An electric drive system cooling abnormality protection method, device and computer equipment

Abstract

The application relates to the technical field of electric driving, and discloses an electric driving system cooling abnormality protection method and device and computer equipment, the method comprising the following steps: obtaining an initial radiator temperature, an initial bus voltage and initial excitation parameters of a motor controller before electrochemical impedance spectrum excitation starting; continuously collecting real-time radiator temperatures at preset sampling intervals within a preset diagnosis window after excitation starting, and calculating the unit loss temperature rise of each sampling point according to the collected temperatures and the initial parameters, wherein the unit loss temperature rise is used for representing the heat dissipation capacity corresponding to each unit of heat generation under the current excitation working condition; and when the unit loss temperature rise of a continuous preset number of sampling points exceeds a threshold value, it is determined that the cooling system is abnormal, and the excitation output is stopped. The application solves the problem that the existing protection means cannot accurately identify the cooling system abnormality in the electrochemical impedance spectrum excitation process, and the power device faces the risk of thermal failure.

Description

Technical Field

[0001] This invention relates to the field of electric drive technology, and specifically to a method, device, and computer equipment for protecting an electric drive system from cooling anomalies. Background Technology

[0002] Electrochemical impedance spectroscopy (EIS) is an advanced method for accurately assessing the state of power batteries (such as health status and lithium plating risk). It typically utilizes the inverter of the motor power unit (IPU) as the excitation source, injecting a specific frequency AC excitation current into the battery pack by controlling the motor stator windings. However, when executing certain low-frequency, high-current, long-duration EIS excitation modes, the power switches or silicon carbide devices inside the IPU generate continuous conduction and switching losses far exceeding those of conventional drive conditions. Furthermore, this excitation process requires continuous, uninterrupted current output and lacks a natural intermittent heat dissipation window.

[0003] However, existing protection strategies for the overheating risk of power devices cannot respond in time before the safe junction temperature of the device is exceeded when there are abnormal operating conditions such as coolant leakage or failure to add coolant after maintenance, which result in no water or low flow. They are prone to false alarms under low-loss conditions and missed alarms under high-loss conditions, making it difficult to meet the fundamental requirements of EIS excitation for the speed and accuracy of protection actions under all operating conditions. Summary of the Invention

[0004] In view of this, embodiments of the present invention provide a method, apparatus and computer device for protecting against abnormal cooling in an electric drive system, in order to solve the problem that existing protection methods cannot accurately identify abnormalities in the cooling system during electrochemical impedance spectroscopy excitation, which leads to the risk of thermal failure of power devices.

[0005] In a first aspect, embodiments of the present invention provide a method for protecting an electric drive system from cooling anomalies, the method comprising: The initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller were obtained before the electrochemical impedance spectroscopy excitation was started. Within a preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, the real-time heat sink temperature of the motor controller is continuously collected at a preset sampling interval. The unit loss temperature rise of each sampling point is calculated based on the real-time heat sink temperature, the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition. When the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of the electrochemical impedance spectroscopy excitation is stopped.

[0006] Furthermore, the acquisition of the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation startup includes: Receive electrochemical impedance spectroscopy excitation requests from the battery management system; The initial excitation parameters are resolved from the electrochemical impedance spectroscopy excitation request, wherein the initial excitation parameters include the excitation current amplitude and the excitation frequency; Before the inverter starts modulation output in the motor controller, the initial heat sink temperature of the heat sink in the inverter is read, and the initial bus voltage is obtained at the same time.

[0007] Furthermore, the step of calculating the unit loss temperature rise at each sampling point based on the real-time radiator temperature, the initial radiator temperature, the initial bus voltage, and the initial excitation parameters includes: For each sampling point, the absolute temperature rise is calculated based on the real-time radiator temperature and the initial radiator temperature; Based on the pre-stored temperature-on-resistance coefficient curve, determine the on-resistance value corresponding to the real-time heat sink temperature; Calculate the real-time power loss based on the on-resistance value, the initial bus voltage, and the initial excitation parameters; The unit loss temperature rise is calculated using the absolute temperature rise and the real-time power loss.

[0008] Furthermore, the calculation of real-time power loss based on the on-resistance value, the initial bus voltage, and the initial excitation parameters includes: Extract the excitation current amplitude and excitation frequency from the initial excitation parameters; The switching loss component is determined based on the initial bus voltage and the excitation frequency, and the conduction loss component is determined based on the excitation current amplitude and the current on-resistance value. The real-time power loss is calculated based on the switching loss component and the conduction loss component.

[0009] Furthermore, before determining that there is an anomaly in the cooling system associated with the electric drive system, the method further includes: Obtain the unit loss temperature rise threshold corresponding to the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters; At each sampling point, the unit loss temperature rise is compared with the unit loss temperature rise threshold. If the temperature rise per unit loss at a continuously preset number of sampling points is greater than or equal to the temperature rise per unit loss threshold, then the cooling system is determined to be abnormal.

[0010] Furthermore, after continuously collecting the real-time radiator temperature of the motor controller, the method further includes: Within the preset diagnostic window, the temperature rise rate of the current sampling point is calculated based on the continuously collected real-time radiator temperature and the preset sampling interval. Obtain the temperature rise rate threshold corresponding to the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters, and compare the temperature rise rate with the temperature rise rate threshold at each sampling point; When the temperature rise rate of a consecutive preset number of sampling points is greater than or equal to the temperature rise rate threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of the electrochemical impedance spectroscopy excitation is stopped.

[0011] Furthermore, after calculating the unit loss temperature rise at each sampling point based on the real-time radiator temperature, the initial radiator temperature, the initial bus voltage, and the initial excitation parameters, the method further includes: When the unit loss temperature rise of a number of consecutive sample points is greater than or equal to the unit loss temperature rise threshold, the absolute temperature rise threshold corresponding to the initial radiator temperature, the initial bus voltage, and the initial excitation parameters is obtained. At each sampling point, the absolute temperature rise is compared with the absolute temperature rise threshold. If the absolute temperature rise is greater than or equal to the absolute temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of the electrochemical impedance spectroscopy excitation is stopped.

[0012] Furthermore, after determining that there is an anomaly in the cooling system associated with the electric drive system and stopping the output of the electrochemical impedance spectroscopy excitation, the method further includes: In response to the determination that there is an abnormality in the cooling system, a cooling system abnormality fault code is sent to the battery management system; The electrochemical impedance spectroscopy excitation function is locked, and responses to electrochemical impedance spectroscopy excitation requests issued by the battery management system are prohibited until a fault recovery signal from the cooling system is received.

[0013] Secondly, embodiments of the present invention provide a cooling anomaly protection device for an electric drive system, the device comprising: The acquisition module is used to acquire the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before the electrochemical impedance spectroscopy excitation is started. The calculation module is used to continuously collect the real-time heat sink temperature of the motor controller within a preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, according to a preset sampling interval. Based on the real-time heat sink temperature, the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters, the unit loss temperature rise of each sampling point is calculated. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition. The determination module is used to determine that there is an abnormality in the cooling system associated with the electric drive system when the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, and to stop the output of the electrochemical impedance spectroscopy excitation.

[0014] Thirdly, embodiments of the present invention provide a computer device, including: a memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, and the processor executing the computer instructions to perform the method described in the first aspect or any corresponding embodiment thereof.

[0015] Fourthly, embodiments of the present invention provide a computer-readable storage medium storing computer instructions that cause a computer to perform the method described in the first aspect or any of its corresponding embodiments.

[0016] The method provided in this application has the following beneficial effects: The method provided in this application obtains the initial radiator temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation, providing accurate baseline state data for subsequent diagnosis and a normalized analysis basis to eliminate differences in different operating conditions. By continuously collecting real-time radiator temperature within a preset diagnostic window after excitation start-up and calculating the unit loss temperature rise at each sampling point based on the initial parameters, the heat dissipation performance of the cooling system is decoupled from heat generation fluctuations using this normalized index that characterizes the heat dissipation capacity corresponding to each unit of heat generation. This allows the protection criterion to adaptively match the actual heat dissipation state under different bus voltages, excitation currents, and initial temperatures. When the unit loss temperature rise at a consecutive preset number of sampling points exceeds a threshold, the cooling system is determined to be abnormal and the excitation output is immediately stopped. The multi-point continuous judgment mechanism eliminates instantaneous noise interference, reduces the false alarm rate, and actively cuts off the heat source before the junction temperature of the power device reaches a dangerous value, achieving rapid and accurate identification and reliable protection of cooling system abnormalities during electrochemical impedance spectroscopy excitation. Attached Figure Description

[0017] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0018] Figure 1 This is a flowchart illustrating a cooling anomaly protection method for an electric drive system according to an embodiment of the present invention. Figure 2 This is a schematic diagram illustrating the change of radiator NTC temperature rise over time under different coolant flow rates according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the adaptive absolute temperature rise three-dimensional relationship according to an embodiment of the present invention; Figure 4 This is a flowchart illustrating another method for protecting an abnormal cooling system in an electric drive system according to an embodiment of the present invention. Figure 5 This is a flowchart illustrating another method for protecting an abnormal cooling system in an electric drive system according to an embodiment of the present invention. Figure 6 This is a schematic diagram of the overall process for waterless protection under EIS operating conditions according to an embodiment of the present invention; Figure 7 This is a structural block diagram of an electric drive system cooling abnormality protection device according to an embodiment of the present invention; Figure 8 This is a schematic diagram of the hardware structure of a computer device according to an embodiment of the present invention. Detailed Implementation

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0020] According to embodiments of the present invention, a method, apparatus, and computer device for protecting an electric drive system from cooling anomalies are provided. It should be noted that the steps shown in the flowcharts in the accompanying drawings can be executed in a computer system such as a set of computer-executable instructions. Furthermore, although a logical order is shown in the flowcharts, in some cases, the steps shown or described may be executed in a different order than that shown here.

[0021] This embodiment provides a method for protecting an electric drive system from abnormal cooling. Figure 1This is a flowchart of an electric drive system cooling anomaly protection method according to an embodiment of the present invention, such as... Figure 1 As shown, the process includes the following steps: Step S101: Obtain the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation start-up.

[0022] In this embodiment of the application, the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation are obtained, including: Step A1: Receive an electrochemical impedance spectroscopy excitation request from the battery management system.

[0023] Specifically, the Battery Management System (BMS) is the core electronic control unit responsible for monitoring, protecting, and managing the charging and discharging process of the power battery pack. When performing electrochemical impedance spectroscopy (EIS) detection, it sends an EIS excitation request to the Inverter Power Unit (IPU). This request contains parameter information such as the amplitude and frequency of the AC excitation current to be injected into the battery pack.

[0024] Once the vehicle has completed high-voltage power-on and the vehicle controller allows the EIS detection function to be activated, the BMS, based on the current battery state assessment, determines that EIS detection is required and sends an EIS excitation request message to the IPU via the Controller Area Network (CAN) communication bus. This request message contains a specific diagnostic identifier to notify the IPU that it is about to enter the EIS excitation state. Upon receiving the request message, the IPU first verifies it to confirm that the message format is correct and the source is reliable. Then, it uses the request as a prerequisite for triggering this protection method and caches the excitation parameters in the request for use in subsequent steps. Before starting the inverter modulation output, the IPU keeps the current power switch in the off state and does not output voltage to the motor stator winding, providing a time window for the stable acquisition of subsequent reference data.

[0025] Step A2: Analyze the initial excitation parameters from the electrochemical impedance spectroscopy excitation request, where the initial excitation parameters include the excitation current amplitude and the excitation frequency.

[0026] Specifically, the excitation current amplitude refers to the peak value of the AC current signal that the BMS requires the IPU to inject into the battery pack, measured in amperes (A). This parameter directly affects the conduction loss of the power switch. The excitation frequency refers to the oscillation frequency of the AC excitation current, measured in hertz (Hz). This parameter directly affects the switching loss of the power switch; the higher the frequency, the more switching actions occur per unit time, and the greater the switching loss.

[0027] After receiving the EIS excitation request from the BMS, the IPU parses the request message according to the protocol. Following a pre-agreed communication protocol format, it extracts the required excitation current amplitude (e.g., a value within the range of 50A to 300A) and excitation frequency (e.g., a specific frequency value in low-frequency mode) from the designated data fields of the message. The IPU temporarily stores the extracted excitation parameters in its internal random access memory (RAM) as input parameters for subsequent real-time power loss calculations. Simultaneously, based on the parsed excitation current amplitude, the IPU determines whether the current EIS operation belongs to a low-frequency, high-current, long-duration mode, i.e., a high-risk operating condition. If it does, the IPU activates the waterless stall protection monitoring module, entering a standby state to ensure all preparatory work is completed before the inverter starts modulation output.

[0028] Step A3: Before the inverter starts modulation output in the motor controller, read the initial heat sink temperature in the inverter and obtain the initial bus voltage.

[0029] Specifically, an inverter is a power conversion unit in a motor controller that converts DC bus voltage to AC voltage output. Its core consists of multiple power switching transistors (such as Insulated Gate Bipolar Transistors (IGBTs) or Silicon Carbide (SiC) devices). A heat sink refers to a heat-dissipating copper layer mounted on the IGBT power module. This copper layer is directly attached to the back of the power switching transistors and contacts the liquid cooling channel wall through thermal grease. It is responsible for conducting the heat generated by the power switching transistors to the coolant. Negative Temperature Coefficient (NTC) thermistors are mounted on the heat-dissipating copper layer, located between the upper and lower bridge arm switching transistors, with one for each of the UVW phases, used to measure the real-time temperature of the heat sink. The bus voltage refers to the DC bus voltage value output by the power battery pack, measured in volts (V). In new energy vehicles, it is usually a 400V or 800V voltage platform. This parameter directly affects the calculation of switching losses.

[0030] Before the inverter starts modulation output and the IPU receives the EIS excitation request from the BMS, the IPU first reads the voltage across the DC bus capacitor using its built-in voltage sensor as the initial bus voltage. This voltage reflects the actual output voltage level of the current power battery pack. Simultaneously, the IPU reads the voltage division value of the sampling resistor of the NTC thermistor mounted on the heat dissipation copper layer using an analog-to-digital converter (ADC). Based on the NTC temperature-resistance characteristic curve, this voltage value is converted into the corresponding temperature value as the initial heat sink temperature. Since the thermal time constant τ of the NTC thermistor is ≤1.5s and the sampling frequency is not less than 100Hz (using a 10ms sampling interval), this initial temperature value accurately reflects the true thermal state of the inverter before heat dissipation begins. For the three-phase NTC temperature, the average value or the highest value among the three phases can be used as a representative value to cover the temperature differences between different bridge arms. After acquiring the initial radiator temperature and initial bus voltage, the IPU stores them together with the parsed initial excitation parameters (excitation current amplitude and excitation frequency) as a reference value for calculating the unit loss temperature rise in the subsequent diagnostic window. At this point, the IPU has completed all the preliminary data acquisition work and can then start inverter modulation according to the BMS's request, begin outputting the EIS excitation current, and simultaneously enter the preset diagnostic window to perform real-time monitoring.

[0031] Step S102: Within the preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, continuously collect the real-time heat sink temperature of the motor controller at a preset sampling interval. Calculate the unit loss temperature rise at each sampling point based on the real-time heat sink temperature, initial heat sink temperature, initial bus voltage, and initial excitation parameters. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition.

[0032] In this embodiment, the preset diagnostic window refers to the time length required from the moment the IPU starts outputting the EIS excitation current to the completion of the first anomaly determination, for example, set to 3 seconds. This window length is calibrated and selected based on the thermal time constant τ≤1.5s of the NTC thermistor and the characteristic that the temperature rise rate can show significant anomalies within a few seconds under waterless conditions. The preset sampling interval refers to the time interval between two adjacent temperature acquisitions within the diagnostic window, for example, set to 10ms (corresponding to a sampling frequency of 100Hz). This sampling frequency matches the thermal response speed of the NTC thermistor and can capture enough data points for subsequent characteristic quantity calculation during the dynamic process of rapid temperature change.

[0033] After the IPU completes the acquisition of the initial heat sink temperature, initial bus voltage, and initial excitation parameters, it starts the inverter modulation output according to the EIS excitation request issued by the BMS, and begins injecting AC excitation current into the motor stator winding. This moment is defined as the start time t0 of the diagnostic window, and the IPU's internal timer starts counting from this moment. Within the subsequent 3-second preset diagnostic window, the IPU periodically reads the sampling resistance voltage division value of the NTC thermistors mounted on the heat sink copper layer of the IGBT power module through the ADC at a preset sampling interval of 10ms. Since one NTC thermistor is installed on each of the three phases (UVW) on the heat sink copper layer, located between the upper and lower bridge arm switching transistors of each phase, the IPU simultaneously samples the three-phase NTC channels at each sampling point and converts the voltage division value of each channel into the corresponding temperature value according to the pre-stored NTC temperature-resistance characteristic curve. Considering the possible differences in the heating of the three-phase power switching transistors, the highest value among the three-phase NTC temperatures is taken as the representative real-time heat sink temperature value of the current sampling point to ensure that the protection criteria cover the worst thermal conditions. During the diagnostic window, the IPU sequentially acquires the real-time radiator temperature for the first sampling point (t0+10ms), the second sampling point (t0+20ms), and so on, up to the 300th sampling point (t0+3000ms). It stores the temperature values ​​of each sampling point along with the initial radiator temperature in its internal cache, providing the data basis for subsequent calculations of the absolute temperature rise, real-time power loss, and unit power loss temperature rise for each sampling point. If an anomaly is triggered before the diagnostic window ends, the IPU immediately stops the EIS excitation output and exits the acquisition process; otherwise, it continues acquiring data until the 3-second diagnostic window completely ends.

[0034] Figure 2 This is a schematic diagram illustrating the change in radiator NTC temperature rise over time under different coolant flow rates in an embodiment of this application. Figure 2 As shown, the horizontal axis represents time, and the vertical axis represents the NTC temperature increase. The graph contains three temperature rise curves originating from the origin, corresponding to the waterless condition, the 1L flow rate condition, and the 5L flow rate condition from top to bottom. All three curves rise continuously with time. At the same time point, the NTC temperature increase is the largest for the waterless condition, followed by the 1L flow rate condition, and the smallest for the 5L flow rate condition.

[0035] In this embodiment of the application, the unit loss temperature rise at each sampling point is calculated based on the real-time radiator temperature, the initial radiator temperature, the initial bus voltage, and the initial excitation parameters, including: Step B1: For each sampling point, calculate the absolute temperature rise based on the real-time radiator temperature and the initial radiator temperature.

[0036] Specifically, absolute temperature rise refers to the increase in the real-time radiator temperature at the current sampling point relative to the initial radiator temperature before the start of electrochemical impedance spectroscopy excitation, expressed in degrees Celsius (°C). The formula for calculation is ΔT_abs = T_ntc(t) - T_ntc0, where T_ntc(t) is the real-time radiator temperature at the current sampling point and T_ntc0 is the initial radiator temperature. This indicator reflects the absolute increase in radiator temperature after the start of EIS excitation and is the basic physical quantity for subsequent normalization processing.

[0037] During the preset diagnostic window, after the motor controller completes the real-time radiator temperature acquisition for each sampling point (i.e., every 10ms), it immediately retrieves the initial radiator temperature T_ntc0 from its internal cache. The IPU subtracts the real-time radiator temperature value T_ntc(t) of the current sampling point from T_ntc0 to obtain the absolute temperature rise ΔT_abs for that sampling point. Since the highest value among the three-phase negative temperature coefficient temperatures is taken as the representative value of the real-time radiator temperature, the calculated absolute temperature rise also represents the worst temperature rise state among the three phases. The IPU repeats the above calculation at each sampling point, successively obtaining the absolute temperature rise ΔT_abs_1 for the first sampling point, ΔT_abs_2 for the second sampling point, until the diagnostic window ends or the abnormal protection is triggered. This absolute temperature rise value will be used as the numerator input for the unit loss temperature rise calculation, and also as an independent judgment basis for the fallback criterion.

[0038] Figure 3 This is a schematic diagram of the three-dimensional relationship of adaptive absolute temperature rise in the embodiments of this application, such as... Figure 3 As shown, the three axes of the three-dimensional coordinate system correspond to the initial radiator temperature Tntc0, bus voltage, and the absolute temperature rise ΔT_abs within 3 seconds. The initial radiator temperature ranges from -20℃ to 60℃, and the bus voltage ranges from 300V to 700V. The vertical axis represents the absolute temperature rise of the radiator within the 3-second diagnostic window. The surface in the figure reflects two sets of relationships: when the bus voltage is fixed, the lower the initial radiator temperature, the higher the corresponding 3-second absolute temperature rise value; when the initial radiator temperature is fixed, the higher the bus voltage, the higher the corresponding 3-second absolute temperature rise value. This three-dimensional surface intuitively demonstrates the corresponding relationship between the 3-second fault absolute temperature rise and the synchronous changes of the initial radiator temperature and bus voltage, providing a visual basis for calibrating the absolute temperature rise threshold under different operating conditions.

[0039] Step B2: Based on the pre-stored temperature-on-resistance coefficient curve, determine the on-resistance value corresponding to the real-time heat sink temperature.

[0040] Specifically, the on-resistance value refers to the equivalent DC resistance between the collector (drain) and emitter (source) of a power switch (insulated-gate bipolar transistor or silicon carbide metal-oxide-semiconductor field-effect transistor, MOSFET) when it is fully turned on, measured in milliohms (mΩ). This parameter is the core input for calculating the conduction loss of power devices. The temperature-on-resistance coefficient curve refers to the characteristic curve obtained through previous bench calibration, which describes the relationship between the on-resistance value and temperature. Since the on-resistance of power switches has a positive temperature coefficient (i.e., the on-resistance increases with increasing temperature), the on-resistance value is dynamically corrected based on the real-time heat sink temperature using this curve to eliminate the influence of temperature changes on the accuracy of loss estimation.

[0041] After acquiring the real-time heatsink temperature at each sampling point, the IPU uses this temperature value as an index to look up the temperature-on-resistance coefficient curve pre-stored in the motor controller's non-volatile memory. This curve was generated during the device selection phase by measuring and calibrating the on-resistance values ​​at different temperature points (covering a range of -40℃ to 150℃) using a thermal testing platform, and is stored in memory as a lookup table. The IPU locates the corresponding temperature range in the lookup table based on the real-time heatsink temperature of the current sampling point and calculates the precise on-resistance value at that temperature point using a linear interpolation algorithm. If the current temperature falls exactly on a calibration point, it is read directly; if it falls between two calibration points, it is interpolated proportionally. The IPU independently performs the above lookup and interpolation operation at each sampling point, ensuring that the on-resistance value used at each sampling point matches the actual temperature of the current device. This dynamically corrected on-resistance value serves as a key input parameter for calculating the conduction loss component, significantly improving the accuracy of loss estimation compared to using a fixed value at room temperature, thus ensuring the normalization effectiveness of the core criterion of unit loss temperature rise over a wide temperature range.

[0042] Step B3: Calculate the real-time power loss based on the on-resistance value, initial bus voltage, and initial excitation parameters.

[0043] In this embodiment of the application, the real-time power loss is calculated based on the on-resistance value, the initial bus voltage, and the initial excitation parameters, including: Step B301: Extract the excitation current amplitude and excitation frequency from the initial excitation parameters.

[0044] Specifically, the excitation current amplitude refers to the peak value of the AC current signal that the battery management system requires the motor controller to inject into the battery pack. This parameter directly affects the conduction loss of the power switch, and its square value multiplied by the conduction resistance constitutes the conduction loss component. The excitation frequency refers to the oscillation frequency of the AC excitation current. This parameter directly affects the switching loss of the power switch. The higher the frequency, the more switching actions per unit time, and the greater the switching loss. It, together with the bus voltage, determines the switching loss component.

[0045] When performing real-time power loss calculation at each sampling point within the preset diagnostic window, the IPU first retrieves the initial excitation parameters from its internal random access memory. According to the preset data structure field offsets, the IPU reads the excitation current amplitude (in amperes) and excitation frequency (in hertz) from the buffer. Since these two parameters remain constant throughout the EIS excitation process (issued once by the BMS before excitation starts), the results obtained at each sampling point are identical. The IPU uses the extracted excitation current amplitude as input for calculating the conduction loss component and the excitation frequency as input for calculating the switching loss component.

[0046] Step B302: Determine the switching loss component based on the initial bus voltage and excitation frequency, and determine the conduction loss component based on the excitation current amplitude and the current on-resistance value.

[0047] Specifically, the switching loss component refers to the power loss generated by the overlap of voltage and current during each turn-on and turn-off process of the power switch. This loss is positively correlated with the bus voltage and the switching frequency (i.e., the excitation frequency). The higher the bus voltage and the higher the switching frequency, the greater the switching loss component per unit time. The conduction loss component refers to the Joule heat loss generated by the excitation current flowing through the on-resistance when the power switch is in a fully on state. According to Joule's law, this loss component is equal to the product of the square of the excitation current amplitude and the current on-resistance value (I²×Rds_on), where the on-resistance value has been dynamically corrected based on the real-time heat sink temperature.

[0048] At each sampling point, the IPU performs parallel calculations of the switching loss component and the conduction loss component. For the switching loss component, the IPU looks up a pre-generated switching loss characteristic lookup table based on the initial bus voltage and excitation frequency. This lookup table was generated during the device selection phase after actual measurement and calibration of switching loss energy under different bus voltages (covering 400V and 800V platforms) and different switching frequency combinations using a dual-pulse test platform. The IPU uses the initial bus voltage and excitation frequency as a two-dimensional index to look up the table and employs a bilinear interpolation algorithm to obtain the switching loss component value under the current operating condition. For the conduction loss component, the IPU squares the excitation current amplitude and multiplies it by the current on-resistance value to obtain the conduction loss component P_conduction = I_eis² × Rds_on. The excitation current amplitude, whether RMS or peak value, must be consistent with the dimensions used during calibration; peak current is used for calculation to match the calibration data. The IPU independently performs the above calculations of the switching loss component and the conduction loss component at each sampling point.

[0049] Step B303: Calculate the real-time power loss based on the switching loss component and the conduction loss component.

[0050] Specifically, real-time power loss refers to the instantaneous total power loss generated by the power switching transistor inside the motor controller at each sampling point under the current electrochemical impedance spectroscopy excitation condition. This loss is the sum of the conduction loss component and the switching loss component, i.e., P_loss = P_switching + P_conduction, with the unit being watts (W). This value is used as the denominator input for the unit loss temperature rise normalization process to eliminate the influence of the difference in heat generation between different excitation conditions on the temperature rise criterion.

[0051] After calculating the switching loss component and the conduction loss component at each sampling point, the IPU performs an addition operation, summing the two to obtain the current real-time power loss at that sampling point: P_loss = P_switching + P_conduction. Since the conduction loss component may vary slightly at each sampling point due to changes in the on-resistance with temperature, while the switching loss component remains constant under the same bus voltage and excitation frequency, the real-time power loss may also fluctuate slightly at each sampling point. The IPU temporarily stores the calculated real-time power loss value in a cache, which is then used as the divisor input for calculating the unit loss temperature rise.

[0052] It should be noted that the loss calculation is based entirely on the device physical parameters of the power switch (conduction loss uses the I²R formula, and switching loss is based on measured calibration data), which is different from the traditional approach of indirectly estimating statistical empirical values ​​based on efficiency maps. Therefore, it can still remain accurate when the temperature changes drastically due to abnormal water circuit conditions, and does not depend on the accuracy of the thermal model.

[0053] Step B4: Calculate the unit loss temperature rise using the absolute temperature rise and real-time power loss.

[0054] Specifically, the unit loss temperature rise refers to the ratio of the absolute temperature rise at the current sampling point to the real-time power loss. The calculation formula is ΔT_norm=ΔT_abs / P_loss, with units of ℃ / W. This indicator is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition, and essentially reflects the transient thermal resistance characteristics of the system. Since the numerator is the real-time measured temperature rise amplitude and the denominator is the heat generation power under the current condition, this ratio decouples the temperature rise from the absolute value, eliminating the influence of different excitation current amplitudes, bus voltages, and initial temperatures on the temperature rise value. This makes the evaluation of heat dissipation capacity under different conditions comparable and is a normalized core criterion applicable to all scenarios.

[0055] After calculating the absolute temperature rise ΔT_abs and the real-time power loss P_loss at each sampling point, the motor controller performs a division operation, using the absolute temperature rise as the dividend and the real-time power loss as the divisor, to calculate the unit loss temperature rise ΔT_norm = ΔT_abs / P_loss at the current sampling point. This division operation uses floating-point arithmetic to ensure accuracy. If the real-time power loss value is zero (which theoretically will not happen because the EIS excitation has been started and the current amplitude is greater than zero), the unit loss temperature rise is processed according to the preset maximum limit value to avoid calculation overflow.

[0056] The IPU repeats the above division operation at each sampling point, sequentially obtaining the unit loss temperature rise ΔT_norm_1 for the first sampling point and ΔT_norm_2 for the second sampling point, until the diagnostic window ends or abnormal protection is triggered. Since the conduction loss component in the real-time power loss fluctuates slightly with temperature changes in the on-resistance, while the switching loss component remains constant under the same excitation conditions, the unit loss temperature rise at each sampling point can dynamically reflect the actual heat dissipation status of the cooling system at the current temperature. This unit loss temperature rise value is compared with the unit loss temperature rise threshold obtained from the initial radiator temperature, initial bus voltage, and initial excitation parameters: when the cooling system is normal, the unit loss temperature rise reflects the transient thermal resistance of a healthy cooling system under normal flow conditions, and the value is low and stable; when there is no water or low flow abnormality, the same amount of heat cannot be effectively dissipated, and the absolute temperature rise increases significantly under the same loss, causing the unit loss temperature rise value to increase sharply and exceed the threshold, thus triggering abnormal judgment.

[0057] It should be noted that the real-time power loss is calculated directly based on the device physical parameters of the power switch, without relying on indirect calculations from thermal models or efficiency maps. Therefore, even under extreme operating conditions where the thermal path deviates significantly from normal due to no water or low flow, the power loss estimate remains accurate, thus ensuring the effectiveness and reliability of the unit loss temperature rise as a normalized heat dissipation capacity indicator under all operating conditions.

[0058] Step S103: When the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of electrochemical impedance spectroscopy excitation is stopped.

[0059] In this embodiment, the unit loss temperature rise threshold refers to the maximum allowable unit loss temperature rise limit within a preset diagnostic window when the cooling system is in normal heat dissipation state (coolant flow rate not less than 5L / min) under a specific initial radiator temperature, initial bus voltage, and initial excitation parameter combination. This threshold is obtained through prior bench calibration and is pre-stored in the non-volatile memory of the motor controller in the form of a three-dimensional lookup table. The IPU directly looks up the table to obtain the threshold during operation based on the current operating conditions. The continuous preset number of sampling points refers to the continuous over-threshold counting condition set to prevent misjudgment caused by instantaneous noise interference. The measurement consists of 3 sampling points (corresponding to a 30ms time span), meaning that the protection action is only triggered when the unit loss temperature rise of 3 consecutive sampling points exceeds the threshold, thus ensuring a fast response while eliminating occasional spike noise; Cooling system abnormality refers to a fault state in the liquid cooling circuit of the electric drive system, such as coolant leakage, failure to add coolant after maintenance, or water pump failure, resulting in a coolant flow rate that is too low (below 5L / min) or even completely cut off. In this state, the heat dissipation capacity drops sharply; Stopping the output of electrochemical impedance spectroscopy excitation means that the IPU immediately stops the pulse width modulation (PWM) output of the inverter, turning off all power switching transistors, thereby cutting off the AC excitation current injected into the motor stator windings and fundamentally preventing heat from continuing to be generated.

[0060] After calculating the unit loss temperature rise at each sampling point, the IPU executes a judgment process. First, the IPU uses the initial radiator temperature, initial bus voltage, and initial excitation parameters (excitation current amplitude and excitation frequency) as a three-dimensional index to query a pre-stored three-dimensional threshold map in memory. It then obtains the unit loss temperature rise threshold under the current operating condition using a trilinear interpolation algorithm. Next, the IPU compares the unit loss temperature rise calculated for the current sampling point with this threshold. If the unit loss temperature rise is less than the threshold, the current sampling point is considered normal, and the IPU resets the continuous over-threshold counter to zero and continues sampling and calculation for the next sampling point. If the unit loss temperature rise is greater than or equal to the threshold, the IPU increments the continuous over-threshold counter by 1 and checks if the counter value has reached a preset number of 3. If the continuous over-threshold counter value is less than 3, the IPU does not trigger protection and continues sampling for the next sampling point for a new round of calculation and comparison. If the continuous over-threshold counter value reaches 3, meaning the unit loss temperature rise at three consecutive sampling points (within a 30ms time span) continuously exceeds the threshold, the IPU determines that the cooling system is abnormal and stops the output of the electrochemical impedance spectroscopy excitation.

[0061] In this embodiment of the application, before determining that there is an anomaly in the cooling system associated with the electric drive system, the method further includes: Step C1: Obtain the unit loss temperature rise threshold corresponding to the initial heat sink temperature, initial bus voltage, and initial excitation parameters.

[0062] Specifically, before calculating the unit loss temperature rise at each sampling point and preparing to enter the anomaly detection phase, the IPU first performs a threshold acquisition operation. The IPU uses the initial radiator temperature T_ntc0, the initial bus voltage Vdc0, and the initial excitation parameters (excitation current amplitude I_eis and excitation frequency f_eis) as a three-dimensional index to access a pre-stored three-dimensional threshold map in memory. This map uses (initial radiator temperature, bus voltage, and excitation current amplitude) as three dimensions, with each grid node storing the unit loss temperature rise threshold for the corresponding operating condition. Based on the four parameter values ​​of the current operating condition, the IPU locates its corresponding grid interval in three-dimensional space and uses a trilinear interpolation algorithm (i.e., linear interpolation is performed in the initial radiator temperature dimension, bus voltage dimension, and excitation current amplitude dimension) to calculate the precise unit loss temperature rise threshold corresponding to the current operating point. If the current operating condition parameters happen to fall on a certain calibration grid node, the threshold of that node is read directly without interpolation. The IPU temporarily stores the interpolated unit loss temperature rise threshold in an internal register as a reference value for real-time comparison. The entire table lookup and interpolation process is completed within the current sampling period, with a time overhead of less than 1ms, and will not affect the real-time performance of the protection response.

[0063] Step C2: At each sampling point, compare the temperature rise per unit loss with the temperature rise per unit loss threshold.

[0064] Specifically, after acquiring the unit loss temperature rise threshold for the current sampling point, the IPU immediately performs a comparison operation. The IPU reads the actual unit loss temperature rise ΔT_norm_current and the corresponding threshold ΔT_norm_max for the current sampling point from the register and sends them to the internal comparator for numerical comparison. If the actual value is less than the threshold (ΔT_norm_current < ΔT_norm_max), the comparison result is "normal," indicating that the temperature rise corresponding to the unit heat output of the cooling system at the current sampling point is within the allowable range under normal cooling flow. The IPU clears the continuous over-threshold counter to zero and then proceeds to the acquisition, calculation, and judgment process for the next sampling point. If the actual value is greater than or equal to the threshold (ΔT_norm_current ≥ ΔT_norm_max), the comparison result is "abnormal," indicating that the temperature rise caused by the same unit heat output at the current sampling point has exceeded the upper limit that a healthy cooling system can achieve, indicating that the heat dissipation capacity has dropped to an abnormal level. The IPU increments the continuous over-threshold counter by 1 and then proceeds to determine whether the preset number of continuous over-thresholds has been reached. Each sampling point performs a comparison operation independently to ensure that the status of each sampling point is evaluated in real time.

[0065] Step C3: If the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, then it is determined that there is an abnormality in the cooling system.

[0066] Specifically, an abnormality in the cooling system refers to a fault state in the liquid cooling circuit of the electric drive system, such as coolant leakage, failure to add coolant after maintenance, or water pump failure, which causes the coolant flow rate to be lower than the safety limit of 5L / min or even completely cut off. In this state, the convective heat transfer capacity of the liquid cooling system drops sharply, and the radiator temperature rise rate and final temperature rise amplitude are significantly higher than those under normal cooling conditions for the same heat output.

[0067] After each sampling point completes the comparison operation, if the comparison result is "abnormal" (unit loss temperature rise ≥ threshold), the IPU's continuous over-threshold counter is incremented by 1. After incrementing by 1, the IPU immediately determines whether the current value of the counter has reached the preset number 3. If the counter value is less than 3, it indicates that although the current sampling point is abnormal, a continuous abnormal trend has not yet formed, and the IPU does not trigger the protection action for the time being, and continues to collect the next sampling point for a new round of calculation, threshold acquisition, and comparison. If the counter value reaches 3, that is, the unit loss temperature rise of three consecutive sampling points (t, t+10ms, and t+20ms) is continuously greater than or equal to the threshold, the IPU determines that there is indeed an abnormality in the cooling system rather than instantaneous noise interference, and then triggers the protection action. If, during the continuous over-threshold counting process, the comparison result of a certain sampling point is "normal" (unit loss temperature rise < threshold), the IPU immediately clears the continuous over-threshold counter to zero, the previous continuous abnormal count is broken, and if an abnormality occurs again, the counting must start from 1 again. This continuous judgment mechanism completes the entire process from the first anomaly occurrence to the final protection trigger within 30ms, ensuring both response speed and significantly reducing the risk of false alarms caused by single-point noise. After an anomaly is determined, the IPU immediately executes protection actions, including stopping the inverter modulation output to cut off the heat source, sending a fault code to the battery management system, and locking the EIS excitation function to prevent subsequent request responses.

[0068] This embodiment provides a method for protecting an electric drive system from abnormal cooling. Figure 4 This is a flowchart of an electric drive system cooling anomaly protection method according to an embodiment of the present invention, such as... Figure 4 As shown, the process includes the following steps: Step S201: Obtain the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation start-up.

[0069] In this embodiment, when the IPU receives the EIS excitation request from the BMS, it first performs protocol parsing on the request message, extracts the excitation current amplitude and excitation frequency from the specified data fields of the message, and temporarily stores these two parameters in the internal random access memory as initial excitation parameters. Subsequently, before the inverter starts pulse width modulation output, the IPU reads the voltage value across the DC bus capacitor through the built-in voltage sensor as the initial bus voltage, which reflects the actual output voltage level of the current power battery pack. At the same time, the IPU reads the sampling resistor voltage division value of the NTC thermistor mounted on the heat dissipation copper layer through the analog-to-digital converter, and converts the voltage value into a temperature value according to the pre-stored NTC temperature-resistance characteristic curve, as the initial heat sink temperature. Since one NTC thermistor is installed on each of the three phases (UVW) on the heat dissipation copper layer, the IPU reads the temperature values ​​of the three phases respectively, and takes the average value or the highest value among the three phases of interest as the initial representative value of the heat sink temperature to ensure that the reference data covers the most comprehensive thermal state. After acquiring and caching the above three data points, the IPU stores the initial heatsink temperature, initial bus voltage, and initial excitation parameters in a designated buffer area of ​​its internal RAM for use in all subsequent calculation steps within the diagnostic window. At this point, the pre-processing data acquisition is complete, and the inverter can then initiate modulation output, begin EIS excitation, and simultaneously enter the diagnostic window for temperature acquisition.

[0070] Step S202: Within the preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, continuously collect the real-time heat sink temperature of the motor controller according to the preset sampling interval.

[0071] In this embodiment, after the IPU completes the acquisition of the initial heat sink temperature, initial bus voltage, and initial excitation parameters, it starts the inverter modulation output according to the EIS excitation request issued by the BMS, and begins to inject AC excitation current into the motor stator winding. This moment is defined as the start time t0 of the diagnostic window, and the IPU's internal timer starts counting from this moment. Within the subsequent 3-second preset diagnostic window, the IPU periodically reads the sampling resistance voltage division value of the NTC thermistors mounted on the heat dissipation copper layer of the IGBT power module through the ADC at a preset sampling interval of 10ms. Since one NTC thermistor is installed on each of the three phases (UVW) on the heat dissipation copper layer, located between the upper and lower bridge arm switching transistors of each phase, the IPU simultaneously samples the three-phase NTC channels at each sampling point and converts the voltage division value of each channel into the corresponding temperature value according to the pre-stored NTC temperature-resistance characteristic curve. Considering that the heating of the three-phase power switching transistors may differ, the highest value among the three-phase NTC temperatures is taken as the representative value of the real-time heat sink temperature at the current sampling point to ensure that subsequent protection criteria cover the worst thermal conditions. During the diagnostic window, the IPU sequentially acquires the real-time radiator temperature for the first sampling point (t0+10ms), the second sampling point (t0+20ms), and so on, up to the 300th sampling point (t0+3000ms). It stores the temperature values ​​of each sampling point along with the initial radiator temperature recorded in step S201 into its internal cache, providing a data basis for subsequent calculations of the absolute temperature rise at each sampling point (used for temperature rise rate calculation and fallback criteria). If an anomaly is triggered before the diagnostic window ends, the IPU immediately stops the EIS excitation output and exits the acquisition process; otherwise, it continues acquisition until the 3-second diagnostic window completely ends.

[0072] Step S203: Within the preset diagnostic window, calculate the temperature rise rate of the current sampling point based on the continuously collected real-time radiator temperature and the preset sampling interval.

[0073] In this embodiment, the temperature rise rate refers to the instantaneous rate of change of the radiator temperature over time within a preset diagnostic window, measured in °C / s. The calculation formula is dT / dt = (T_ntc(t) - T_ntc(t-Δt_sample)) / Δt_sample, where T_ntc(t) is the real-time radiator temperature at the current sampling point, T_ntc(t-Δt_sample) is the real-time radiator temperature at the previous sampling point, and Δt_sample is the preset sampling interval (e.g., 10ms). This indicator directly reflects the rate of temperature rise of the radiator per unit time. Under severe waterless conditions, due to the lack of coolant, the convective heat transfer capacity is almost lost, and the heat generated by the power switching transistor cannot be effectively removed. The temperature rise rate can be 5 to 10 times higher than that under normal cooling conditions within 1 second after the EIS excitation begins. Therefore, this indicator can be used as a preliminary rapid screening criterion for abnormal conditions.

[0074] During the preset diagnostic window, after the IPU completes the acquisition of the real-time radiator temperature at each sampling point (i.e., every 10ms), it retrieves the real-time radiator temperature value of the previous sampling point (i.e., 10ms ago) from its internal cache. The IPU subtracts the real-time radiator temperature of the previous sampling point from the current sampling point's real-time radiator temperature to obtain the temperature increment between adjacent sampling points. Then, it divides the temperature increment by the preset sampling interval (10ms, i.e., 0.01s) to calculate the temperature rise rate of the current sampling point. For the first sampling point (t0+10ms) within the diagnostic window, since there is no previous sampling point, the temperature rise rate is not calculated for this sampling point. Normal calculation begins from the second sampling point (t0+20ms). The IPU obtains the temperature rise rate dT / dt_1 (the second sampling point) and dT / dt_2 (the third sampling point) sequentially at each valid sampling point until the diagnostic window ends or the abnormal protection is triggered. Because a high-frequency sampling interval of 10ms is used, the calculated temperature rise rate can truly reflect the dynamic change process of the radiator temperature, and will not lose the key information of rapid temperature rise due to excessively long sampling intervals.

[0075] Step S204: Obtain the temperature rise rate threshold corresponding to the initial heat sink temperature, initial bus voltage, and initial excitation parameters, and compare the temperature rise rate with the temperature rise rate threshold at each sampling point.

[0076] In this embodiment, the temperature rise rate threshold refers to the maximum allowable temperature rise rate limit within a preset diagnostic window when the cooling system is in normal heat dissipation state (coolant flow rate not less than 5L / min) under a specific combination of initial radiator temperature, initial bus voltage, and initial excitation parameters. This threshold is obtained through prior bench calibration. The calibration process is similar to that for the unit loss temperature rise threshold. Under conditions of simulated ambient temperature from -40℃ to 85℃, full bus voltage platforms of 400V and 800V, and full excitation current ranges of 50A to 300A, normal cooling water flow is introduced for each combination of (initial radiator temperature, bus voltage, excitation current), and the maximum temperature rise rate of each sampling point within the diagnostic window is recorded. This value is used as the temperature rise rate threshold under that operating condition. The thresholds for all combinations are pre-stored in the non-volatile memory of the IPU in the form of a three-dimensional lookup table.

[0077] After calculating the temperature rise rate at each valid sampling point (i.e., the second sampling point and thereafter), the IPU first performs a threshold acquisition operation. Using the initial radiator temperature, initial bus voltage, and initial excitation parameters (excitation current amplitude and excitation frequency) as a three-dimensional index, the IPU accesses a pre-stored three-dimensional threshold map in memory and calculates the precise temperature rise rate threshold corresponding to the current operating point using a trilinear interpolation algorithm. Subsequently, the IPU performs a comparison operation, reading the actual temperature rise rate and the corresponding temperature rise rate threshold from the register for the current sampling point, and sending both to an internal comparator for numerical comparison. If the actual temperature rise rate is less than the threshold, the comparison result is "normal," indicating that the temperature rise rate at the current sampling point is within the allowable range under normal cooling flow. The IPU clears the continuous over-threshold counter to zero and then proceeds to the next sampling point's acquisition, calculation, and judgment process. If the actual temperature rise rate is greater than or equal to the threshold, the comparison result is "abnormal," indicating that the temperature rise rate at the current sampling point has exceeded the upper limit achievable by a healthy cooling system, indicating a significant decrease in heat dissipation capacity. The IPU increments the continuous over-threshold counter by 1 and then proceeds to determine whether the preset number of continuous over-thresholds has been reached. Each valid sampling point independently performs a lookup table interpolation to obtain the threshold and a comparison operation to ensure that abnormal states of the temperature rise rate can be captured in real time.

[0078] Step S205: When the temperature rise rate of a continuously preset number of sampling points is greater than or equal to the temperature rise rate threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of electrochemical impedance spectroscopy excitation is stopped.

[0079] In this embodiment, after the comparison operation is completed at each valid sampling point, if the comparison result is "abnormal" (temperature rise rate ≥ threshold), the IPU's continuous over-threshold counter is incremented by 1 based on the current value. After incrementing by 1, the IPU immediately determines whether the current value of the counter has reached a preset number of 3. If the counter value is less than 3, it indicates that although the current sampling point is abnormal, a continuous abnormal trend has not yet formed, and the IPU does not trigger the protection action for the time being, and continues to collect the next sampling point for a new round of calculation, threshold acquisition, and comparison. If the counter value reaches 3, that is, the temperature rise rate of three consecutive valid sampling points (t+20ms, t+30ms, and t+40ms, corresponding to the interval from 20ms to 40ms after the excitation starts) is continuously greater than or equal to the threshold, the IPU determines that there is indeed an abnormality in the cooling system rather than instantaneous noise interference, and then triggers the protection action.

[0080] If, during the continuous over-threshold counting process, the comparison result of a certain valid sampling point is "normal" (temperature rise rate < threshold), the IPU immediately resets the continuous over-threshold counter to zero, breaking the previous continuous abnormal count. If an abnormality occurs again, the count must start from 1 again. This continuous judgment mechanism completes the entire process from the first abnormality to the final protection trigger in a very short time (maximum 30ms from the second valid sampling point). Compared with the 3-second diagnostic window based on the temperature rise per unit loss as the main criterion, the temperature rise rate as a pre-screening criterion can significantly compress the protection response time to less than 1 second (in severe waterless conditions, the temperature rise rate significantly exceeds the threshold within the first second), thereby cutting off the heat source earlier before the junction temperature of the power switch tube rises sharply to a dangerous value.

[0081] This embodiment provides a method for protecting an electric drive system from abnormal cooling. Figure 5 This is a flowchart of an electric drive system cooling anomaly protection method according to an embodiment of the present invention, such as... Figure 5 As shown, the process includes the following steps: Step S301: Obtain the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation start-up.

[0082] In this embodiment, when the IPU receives the EIS excitation request from the BMS, it first performs protocol parsing on the request message, extracts the excitation current amplitude and excitation frequency from the specified data fields of the message, and temporarily stores these two parameters in the internal random access memory as initial excitation parameters. Subsequently, before the inverter starts pulse width modulation output, the IPU reads the voltage value across the DC bus capacitor through the built-in voltage sensor as the initial bus voltage, which reflects the actual output voltage level of the current power battery pack. At the same time, the IPU reads the sampling resistor voltage division value of the NTC thermistor mounted on the heat dissipation copper layer through the analog-to-digital converter, and converts the voltage value into a temperature value according to the pre-stored NTC temperature-resistance characteristic curve, as the initial heat sink temperature. Since one NTC thermistor is installed on each of the three phases (UVW) on the heat dissipation copper layer, the IPU reads the temperature values ​​of the three phases respectively, and takes the average value or the highest value among the three phases of interest as the initial representative value of the heat sink temperature to ensure that the reference data covers the most comprehensive thermal state. After acquiring and caching the above three data points, the IPU stores the initial heatsink temperature, initial bus voltage, and initial excitation parameters in a designated buffer area of ​​its internal RAM for use in all subsequent calculation steps within the diagnostic window. At this point, the pre-processing data acquisition is complete, and the inverter can then initiate modulation output, begin EIS excitation, and simultaneously enter the diagnostic window for temperature acquisition.

[0083] Step S302: Within the preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, continuously collect the real-time heat sink temperature of the motor controller at a preset sampling interval. Calculate the unit loss temperature rise at each sampling point based on the real-time heat sink temperature, initial heat sink temperature, initial bus voltage, and initial excitation parameters. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition.

[0084] In this embodiment, within a 3-second diagnostic window set from the moment the IPU starts outputting the EIS excitation current, the IPU periodically reads the voltage division values ​​of the three-phase NTC thermistors mounted on the heat dissipation copper layer of the IGBT power module via the ADC at 10ms sampling intervals. Based on the pre-stored NTC temperature-resistance characteristic curve, the voltage division values ​​of each channel are converted into temperature values, and the highest value among the three phases is taken as the representative real-time heat sink temperature of the current sampling point. After completing the real-time heat sink temperature acquisition for each sampling point, the real-time heat sink temperature of the current sampling point is subtracted from the initial heat sink temperature to obtain the absolute temperature rise ΔT_abs. Using the current real-time heat sink temperature as an index, the pre-stored temperature-on-resistance coefficient curve is queried, and the dynamically corrected on-resistance value Rd at the current temperature is obtained through linear interpolation. s_on; then, based on the initial bus voltage and excitation frequency, the switching loss power is obtained by looking up the switching loss characteristic table. At the same time, the conduction loss component is obtained by multiplying the square of the excitation current amplitude by the dynamic conduction resistance value. The two are added together to obtain the real-time loss power P_loss; finally, the absolute temperature rise is divided by the real-time loss power to obtain the unit loss temperature rise ΔT_norm=ΔT_abs / P_loss. This index is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition. In essence, it is a reflection of the transient thermal resistance of the system and is extremely sensitive to the coolant flow rate. When the cooling system is normal, the value is low and stable. When there is no water or low flow abnormality, the absolute temperature rise under the same loss increases significantly, resulting in a sharp increase in the unit loss temperature rise, thus providing a normalized core criterion for subsequent anomaly judgment.

[0085] Step S303: When the unit loss temperature rise of the continuous preset number of sampling points is not greater than or equal to the unit loss temperature rise threshold, obtain the absolute temperature rise threshold corresponding to the initial heat sink temperature, the initial bus voltage and the initial excitation parameters.

[0086] In this embodiment, the absolute temperature rise threshold refers to the maximum allowable absolute temperature rise limit within a preset diagnostic window when the cooling system is in normal heat dissipation state (coolant flow rate not less than 5L / min) under a specific combination of initial radiator temperature, initial bus voltage, and initial excitation parameters. This threshold is calibrated in parallel with the unit loss temperature rise threshold and temperature rise rate threshold in the same rack calibration process. Under the conditions of a full ambient temperature range of -40℃ to 85℃, covering the full bus voltage platforms of 400V and 800V, and covering the full excitation current range of 50A to 300A, normal cooling water flow is introduced for each combination of (initial radiator temperature, bus voltage, excitation current), and the maximum absolute temperature rise value of each sampling point within the diagnostic window is recorded. This value is used as the absolute temperature rise threshold under this operating condition and is pre-stored in the non-volatile memory of the motor controller in the form of a three-dimensional lookup table. This criterion serves as a fallback protection mechanism to deal with extreme situations where the main criterion for unit loss temperature rise fails to be triggered due to minor deviations in the loss estimation model under extreme edge scenarios.

[0087] During the preset diagnostic window, if the IPU determines that the main judgment process does not meet the condition that the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, i.e., there are never three consecutive sampling points in the diagnostic window where the unit loss temperature rise exceeds the threshold, or the unit loss temperature rise of a certain sampling point is lower than the threshold, causing the counter to be cleared, the IPU will not immediately determine that the cooling system is normal. Instead, it will enter the judgment path of the fallback criterion to deal with potential risks in edge extreme scenarios. The IPU uses the initial heat sink temperature T_ntc0, the initial bus voltage Vdc0, and the initial excitation parameters (excitation current amplitude I_eis and excitation frequency f_eis) as a three-dimensional index to access the three-dimensional threshold map pre-stored in memory and uses a trilinear interpolation algorithm to calculate the precise absolute temperature rise threshold corresponding to the current operating point. This absolute temperature rise threshold and the absolute temperature rise ΔT_abs use the same physical definition and calculation method (both are T_ntc(t)-T_ntc0), so they are directly comparable. The IPU temporarily stores the absolute temperature rise threshold obtained from the interpolation calculation in an internal register as a reference value for real-time comparison.

[0088] Step S304: At each sampling point, the absolute temperature rise is compared with the absolute temperature rise threshold.

[0089] In this embodiment, after calculating the absolute temperature rise and obtaining the absolute temperature rise threshold at each sampling point, the IPU performs a comparison operation for the fallback criterion. The IPU reads the actual absolute temperature rise ΔT_abs_current and the corresponding absolute temperature rise threshold ΔT_abs_max of the current sampling point from the register, and sends the two to the internal comparator for numerical comparison.

[0090] If the actual absolute temperature rise is less than the threshold (ΔT_abs_current<ΔT_abs_max), the comparison result is "normal", indicating that the absolute temperature rise of the heat sink at the current sampling point is within the allowable range under normal cooling flow. The IPU does not trigger the fallback protection and continues to collect the next sampling point for a new round of calculation, threshold acquisition and comparison.

[0091] If the actual absolute temperature rise is greater than or equal to the threshold (ΔT_abs_current ≥ ΔT_abs_max), the comparison result is "abnormal", indicating that the absolute temperature rise of the heat sink at the current sampling point has exceeded the upper limit that a healthy cooling system can reach under the same operating conditions, indicating that the heat dissipation capacity has decreased significantly, and the IPU directly enters the judgment logic.

[0092] Unlike the unit loss temperature rise criterion and the temperature rise rate criterion, the absolute temperature rise fallback criterion does not perform cumulative counting of multiple sampling points in the comparison stage. Instead, each sampling point is compared independently. Once an anomaly is detected, subsequent judgments are triggered immediately. This is determined by the attribute of absolute temperature rise as the last line of defense: when the core criterion (unit loss temperature rise) fails to be triggered due to a small deviation in the model, it indicates that the operating condition is already at an extreme edge. At this time, there is no need for a continuous confirmation mechanism to prevent false alarms, and protection should be triggered directly.

[0093] Step S305: When the absolute temperature rise is greater than or equal to the absolute temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of electrochemical impedance spectroscopy excitation is stopped.

[0094] In this embodiment, if the comparison result is "abnormal" (absolute temperature rise ≥ absolute temperature rise threshold), the IPU does not continuously exceed the threshold count (this criterion does not have a continuous counting condition; a single exceedance of the threshold triggers it), directly determining that the cooling system is abnormal. The absolute temperature rise criterion, as a fallback protection mechanism, does not undertake the primary judgment task (the primary judgment is completed by the unit loss temperature rise, whose normalization characteristics can eliminate operating condition differences and cover most abnormal scenarios). However, when the unit loss temperature rise primary criterion fails to trigger due to a slight deviation in the loss estimation model under extreme edge scenarios, the absolute temperature rise can effectively capture the abnormality as a last line of defense, forming a double insurance with the primary criterion to ensure that there is no missed protection under any circumstances, thereby maximizing the safety of power devices.

[0095] In this embodiment of the application, after determining that there is an anomaly in the cooling system associated with the electric drive system and stopping the output of electrochemical impedance spectroscopy excitation, the method further includes: Step D1: In response to the determination that there is an abnormality in the cooling system, a cooling system abnormality fault code is sent to the battery management system.

[0096] Specifically, the cooling system abnormality fault code refers to a set of standardized digital codes generated by the motor controller according to a pre-agreed communication protocol after determining that there is an abnormality in the cooling system (such as the coolant flow rate being lower than the safety limit of 5L / min or even completely cut off). This code includes information such as the fault type identifier (e.g., "cooling system abnormality during EIS excitation"), key state parameters at the time of the fault (e.g., current radiator temperature, bus voltage, etc.), and fault timestamp. It is used to inform the battery management system of the specific reason for the termination of this electrochemical impedance spectroscopy excitation, so that the BMS can record subsequent faults, provide alarm prompts, and provide maintenance guidance accordingly. In response to the determination that there is an abnormality in the cooling system, the IPU enters the initial action of the fault post-processing procedure after any determination path is triggered. This action is a prerequisite for subsequent fault notification and function lockout.

[0097] When the main judgment process determines that the cooling system is abnormal (the unit loss temperature rise of 3 consecutive sampling points exceeds the threshold), or the pre-screening process determines that the cooling system is abnormal (the temperature rise rate of 3 consecutive valid sampling points exceeds the threshold), or the fallback judgment process determines that the cooling system is abnormal (the single absolute temperature rise exceeds the threshold), the IPU immediately triggers the fault post-processing process in steps D1-D2.

[0098] First, the IPU generates a cooling system fault code message according to the standard frame format of the Controller Area Network (CLAN) communication protocol. The data field of this message contains a predefined fault code number (e.g., 0xEIS_COOL_ERR), diagnostic information such as the maximum unit loss temperature rise, maximum absolute temperature rise, maximum temperature rise rate, and current radiator temperature recorded in the diagnostic window. The IPU sends this fault code message to the BMS via the CAN bus. Upon receiving the fault code, the BMS parses and records it. On one hand, it issues a cooling system fault alarm to the driver via the instrument panel or central control screen; on the other hand, it records the event of EIS excitation being interrupted due to cooling abnormality in the BMS's fault log for later retrieval and analysis during maintenance and diagnosis. Simultaneously with sending the fault code, the IPU also records the time of the fault occurrence, the trigger criterion type (unit loss temperature rise / temperature rise rate / absolute temperature rise), and the instantaneous values ​​of each characteristic quantity in its local storage unit for tracing the root cause of the fault during diagnosis.

[0099] Step D2: Lock the electrochemical impedance spectroscopy excitation function and prohibit responding to electrochemical impedance spectroscopy excitation requests issued by the battery management system until a fault recovery signal from the cooling system is received.

[0100] Specifically, locking the electrochemical impedance spectroscopy excitation function refers to the IPU's operation of forcibly clearing and maintaining the internal software flag (such as EIS_Enable_Flag) used to control the EIS excitation enable state after determining that the cooling system is abnormal. This flag is the main switch for the IPU to respond to the EIS excitation request issued by the BMS. Disabling the response to the electrochemical impedance spectroscopy excitation request issued by the battery management system means that the IPU will not process any subsequent EIS excitation request messages received from the BMS, including not parsing the excitation parameters, not starting the inverter modulation output, not activating the waterless stall protection monitoring module, and directly returning a "EIS function unavailable" response frame or ignoring the request. The fault recovery signal refers to the authorization command issued by the BMS to the IPU through the CAN bus after the cooling system abnormality problem is resolved, which is specifically used to clear the fault lock state. This command usually needs to be combined with manual confirmation (such as the maintenance personnel completing the coolant filling and manually resetting the fault code) before being triggered by the BMS. Its signal content includes fault confirmation code and recovery timestamp information.

[0101] After sending the cooling system fault code, the IPU first sets the internal EIS excitation function enable flag (EIS_Enable_Flag) to logic "0" (locked state). After this flag is cleared, the task module in the IPU main loop responsible for listening to and parsing the EIS excitation request sent by the BMS will be bypassed. When the BMS sends the EIS excitation request again, the IPU will detect that EIS_Enable_Flag is locked at the entry judgment of the request reception stage. It will directly discard the request message and reply with an "IS function is temporarily unavailable" response frame. It will not enter the request reception process, nor will it start the inverter modulation output.

[0102] Simultaneously, the IPU starts an internal lockout timer, which runs continuously in the locked state to record the duration of the fault. During the lockout, the IPU continuously monitors the fault recovery signal reception status on the CAN bus. Once the cooling system fault is resolved (e.g., after maintenance personnel complete coolant refilling and pipeline leak detection), the BMS sends a fault recovery signal to the IPU via the CAN bus. Upon receiving this signal, the IPU first verifies its validity (including checksum and source ID confirmation). If everything is correct, it unlocks the EIS excitation function, resets EIS_Enable_Flag to logic "1", clears the locally stored fault record, and resets the continuous over-threshold counter to zero. Afterward, the IPU resumes normal response to EIS excitation requests from the BMS, allowing the next EIS excitation to be executed. If no fault recovery signal is received during the lockout period, the IPU remains locked until the vehicle is powered off, ensuring that under no circumstances will the EIS excitation be repeatedly executed before the cooling system is repaired, thus preventing repeated thermal failure risks and achieving intrinsic safety in fault conditions.

[0103] Figure 6 This is a schematic diagram of the overall process for waterless protection under EIS operating conditions in the embodiments of this application, as shown below. Figure 6 As shown, the process begins with the vehicle's power-on initialization. After the vehicle completes power-on initialization, the BMS sends an EIS request to the IPU. The process is divided into two parallel branches: the left branch involves the IPU collecting the bus voltage, NTC initial value, and EIS bus current command, and querying the three judgment thresholds corresponding to the waterless condition: absolute temperature rise, temperature rise rate, and unit loss temperature rise; the right branch involves the IPU synchronously executing EIS excitation and continuously collecting the real-time change value of NTC, calculating the absolute temperature rise, temperature rise rate, and unit loss temperature rise within a set time based on the collected data. After both branches are completed, a unified judgment node is entered, comparing the calculated actual temperature rise values ​​with the judgment thresholds obtained from the lookup table. If the actual value is greater than the judgment threshold, a waterless flag is fed back and EIS execution is stopped; if the actual value does not exceed the judgment threshold, EIS continues to execute normally.

[0104] This embodiment also provides an electric drive system cooling abnormality protection device, which is used to implement the above embodiments and preferred embodiments, and will not be repeated as already described. As used below, the term "module" can be a combination of software and / or hardware that implements a predetermined function. Although the device described in the following embodiments is preferably implemented in software, hardware implementation, or a combination of software and hardware, is also possible and contemplated.

[0105] This embodiment provides a protection device for abnormal cooling in an electric drive system, such as... Figure 7 As shown, it includes: The acquisition module 71 is used to acquire the initial heat sink temperature, initial bus voltage and initial excitation parameters of the motor controller before the electrochemical impedance spectroscopy excitation is started. The calculation module 72 is used to continuously collect the real-time heat sink temperature of the motor controller within a preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, according to a preset sampling interval. It calculates the unit loss temperature rise of each sampling point based on the real-time heat sink temperature, the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition. The execution module 73 is used to determine that there is an abnormality in the cooling system associated with the electric drive system when the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, and to stop the output of electrochemical impedance spectroscopy excitation.

[0106] In this embodiment of the application, the acquisition module 71 is specifically used to receive the electrochemical impedance spectroscopy excitation request issued by the battery management system; parse the initial excitation parameters from the electrochemical impedance spectroscopy excitation request, wherein the initial excitation parameters include the excitation current amplitude and the excitation frequency; and read the initial heat sink temperature of the heat sink in the inverter before the inverter starts the modulation output in the motor controller, and at the same time obtain the initial bus voltage.

[0107] In this embodiment, the calculation module 72 is specifically used to calculate the absolute temperature rise for each sampling point based on the real-time radiator temperature and the initial radiator temperature; determine the on-resistance value corresponding to the real-time radiator temperature based on the pre-stored temperature-on-resistance coefficient curve; calculate the real-time power loss based on the on-resistance value, the initial bus voltage, and the initial excitation parameters; and calculate the unit power loss temperature rise using the absolute temperature rise and the real-time power loss.

[0108] In this embodiment of the application, the calculation module 72 is specifically used to extract the excitation current amplitude and excitation frequency from the initial excitation parameters; determine the switching loss component based on the initial bus voltage and excitation frequency; and determine the conduction loss component based on the excitation current amplitude and the current on-resistance value. Real-time power loss is calculated based on switching loss components and conduction loss components.

[0109] In this embodiment of the application, the device further includes: a first determination module, used to obtain a unit loss temperature rise threshold corresponding to the initial radiator temperature, the initial bus voltage and the initial excitation parameters; at each sampling point, compare the unit loss temperature rise with the unit loss temperature rise threshold; if the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, then determine that there is an abnormality in the cooling system.

[0110] In this embodiment of the application, the device further includes: a second determination module, configured to calculate the temperature rise rate of the current sampling point within a preset diagnostic window based on the continuously collected real-time radiator temperature and a preset sampling interval; obtain a temperature rise rate threshold corresponding to the initial radiator temperature, initial bus voltage, and initial excitation parameters; and compare the temperature rise rate with the temperature rise rate threshold at each sampling point; when the temperature rise rate of a consecutive preset number of sampling points is greater than or equal to the temperature rise rate threshold, determine that there is an abnormality in the cooling system associated with the electric drive system, and stop the output of electrochemical impedance spectroscopy excitation.

[0111] In this embodiment of the application, the device further includes: a third determination module, used to obtain an absolute temperature rise threshold corresponding to the initial radiator temperature, initial bus voltage and initial excitation parameters when the unit loss temperature rise of the sampling points is not greater than or equal to the unit loss temperature rise threshold; at each sampling point, the absolute temperature rise is compared with the absolute temperature rise threshold; when the absolute temperature rise is greater than or equal to the absolute temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of electrochemical impedance spectroscopy excitation is stopped.

[0112] In this embodiment of the application, the device further includes: a response module, configured to send a cooling system abnormality fault code to the battery management system in response to determining that an abnormality exists in the cooling system; and to lock the electrochemical impedance spectroscopy excitation function, prohibiting the response to the electrochemical impedance spectroscopy excitation request issued by the battery management system until a fault recovery signal of the cooling system is received.

[0113] Please see Figure 8 , Figure 8 This is a schematic diagram of the structure of a computer device provided in an optional embodiment of the present invention, such as... Figure 8As shown, the computer device includes one or more processors 10, memory 20, and interfaces for connecting the components, including high-speed interfaces and low-speed interfaces. The components communicate with each other via different buses and can be mounted on a common motherboard or otherwise installed as needed. The processors can process instructions executed within the computer device, including instructions stored in or on memory to display graphical information of a GUI on external input / output devices (such as display devices coupled to the interfaces). In some alternative implementations, multiple processors and / or multiple buses can be used with multiple memories and multiple memory modules, if desired. Similarly, multiple computer devices can be connected, each providing some of the necessary operations (e.g., as a server array, a group of blade servers, or a multiprocessor system).

[0114] Processor 10 may be a central processing unit, a network processor, or a combination thereof. Processor 10 may further include a hardware chip. The hardware chip may be an application-specific integrated circuit (ASIC), a programmable logic device (PLD), or a combination thereof. The programmable logic device may be a complex programmable logic device (CAMP), a field-programmable gate array (FPGA), a general-purpose array logic (GDA), or any combination thereof.

[0115] The memory 20 stores instructions executable by at least one processor 10 to cause at least one processor 10 to perform the method shown in the above embodiments.

[0116] The memory 20 may include a program storage area and a data storage area. The program storage area may store the operating system and applications required for at least one function; the data storage area may store data created based on the use of the computer device as shown by a landing page for an app. Furthermore, the memory 20 may include high-speed random access memory and may also include non-transitory memory, such as at least one disk storage device, flash memory device, or other non-transitory solid-state storage device. In some alternative embodiments, the memory 20 may optionally include memory remotely located relative to the processor 10, which can be connected to the computer device via a network. Examples of such networks include, but are not limited to, the Internet, intranets, local area networks, mobile communication networks, and combinations thereof.

[0117] The memory 20 may include volatile memory, such as random access memory; the memory may also include non-volatile memory, such as flash memory, hard disk or solid-state drive; the memory 20 may also include a combination of the above types of memory.

[0118] The computer device also includes a communication interface 30 for communicating with other devices or communication networks.

[0119] This invention also provides a computer-readable storage medium. The methods described above according to embodiments of the invention can be implemented in hardware or firmware, or implemented as computer code that can be recorded on a storage medium, or implemented as computer code downloaded via a network and originally stored on a remote storage medium or a non-transitory machine-readable storage medium and then stored on a local storage medium. Thus, the methods described herein can be processed by software stored on a storage medium using a general-purpose computer, a dedicated processor, or programmable or dedicated hardware. The storage medium can be a magnetic disk, optical disk, read-only memory, random access memory, flash memory, hard disk, or solid-state drive, etc.; further, the storage medium can also include combinations of the above types of memory. It is understood that computers, processors, microprocessor controllers, or programmable hardware include storage components capable of storing or receiving software or computer code, which, when accessed and executed by the computer, processor, or hardware, implements the methods shown in the above embodiments.

[0120] Although embodiments of the invention have been described in conjunction with the accompanying drawings, those skilled in the art can make various modifications and variations without departing from the spirit and scope of the invention, and all such modifications and variations fall within the scope defined by the appended claims.

Claims

1. A method for protecting an electric drive system from cooling anomalies, characterized in that, The method includes: The initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller were obtained before the electrochemical impedance spectroscopy excitation was started. Within a preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, the real-time heat sink temperature of the motor controller is continuously collected at a preset sampling interval. The unit loss temperature rise of each sampling point is calculated based on the real-time heat sink temperature, the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition. When the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of the electrochemical impedance spectroscopy excitation is stopped.

2. The method according to claim 1, characterized in that, The acquisition of the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before electrochemical impedance spectroscopy excitation startup includes: Receive electrochemical impedance spectroscopy excitation requests from the battery management system; The initial excitation parameters are resolved from the electrochemical impedance spectroscopy excitation request, wherein the initial excitation parameters include the excitation current amplitude and the excitation frequency; Before the inverter starts modulation output in the motor controller, the initial heat sink temperature of the heat sink in the inverter is read, and the initial bus voltage is obtained at the same time.

3. The method according to claim 1, characterized in that, The calculation of the unit loss temperature rise at each sampling point based on the real-time radiator temperature, the initial radiator temperature, the initial bus voltage, and the initial excitation parameters includes: For each sampling point, the absolute temperature rise is calculated based on the real-time radiator temperature and the initial radiator temperature; Based on the pre-stored temperature-on-resistance coefficient curve, determine the on-resistance value corresponding to the real-time heat sink temperature; Calculate the real-time power loss based on the on-resistance value, the initial bus voltage, and the initial excitation parameters; The unit loss temperature rise is calculated using the absolute temperature rise and the real-time power loss.

4. The method according to claim 3, characterized in that, The calculation of real-time power loss based on the on-resistance value, the initial bus voltage, and the initial excitation parameters includes: Extract the excitation current amplitude and excitation frequency from the initial excitation parameters; The switching loss component is determined based on the initial bus voltage and the excitation frequency, and the conduction loss component is determined based on the excitation current amplitude and the current on-resistance value. The real-time power loss is calculated based on the switching loss component and the conduction loss component.

5. The method according to claim 1, characterized in that, Before determining that there is an anomaly in the cooling system associated with the electric drive system, the method further includes: Obtain the unit loss temperature rise threshold corresponding to the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters; At each sampling point, the unit loss temperature rise is compared with the unit loss temperature rise threshold. If the temperature rise per unit loss at a continuously preset number of sampling points is greater than or equal to the temperature rise per unit loss threshold, then the cooling system is determined to be abnormal.

6. The method according to claim 1, characterized in that, After continuously collecting the real-time radiator temperature of the motor controller, the method further includes: Within the preset diagnostic window, the temperature rise rate of the current sampling point is calculated based on the continuously collected real-time radiator temperature and the preset sampling interval. Obtain the temperature rise rate threshold corresponding to the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters, and compare the temperature rise rate with the temperature rise rate threshold at each sampling point; When the temperature rise rate of a consecutive preset number of sampling points is greater than or equal to the temperature rise rate threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of the electrochemical impedance spectroscopy excitation is stopped.

7. The method according to claim 1, characterized in that, After calculating the unit loss temperature rise at each sampling point based on the real-time radiator temperature, the initial radiator temperature, the initial bus voltage, and the initial excitation parameters, the method further includes: When the unit loss temperature rise of a number of consecutive sample points is greater than or equal to the unit loss temperature rise threshold, the absolute temperature rise threshold corresponding to the initial radiator temperature, the initial bus voltage, and the initial excitation parameters is obtained. At each sampling point, the absolute temperature rise is compared with the absolute temperature rise threshold. If the absolute temperature rise is greater than or equal to the absolute temperature rise threshold, it is determined that there is an abnormality in the cooling system associated with the electric drive system, and the output of the electrochemical impedance spectroscopy excitation is stopped.

8. The method according to claim 1, characterized in that, After determining that there is an anomaly in the cooling system associated with the electric drive system and stopping the output of the electrochemical impedance spectroscopy excitation, the method further includes: In response to the determination that there is an abnormality in the cooling system, a cooling system abnormality fault code is sent to the battery management system; The electrochemical impedance spectroscopy excitation function is locked, and responses to electrochemical impedance spectroscopy excitation requests issued by the battery management system are prohibited until a fault recovery signal from the cooling system is received.

9. A cooling abnormality protection device for an electric drive system, characterized in that, The device includes: The acquisition module is used to acquire the initial heat sink temperature, initial bus voltage, and initial excitation parameters of the motor controller before the electrochemical impedance spectroscopy excitation is started. The calculation module is used to continuously collect the real-time heat sink temperature of the motor controller within a preset diagnostic window after the electrochemical impedance spectroscopy excitation is started, according to a preset sampling interval. Based on the real-time heat sink temperature, the initial heat sink temperature, the initial bus voltage, and the initial excitation parameters, the unit loss temperature rise of each sampling point is calculated. The unit loss temperature rise is used to characterize the heat dissipation capacity corresponding to each unit of heat generated by the electric drive system under the current excitation condition. The determination module is used to determine that there is an abnormality in the cooling system associated with the electric drive system when the unit loss temperature rise of a consecutive preset number of sampling points is greater than or equal to the unit loss temperature rise threshold, and to stop the output of the electrochemical impedance spectroscopy excitation.

10. A computer device, characterized in that, include: A memory and a processor, the memory and the processor being communicatively connected to each other, the memory storing computer instructions, the processor executing the computer instructions to perform the method of any one of claims 1 to 8.

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