Junction temperature estimation method and device of power module, motor controller and medium

Abstract

The invention provides a junction temperature estimation method and device of a power module, a motor controller and a medium. The junction temperature method comprises the following steps: determining a first state parameter when cooling water enters a power module of the motor controller; wherein the first state parameter comprises cooling water flow and cooling water temperature; determining a first coefficient according to the first state parameter; wherein the first coefficient represents a change relationship between a first temperature currently collected by a temperature sensor of the power module and a current junction temperature of the power module; and estimating the current junction temperature of the power module according to the first coefficient, the cooling water temperature and the first temperature.

Description

Technical Field

[0001] The present invention relates to the field of vehicles, and in particular to a method and device for estimating the junction temperature of a power module, a motor controller, and a medium. Background Art

[0002] The global penetration rate of new energy vehicles (NEVs) continues to climb. As one of the three major components of electric vehicles, the electronic control system still has significant room for improvement in terms of efficiency, size, and stability. Due to the operating environment of electric vehicles, the lifespan and reliability of motor controllers are currently lower than those of fuel-powered vehicles. Temperature is a major factor in motor controller failure. During operation, electric vehicles generate significant energy losses in the motor controller, which manifests as an increase in the junction temperature of the power module (IGBT). Summary of the Invention

[0003] The present invention mainly provides a method and device for estimating the junction temperature of a power module, a motor controller and a medium.

[0004] The technical solution of the present invention is achieved as follows: In a first aspect, an embodiment of the present application provides a method for estimating the junction temperature of a power module, the method comprising: determining a first state parameter when cooling water enters the power module of a motor controller; wherein the first state parameter comprises a cooling water flow rate and a cooling water temperature; determining a first coefficient based on the first state parameter; wherein the first coefficient represents a changing relationship between a first temperature currently collected by a temperature sensor of the power module and a current junction temperature of the power module; estimating the current junction temperature of the power module based on the first coefficient, the cooling water temperature and the first temperature.

[0005] It can be understood that in the junction temperature method of the power module provided in the embodiment of the present application, the first state parameter of the cooling water when entering the power module of the motor controller is determined, the first state parameter of the cooling water is used to determine the first coefficient, and then the current junction temperature of the power module is estimated based on the first coefficient, the cooling water temperature and the first temperature; in this way, since the first coefficient used to estimate the current junction temperature of the power module changes with the change of the state parameter of the cooling water entering the power module, that is, the first coefficient is adapted to the state of the cooling water when it currently enters the power module, it is beneficial to improve the accuracy of the estimation of the junction temperature of the power module based on the first coefficient.

[0006] In some embodiments, determining the first coefficient based on the first state parameter includes: determining the first coefficient based on the first state parameter and a rated state parameter of an external circulation cooling water pump; wherein the cooling water comes from the external circulation cooling water pump.

[0007] It can be understood that in the above embodiment, determining the first coefficient by using the first state parameter and the rated state parameter of the external circulation cooling water pump is beneficial to further improve the accuracy of estimating the current junction temperature of the power module.

[0008] In some embodiments, the rated state parameters include: rated cooling water flow and rated cooling water temperature; determining the first coefficient based on the first state parameter and the rated state parameters of the external circulation cooling water pump includes: determining the first coefficient based on the ratio of the cooling water flow to the rated cooling water flow and the ratio of the cooling water temperature to the rated cooling water temperature.

[0009] It can be understood that in the above embodiment, since the first coefficient represents the changing relationship between the first temperature currently collected by the temperature sensor of the power module and the current junction temperature of the power module, the first coefficient determined based on the ratio of the cooling water flow rate to the rated cooling water flow rate and the ratio of the cooling water temperature to the rated cooling water temperature is more in line with the actual working conditions, so that the estimated value of the current junction temperature of the power module is more accurate and more in line with the actual working conditions.

[0010] In some embodiments, determining the first coefficient according to a ratio of the cooling water flow rate to the rated cooling water flow rate and a ratio of the cooling water temperature to the rated cooling water temperature includes: The first coefficient is determined according to the following formula: ; Wherein, k represents the first coefficient; Q represents the cooling water flow rate when the cooling water enters the power module of the motor controller; Q max Indicates the rated cooling water flow; T cool Indicates the cooling water temperature when the cooling water enters the power module of the motor controller; T coolmax Indicates the rated cooling water temperature; a, b and A are pre-calibrated values.

[0011] It can be understood that in the above embodiment, a specific expression for determining the first coefficient is given, and a pre-calibrated influencing factor affecting the first coefficient is added, so that the calculation of the first coefficient is more accurate, and further the estimation result of the current junction temperature of the power module is more accurate.

[0012] In some embodiments, the current junction temperature of the power module is estimated based on the first coefficient, the first temperature and the cooling water temperature, including: determining a first product of the first coefficient and the first temperature; determining the difference between a pre-calibrated second coefficient and the first coefficient; determining a second product of the difference and the cooling water temperature; and estimating the current junction temperature of the power module based on the first product and the second product.

[0013] It can be understood that in the above embodiment, a specific process for determining the current junction temperature of the power module based on the first coefficient, the first temperature, and the cooling water temperature is provided. In this process, since the current junction temperature of the power module can be determined only through simple multiplication and addition and subtraction, the current junction temperature of the power module can be accurately calculated without considering the impact of the power module loss on the junction temperature of the power module. Therefore, the chip load consumed when estimating the current junction temperature of the power module is reduced, while also improving the accuracy of the estimation of the current junction temperature of the power module. The estimated current junction temperature of the power module is closer to the actual junction temperature of the power module, solving the problem that the actual junction temperature of the power module is difficult to measure.

[0014] In some embodiments, estimating the current junction temperature of the power module based on the first product and the second product includes: obtaining a pre-calibrated intercept; and estimating the current junction temperature of the power module based on the first product, the second product, and the intercept.

[0015] It can be understood that in the above embodiment, a specific process of estimating the current junction temperature of the power module based on the first product and the second product is given. When estimating the current junction temperature of the power module, the independent variables used are all from the sensor. Since the sensor itself has a zero point error, in order to reduce the inaccuracy caused by the error, a pre-calibrated intercept is added, for example. This can make the estimation of the current junction temperature of the power module more accurate.

[0016] In some embodiments, estimating the current junction temperature of the power module according to the first product, the second product and the intercept includes: the current junction temperature of the power module is equal to the first product and the accumulated value of the second product and the intercept.

[0017] It can be understood that in the above embodiment, a specific expression is given for estimating the current junction temperature of the power module based on the first product, the second product and the intercept. In this process, since the expression is relatively simple, the load of the chip consumed when estimating the current junction temperature of the power module is reduced.

[0018] In the second aspect, an embodiment of the present application provides a junction temperature estimation device for a power module, comprising a first determination unit, a second determination unit, and a third determination unit; the first determination unit is configured to determine a first state parameter when cooling water enters the power module of the motor controller; wherein the first state parameter includes the cooling water flow rate and the cooling water temperature; the second determination unit is configured to determine a first coefficient based on the first state parameter; wherein the first coefficient represents the changing relationship between the first temperature currently collected by the temperature sensor of the power module and the current junction temperature of the power module; the third determination unit is configured to estimate the current junction temperature of the power module based on the first coefficient, the cooling water temperature, and the first temperature.

[0019] In a third aspect, an embodiment of the present application provides a motor controller, comprising a main control board, a drive board, a power module, and a cooling water channel. The main control board is configured to implement the junction temperature estimation method of the power module of the first aspect when running a computer program.

[0020] In a fourth aspect, an embodiment of the present application provides a computer-readable storage medium having a computer program stored thereon, which, when executed by a processor, implements the junction temperature method of a power module according to the first aspect. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings herein are incorporated into and constitute a part of this specification. These drawings illustrate embodiments consistent with the present application and, together with the specification, serve to illustrate the technical solutions of the present application. Obviously, the drawings described below are merely some embodiments of the present application. Those skilled in the art can, without inventive effort, derive other drawings from these drawings.

[0022] The flowcharts shown in the accompanying drawings are for illustrative purposes only and do not necessarily include all contents and operations / steps, nor must they be executed in the order described. For example, some operations / steps may be decomposed, while others may be combined or partially combined. Therefore, the actual execution order may vary depending on the actual situation.

[0023] Figure 1 A schematic flow chart of a method for estimating junction temperature of a power module provided in an embodiment of the present application; Figure 2 A schematic flow chart of a calibration process for a relationship between a junction temperature of a power module and a first temperature provided in an embodiment of the present application; Figure 3 A method for Figure 1 Schematic diagram of the results obtained by verifying the accuracy of the power module junction temperature estimation method; Figure 4 A schematic structural diagram of a junction temperature estimation device for a power module provided in an embodiment of the present application; Figure 5 A schematic diagram of the structure of a motor controller provided in an embodiment of the present application. DETAILED DESCRIPTION

[0024] To make the purpose, technical solutions and advantages of the embodiments of the present application clearer, the specific technical solutions of the present application will be further described in detail below in conjunction with the drawings in the embodiments of the present application. The following embodiments are used to illustrate the present application but are not intended to limit the scope of the present application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which this application pertains. The terms used herein are for the purpose of describing the embodiments of this application only and are not intended to limit this application.

[0026] In the following description, references to “some embodiments,” “this embodiment,” “embodiments of the present application,” and examples, etc., describe a subset of all possible embodiments. However, it can be understood that “some embodiments” may be the same subset or different subsets of all possible embodiments, and may be combined with each other without conflict.

[0027] Descriptions such as "first, second, third" appearing in the embodiments of the present application do not have a specific meaning (such as there is no distinction in order, nor does it indicate a special limitation on the number of devices in the embodiments of the present application). They are only for the convenience of clearly describing the embodiments of the present application and do not constitute any limitation on the embodiments of the present application.

[0028] Before further describing the embodiments of the present application in detail, the nouns and terms that may be involved in the embodiments of the present application are first described. The nouns and terms involved in the embodiments of the present application are subject to the following explanations.

[0029] The motor controller primarily consists of a main control board, a driver board, a power module, cooling channels, and a housing. The main control board primarily controls the motor; the driver board primarily drives and controls the motor according to the main control board's instructions. The power module, primarily an insulated gate bipolar transistor (IGBT) or SiC metal-oxide-semiconductor field-effect transistor (MOSFET), has the core function of converting the battery's direct current (DC) into three-phase alternating current (AC) to drive the motor (in drive mode) or rectifying the AC generated by the motor back into DC to recharge the battery (in energy recovery mode).

[0030] The junction temperature of an IGBT refers to the maximum operating temperature of the semiconductor chip within it, typically higher than the temperature of the chip's housing. IGBTs generate heat during operation. If this heat cannot be dissipated promptly, the junction temperature will rise, affecting the IGBT's performance and lifespan. Therefore, junction temperature is a crucial factor in determining whether an IGBT is operating safely. Excessively high junction temperature can damage power devices, impacting equipment performance and lifespan, and even causing failures. Accurately estimating and controlling junction temperature is crucial for determining whether an IGBT is operating safely. Excessively high junction temperature can damage power devices, impacting equipment performance and lifespan, and even causing failures. Optimizing motor performance and extending motor life requires accurate estimation and control of junction temperature.

[0031] To facilitate understanding of the technical solutions of the embodiments of the present application, the following describes the relevant technologies or terms of the embodiments of the present application. The following relevant technologies or terms can be combined with the technical solutions of the embodiments of the present application as optional solutions, and all of them fall within the scope of protection of the embodiments of the present application.

[0032] The global penetration rate of new energy vehicles (NEVs) continues to climb. As one of the three major components of electric vehicles, the electronic control system still has significant room for improvement in terms of efficiency, size, and stability. Due to the operating environment of electric vehicles, the lifespan and reliability of motor controllers are currently lower than those of fuel-powered vehicles. Temperature is a major factor in motor controller failure.

[0033] During the operation of electric vehicles, the motor controller generates a large amount of energy loss, which manifests as an increase in the junction temperature of the chip on the power module (IGBT). Normally, the junction temperature of Si chips does not exceed 150°C, and the junction temperature of SiC chips does not exceed 175°C.

[0034] Because motor output power fluctuates dramatically with vehicle operating conditions, the junction temperature of the power module chip also fluctuates rapidly. Due to process limitations, direct temperature sampling of most power module chips is currently impossible, and model prediction is often required. Accurately predicting and calculating rapidly changing junction temperatures is a prerequisite for effective thermal management.

[0035] For IGBT junction temperature prediction, the two main methods currently used in industrial products are the thermally sensitive electrical parameter method and the thermal impedance model electrical coupling estimation method. The latter, with its advantages of low cost and low susceptibility to interference, has become the mainstream junction temperature prediction method used by major OEMs.

[0036] One IGBT junction temperature estimation method uses the bus voltage waveform to obtain IGBT thermal parameters, which in turn determine IGBT losses. Based on the losses and thermal resistance and capacitance parameters, a thermal resistance network model is constructed to determine the temperature distribution of each layer. This method can reduce errors, but it requires high sampling accuracy and consumes a large amount of chip load.

[0037] In another IGBT junction temperature estimation method, a third-order Foster thermal network model of the coolant, IGBT chip, diode, and NTC sensor is constructed. The thermal resistance coefficient and the IGBT chip temperature rise correction factor are measured experimentally to obtain the accurate IGBT junction temperature. This method also requires a large amount of chip load.

[0038] Another IGBT junction temperature estimation method uses a large amount of data to explore the IGBT heating patterns and distribute them to derive the module's loss and thermal resistance calculation formulas. This method requires extensive pre-simulation and testing to calibrate the formulas.

[0039] During their research and analysis of the three aforementioned IGBT junction temperature estimation methods, the inventors of this application discovered that these methods require a significant chip load when estimating the junction temperature of a power module. Furthermore, the prediction of IGBT junction temperature in actual automotive power modules is primarily used to control module temperature and predict module life. Under common vehicle operating conditions, the IGBT carrier frequency and bus voltage typically reach a specific threshold. Given the limited operating boundaries of automotive applications, there is no simple and reasonable strategy for rapidly predicting IGBT junction temperature, and the accuracy of the estimated current IGBT junction temperature is low.

[0040] Based on the above analysis, the embodiments of the present application provide the following power module junction temperature method, device, motor controller, and medium.

[0041] Figure 1 A schematic diagram of a process flow of a method for estimating junction temperature of a power module provided in an embodiment of the present application is shown as follows: Figure 1 As shown, the method includes the following steps: S101 : Determine a first state parameter of cooling water when it enters a power module of a motor controller.

[0042] The first state parameter includes cooling water flow and cooling water temperature.

[0043] S102. Determine a first coefficient according to the first state parameter.

[0044] The first coefficient represents a change relationship between a first temperature currently collected by a temperature sensor of the power module and a current junction temperature of the power module.

[0045] S103 : Estimate the current junction temperature of the power module according to the first coefficient, the cooling water temperature, and the first temperature.

[0046] It can be understood that in the junction temperature method of the power module provided in the embodiment of the present application, the first state parameter of the cooling water when entering the power module of the motor controller is determined, the first state parameter of the cooling water is used to determine the first coefficient, and then the current junction temperature of the power module is estimated based on the first coefficient, the cooling water temperature and the first temperature; in this way, since the first coefficient used to estimate the current junction temperature of the power module changes with the change of the state parameter of the cooling water entering the power module, that is, the first coefficient is adapted to the state of the cooling water when it currently enters the power module, it is beneficial to improve the calculation accuracy of the junction temperature of the power module based on the first coefficient.

[0047] The following describes further optional implementations and related terms of each of the above steps.

[0048] S101 : Determine a first state parameter of cooling water when it enters a power module of a motor controller.

[0049] In some embodiments, the cooling water may come from an external circulation cooling water pump; in other embodiments, it may also come from other equipment that can provide cooling water, etc. This application does not specifically limit this. The following explanation will be given using the example of cooling water coming from an external circulation cooling water pump.

[0050] For example, in some embodiments, the first state parameter includes the cooling water flow rate Q and the cooling water temperature T cool .

[0051] It can be understood that the cooling water flow rate Q represents the water flow rate when the cooling water enters the power module of the motor controller (it can also be called the cooling water flow rate when the cooling water enters the power module of the motor controller). Cooling water temperature T cool It indicates the temperature of the cooling water when it enters the power module of the motor controller (it can also be called the cooling water temperature when the cooling water enters the power module of the motor controller). Both parameter values are parameters when the cooling water enters the power module (such as IGBT) but has not yet flowed through the IGBT.

[0052] In one possible implementation, the cooling water flow rate Q when the cooling water enters the power module of the motor controller can be determined by looking up a table of the correspondence between the cooling water flow meter or the real-time speed and flow rate of the water pump. Of course, the present application does not limit the measurement method of the cooling water flow rate Q. In short, it is sufficient to be able to obtain this parameter.

[0053] In a possible implementation, the cooling water temperature T when the cooling water enters the power module of the motor controller is cool, can be determined by the temperature sensor. Of course, in this application, the cooling water temperature T cool There is no limitation on the measurement method, as long as the parameter can be obtained.

[0054] It can be understood that due to the cooling water flow Q and cooling water temperature T cool These two state parameters are easier to obtain, and thus the load on the chip caused by obtaining parameters for estimating the current junction temperature can be reduced.

[0055] S102: Determine a first coefficient k according to the first state parameter.

[0056] In some embodiments, the first coefficient k represents the first temperature T currently collected by the temperature sensor of the power module. NTC The current junction temperature T j The changing relationship.

[0057] In the embodiments of the present application, the type of temperature sensor used in the power module is not particularly limited and may be a thermistor, a thermocouple RTD (resistance temperature sensor), a digital thermometer IC, an analog thermometer IC, or the like. Due to the advantages of thermistors such as simple structure, low cost, and ease of use, the following description will use a thermistor as an example of a power module temperature sensor.

[0058] It is understood that thermistors are classified into PTC (positive temperature coefficient) thermistors and NTC (negative temperature coefficient) thermistors. Because NTC thermistors can be miniaturized while also exhibiting minimal fluctuations in resistance-temperature characteristics and rapid response to various temperature changes, the embodiments of this application will be described using NTC thermistors as an example.

[0059] For example, in some embodiments, the first temperature T is collected by an NTC temperature sensor embedded in the power module near the chip area. NTC , that is, the first temperature T NTC The temperature of the power module collected by the NTC temperature sensor.

[0060] In order to improve the accuracy of the estimation of the current junction temperature of the power module, as an optional implementation, when determining the first coefficient k, the influence of the rated state parameters of the external circulation cooling water pump on the first coefficient k can also be considered. Therefore, the first coefficient k can also be determined based on the first state parameters and the rated state parameters of the external circulation cooling water pump.

[0061] For example, in some embodiments, the rated state parameters of the external circulation cooling water pump include the rated cooling water flow rate Q maxAnd the rated cooling water temperature T coolmax . Rated cooling water flow Q max Greater than or equal to the cooling water flow rate Q; rated cooling water temperature T coolmax Greater than or equal to the cooling water temperature T cool .

[0062] In a possible implementation, determining the first coefficient k according to the first state parameter and the rated state parameter of the external circulation cooling water pump includes: determining the first coefficient k according to the cooling water flow rate Q and the rated cooling water flow rate Q max The ratio and cooling water temperature T cool With the rated cooling water temperature T coolmax The ratio of , determines the first coefficient k.

[0063] It can be understood that since the first coefficient represents the relationship between the first temperature currently collected by the temperature sensor of the power module and the current junction temperature of the power module, the cooling water flow rate Q and the rated cooling water flow rate Q are max The ratio and cooling water temperature T cool With the rated cooling water temperature T coolmax The first coefficient k determined by the ratio of is more consistent with the actual working conditions, so that the estimated value of the current junction temperature of the power module is more accurate and more consistent with the actual working conditions.

[0064] For example, the first coefficient k can be determined by the following formula (1): (1) Among them, a, b, and A are all pre-calibrated values. Specifically, a represents the influence coefficient of the pre-calibrated cooling water flow Q on the first coefficient k; b represents the pre-calibrated cooling water temperature T cool The influence coefficient on the first coefficient k; A represents the pre-calibrated first weight.

[0065] It can be understood that, since the pre-calibrated influencing factors (i.e., a, b, A) that have an impact on the first coefficient are added when determining the specific expression of the first coefficient k, the calculation of the first coefficient is more accurate, and the estimation result of the current junction temperature of the power module is further made more accurate.

[0066] S103 : Estimate the current junction temperature of the power module according to the first coefficient, the cooling water temperature, and the first temperature.

[0067] When estimating the current junction temperature of the power module based on the first coefficient, the cooling water temperature and the first temperature, since the first coefficient used to estimate the current junction temperature of the power module changes with the change of the state parameters of the cooling water entering the power module, that is, the first coefficient is adapted to the state of the cooling water when it currently enters the power module, it is beneficial to improve the estimation accuracy of the junction temperature of the power module based on the first coefficient.

[0068] In order to further improve the accuracy of estimating the current junction temperature of the power module, as an optional implementation, when estimating the current junction temperature T j When the cooling water enters the power module of the motor controller, the cooling water temperature T cool , according to the first coefficient k, the first temperature T NTC and cooling water temperature T cool , estimate the current junction temperature T of the power module j .

[0069] In a possible implementation, according to the first coefficient k, the first temperature T NTC and cooling water temperature T cool , estimate the current junction temperature T of the power module j Including: determining the first coefficient k and the first temperature T NTC Determine the difference between the pre-calibrated second coefficient B and the first coefficient k; determine the difference and the cooling water temperature T cool The second product of the first product and the second product; Estimate the current junction temperature T of the power module j .

[0070] The difference between the pre-calibrated second coefficient B and the first coefficient k can represent the cooling water temperature T cool The current junction temperature T j The changing relationship.

[0071] Furthermore, in some embodiments, estimating the current junction temperature of the power module according to the first product and the second product includes: obtaining a pre-calibrated intercept C; estimating the current junction temperature T of the power module according to the first product, the second product and the intercept C. j .

[0072] When estimating the current junction temperature of the power module, all the independent variables used come from the sensor. Since the sensor itself has a zero-point error, in order to reduce the inaccuracy caused by the error, a pre-calibrated intercept is added, for example. This can make the estimation of the current junction temperature of the power module more accurate.

[0073] For example, the current junction temperature T of the power module can be estimated by the following formula (2): j .

[0074] (2) Where C represents the pre-calibrated intercept.

[0075] It can be understood that since the current junction temperature of the power module can be determined by simple multiplication and addition and subtraction, the current junction temperature of the power module can be accurately calculated without considering the impact of the power module loss on the junction temperature of the power module. Therefore, the pre-calibration of the module loss and the table lookup and calculation of the real-time loss are reduced, and the load of the chip consumed when estimating the current junction temperature of the power module is reduced. At the same time, the accuracy of the estimation of the current junction temperature of the power module is improved. The estimated current junction temperature of the power module is closer to the actual junction temperature of the power module, which solves the problem that the actual junction temperature of the power module is difficult to measure.

[0076] The following examples describe possible implementations of the method for estimating the junction temperature of a power module described in one or more of the above embodiments.

[0077] In the following implementation scheme, a method for estimating the junction temperature of a power module is described. Since the first coefficient used to estimate the current junction temperature of the power module changes with the change of the state parameters of the cooling water entering the power module, that is, the first coefficient is adapted to the state of the cooling water when it currently enters the power module, it is beneficial to improve the accuracy of the estimation of the junction temperature of the power module based on the first coefficient.

[0078] The specific implementation plan is as follows: A junction temperature estimation method for a power module based on an NTC sensor is proposed. The method can accurately and quickly predict the junction temperature of the power module of a motor controller according to the cold boundary conditions and the sampling temperature of the NTC sensor.

[0079] The strategy is to collect the cooling water flow Q and cooling water temperature T when the cooling water enters the power module of the motor controller. cool And the first temperature T collected by the temperature sensor of the power module (such as NTC thermistor) NTC Input to the calibrated power module junction temperature T j With the first temperature T NTC The current junction temperature T of the power module is obtained from the changing relationship. j .

[0080] In a possible implementation, for the junction temperature T j With the first temperature T NTCThe idea of the calibration process of the changing relationship is: based on the principle that when the cooling boundary conditions are determined, the junction temperature of the IGBT and the sampling temperature of the NTC sensor are approximately linearly related, the slope and intercept of the relationship between the junction temperature of the IGBT and the sampling temperature of the NTC sensor are calibrated through experiments at different cooling water temperatures and cooling water flow rates; by collecting data on typical working conditions of the motor controller on the assembly test bench, the calibration of the relationship between the junction temperature of the IGBT and the sampling temperature of the NTC sensor is completed.

[0081] For example, the junction temperature of the IGBT and the sampling temperature of the NTC sensor are approximately linearly related, which is specifically expressed as formula (3): (3) Among them, T cool represents the cooling water temperature; k represents the first coefficient.

[0082] For example, the expression of the first coefficient k can refer to the following formula (4): (4) Where B represents the second coefficient; T j Indicates the junction temperature of the IGBT; T NTC The sampling temperature of the NTC temperature sensor embedded in the module (i.e., an example of the first temperature); T cool is the real-time cooling water temperature (i.e., an example of the cooling water temperature when the cooling water enters the power module of the motor controller), Q is the real-time cooling water flow (i.e., an example of the cooling water flow when the cooling water enters the power module of the motor controller), Q max and T coolmax are the maximum cooling water flow rate (an example of the rated cooling water flow rate of an external cooling water pump) and the maximum operating temperature of the cooling water (an example of the rated cooling water flow rate of an external cooling water pump), respectively. k is the slope (an example of the first coefficient), which is primarily determined by the real-time cooling water temperature and flow rate. The parameters to be calibrated are A, B, C, and a, b. a is the coefficient of influence of the cooling flow rate on the slope, b is the coefficient of influence of the cooling temperature on the slope, A is the first weight, B is the second coefficient, and C is the intercept. A, B, and C can be collectively referred to as calibration coefficients.

[0083] The calibration process of A, B, C, a and b can be referred to Figure 2 , Figure 2 A schematic flow chart of a calibration process for a relationship between the junction temperature of a power module and a first temperature provided in an embodiment of the present application is shown in FIG. Figure 2 As shown in Figure 2, the calibration process includes the following steps: S201. Input data and perform linear fitting.

[0084] In some embodiments, the input data includes different operating conditions of the motor controller, different cooling boundary conditions, and the first temperature T collected by the NTC temperature sensor under different operating conditions and different cooling boundary conditions of the motor controller. NTC (m) and the actual junction temperature T of the tested IGBT j (m).

[0085] In some embodiments, the operating conditions of the motor controller include the motor speed Z and the motor torque Nj; the cooling boundary conditions include the cooling water temperature T cool and cooling water flow Q, while cooling water temperature T cool And the cooling water flow Q depends on the external circulation cooling water pump.

[0086] Where m = 1, 2, 3, ..., n, represents the mth data point under a cooling boundary condition, and the total number of data points is n.

[0087] It can be understood that by permuting and combining all the motor speed Z (α) data and motor torque Nj (β) data of a certain motor controller, different operating conditions of the motor controller can be obtained.

[0088] Among them, α=1, 2, 3, ..., d, represents the αth motor speed data of a certain motor controller, and the total number of all motor speed data of a certain motor controller is d.

[0089] Among them, β=1, 2, 3, ..., e, represents the βth motor torque data of a certain motor controller, and the total number of all motor torque data of a certain motor controller is e.

[0090] Among them, all motor speed Z (α) data and motor torque Nj (β) data can be arranged and combined according to the control variable method or the random method, etc. The embodiment of this application does not make any special restrictions on this. The purpose is to cover all operating conditions of the motor controller within the motor external characteristic curve.

[0091] It is understandable that all cooling water temperatures T that a certain external circulation cooling water pump can provide cool The (γ) data and all the cooling water flow Q (δ) data are arranged and combined to obtain different cooling boundary conditions.

[0092] Among them, γ=1, 2, 3, ..., f, represents the γth cooling water temperature data of a certain external circulation cooling water pump, and the total number of all cooling water temperature data that a certain external circulation cooling water pump can provide is f.

[0093] Among them, δ=1, 2, 3, ..., g, represents the δth cooling water flow data of a certain external circulation cooling water pump, and the total number of all cooling water flow data that a certain external circulation cooling water pump can provide is g.

[0094] Among them, for all cooling water temperatures T cool The permutations and combinations of the (γ) data and all the cooling water flow Q (δ) data may be performed according to the control variable method or according to a random method, etc. The embodiments of the present application do not specifically limit this. The permutations and combinations according to the control variable method will be used as an example for illustrative explanation.

[0095] Among them, the sizes of d, e, f and g can be the same or different, and this application does not make any special restrictions on this. d and e depend on the motor model, and f and g depend on the model of the external circulation cooling water pump; the following examples are used to illustrate d as 5, e as 5, f as 4 and g as 3.

[0096] That is to say, the total number of motor speed data of a certain motor controller is 5, for example, Z (1) = 150 rpm, Z (2) = 1000 rpm, Z (3) = 4000 rpm, Z (4) = 7000 rpm and Z (5) = 10000 rpm.

[0097] That is to say, the total number of all motor torque data of a certain motor controller is 5, for example, Nj(1)=50Nm, Nj(2)=130Nm, Nj(3)=150Nm, Nj(4)=200Nm and Nj(5)=330Nm.

[0098] That is to say, the total number of cooling water temperature data that a certain external circulation cooling water pump can provide is 4, for example, T cool (1) = 25°C, T cool (2) = 35°C, T cool (3) = 50°C and T cool (4) = 65℃.

[0099] That is to say, the total number of cooling water flow data that a certain external circulation cooling water pump can provide is 3, for example, Q (1) = 3 L / min, Q (2) = 5 L / min and Q (3) = 8 L / min.

[0100] The calibration test conditions are selected based on the performance characteristics of the electric drive product (i.e., the motor controller). The test conditions must cover the operating range of the electric drive. Taking the driving conditions as an example, the test conditions that need to be covered for a certain electric drive in this embodiment are shown in Table 1.

[0101] Table 1 Calibration conditions required for a certain electric drive

[0102] First, the calibration data under a fixed cooling boundary condition under the driving / generating condition is screened. For example, in this embodiment, under the conditions of a cooling water temperature of 25°C and a cooling water flow rate of 3L / min, the torques are 50Nm, 150Nm, and 330Nm at motor speeds of 150rpm, 1000rpm, and 4000rpm, respectively; at a motor speed of 7000rpm, the torques are 50Nm and 200Nm, respectively; and at a motor speed of 10000rpm, the torques are 50Nm and 130Nm, respectively. NTC sampling temperature (i.e., first temperature) T NTC (m) and the corresponding actual junction temperature T of the tested IGBT j (m), as shown in Table 2.

[0103] For the convenience of describing the principle, for example, the cooling water temperature is 25°C and the cooling water flow rate is 3L / min as the first cooling boundary condition, that is, T cool (1)=25℃, Q(1)=3L / min.

[0104] Table 2 Actual junction temperature T under different working conditions under the first cooling boundary condition j (m) and the first temperature T NTC (m)

[0105] According to the selected cooling boundary conditions, the first temperature T obtained by the motor controller under different working conditions NTC (m) and the corresponding actual junction temperature T of the power module j (m) data, the working condition under the cooling boundary condition is linearly fitted to obtain the correlation relationship T under the cooling boundary condition (such as 25℃, 3L / min) j =k(1)×T NTC +h(1), where h(1) represents the intercept in this association.

[0106] After the relationship fitting is completed under the cooling boundary condition (such as 25℃, 3L / min), adjust to the next cooling boundary (such as 25℃, 5L / min) until all cooling boundaries are traversed to obtain the junction temperature T under different cooling boundary conditions. j Follow T NTC Slope of change (i.e. first coefficient): T j =k(i)×T NTC +h(i), where h(i) represents the junction temperature T under different cooling boundary conditions j Follow T NTCThe intercept in the expression of the slope of change; where i = 1, 2, ..., N, N is the number of all tested cooling boundary combinations, as shown in Table 3.

[0107] Table 3. Junction temperature relationship slope under different cooling boundary conditions

[0108] It can be understood that each cooling boundary in Table 3 corresponds to a T j and a T NTC , therefore, T in Table 3 j They may be the same or different; T in Table 3 NTC It may be the same, or it may be different.

[0109] Taking into account the actual working conditions, some users make more extreme choices, which will exceed the rated cooling water temperature and / or rated cooling water flow that the external circulation cooling water pump can provide. In this embodiment, the rated cooling water temperature that the external circulation cooling water pump can provide is the maximum cooling water temperature (such as 65°C), and the rated cooling water flow that the external circulation cooling water pump can provide is the maximum cooling water flow (such as 8L / min). Therefore, as an optional implementation method, redundant settings can be made in the linear fitting stage, that is, breaking through the rated cooling water temperature and / or rated cooling water flow that the external circulation cooling water pump can provide. For example, taking the rated cooling water temperature that can be provided by the external circulation cooling water pump but not breaking through the rated cooling water flow that the external circulation cooling water pump can provide as an example, the rated cooling water temperature that can be provided by the external circulation cooling water pump is set to 85°C.

[0110] When the rated cooling water temperature provided by the external cooling water pump is set to 85°C, the following data are also required: the cooling boundary conditions are (such as 85°C, 3L / min), the actual junction temperature T of the motor controller under different working conditions j Data and first temperature T NTC Data; cooling boundary conditions are (e.g. 85°C, 5L / min), the actual junction temperature T of the motor controller under different working conditions j Data and first temperature T NTC Data; cooling boundary conditions are (such as 85℃, 8L / min), the actual junction temperature T of the motor controller under different working conditions j Data and first temperature T NTC data.

[0111] Similarly, it is necessary to perform linear fitting on the data of the motor controller under different working conditions with cooling boundary conditions (such as 85°C, 3L / min) to obtain the junction temperature T under the cooling boundary conditions. j Follow T NTCThe slope of the change; it is necessary to perform linear fitting on the data under different working conditions of the motor controller with cooling boundary conditions (such as 85℃, 5L / min) to obtain the junction temperature T under the cooling boundary conditions j Follow T NTC The slope of the change; it is necessary to perform linear fitting on the data under different working conditions of the motor controller with cooling boundary conditions (such as 85℃, 8L / min) to obtain the junction temperature T under the cooling boundary conditions j Follow T NTC The slope of change.

[0112] S202 , performing logarithmic linear fitting on the obtained cooling water temperature data, cooling water flow data, and the first coefficient (ie, slope) data obtained by fitting, to obtain a first coefficient calculation formula and calibration values of a, b, and A.

[0113] Specifically, the cooling water temperature T collected in step S201 is cool (i), cooling water flow Q(i) and the calculated slope (i.e., the first coefficient) k(i) under different cooling boundary conditions are subjected to logarithmic linear fitting to obtain the calculation formula of the first coefficient.

[0114] For example, the calculation formula of the first coefficient k can refer to the following formula (5): (5) Among them, a, b, and A are all calibrated values; a represents the influence coefficient of the cooling water flow Q on the first coefficient k, and b represents the cooling water temperature T cool The influence coefficient on the first coefficient k, A represents the first weight, i=1, 2, 3, ..., N, N represents the number of combinations of all cooling boundary conditions.

[0115] It can be understood that formula (4) is equivalent to the expression of the first coefficient k listed in advance, and the unknown quantities that need to be calibrated include a, b, and A. Formula (5) is the inverse operation of formula (4). Formula (5) is equivalent to a three-variable linear function. For example, k (i), cooling water temperature data, cooling water flow data, Q in Table 3 can be max and T coolmax Substitute into formula (5) for fitting (such as least square method), and the fitting results are parameters a=0.3308, b=0.149, and A=3.4813. In this example, the rated cooling water flow Q max is the maximum cooling water flow, i.e. Q max 8L / min; the rated cooling water temperature is the maximum cooling water temperature, that is, T coolmax65°C. Of course, in the embodiments of the present application, the values of a, b, and A are not limited to the values given in the above examples. If the values of cooling water temperature and cooling water flow rate in Table 3 are different, the values of a, b, and A obtained by fitting may be different. In addition, in the embodiments of the present application, the values of rated cooling water flow rate and rated cooling water temperature are not limited to the values given in the above examples.

[0116] S203, taking the calibrated first coefficient calculation formula as input, and taking the cooling water temperature T cool Data is the independent variable, with junction temperature T j The data was used as the dependent variable, and linear fitting was performed to obtain the calibration values of B and C.

[0117] Specifically, all the calibrated data in Table 1 are used as input, with the cooling water temperature T cool Data is the independent variable, junction temperature T j The data is used as the dependent variable for linear fitting to obtain the calibration relationship, which is the following formula (6): (6) Where i = 1, 2, ..., N. N represents the number of combinations of cooling boundary conditions.

[0118] It can be understood that the first coefficient k is calculated by the formula obtained by calibration in step S202. That is, in step S202, the calibrated values of a, b, and A are used to substitute the calibrated values of a, b, and A into formula (4) to obtain the calibrated first coefficient k. Substituting the calibrated first coefficient k into formula (6), since T j (i) T NTC (i) and T cool (i) are all calibrated data, that is, T j (i) T NTC (i) and T cool (i) and the first coefficient k are both known quantities, so formula (6) is equivalent to a two-variable linear function. For example, when the calibrated first coefficient k and T under different cooling boundary conditions calibrated in Table 3 are j 、T NTC 、T cool The corresponding cooling water temperature and cooling water flow data are substituted into formula (6) and fitted (for example, using the least squares method), and the calibrated parameters B and C can be obtained. For example, B=1.0821 and C=-3.4288 are obtained by fitting.

[0119] Of course, in the embodiment of the present application, the values of B and C are not limited to the values given in the above examples. The values of cooling water temperature and cooling water flow in Table 1 are different, and the NTC sampling temperature in Table 2 is different. The values of B and C obtained by fitting may be different.

[0120] S204. Arrange calibration parameters to obtain a junction temperature calculation model for a power module of a certain motor controller.

[0121] For example, Q max =8L / min, T coolmax =65℃, a=0.3308, b=0.149 and A=3.4813 are substituted into formula (4) to obtain k; k, B and C are substituted into formula (3) to obtain T j .

[0122] For example, T j The specific expression of is as follows: (7) After obtaining the junction temperature calculation model, you only need to convert the real-time module NTC temperature T NTC , cooling water flow Q and cooling water temperature T cool Once determined, substitute it into formula (7) to get the current junction temperature of the power module.

[0123] The embodiment of the present application targets the limited operating conditions and cold working boundary of the inverter for new energy vehicles, and directly obtains the junction temperature estimation correlation through bench calibration, avoiding the loss calibration calculation and thermal network calibration calculation required by the traditional loss + thermal network model, saving chip load rate compared with the traditional model. Compared with the published linear fitting relationship, such as the junction temperature and the T collected by NTC, NTC This application proposes a nonlinear fitting relationship that takes into account the impact of different cooling boundaries on this linear relationship. This expands the application scope of the fitting relationship, expands applicable operating conditions, and improves the accuracy of estimating the current junction temperature of the power module. The established junction temperature prediction model can not only be integrated into the controller software to predict junction temperature (for example, to identify whether a certain cooling condition meets the product's heat dissipation requirements, as traditional methods have difficulty in completing rapid junction temperature prediction at the model level), but can also predict and judge the junction temperature under specific operating conditions during the product development and optimization stages, guiding product design and development.

[0124] Figure 3 A method for Figure 1 The schematic diagram of the results obtained by verifying the accuracy of the power module junction temperature estimation method is shown in the figure. Figure 3 As shown, in the range of 20℃~150℃, the prediction accuracy of the method provided in this application is within ±10℃.

[0125] It should be noted that although the steps of the method of the present application are described in a specific order in the drawings, this does not require or imply that the steps must be performed in this specific order, or that all steps must be performed to achieve the desired results. Additionally or alternatively, some steps may be omitted, multiple steps may be combined into one step, and / or one step may be decomposed into multiple steps; or steps in different embodiments may be combined to form a new technical solution.

[0126] Based on the same inventive concept as the aforementioned embodiments, an embodiment of the present application provides a junction temperature estimation device for a power module.

[0127] Figure 4 A schematic diagram of the structure of a junction temperature estimation device for a power module provided in an embodiment of the present application is shown in FIG. Figure 4 As shown, the junction temperature estimation device 100 of a power module includes: a first determining unit 1001 , a second determining unit 1002 and a third determining unit 1003 .

[0128] The first determining unit 1001 is configured to determine a first state parameter when cooling water enters the power module of the motor controller; wherein the first state parameter includes a cooling water flow rate and a cooling water temperature.

[0129] The second determining unit 1002 is configured to determine a first coefficient according to the first state parameter; wherein the first coefficient represents a change relationship between a first temperature currently collected by the temperature sensor of the power module and a current junction temperature of the power module; The third determining unit 1003 is configured to estimate the current junction temperature of the power module according to the first coefficient, the cooling water temperature and the first temperature.

[0130] The description of the above device embodiment is similar to the description of the above method embodiment and has similar beneficial effects as the method embodiment. For technical details not disclosed in the device embodiment of this application, please refer to the description of the method embodiment of this application for understanding.

[0131] It should be noted that the division of modules in the embodiments of the present application is schematic and is merely a logical functional division. In actual implementation, other division methods may be used. Furthermore, the functional units in the various embodiments of the present application may be integrated into a single processing unit, or may exist physically separately, or two or more units may be integrated into a single unit. The aforementioned integrated units may be implemented in the form of hardware or software functional units. They may also be implemented in the form of a combination of software and hardware.

[0132] It should be noted that in the embodiments of the present application, if the above-mentioned method is implemented in the form of a software function module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiments of the present application can be essentially embodied in the form of a software product, or the part that contributes to the relevant technology. The computer software product is stored in a storage medium and includes a number of instructions for enabling an electronic device to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes various media that can store program codes, such as a USB flash drive, a mobile hard disk, a read-only memory (ROM), a magnetic disk or an optical disk. In this way, the embodiments of the present application are not limited to any specific combination of hardware and software.

[0133] The embodiment of the present application provides a motor controller, Figure 5 A schematic diagram of the structure of a motor controller provided in an embodiment of the present application is shown in FIG. Figure 5 As shown, it includes a main control board 501 , a drive board 502 , a power module 503 and a cooling water channel 504 .

[0134] The main control board 501 is configured to implement the steps of the method provided in the above embodiment when running a computer program.

[0135] The description of the driving board 502 and the power module 503 may refer to the related descriptions in the aforementioned method, which will not be repeated here.

[0136] An embodiment of the present application also provides a computer-readable storage medium for storing a computer program.

[0137] Optionally, the computer-readable storage medium can be applied to the motor controller in the embodiment of the present application, and the computer program enables the processor or motor controller to execute the various methods of the embodiment of the present application. For the sake of brevity, they are not repeated here.

[0138] It should be noted that the description of the motor controller and computer-readable storage medium embodiments described above is similar to the description of the method embodiment described above, and has similar beneficial effects as the method embodiment. For any technical details not disclosed in the motor controller and computer-readable storage medium embodiments of this application, please refer to the description of the method embodiment of this application for understanding.

[0139] It should be understood that "one embodiment" or "an embodiment" or "some embodiments" mentioned throughout the specification means that the specific features, structures or characteristics related to the embodiment are included in at least one embodiment of the present application. Therefore, "in one embodiment" or "in an embodiment" or "in some embodiments" appearing throughout the specification do not necessarily refer to the same embodiment. In addition, these specific features, structures or characteristics can be combined in one or more embodiments in any suitable manner. It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application. The above-mentioned serial numbers of the embodiments of the present application are for description only and do not represent the advantages and disadvantages of the embodiments. The above description of the various embodiments tends to emphasize the differences between the various embodiments. The same or similar aspects can be referenced to each other. For the sake of brevity, they will not be repeated here.

[0140] The term "and / or" in this article is only a description of the association relationship between associated objects, indicating that there can be three relationships. For example, object A and / or object B can mean: object A exists alone, object A and object B exist at the same time, and object B exists alone.

[0141] It should be noted that, in this document, the terms "comprises," "includes," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus comprising a series of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not exclude the presence of other identical elements in the process, method, article, or apparatus comprising the element.

[0142] In the several embodiments provided in this application, it should be understood that the disclosed devices and methods can be implemented in other ways. The embodiments described above are merely illustrative. For example, the division of the modules is merely a logical function division. In actual implementation, there may be other division methods, such as: multiple modules or components can be combined, or can be integrated into another system, or some features can be ignored or not executed. In addition, the coupling, direct coupling, or communication connection between the components shown or discussed can be through some interfaces, and the indirect coupling or communication connection of devices or modules can be electrical, mechanical or other forms.

[0143] The modules described above as separate components may or may not be physically separated, and the components displayed as modules may or may not be physical modules; they may be located in one place or distributed across multiple network units; some or all of the modules may be selected according to actual needs to achieve the purpose of this embodiment.

[0144] In addition, all functional modules in the embodiments of the present application can be integrated into one processing unit, or each module can be a separate unit, or two or more modules can be integrated into one unit; the above-mentioned integrated modules can be implemented in the form of hardware or in the form of hardware plus software functional units.

[0145] Those skilled in the art will understand that all or part of the steps of the above-mentioned method embodiment can be completed by hardware related to program instructions, and the aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it executes the steps of the above-mentioned method embodiment; and the aforementioned storage medium includes: mobile storage devices, read-only memories (ROM), magnetic disks or optical disks, and other media that can store program codes.

[0146] Alternatively, if the above-mentioned integrated unit of the present application is implemented in the form of a software functional module and sold or used as an independent product, it can also be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the embodiment of the present application, or the part that contributes to the relevant technology, can be embodied in the form of a software product. The computer software product is stored in a storage medium and includes a number of instructions for enabling an electronic device to execute all or part of the methods described in each embodiment of the present application. The aforementioned storage medium includes: various media that can store program codes, such as mobile storage devices, ROMs, magnetic disks or optical disks.

[0147] The methods disclosed in the several method embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments.

[0148] The features disclosed in the several product embodiments provided in this application can be arbitrarily combined without conflict to obtain new product embodiments.

[0149] The features disclosed in the several method or device embodiments provided in this application can be arbitrarily combined without conflict to obtain new method embodiments or device embodiments.

[0150] The above is only an implementation method of the present application, but the scope of protection of the present application is not limited thereto. Any technician familiar with this technical field can easily think of changes or replacements within the technical scope disclosed in this application, which should be covered by the scope of protection of the present application.

Claims

1. A method for estimating junction temperature of a power module, characterized in that: The method comprises: Determine a first state parameter of cooling water when it enters a power module of a motor controller; wherein the first state parameter includes a cooling water flow rate and a cooling water temperature; Determining a first coefficient based on the first state parameter; wherein the first coefficient represents a change relationship between a first temperature currently collected by a temperature sensor of the power module and a current junction temperature of the power module; A current junction temperature of the power module is estimated according to the first coefficient, the cooling water temperature, and the first temperature.

2. The junction temperature estimation method according to claim 1, wherein: The determining of the first coefficient according to the first state parameter includes: A first coefficient is determined according to the first state parameter and a rated state parameter of an external circulation cooling water pump; wherein the cooling water comes from the external circulation cooling water pump.

3. The junction temperature estimation method according to claim 2, wherein: The rated state parameters include: rated cooling water flow and rated cooling water temperature; The determining of the first coefficient according to the first state parameter and the rated state parameter of the external circulation cooling water pump includes: A first coefficient is determined according to a ratio of the cooling water flow rate to the rated cooling water flow rate and a ratio of the cooling water temperature to the rated cooling water temperature.

4. The junction temperature estimation method according to claim 3, wherein: The determining of the first coefficient according to the ratio of the cooling water flow rate to the rated cooling water flow rate and the ratio of the cooling water temperature to the rated cooling water temperature includes: The first coefficient is determined according to the following formula: ； Wherein, k represents the first coefficient; Q represents the cooling water flow rate when the cooling water enters the power module of the motor controller; Q max Indicates the rated cooling water flow rate; T cool Indicates the cooling water temperature when the cooling water enters the power module of the motor controller; T coolmax Indicates the rated cooling water temperature; a, b and A are pre-calibrated values.

5. The junction temperature estimation method according to any one of claims 1 to 4, characterized in that: The estimating the current junction temperature of the power module according to the first coefficient, the first temperature, and the cooling water temperature includes: determining a first product of the first coefficient and the first temperature; determining a difference between a pre-calibrated second coefficient and the first coefficient; determining a second product of the difference and the cooling water temperature; A current junction temperature of the power module is estimated according to the first product and the second product.

6. The junction temperature estimation method according to claim 5, characterized in that: The estimating the current junction temperature of the power module according to the first product and the second product includes: Get the pre-calibrated intercept; A current junction temperature of the power module is estimated according to the first product, the second product, and the intercept.

7. The junction temperature estimation method according to claim 6, wherein: The estimating the current junction temperature of the power module according to the first product, the second product and the intercept includes: The current junction temperature of the power module is equal to the first product, the sum of the second product and the intercept.

8. A junction temperature estimation device for a power module, characterized in that: comprising a first determining unit, a second determining unit and a third determining unit; The first determining unit is configured to determine a first state parameter of cooling water when entering the power module of the motor controller; wherein the first state parameter includes cooling water flow rate and cooling water temperature; The second determining unit is configured to determine a first coefficient based on the first state parameter; wherein the first coefficient represents a change relationship between a first temperature currently collected by the temperature sensor of the power module and a current junction temperature of the power module; The third determining unit is configured to estimate a current junction temperature of the power module according to the first coefficient, the cooling water temperature, and the first temperature.

9. A motor controller, comprising a main control board, a drive board, a power module and a cooling water channel, characterized in that: The main control board is configured to execute the steps of the method according to any one of claims 1 to 7 when running a computer program.

10. A computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the steps of the method according to any one of claims 1 to 7 are implemented.

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