equilibrium condition at the current water temperature and speed. max ;

[0177] (2) If the estimated capacitor temperature T c,k Still exceeds the overtemperature threshold T t And the duration exceeds t t2 , then according to the capacitor temperature exceeds T c,k Exceeding the overtemperature threshold T t The upper limit of the output torque is the interpolation value of the torque value at the thermal equilibrium operating point under the current water temperature and speed = Q max ×(T t2 -T c,k ) / (T t2 -T t ), where T t2 Slightly higher than T t The capacitor over-temperature threshold at which the torque output is required to be 0;

[0178] (3) If the estimated capacitor temperature T c,k Still exceeds the overtemperature threshold T t And the duration exceeds t t3 , the upper limit of the output torque is limited to 0.

[0179] In this embodiment, the execution subject of the method may be a computing device such as a computer or a server, and this is not limited in this embodiment.

[0180] In this embodiment, the execution subject of the method can also be a smart phone, a tablet computer or the like smart device, and no limitation is made in this embodiment.

[0181] It can be seen that, by implementing the driving motor controller DC bus capacitor over-temperature risk assessment method described in this embodiment, over-temperature risk assessment of the driving motor controller DC bus capacitor can be performed without the need for a sensor, and when it is assessed that there is an over-temperature risk, the torque output of the motor is limited in a timely manner, so as to ensure the safety of the capacitor while reducing unnecessary power interruption and improving driving safety and continuity of vehicle operation.

[0182] Embodiment 3

[0183] Please refer to Figure 4 , Figure 4 A structure schematic diagram of a driving motor controller DC bus capacitor over-temperature risk assessment device provided in this embodiment is shown in FIG. 3. As shown in FIG. 3, the driving motor controller DC bus capacitor over-temperature risk assessment device includes: Figure 4

[0184] The first acquisition unit 310 is configured to acquire the DC bus capacitor temperature rise rate of the driving motor controller at each steady-state operating point according to bench testing.

[0185] The second acquisition unit 320 is configured to acquire the initial capacitor temperature of the driving motor controller DC bus capacitor when the driving motor controller of the target vehicle is powered on.

[0186] The first determination unit 330 is configured to determine the current operating condition of the driving motor controller.

[0187] The second determination unit 340 is configured to determine the target temperature rise rate corresponding to the current operating condition according to the DC bus capacitor temperature rise rate.

[0188] The calculation unit 350 is configured to calculate a capacitor temperature rise estimation curve according to the initial capacitor temperature, the current operating condition and the target temperature rise rate.

[0189] The judgment unit 360 is configured to judge whether the driving motor controller DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve.

[0190] The limit control unit 370 is configured to limit the torque output of the driving motor controller when it is judged that the driving motor controller DC bus capacitor has an over-temperature risk.

[0191] In this embodiment, the explanation and description of the driving motor controller DC bus capacitor over-temperature risk assessment device can refer to the description in Embodiment 1 or Embodiment 2, and no more description is made in this embodiment.

[0192] ​It can be seen that the drive motor controller DC bus capacitor over-temperature risk assessment device described in the embodiment can assess the over-temperature risk of the drive motor controller DC bus capacitor without the need for sensors, and limit the torque output of the motor in time when the over-temperature risk is assessed, so as to ensure the safety of the capacitor while reducing unnecessary power interruption and improving driving safety and continuity of vehicle operation.

[0193] Embodiment 4

[0194] Referring to Figure 5 , Figure 5 A structure diagram of a drive motor controller DC bus capacitor over-temperature risk assessment device provided in the embodiment is shown in the figure. Figure 5 As shown in the figure, the drive motor controller DC bus capacitor over-temperature risk assessment device comprises:

[0195] A first acquisition unit 310 is configured to acquire the DC bus capacitor temperature rise rate of the drive motor controller at each steady state operating point according to bench testing;

[0196] A second acquisition unit 320 is configured to acquire the initial capacitor temperature of the drive motor controller DC bus capacitor when the drive motor controller of the target vehicle is powered on;

[0197] A first determination unit 330 is configured to determine the current operating condition of the drive motor controller;

[0198] A second determination unit 340 is configured to determine the target temperature rise rate corresponding to the current operating condition according to the DC bus capacitor temperature rise rate;

[0199] A calculation unit 350 is configured to calculate a capacitor temperature rise estimation curve according to the initial capacitor temperature, the current operating condition and the target temperature rise rate;

[0200] A judgment unit 360 is configured to judge whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve;

[0201] A limit control unit 370 is configured to limit the torque output of the drive motor controller when it is judged that the DC bus capacitor has an over-temperature risk.

[0202] As an optional implementation, the first acquisition unit 310 comprises:

[0203] A first acquisition sub-unit 311 is configured to acquire a preset steady state operating point; wherein the steady state operating point comprises one or more of the cooling liquid temperature, the motor speed, the motor torque, the cooling condition reference signal and the power related reference signal;

[0204] The first obtaining sub-unit 311 is further configured to obtain temperature variation data of the DC bus capacitor of the drive motor controller at each steady-state operating point according to the bench test; wherein the initial temperature of the DC bus capacitor on the test bench is consistent with the preset water temperature in the bench test.

[0205] The first calculating sub-unit 312 is configured to calculate a temperature rise rate corresponding to each steady-state operating point according to the temperature variation data.

[0206] As an optional implementation, the first calculating sub-unit 312 is specifically configured to, for each steady-state operating point, determine whether the DC bus capacitor can rise from the preset water temperature to the preset over-temperature threshold according to the temperature variation data; and when the DC bus capacitor can rise from the preset water temperature to the preset over-temperature threshold, obtain a first temperature rise time according to the temperature variation data, and calculate the temperature rise rate according to the first temperature rise time and the preset over-temperature threshold.

[0207] As an optional implementation, the first calculating sub-unit 312 is specifically further configured to, when the DC bus capacitor cannot rise from the preset water temperature to the preset over-temperature threshold, calculate a temperature rise rate below the thermal equilibrium point and a temperature rise rate above the thermal equilibrium point according to the temperature variation data.

[0208] As an optional implementation, the first calculating sub-unit 312 comprises:

[0209] The determining module is configured to determine a current steady-state operating point to be calculated and a thermal equilibrium temperature value corresponding to the current steady-state operating point;

[0210] The obtaining module is configured to obtain, according to the temperature variation data, a second temperature rise time of the capacitor temperature of the DC bus capacitor from the initial temperature to the thermal equilibrium temperature value for the first time;

[0211] The calculating module is configured to calculate, according to the thermal equilibrium temperature value and the second temperature rise time, a temperature rise rate of the current steady-state operating point below the thermal equilibrium point;

[0212] The determining module is further configured to, after the capacitor temperature of the DC bus capacitor reaches a thermal equilibrium state, and when a deviation between the thermal equilibrium temperature value and the preset over-temperature threshold is greater than a preset deviation threshold, determine a new steady-state operating point according to the temperature variation data and the current steady-state operating point;

[0213] The obtaining module is further configured to obtain, according to the temperature variation data, the current steady-state operating point and the new steady-state operating point, a duration of the capacitor temperature of the DC bus capacitor from a new thermal equilibrium temperature value back to the thermal equilibrium temperature value;

[0214] The calculating module is further configured to calculate, according to the thermal equilibrium temperature value, the new thermal equilibrium temperature value and the duration, a temperature rise rate of the current steady-state operating point above the thermal equilibrium point;

[0215] The water temperature and the rotating speed of the new steady state operating point are the same as the water temperature and the rotating speed of the current steady state operating point, and the torque of the new steady state operating point is greater than the torque of the current steady state operating point, and the deviation between the new thermal equilibrium temperature value of the new steady state operating point and the preset over-temperature threshold value is not greater than the deviation threshold value.

[0216] As an optional implementation, the second obtaining unit 320 includes:

[0217] The reading sub-unit 321 is configured to read the last estimated capacitor temperature value, the last water temperature value and the last absolute time stored when the drive motor controller was last powered off.

[0218] The second obtaining sub-unit 322 is configured to obtain the current water temperature value and the current absolute time when the drive motor controller is currently powered on.

[0219] The second calculation sub-unit 323 is configured to calculate the capacitor initial temperature of the direct current bus capacitor when the drive motor controller is powered on according to the last estimated capacitor temperature value, the last water temperature value, the last absolute time, the current water temperature value and the current absolute time.

[0220] As an optional implementation, the calculation unit 350 includes:

[0221] The first judgment sub-unit 351 is configured to judge whether the current operating condition is a thermal equilibrium point condition.

[0222] The third calculation sub-unit 352 is configured to calculate the capacitor temperature rise estimation curve according to the capacitor initial temperature and the target temperature rise rate when the current operating condition is not the thermal equilibrium point condition.

[0223] The first determination sub-unit 353 is configured to determine the target thermal equilibrium temperature corresponding to the current operating condition when the current operating condition is the thermal equilibrium point condition.

[0224] The third calculation sub-unit 352 is further configured to calculate the capacitor temperature rise estimation curve according to the target thermal equilibrium temperature, the target temperature rise rate and the capacitor initial temperature.

[0225] As an optional implementation, the judgment unit 360 includes:

[0226] The second judgment sub-unit 361 is configured to judge whether the capacitor temperature exceeds the preset over-temperature threshold value according to the capacitor temperature rise estimation curve.

[0227] The second judgment sub-unit 361 is further configured to judge whether the duration that the capacitor temperature exceeds the preset over-temperature threshold value is greater than the preset first over-temperature time threshold value according to the capacitor temperature rise estimation curve when the capacitor temperature exceeds the preset over-temperature threshold value.

[0228] The second determining sub-unit 362 is configured to determine that the DC bus capacitor is at risk of over-temperature when the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than the first over-temperature time threshold.

[0229] As an optional implementation, the limiting control unit 370 includes:

[0230] The third obtaining sub-unit 371 is configured to obtain a current water temperature and a current rotating speed of the drive motor controller under a current operating condition.

[0231] The third determining sub-unit 372 is configured to determine a maximum torque value corresponding to a thermal balance condition according to the current water temperature and the current rotating speed.

[0232] The third determining sub-unit 372 is further configured to determine the upper limit of the output torque of the drive motor controller as the maximum torque value.

[0233] The third obtaining sub-unit 371 is further configured to obtain a target capacitor temperature exceeding the preset over-temperature threshold when it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold and the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than a preset second over-temperature time threshold; and the second over-temperature time threshold is greater than the first over-temperature time threshold.

[0234] The fourth calculating sub-unit 373 is configured to calculate a torque value difference according to the target capacitor temperature, the preset over-temperature threshold, and the maximum torque value.

[0235] The fourth determining sub-unit 374 is configured to determine the upper limit of the output torque of the drive motor controller as the torque value difference.

[0236] The fourth determining sub-unit 374 is further configured to determine the upper limit of the output torque of the drive motor controller as 0 when it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold and the duration that the capacitor temperature exceeds the preset over-temperature threshold is greater than a preset third over-temperature time threshold; and the third over-temperature time threshold is greater than the second over-temperature time threshold.

[0237] In this embodiment, the description of the drive motor controller DC bus capacitor over-temperature risk evaluation device can refer to the description in Embodiment 1 or Embodiment 2, and no further description is given herein.

[0238] It can be seen that the drive motor controller DC bus capacitor over-temperature risk evaluation device described in this embodiment can evaluate the over-temperature risk of the DC bus capacitor of the drive motor controller without the need for a sensor, and limit the torque output of the motor in time when the over-temperature risk is evaluated, so as to ensure the safety of the capacitor while reducing unnecessary power interruption and improving driving safety and continuity of vehicle operation.

[0239] The electronic device provided in the embodiments of the present application comprises a memory and a processor, the memory is used to store a computer program, and the processor runs the computer program to enable the electronic device to execute the motor controller DC bus capacitor over-temperature risk assessment method in the embodiments 1 or 2 of the present application.

[0240] The computer readable storage medium provided in the embodiments of the present application stores computer program instructions, and the computer program instructions are read and run by a processor to execute the motor controller DC bus capacitor over-temperature risk assessment method in the embodiments 1 or 2 of the present application.

[0241] In several embodiments provided in the present application, it should be understood that the disclosed apparatus and method can also be implemented by other manners. The apparatus embodiments described above are only schematic, for example, the flow charts and block diagrams in the drawings show the possible implementation architectures, functions and operations of the apparatus, method and computer program product according to the embodiments of the present application. In this regard, each block in the flow charts or block diagrams can represent a module, a program segment or a part of code, which contains one or more executable instructions for implementing the specified logical function. It should also be noted that, in some alternative implementation manners, the functions noted in the blocks can also occur in different order from that noted in the drawings. For example, two consecutive blocks can actually be executed substantially in parallel, and sometimes they can also be executed in reverse order, depending on the functions involved. It should also be noted that each block in the block diagrams and / or flow charts, and the combination of blocks in the block diagrams and / or flow charts, can be implemented by a dedicated hardware-based system for implementing the specified functions or actions, or can be implemented by a combination of special-purpose hardware and computer instructions.

[0242] In addition, each functional module in the embodiments of the present application can be integrated together to form an independent part, or each module can exist independently, or two or more modules can be integrated to form an independent part.

[0243] If the functions are implemented in the form of software function modules and sold or used as independent products, they can be stored in a computer readable storage medium. Based on this understanding, the technical solutions of the present application essentially or the parts of the prior art that make contributions or parts of the technical solutions can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of the present application. The aforementioned storage medium includes: a U disk, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk or an optical disk, and various media that can store program codes.

[0244] The above merely provides an example of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0245] The above merely provides an example of the present application and is not intended to limit the protection scope of the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application. It should be noted that similar reference numbers and letters represent similar items in the following drawings, so once an item is defined in one drawing, it does not need to be further defined and explained in subsequent drawings.

[0246] It should be noted that, in this document, the terms such as first and second are used merely to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "contain" or any other variants thereof are intended to cover non-exclusive inclusion, so that the processes, methods, articles or devices including a series of elements not only include those elements, but also include other elements not explicitly listed or inherent to such processes, methods, articles or devices. Without more limitations, the element defined by the statement "including a" does not exclude the presence of another identical element in the process, method, article or device including the element.

Claims

1. A method for assessing overtemperature risk of a DC bus capacitor of a drive motor controller, characterized in that: The method comprises: obtaining a temperature rise rate of a DC bus capacitor of a drive motor controller at each steady state operating point according to a bench test; obtaining an initial temperature of the DC bus capacitor of the drive motor controller when the drive motor controller of a target vehicle is powered on; determining a current operating condition of the drive motor controller; determining a target temperature rise rate corresponding to the current operating condition according to the temperature rise rate of the DC bus capacitor; calculating a capacitor temperature rise estimation curve according to the initial temperature of the DC bus capacitor, the current operating condition and the target temperature rise rate; judging whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve; if yes, limiting a torque output of the drive motor controller.

2. The method of claim 1, wherein the method further comprises: The method of obtaining the temperature rise rate of the DC bus capacitor of the drive motor controller at each steady state operating point according to the bench test comprises: obtaining preset steady state operating points; wherein the steady state operating points include one or more of coolant temperature, motor speed, motor torque, cooling condition reference signal and power related reference signal; obtaining temperature change data of the DC bus capacitor of the drive motor controller at each steady state operating point according to a bench test; wherein in the bench test, an initial temperature of the DC bus capacitor on the bench is consistent with a preset water temperature; calculating a temperature rise rate corresponding to each steady state operating point according to the temperature change data.

3. The method of claim 2, wherein the method further comprises: The method of calculating the temperature rise rate corresponding to each steady state operating point according to the temperature change data comprises: for each steady state operating point, judging whether the DC bus capacitor can rise from the preset water temperature to a preset over-temperature threshold according to the temperature change data; if yes, obtaining a first temperature rise time according to the temperature change data, and calculating a temperature rise rate according to the first temperature rise time and the preset over-temperature threshold.

4. The method of claim 3, wherein the method further comprises: The method further comprises: when it is judged according to the temperature change data that the DC bus capacitor cannot rise from the preset water temperature to the preset over-temperature threshold, calculating a temperature rise rate below a thermal equilibrium point and a temperature rise rate above the thermal equilibrium point according to the temperature change data.

5. The method of claim 4, wherein the method further comprises: The method of calculating the temperature rise rate below the thermal equilibrium point and the temperature rise rate above the thermal equilibrium point according to the temperature change data comprises: determining a current steady state operating point to be calculated and a thermal equilibrium temperature value corresponding to the current steady state operating point; obtaining a second temperature rise time in which the capacitor temperature of the DC bus capacitor rises from the initial temperature to the thermal equilibrium temperature value for the first time according to the temperature change data; calculating a temperature rise rate below the thermal equilibrium point of the current steady state operating point according to the thermal equilibrium temperature value and the second temperature rise time; after the capacitor temperature of the DC bus capacitor reaches a thermal equilibrium state, and when a deviation between the thermal equilibrium temperature value and the preset over-temperature threshold is greater than a preset deviation threshold, determining a new steady state operating point according to the temperature change data and the current steady state operating point; obtaining a duration in which the capacitor temperature of the DC bus capacitor returns from a new thermal equilibrium temperature value to the thermal equilibrium temperature value again according to the temperature change data, the current steady state operating point and the new steady state operating point; According to the heat balance temperature value, the new heat balance temperature value, and the duration, a temperature rise rate of the current steady state operating point above the heat balance point is calculated; Wherein, the water temperature and the rotating speed of the new steady state operating point are the same as the water temperature and the rotating speed of the current steady state operating point, and the torque of the new steady state operating point is greater than the torque of the current steady state operating point, and the deviation between the new heat balance temperature value of the new steady state operating point and the preset over-temperature threshold value is not greater than the deviation threshold value.

6. The method of claim 1, wherein, The method comprises the following steps: reading the last estimated capacitor temperature value, the last water temperature value, and the last absolute time stored when the driving motor controller was last powered off; acquiring the current water temperature value and the current absolute time when the driving motor controller is powered on this time; calculating the capacitor initial temperature of the DC bus capacitor of the driving motor controller when the driving motor controller is powered on according to the last estimated capacitor temperature value, the last water temperature value, the last absolute time, the current water temperature value, and the current absolute time.

7. The method of claim 1, wherein, The method comprises the following steps: determining whether the current operating condition is a heat balance point condition; if not, calculating a capacitor temperature rise estimation curve according to the capacitor initial temperature and the target temperature rise rate; if yes, determining the target heat balance temperature corresponding to the current operating condition; calculating a capacitor temperature rise estimation curve according to the target heat balance temperature, the target temperature rise rate, and the capacitor initial temperature.

8. The method of claim 1, wherein, The method comprises the following steps: determining whether there is an over-temperature risk of the DC bus capacitor according to the capacitor temperature rise estimation curve; determining whether the capacitor temperature exceeds the preset over-temperature threshold value according to the capacitor temperature rise estimation curve; if yes, determining whether the duration that the capacitor temperature exceeds the preset over-temperature threshold value is greater than a preset first over-temperature time threshold value according to the capacitor temperature rise estimation curve; 9. The method of claim 8, wherein the method further comprises: if yes, determining that the DC bus capacitor has an over-temperature risk. The method comprises the following steps: acquiring the current water temperature and the current rotating speed of the driving motor controller under the current operating condition; determining the maximum torque value corresponding to the heat balance condition according to the current water temperature and the current rotating speed; determining the upper limit of the output torque of the driving motor controller as the maximum torque value; when it is determined according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold value, and the duration that the capacitor temperature exceeds the preset over-temperature threshold value is greater than a preset second over-temperature time threshold value, acquiring the target capacitor temperature that exceeds the preset over-temperature threshold value; wherein, the second over-temperature time threshold value is greater than the first over-temperature time threshold value; calculating a torque value difference according to the target capacitor temperature, the preset over-temperature threshold value, and the maximum torque value; determining the upper limit of the output torque of the driving motor controller as the torque value difference; When it is judged according to the capacitor temperature rise estimation curve that the capacitor temperature exceeds the preset over-temperature threshold and the duration of exceeding the preset over-temperature threshold is greater than the preset third over-temperature time threshold, the upper limit of the output torque of the drive motor controller is determined as 0; wherein the third over-temperature time threshold is greater than the second over-temperature time threshold.

10. A drive motor controller DC bus capacitor over-temperature risk assessment apparatus, characterized by, The drive motor controller DC bus capacitor over-temperature risk evaluation device comprises: A first acquisition unit is configured to acquire the DC bus capacitor temperature rise rate of the drive motor controller at each steady-state operating point according to bench testing; A second acquisition unit is configured to acquire the initial capacitor temperature of the DC bus capacitor of the drive motor controller when the drive motor controller of the target vehicle is powered on; A first determination unit is configured to determine the current operating condition of the drive motor controller; A second determination unit is configured to determine the target temperature rise rate corresponding to the current operating condition according to the DC bus capacitor temperature rise rate; A calculation unit is configured to calculate a capacitor temperature rise estimation curve according to the initial capacitor temperature, the current operating condition, and the target temperature rise rate; A judgment unit is configured to judge whether the DC bus capacitor has an over-temperature risk according to the capacitor temperature rise estimation curve; A limit control unit is configured to limit the torque output of the drive motor controller when it is judged that the DC bus capacitor has an over-temperature risk.

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