Online evaluation method, device, motor controller and medium for output current limitation

Abstract

The present invention provides an online evaluation method, device, motor controller and medium for output current limitation, which relates to the technical field of motor controllers, and comprises the following steps: obtaining a real-time coolant flow rate and a real-time coolant temperature of a power module in a motor controller to obtain a real-time thermal resistance; collecting power parameters of the motor controller to obtain a maximum output current allowed by a chip of the power module in the motor controller at a maximum junction temperature to generate a first curve; generating a second curve according to a voltage limit preset in the motor controller for the power module under a switch-off transient; using a minimum value envelope to generate a change curve of chip junction temperature and maximum output current as a target curve; collecting the real-time chip junction temperature of the power module, and obtaining a corresponding maximum output current as an evaluation result according to the target curve to solve the problem that the maximum current output capacity limit set by the existing motor controller does not match the actual output capacity that can be exerted, resulting in the motor controller being unable to fully output.

Description

Technical Field

[0001] The present invention relates to the technical field of motor controllers, and in particular to an online evaluation method and device for output current limitation, a motor controller and a medium. Background Art

[0002] In the motor controller, in order to prevent the motor controller and the motor from being damaged by excessive output current, the motor controller output current needs to be limited. Existing automotive motor controllers mostly use the maximum current output capacity under the worst working conditions as the maximum current output limit under any working condition. However, during vehicle operation, most situations are not in the worst working conditions. This kind of setting makes the current output capacity limit of the vehicle under non-bad working conditions mismatched with the actual current output capacity of the power module that can be fully utilized. Therefore, the current output capacity of the power module cannot be fully utilized under all working conditions. Summary of the invention

[0003] In order to overcome the above-mentioned technical defects, the purpose of the present invention is to provide an online evaluation method, device, motor controller and medium for output current limitation, which is used to solve the problem that the maximum current output capacity limit set by the existing motor controller does not match the actual output capacity, resulting in the motor controller being unable to fully output.

[0004] The present invention discloses an online evaluation method for output current limitation, comprising:

[0005] Providing a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module;

[0006] Acquire the real-time coolant flow rate and the real-time coolant temperature of the power module in the motor controller, and obtain the real-time thermal resistance according to the first mapping table;

[0007] Collecting motor controller power parameters, wherein the motor controller power parameters include power factor, fundamental frequency, switching frequency, bus voltage and output current;

[0008] According to the power parameters, real-time thermal resistance and real-time coolant temperature of the motor controller, the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature is obtained, and a first curve of the maximum output current corresponding to different chip junction temperatures is generated;

[0009] According to the preset voltage limit for the power module in the switch-off transient state in the motor controller, the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current is obtained, and a second curve of the maximum output current corresponding to different chip junction temperatures is generated;

[0010] Based on the superposition of the first curve and the second curve and the minimum value envelope, a change curve of the chip junction temperature and the maximum output current is generated as a target curve;

[0011] The real-time chip junction temperature of the power module is collected, and the corresponding maximum output current is obtained as an evaluation result according to the target curve.

[0012] Preferably, obtaining the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature includes:

[0013] Pre-calibrate the conduction loss and switching loss of several sample chips at the highest junction temperature;

[0014] Use circuit simulation or analytical calculation to obtain the maximum output current allowed corresponding to the highest chip junction temperature of each sample;

[0015] Calculating the functional relationship between the maximum chip junction temperature of each sample and the maximum allowed output current to generate a second mapping table;

[0016] The maximum chip junction temperature of the power module in the motor controller is calculated by using the second mapping table to obtain the corresponding maximum allowed output current.

[0017] Preferably, the calculating the functional relationship between the maximum chip junction temperature of each sample and the maximum allowed output current to generate a second mapping table includes:

[0018] A functional relationship is established based on the difference between the highest chip junction temperature and the real-time coolant temperature relative to the motor controller power parameter and the real-time thermal resistance product, and a second mapping table is generated by interpolation.

[0019] Preferably, the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current is obtained according to the preset voltage limit for the power module in the motor controller under the transient state of the switch shutdown, and the second curve of the maximum output current corresponding to different junction temperatures is generated, including:

[0020] Control the dynamic switch of the motor controller, detect the voltage of the power module in real time, draw the voltage change curves of the switch turn-off transient corresponding to multiple sets of chip junction temperatures, and generate the second curve of the maximum output current corresponding to different junction temperatures.

[0021] Preferably, before providing a first mapping table including a mapping relationship between the coolant flow rate and the thermal resistance of the power module, the method further comprises:

[0022] A plurality of sets of coolant flow rates and thermal resistances are collected, and a first mapping table is generated using a finite element thermal-fluid coupling simulation experiment or a relationship curve of thermal resistance-coolant flow rate calibrated by interpolation.

[0023] Preferably, the first curve, the second curve and the target curve vary according to real-time thermal resistance and motor controller power parameters;

[0024] A first curve, a second curve or a target curve corresponding to a plurality of real-time thermal resistances and motor controller power parameters are pre-stored, and the real-time thermal resistances and motor controller power parameters corresponding to the real-time chip junction temperature are matched and obtained.

[0025] The present invention also provides an online evaluation device for the maximum output current of a motor controller, comprising:

[0026] A preprocessing module is used to provide a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module; obtain a real-time coolant flow rate and a real-time coolant temperature of the power module in the motor controller, and obtain the real-time thermal resistance according to the first mapping table; collect power parameters of the motor controller, wherein the power parameters of the motor controller include power factor, fundamental frequency, switching frequency, and bus voltage;

[0027] A first processing module is used to calculate the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature according to the motor controller power parameter, the real-time thermal resistance and the real-time coolant temperature, and generate a first curve of the maximum output current corresponding to different junction temperatures;

[0028] A second processing module is used to obtain the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current according to the preset voltage limit for the power module in the switch off transient state in the motor controller, and generate a second curve of the maximum output current corresponding to different junction temperatures;

[0029] A third processing module, configured to generate a change curve of chip junction temperature and maximum output current as a target curve based on the superposition of the first curve and the second curve and enveloping the curve with a minimum value;

[0030] The output module is used to collect the real-time chip junction temperature of the power module and obtain the corresponding maximum output current as the evaluation result according to the target curve.

[0031] Preferably, it also includes:

[0032] The storage module is used to pre-store the first mapping table, the second mapping table, or the first curve, the second curve or the target curve corresponding to a plurality of real-time thermal resistances and motor controller power parameters.

[0033] The present invention also provides a motor controller.

[0034] comprising a memory for storing executable program code; and

[0035] A processor is used to call the executable program code in the memory, and the execution step includes the evaluation method.

[0036] The present invention also provides a readable storage medium having a computer program stored thereon.

[0037] When the computer program is executed by a processor, the steps of the evaluation method are implemented.

[0038] Compared with the prior art, the above technical solution has the following beneficial effects:

[0039] The online evaluation method for the output current limit of the motor controller provided in this solution obtains the maximum allowable output current by obtaining the maximum chip temperature and the voltage limit of the power module preset in the motor controller under the switch-off transient, and envelops the minimum value of the two to obtain the maximum output current of the motor controller under this working condition. At the same time, the limitation of the output current caused by the maximum chip junction temperature and the voltage overshoot of the shutdown transient is considered, so as to solve the problem that the maximum current output capacity limit set by the existing motor controller does not match the actual output capacity that can be exerted, resulting in the inability of the motor controller to fully output. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 It is a flow chart of Embodiment 1 of the online evaluation method for output current limitation of the present invention;

[0041] Figure 2 A reference diagram of a thermal resistance-coolant flow rate relationship curve under one working condition in Embodiment 1 of the online evaluation method for output current limitation of the present invention;

[0042] Figure 3 A reference diagram of a turn-off voltage overshoot curve at different chip junction temperatures under one working condition in Embodiment 1 of the online evaluation method for output current limitation of the present invention;

[0043] Figure 4 A reference diagram of a second curve under a working condition in Embodiment 1 of the online evaluation method for output current limitation of the present invention;

[0044] Figure 5 A reference diagram of a target curve under one working condition in Embodiment 1 of the online evaluation method for output current limitation of the present invention;

[0045] Figure 6 This is a schematic diagram of modules in Embodiment 2 of the online evaluation device for output current limitation of the present invention.

[0046] Reference numerals:

[0047] 7-online evaluation device for output current limitation; 71-preprocessing module; 72-first processing module; 73-second processing module; 74-third processing module; 75-output module; 76-storage module. DETAILED DESCRIPTION

[0048] The advantages of the present invention are further described below in conjunction with the accompanying drawings and specific embodiments.

[0049] Exemplary embodiments will be described in detail herein, examples of which are shown in the accompanying drawings. When the following description refers to the drawings, the same numbers in different drawings represent the same or similar elements unless otherwise indicated. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the present disclosure. Instead, they are merely examples of devices and methods consistent with some aspects of the present disclosure as detailed in the appended claims.

[0050] The terms used in this disclosure are for the purpose of describing specific embodiments only and are not intended to limit the disclosure. The singular forms of "a", "said" and "the" used in this disclosure and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise. It should also be understood that the term "and / or" used herein refers to and includes any or all possible combinations of one or more associated listed items.

[0051] It should be understood that although the terms first, second, third, etc. may be used in the present disclosure to describe various information, such information should not be limited to these terms. These terms are only used to distinguish the same type of information from each other. For example, without departing from the scope of the present disclosure, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the word "if" as used herein may be interpreted as "at the time of" or "when" or "in response to determining".

[0052] In the description of the present invention, it is necessary to understand that the terms "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0053] In the description of the present invention, unless otherwise specified and limited, it should be noted that the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a mechanical connection or an electrical connection, or it can be the internal connection between two components. It can be a direct connection or an indirect connection through an intermediate medium. For ordinary technicians in this field, the specific meanings of the above terms can be understood according to the specific circumstances.

[0054] In the following description, the suffixes such as "module", "component" or "unit" used to represent elements are only used to facilitate the description of the present invention, and have no specific meanings. Therefore, "module" and "component" can be used interchangeably.

[0055] Embodiment 1: This embodiment provides an online evaluation method for output current limitation, which is used to evaluate the maximum output current allowed by the motor controller under real-time working conditions online, so that the maximum current output capacity limit set by the motor controller matches the actual output capacity that can be exerted, thereby improving work efficiency. For details, refer to Figure 1 , including the following steps:

[0056] Firstly, a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module is provided;

[0057] It should be noted that the above thermal resistance is the thermal resistance of the chip-coolant. Since the coolant composition in the motor controller is fixed, the thermal resistance is mainly determined by the coolant flow rate. Therefore, in the above steps, the corresponding thermal resistance is obtained according to the coolant flow rate (as shown in Figure 2 As shown, it is a reference graph of the relationship between thermal resistance and coolant flow rate). Due to the different types of power modules set in different electric controls, the number and types of thermal resistances contained in the actual chip are also different. As an example but not limited to: IGBT / FRD module, it includes IGBT chip thermal resistance, FRD chip thermal resistance and IGBT-FRD coupling thermal resistance, while for SiCMOSFET module, it only includes the thermal resistance of SiCMOSFET chip. Under different coolant flow rates, the relative proportion of each thermal resistance parameter remains unchanged. Therefore, the thermal resistance extraction strategy can be set to extract the thermal resistance results mainly for IGBT / SiC MOSFET chips, and the remaining thermal resistances are converted according to the ratio obtained by looking up the table (i.e., the first mapping table).

[0058] Specifically, before providing a first mapping table including a mapping relationship between the coolant flow rate and the thermal resistance of the power module, the method includes: collecting several groups of coolant flow rates and thermal resistances, and using a finite element thermal-fluid coupling simulation experiment or an interpolation-calibrated thermal resistance-coolant flow rate relationship curve to generate the first mapping table. In this embodiment, several groups of coolant flow rates and thermal resistances are obtained in advance to generate a mapping relationship between the coolant flow rate and the thermal resistance, such as actual measurement calibration or simulation experiments, which can improve the accuracy of the mapping relationship and directly obtain it by looking up the table for easy operation.

[0059] S100: Acquire the real-time coolant flow rate and the real-time coolant temperature of the power module in the motor controller, and obtain the real-time thermal resistance according to the first mapping table;

[0060] In the above steps, the real-time thermal resistance can be directly obtained according to the above-mentioned first mapping table. In addition, the real-time coolant flow rate and the real-time coolant temperature can be measured by commonly used methods in the prior art, including but not limited to directly obtaining by using sensors, etc., or the real-time collection method of coolant flow rate or temperature that has been disclosed.

[0061] S200: Collecting power parameters of a motor controller, wherein the power parameters of the motor controller include power factor, fundamental frequency, switching frequency, bus voltage, and output current;

[0062] In this embodiment, the motor controller parameters are mainly determined by the operating conditions, which are specifically obtained by using existing technical means as mentioned above, including but not limited to sensor acquisition, etc., recording the power factor, fundamental frequency, switching frequency, bus voltage and output current.

[0063] S300: According to the power parameter, real-time thermal resistance and real-time coolant temperature of the motor controller, the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature is obtained, and a first curve of the maximum output current corresponding to different chip junction temperatures is generated;

[0064] Pre-calibrate the conduction loss and switching loss of several sample chips at the highest junction temperature; use circuit simulation or analytical calculation to obtain the maximum allowable output current corresponding to the maximum chip junction temperature of each sample; calculate the functional relationship between the maximum chip junction temperature of each sample and the maximum allowable output current, and generate a second mapping table; use the highest chip junction temperature of the power module in the calculated motor controller to obtain the corresponding maximum allowable output current based on the second mapping table, and generate a first curve of the maximum output current corresponding to different chip junction temperatures.

[0065] In the above steps, the data can be tabulated according to circuit simulation or relationship analysis calculation based on several actual measurement values, and the functional relationship between the maximum chip junction temperature of each sample and the maximum allowable output current can be generated to generate a second mapping table. The corresponding maximum chip junction temperature is obtained according to the chip of the power module in the motor controller (the maximum chip junction temperature is obtained in advance), and the corresponding maximum allowable output current can be obtained. It should be noted that the corresponding maximum allowable output current obtained above is a certain value under a certain real-time thermal resistance and motor controller power parameter (operating condition). The above first curve is located in a coordinate system with different chip junction temperatures as the X-axis and the maximum output current as the Y-axis, and is presented as a straight line on the Y-axis corresponding to the maximum allowable output current corresponding to the above-mentioned maximum chip junction temperature, and parallel to the X-axis.

[0066] The chip junction temperature and output current are used as unknown variables, and the rest are known variables. Specifically, the functional relationship between the maximum chip junction temperature of each sample and the maximum allowable output current is calculated to generate a second mapping table, including:

[0067] A functional relationship is established based on the difference between the chip junction temperature and the real-time coolant temperature relative to the motor controller power parameter and the real-time thermal resistance product, and a second mapping table is generated based on the interpolation of the highest chip junction temperature of each sample and the maximum allowed output current.

[0068] In the above steps, the functional relationship can be expressed as:

[0069]

[0070] The above T jmax is the maximum chip junction temperature; T f is the coolant temperature; is the real-time thermal resistance, the maximum allowable module loss P loss The power parameters of the motor controller are: power factor p, fundamental frequency f AC , switching frequency f SW , bus voltage V DC , the maximum output current I rms_maxTj Determine; the power factor p, fundamental frequency f AC , switching frequency f SW , bus voltage V DC The power parameters of the motor controller are known, so the chip junction temperature T under real-time thermal resistance can be obtained. jmax The maximum output current I rms_maxTj The mapping relationship of T j is the chip junction temperature, I rms_max is the maximum output current; I rms_maxTjis the maximum output current corresponding to the chip junction temperature. A table can be prepared based on the maximum chip junction temperature and the maximum allowable output current of each sample, and a second mapping table can be generated during operation by a method such as a linear difference.

[0071] S400: according to the preset voltage limit for the power module in the switch-off transient state in the motor controller, obtain the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum output current allowed, and generate a second curve of the maximum output current corresponding to different chip junction temperatures;

[0072] As an illustration, in the above step S300, the limitation of the maximum output current due to the temperature (i.e., obtaining the maximum output current allowed corresponding to the highest chip temperature) is considered, and in the step S400, the limitation of the maximum output current due to the voltage overshoot at the switch-off transient in the motor controller is considered, that is, in addition to the limitation of the voltage (or current) output capacity due to the highest chip junction temperature, the voltage overshoot V at the power module shutdown transient is ce_max It is another important factor that restricts the current output capacity. It is necessary to ensure that V ce_max Under any operating condition, the voltage is lower than the chip blocking voltage value (i.e., the voltage limit for the power module preset in the motor controller under the switch-off transient state) to prevent chip breakdown.

[0073] Specifically, the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current is obtained according to the preset voltage limit for the power module in the motor controller under the transient state of the switch shutdown, and a second curve of the maximum output current corresponding to different junction temperatures is generated, including:

[0074] Control the dynamic switch of the motor controller, detect the voltage of the power module in real time, draw the voltage change curves under the switch-off transient corresponding to multiple sets of chip junction temperatures, and generate the second curve of the maximum output current corresponding to different junction temperatures.

[0075] In this embodiment, refer to Figure 3 ,The corresponding relationship curve of the turn-off voltage overshoot under different chip junction temperatures under multiple bus voltages. The voltage overshoot of the power module at the switch-off transient is affected by factors such as the motor controller bus voltage, output current, and chip junction temperature. For example, for IGBT / FRD modules, when the load current is the same, V ce_max It is negatively correlated with the chip junction temperature, that is, the higher the junction temperature, the lower the V ce_max The smaller the junction temperature, the higher the maximum voltage allowed by the chip body. Therefore, it can be considered that the higher the junction temperature of the chip, the greater the output current allowed under the same bus voltage;

[0076] Based on the above, according to the test results of the dynamic switching process of the vehicle motor controller system, the corresponding relationship curves of the shutdown voltage overshoot under different chip junction temperatures under multiple bus voltages are drawn to obtain the voltage change curves under the switching shutdown transient corresponding to multiple chip junction temperatures, and tabulate them. During the operation of the electric control, the bus voltage is detected in real time, and the linear difference method and other methods are used to look up the table to obtain the chip junction temperature-maximum output current change curve (maximum current voltage stress curve) as one of the limiting values ​​of the current output capacity, that is, the above second curve (see Figure 4 ).

[0077] S500: Generate a change curve of chip junction temperature and maximum allowable output current as a target curve based on the superposition of the first curve and the second curve and enveloping them with a minimum value;

[0078] Specifically, the maximum output current allowed at the highest junction temperature of the chip is superimposed with the voltage stress curve of the maximum current, and the minimum envelope is taken, which is the maximum output current allowed by the electric control at different junction temperatures (that is, considering both the highest chip junction temperature and the voltage overshoot of the shutdown transient). Figure 5 The maximum junction temperature limiting current and the voltage overshoot limiting current curve are superimposed as the maximum allowable current output value at different junction temperatures. Among them, parallel to the X-axis, located at I rms_maxTj The straight line at the position is the first curve obtained under this condition, which is Figure 4 The second curve under this condition is similar to the one in the middle. The minimum value of the two is enveloping as shown in the figure to obtain T j Corresponding I rms_max . It should be noted that the relative positions of the two curves under different motor operating conditions (i.e., different real-time thermal resistances and motor controller power parameters) will constantly change, the drawn envelope curve will also change, and the two curves may not overlap. That is, the first curve, the second curve, and the target curve change according to the real-time thermal resistance and the motor controller power parameters; therefore, in order to quickly obtain the maximum allowable output current under different operating conditions, the first curve, the second curve, or the target curve corresponding to a number of real-time thermal resistances and motor controller power parameters can be stored in advance, and the real-time thermal resistance corresponding to the real-time chip junction temperature and the motor controller power parameters can be matched and obtained, that is, the target curves under multiple operating conditions are preset, listed, and directly obtained by looking up the table under actual operating conditions.

[0079] S600: Collecting the real-time chip junction temperature of the power module, and obtaining the corresponding maximum output current as an evaluation result according to the target curve.

[0080] In the above steps, the real-time chip junction temperature of the power module is collected using the acquisition method disclosed in the prior art. It should be noted that the purpose of obtaining the chip junction temperature in this solution is different from that in the prior art. It is used to calculate the maximum output current allowed under the working condition. For example, the chip junction temperature can be monitored in real time through methods such as online junction temperature extraction of the chip and NTC indirect calibration test to determine the real-time maximum output current value allowed under the real-time chip junction temperature.

[0081] In this embodiment, the problem that the existing automotive motor controllers mostly use the maximum current output capacity under the worst working conditions as the current output limit under any working conditions, which makes it impossible for electric vehicles to fully utilize the current output capacity of the power module under all working conditions, is solved. The maximum allowable output current is obtained by obtaining the maximum chip temperature and the voltage limit for the power module under the switch shutdown transient preset in the motor controller, while considering the limitations of the maximum chip junction temperature and the voltage overshoot of the shutdown transient on the output current. The thermal stress and voltage stress current output limits of the power module are comprehensively considered, thereby reducing the analysis error caused by single-dimensional analysis and making the evaluation result more accurate.

[0082] Embodiment 2: This embodiment provides an online evaluation device 7 for output current limitation, see Figure 6 , for motor controllers, including:

[0083] The preprocessing module 71 is used to provide a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module; obtain a real-time coolant flow rate and a real-time coolant temperature of the power module in the motor controller, and obtain the real-time thermal resistance according to the first mapping table; collect power parameters of the motor controller, wherein the power parameters of the motor controller include a power factor, a fundamental frequency, a switching frequency, a bus voltage, and an output current;

[0084] Specifically, the real-time thermal resistance can be directly obtained according to the above-mentioned first mapping table. The motor controller parameters are mainly determined by the operating conditions. In addition, the real-time coolant flow rate, real-time coolant temperature and motor controller parameters can be measured by common methods in the prior art.

[0085] A first processing module 72 is used to obtain the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature according to the motor controller power parameter, the real-time thermal resistance and the real-time coolant temperature, and generate a first curve of the maximum output current corresponding to different chip junction temperatures;

[0086] Specifically, a functional relationship is established based on the difference between the chip junction temperature and the real-time coolant temperature relative to the motor controller power parameter and the real-time thermal resistance product to obtain the maximum output current allowed by the chip at the highest junction temperature. The above-mentioned first curve is located in a coordinate system with different chip junction temperatures as the X-axis and the maximum output current as the Y-axis, and appears as a straight line on the Y-axis corresponding to the maximum allowable output current corresponding to the above-mentioned highest chip junction temperature, and parallel to the X-axis.

[0087] The second processing module 73 is used to obtain the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum output current allowed according to the voltage limit of the power module preset in the motor controller when the switch is turned off transiently, and generate a second curve of the maximum output current corresponding to different chip junction temperatures;

[0088] Specifically, the second curve can be generated by controlling the dynamic switch of the motor controller, detecting the voltage of the power module in real time, and drawing voltage change curves under switch-off transients corresponding to multiple sets of chip junction temperatures.

[0089] A third processing module 74 is used to generate a change curve of chip junction temperature and maximum allowable output current as a target curve based on the superposition of the first curve and the second curve and the minimum value envelope;

[0090] In the above module, the maximum output current allowed by the electric control at different junction temperatures (i.e., considering both the maximum chip junction temperature and the voltage overshoot of the shutdown transient) is obtained. It should be noted that the relative positions of the two curves will change continuously under different motor operating conditions (i.e., different real-time thermal resistance and motor controller power parameters).

[0091] The output module 75 is used to collect the real-time chip junction temperature of the power module and obtain the corresponding maximum output current as the evaluation result according to the target curve.

[0092] Specifically, in the above steps, the real-time chip junction temperature of the power module is collected using methods disclosed in the prior art, such as online junction temperature extraction, NTC indirect calibration test, and the like.

[0093] Specifically, the evaluation device may further include:

[0094] The storage module 76 is used to pre-store the first mapping table, the second mapping table, or the first curve, the second curve or the target curve corresponding to a plurality of real-time thermal resistances and motor controller power parameters.

[0095] Considering that the first curve, the second curve and the target curve change according to the real-time thermal resistance and the power parameters of the motor controller; the first curve, the second curve or the target curve corresponding to several real-time thermal resistances and the power parameters of the motor controller can be stored in advance, and the real-time thermal resistance and the power parameters of the motor controller corresponding to the real-time chip junction temperature can be matched and obtained, that is, the target curves under multiple working conditions are preset, and a list is made, and the target curves are directly obtained by looking up the table under actual working conditions, so as to improve the efficiency of obtaining the maximum output current in actual scenarios.

[0096] In this embodiment, the first processing module and the second processing module are used to obtain the maximum chip temperature and the maximum allowable output current obtained by the voltage limit of the power module under the switch shutdown transient preset in the motor controller, and then the third processing module is used to obtain the minimum value of the two, including the maximum chip junction temperature and the shutdown transient voltage overshoot limitations on the output current, so that the evaluated maximum current output capacity limit of the motor controller matches the actual output capacity that can be exerted, thereby improving the operating efficiency of the motor controller, considering the limitations on the output capacity in multiple dimensions, and improving the accuracy of the evaluation results.

[0097] Embodiment three:

[0098] To achieve the above object, the present invention also provides a motor controller that can execute the program code in the above embodiment 1. The computer device of this embodiment includes at least but is not limited to: a memory and a processor that can be connected to each other through a device bus. It should be noted that only devices with components are shown, but it should be understood that it is not required to implement all the components shown, and more or fewer components can be implemented instead.

[0099] In this embodiment, the memory may be an internal storage unit of the motor controller or an external storage device of the motor controller. In this embodiment, the memory is generally used to store operating devices or data installed in the motor controller, such as program codes and data (such as motor controller power parameters, first mapping table, second mapping table) of the online evaluation method of the maximum output current of the motor controller in the first embodiment. In addition, the memory can also be used to temporarily store various types of data that are output or to be output (such as data corresponding to the target curve, etc.).

[0100] The processor is usually used to control the overall operation of the motor controller. In this embodiment, the processor is used to run the program code stored in the memory or process data, such as running the online evaluation method of output current limitation of the first embodiment.

[0101] Embodiment 4:

[0102] To achieve the above-mentioned purpose, the present invention also provides a readable storage device on which a computer program is stored, and when the program is executed by a processor, a corresponding function is realized. The computer readable storage medium of this embodiment is used to store data, and when executed by the processor, the online evaluation method for output current limitation of embodiment 1 and the online evaluation device for output current limitation of embodiment 2 are realized.

[0103] It should be noted that the embodiments of the present invention have better practicability and do not impose any form of limitation on the present invention. Any technician familiar with the field may use the technical content disclosed above to change or modify it into an equivalent effective embodiment. However, any modification or equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution of the present invention.

Claims

1. An online evaluation method for output current limitation, characterized in that: For motor controllers, including: Providing a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module; Acquire the real-time coolant flow rate and the real-time coolant temperature of the power module in the motor controller, and obtain the real-time thermal resistance according to the first mapping table; Collecting motor controller power parameters, wherein the motor controller power parameters include power factor, fundamental frequency, switching frequency, bus voltage and output current; According to the power parameters, real-time thermal resistance and real-time coolant temperature of the motor controller, the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature is obtained, and a first curve of the maximum output current corresponding to different chip junction temperatures is generated; According to the preset voltage limit for the power module in the switch-off transient state in the motor controller, the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current is obtained, and a second curve of the maximum output current corresponding to different chip junction temperatures is generated; Based on the superposition of the first curve and the second curve and the minimum value envelope, a change curve of the chip junction temperature and the maximum output current is generated as a target curve; The real-time chip junction temperature of the power module is collected, and the corresponding maximum output current is obtained as the evaluation result according to the target curve, where The step of obtaining the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature includes: Pre-calibrate the conduction loss and switching loss of several sample chips at the highest junction temperature; Use circuit simulation or analytical calculation to obtain the maximum output current allowed corresponding to the highest chip junction temperature of each sample; Calculating the functional relationship between the maximum chip junction temperature of each sample and the maximum allowed output current to generate a second mapping table; Based on the second mapping table, the maximum chip junction temperature of the power module in the motor controller is used to obtain the corresponding maximum allowed output current; The calculating the functional relationship between the maximum chip junction temperature of each sample and the maximum allowed output current to generate a second mapping table includes: Establish a functional relationship according to the difference between the highest chip junction temperature and the real-time coolant temperature relative to the motor controller power parameter and the real-time thermal resistance product, and interpolate to generate a second mapping table; The method obtains the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current according to the preset voltage limit of the power module in the motor controller under the transient state of the switch shutdown, and generates a second curve of the maximum output current corresponding to different junction temperatures, including: Control the dynamic switch of the motor controller, detect the voltage of the power module in real time, draw the voltage change curves under the switch-off transient corresponding to multiple sets of chip junction temperatures, and generate the second curve of the maximum output current corresponding to different junction temperatures.

2. The online evaluation method according to claim 1, characterized in that: Before providing a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module, the method includes: A plurality of sets of coolant flow rates and thermal resistances are collected, and a first mapping table is generated using a finite element thermal-fluid coupling simulation experiment or a relationship curve of thermal resistance-coolant flow rate calibrated by interpolation.

3. The online evaluation method according to claim 1, characterized in that: include: The first curve, the second curve and the target curve vary according to the real-time thermal resistance and the motor controller power parameter; A first curve, a second curve or a target curve corresponding to a plurality of real-time thermal resistances and motor controller power parameters are pre-stored, and the real-time thermal resistances and motor controller power parameters corresponding to the real-time chip junction temperature are matched and obtained.

4. An online evaluation device for output current limitation, characterized in that: For motor controllers, including: A preprocessing module is used to provide a first mapping table including a mapping relationship between a coolant flow rate and a thermal resistance of a power module; obtain a real-time coolant flow rate and a real-time coolant temperature of the power module in the motor controller, and obtain the real-time thermal resistance according to the first mapping table; collect power parameters of the motor controller, wherein the power parameters of the motor controller include power factor, fundamental frequency, switching frequency, and bus voltage; A first processing module is used to calculate the maximum output current allowed by the chip of the power module in the motor controller at the highest junction temperature according to the motor controller power parameter, the real-time thermal resistance and the real-time coolant temperature, and generate a first curve of the maximum output current corresponding to different junction temperatures; A second processing module is used to obtain the voltage stress change when different chip junction temperatures of the power module in the motor controller correspond to the maximum allowable output current according to the preset voltage limit for the power module in the switch off transient state in the motor controller, and generate a second curve of the maximum output current corresponding to different junction temperatures; A third processing module, configured to generate a change curve of chip junction temperature and maximum output current as a target curve based on the superposition of the first curve and the second curve and enveloping the curve with a minimum value; The output module is used to collect the real-time chip junction temperature of the power module and obtain the corresponding maximum output current as the evaluation result according to the target curve, wherein The first processing module uses circuit simulation or analytical calculation to obtain the maximum allowable output current corresponding to the highest chip junction temperature of each sample; calculates the functional relationship between the highest chip junction temperature of each sample and the maximum allowable output current to generate a second mapping table; based on the second mapping table, the highest chip junction temperature of the power module in the motor controller is used to obtain the corresponding maximum allowable output current; The first processing module establishes a functional relationship according to the difference between the highest chip junction temperature and the real-time coolant temperature relative to the motor controller power parameter and the real-time thermal resistance product, and interpolates to generate a second mapping table; The second processing module controls the dynamic switch of the motor controller, detects the voltage of the power module in real time, draws voltage change curves under switch-off transient corresponding to multiple sets of chip junction temperatures, and generates a second curve of maximum output current corresponding to different junction temperatures.

5. The online evaluation device according to claim 4, characterized in that: Also includes: The storage module is used to pre-store the first mapping table, the second mapping table, or the first curve, the second curve or the target curve corresponding to a plurality of real-time thermal resistances and motor controller power parameters.

6. A motor controller, characterized in that: including a memory for storing executable program code; as well as A processor is used to call the executable program code in the memory, and the execution steps include the online evaluation method according to any one of claims 1 to 3.

7. 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 online evaluation method according to any one of claims 1 to 3 are implemented.

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