Average loss determination method, device and equipment

Abstract

The invention provides an average loss determination method, device and equipment, and relates to the technical field of electronics. The method comprises the following steps: acquiring a first switching frequency correction coefficient corresponding to each set modulation ratio; determining a second switching frequency correction coefficient according to the current modulation ratio of the power device and the first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio; according to the second switching frequency correction coefficient, correcting the switching loss of an insulated gate bipolar transistor and the turn-off loss of a diode of the power device; acquiring the conduction loss of an insulated gate bipolar transistor and the conduction loss of a diode of the power device; and determining the average loss of the power device according to the conduction loss of the insulated gate bipolar transistor, the conduction loss of the diode, the corrected switching loss of the insulated gate bipolar transistor and the corrected turn-off loss of the diode. According to the scheme, the average loss of the power device in the overmodulation region can be determined more accurately.

Description

Technical Field

[0001] The present invention belongs to the field of electronic technology, and in particular relates to a method, device and equipment for determining average loss. Background Art

[0002] During the operation of power devices, the junction temperature can be monitored to ensure that the power devices operate within a safe temperature range. However, the average loss is required for junction temperature estimation, and the accuracy of the average loss calculation affects the accuracy of junction temperature estimation.

[0003] In the prior art, when a power device is in an overmodulation region, a space vector pulse width modulation (SVPWM) frequency is used as the actual switching frequency of the power device, and the average loss is calculated based on the actual switching frequency.

[0004] However, the average loss calculation in this existing method is not accurate. Summary of the invention

[0005] The embodiments of the present invention provide a method, device and equipment for determining average loss, which can solve the problem of inaccurate average loss calculation of power devices.

[0006] In a first aspect, an embodiment of the present invention provides a method for determining an average loss, including:

[0007] Obtaining a first switching frequency correction coefficient corresponding to each set modulation ratio, wherein the set modulation ratio is greater than or equal to 1, and the first switching frequency correction coefficient is determined by a duty cycle output by a power device in an overmodulation region under the set modulation ratio;

[0008] Determine a second switching frequency correction coefficient according to a current modulation ratio of the power device and a first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio;

[0009] According to the second switching frequency correction coefficient, correcting the insulated gate bipolar transistor switching loss and the diode turn-off loss of the power device;

[0010] Obtaining the insulated gate bipolar transistor conduction loss and the diode conduction loss of the power device;

[0011] The average loss of the power device is determined based on the IGBT conduction loss, the diode conduction loss, the corrected IGBT switching loss and the corrected diode turn-off loss.

[0012] In a second aspect, an embodiment of the present invention provides an average loss determination device, including:

[0013] A first coefficient acquisition module, used to acquire a first switching frequency correction coefficient corresponding to each set modulation ratio, the set modulation ratio is greater than or equal to 1, and the first switching frequency correction coefficient is determined by the duty cycle output by the power device in the overmodulation region under the set modulation ratio;

[0014] A second coefficient acquisition module, used to determine a second switching frequency correction coefficient according to a current modulation ratio of the power device and a first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio;

[0015] A loss correction module, used to correct the insulated gate bipolar transistor switching loss and diode turn-off loss of the power device according to the second switching frequency correction coefficient;

[0016] A loss acquisition module, used to acquire the conduction loss of the insulated gate bipolar transistor and the conduction loss of the diode of the power device;

[0017] The average loss determination module is used to determine the average loss of the power device according to the conduction loss of the insulated gate bipolar transistor, the conduction loss of the diode, the corrected switching loss of the insulated gate bipolar transistor and the corrected turn-off loss of the diode.

[0018] In a third aspect, an embodiment of the present invention provides a motor controller, which comprises at least: a processing chip and the power device, wherein the processing chip is used to execute the above method to determine the average loss of the power device.

[0019] The average loss determination method, device and equipment of the embodiments of the present invention can more accurately obtain the actual switching frequency of the power device in the overmodulation area by obtaining the switching frequency correction coefficient of the power device in the overmodulation area and correcting the original switching frequency of the power device. At the same time, the actual switching frequency is used to calculate the average loss of the power device, which can ensure that the calculated average loss is the same as the actual loss of the power device in the overmodulation area, thereby ensuring the accuracy of the average loss calculation. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solution of the embodiment of the present invention, the following is a brief introduction to the drawings required for use in the embodiment of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0021] Figure 1 A schematic diagram of the system framework provided for an embodiment of the present application;

[0022] Figure 2 A schematic diagram of a flow chart of a method for determining average loss provided in an embodiment of the present application;

[0023] Figure 3 A schematic diagram of a process for obtaining a second switch power correction coefficient provided in an embodiment of the present application;

[0024] Figure 4 A schematic diagram of a simulation process provided for an embodiment of the present application;

[0025] Figure 5 A schematic diagram of the automatic execution flow of a MATLAB script provided in an embodiment of the present application;

[0026] Figure 6 A schematic diagram of the structure of an average loss determination device provided in an embodiment of the present application;

[0027] Figure 7 A schematic diagram of the hardware structure of an electronic device provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] The features and exemplary embodiments of various aspects of the present invention will be described in detail below. In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present invention, rather than to limit the present invention. For those skilled in the art, the present invention can be implemented without the need for some of these specific details. The following description of the embodiments is only to provide a better understanding of the present invention by illustrating examples of the present invention.

[0029] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the statement "include..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0030] The method provided in the embodiment of the present application can be applied to the average power loss calculation scenario of the power device in the motor controller. In the motor controller application, in order to maximize the output capacity of the power device, the thermal state of the power device is generally monitored by junction temperature estimation. Exemplarily, a junction temperature estimation development strategy for a motor operating in a non-locked rotor condition includes the following steps: (1) designing an average loss formula for the power device; (2) extracting the average loss formula coefficients offline through the power device manual; (3) designing a suitable thermal network model through thermal simulation results, and extracting the thermal resistance parameters between each virtual node; (4) implementing the formulas and parameters related to step (1) and step (2) in the chip through software. It can be seen that the accuracy of the average loss calculation affects the accuracy of the junction temperature estimation, and thus affects the output capacity of the power device.

[0031] Among them, junction temperature estimation can refer to the temperature of the semiconductor junction inside the power device. This temperature is an important parameter to measure the thermal state of the power device. In motor controller applications, in order to maximize the output capacity of the power device, the thermal state of the power device is generally monitored by junction temperature estimation. This is because the power device generates heat during operation, and excessive temperature may cause the device performance to degrade or even damage. By monitoring and controlling the junction temperature, it can ensure that the power device operates within a safe temperature range, thereby improving the stability and reliability of the system.

[0032] Among them, the switching frequency of the power device needs to be obtained during the average loss calculation process. In order to facilitate the acquisition of the switching frequency, the switching frequency of the power device is currently set to the space vector pulse width modulation (SVPWM) frequency. When the motor controller is in the non-overmodulation area, the SVPWM modulation frequency is equal to the actual switching frequency of the power device, and the calculated loss of the power device is accurate. However, in the overmodulation area, within a stator current cycle, there must be a certain period of time when the duty cycle modulated by SVPWM is 100%. Therefore, the SVPWM modulation frequency must be greater than the actual switching frequency of the power device, and the calculated power device loss is greater than the actual loss. Therefore, the average loss currently calculated in the overmodulation area is too large, resulting in the estimated junction temperature being higher than the actual junction temperature, which limits the output capacity of the power device.

[0033] In response to the above problems, an embodiment of the present application provides a method through MATLAB simulation and data processing, which is independent of the motor type, power device type and bench test, and can obtain the correction coefficient of the power device switching frequency under a specific SVPWM overmodulation, and implement the average loss correction in the motor controller, thereby solving the problem that the SVPWM modulation frequency calculated in the overmodulation area is inevitably greater than the actual switching frequency of the power device, resulting in the average loss calculation of the power device being too large.

[0034] The technical solution of the present application is described in detail below through specific embodiments. It should be noted that the following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments.

[0035] Figure 1 This is a schematic diagram of the system framework provided in the embodiment of the present application. Figure 1 As shown in the figure, the implementation of this solution mainly relies on three parts: ①MATLAB script; ②Simulink model; ③motor controller. Among them, the MATLAB script is responsible for inputting given, Simulink model simulation configuration and simulation result processing, the Simulink model is responsible for converting the input into U-phase duty cycle through the SVPWM overmodulation algorithm and saving it to the MATLAB workspace, and the MATLAB processing results are implemented in software coding on the main control chip of the motor controller.

[0036] The entire solution process is described in detail below through some embodiments.

[0037] Figure 2 A flow chart of the average loss determination method provided in the embodiment of the present application. The method can be used in the above Figure 1 The motor controller is implemented in the main control chip. Figure 2 As shown, the method may include the following steps:

[0038] Step S210: obtaining a first switching frequency correction coefficient corresponding to each set modulation ratio.

[0039] Wherein, the modulation ratio is set to be greater than or equal to 1, and the first switching frequency correction coefficient is determined by the duty cycle output by the power device in the overmodulation region under the set modulation ratio. Generally, overmodulation refers to a state in which some peak values ​​of the modulation signal exceed the maximum allowable value of the system or device under consideration. In this embodiment, the overmodulation region may refer to a region in which the amplitude of the output voltage exceeds its linear modulation range.

[0040] In this embodiment, M represents the modulation ratio. In the SVPWM overmodulation algorithm, when the modulation ratio M is greater than 1, the output voltage will exceed its maximum value, and the duty cycle will reach 100%, which is the so-called overmodulation region. In this case, the SVPWM modulation frequency will be greater than the actual switching frequency of the power device. In order to calculate the average loss of the power device, it is necessary to integrate the actual switching frequency of the power device. In the overmodulation region, since the SVPWM modulation frequency is greater than the actual switching frequency of the power device, the calculated average loss of the power device will be greater than the actual loss. This is because in the overmodulation region, the actual operating conditions of the power device are different from its rated operating conditions, resulting in an increase in its power loss.

[0041] In this embodiment, N set modulation ratios can be configured according to the initial value of the modulation ratio and the first step length. For example, assuming that the initial value of the modulation ratio is 1 and the first compensation is 0.01, the first set modulation ratio can be 1, the second set modulation ratio can be 1.01, and so on. The Nth set modulation ratio can be 1+0.01*(N-1). In addition, the value of the set modulation ratio should not be too large. A set threshold can be configured. When the value of the Mth set modulation ratio is the set threshold, the set modulation ratio will not be configured further, that is, N=M. Wherein, N and M are both positive integers.

[0042] In this embodiment, the first switching frequency correction coefficient can be obtained by Figure 1 The Simulink model shown in the figure is simulated. Specifically, the SVPWM overmodulation algorithm model can be established using MATLAB's Simulink. The model inputs the modulation ratio M and the current frequency fe. The current frequency fe is read from the MATLAB workspace, and the U-phase duty cycle output by the model simulation is automatically saved to the workspace. The workspace is an area for storing and viewing variables. Users can create, edit, save and call variables in this workspace.

[0043] Step S220: determining a second switching frequency correction coefficient according to the current modulation ratio of the power device and the first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio.

[0044] In this embodiment, the main control chip can read the current modulation ratio M of the motor controller. In addition, as mentioned above, the first switching frequency correction coefficient corresponding to each set modulation ratio can be obtained through simulation, which can also be burned into the main control chip.

[0045] Among them, the main control chip can find the i-th set modulation ratio that is similar to or the same as the current modulation ratio M from the N set modulation ratios through the current modulation ratio M. Exemplarily, based on the first switching frequency correction coefficient corresponding to the i-th set modulation ratio, the second switching frequency correction coefficient can be determined. However, in order to improve the correction effect, in some embodiments, several more set modulation ratios can be found from the N set modulation ratios, and the second switching frequency correction coefficient can be determined based on the first switching frequency correction coefficients of these set modulation ratios.

[0046] Among them, it has been mentioned in the previous article that in the overmodulation area, the SVPWM modulation frequency must be greater than the actual switching frequency of the power device, so the SVPWM modulation frequency is corrected by the second switching frequency correction coefficient, so that in the overmodulation area, the corrected SVPWM modulation frequency can be close to or equal to the actual switching frequency of the power device, thereby ensuring the accuracy of the subsequent average loss calculation.

[0047] Step S230: Correcting the insulated gate bipolar transistor switching loss and diode turn-off loss of the power device according to the second switching frequency correction coefficient.

[0048] In this embodiment, when calculating the average loss, it is necessary to first calculate the switching loss of the insulated-gate bipolar transistor (IGBT) and the turn-off loss of the diode (Diode).

[0049] Exemplarily, the IGBT switching loss calculation formula is as follows:

[0050]

[0051] In the above formula, P IGBT_AvgSW represents the IGBT switching loss, f sw is the switching frequency of the power device, E on (t is the IGBT conduction energy, E off (t) is the IGBT turn-off energy, T 0 is the motor stator current period.

[0052] For example, the diode turn-off loss calculation formula is as follows:

[0053]

[0054] In the above formula, P Diode_AvgSW Represents the diode turn-off loss, E rr is the diode turn-off energy, f sw is the switching frequency of the power device, T 0 is the motor stator current period.

[0055] Among them, IGBT switching loss and diode turn-off loss are the average values ​​of a stator current cycle, and the switching frequency f is required for calculation. sw . But if the switching frequency f sw If the actual value is used, the actual switching frequency of the power device needs to be integrated. Since the stator current cycle changes according to the working conditions, the starting and ending points of the integration are difficult to determine. Therefore, in order to facilitate calculation in the chip, f sw Set to SVPWM modulation frequency. However, because the SVPWM modulation frequency in the overmodulation area must be greater than the actual switching frequency of the power device, the SVPWM modulation frequency needs to be corrected.

[0056] In this embodiment, the switching frequency f is corrected by the second switching frequency correction coefficient. swAfter correction, the corrected insulated gate bipolar transistor switching loss and diode turn-off loss are obtained.

[0057] Step S240: Obtaining the insulated gate bipolar transistor conduction loss and the diode conduction loss of the power device.

[0058] Step S250: determining the average loss of the power device according to the IGBT conduction loss, the diode conduction loss, the corrected IGBT switching loss and the corrected diode turn-off loss.

[0059] In this embodiment, taking the motor controller as a three-phase two-level motor controller as an example, in the three-phase two-level motor controller, the average loss of the power device of a single bridge arm in one stator current cycle includes IGBT conduction loss, IGBT switching loss, Diode conduction loss and Diode turn-off loss.

[0060] The above has calculated the corrected insulated gate bipolar transistor switching loss and diode turn-off loss. The remaining IGBT conduction loss and diode conduction loss can be calculated by the following formula:

[0061] The IGBT conduction loss calculation formula is as follows:

[0062]

[0063] In the above formula, P IGBT_AvgCond Indicates the IGBT conduction loss, I c (t) = I o *sin(ωt), is the instantaneous current flowing through the IGBT, I o is the output current amplitude of the motor controller, ω is the angular velocity of the motor stator current, and the collector-emitter voltage U CE (t) = U CE0 (T j )+R C (T j )*I c (t), D(t) is the IGBT duty cycle function, T 0 is the motor stator current period, U CE0 (T j ) is the collector-emitter threshold voltage, R C (T j ) is the on-state slope resistance of the IGBT.

[0064] The diode conduction loss calculation formula is as follows:

[0065]

[0066] In the above formula, P Diode_AvgCondRepresents the diode conduction loss, I f (t) = I o *sin(ωt), is the forward current flowing through the diode, the forward voltage drop U F (t) = U F0 (T j )+R F (T j )*I f (t), U F0 (T j ) is the forward voltage drop threshold voltage, R F is the diode on-state slope resistance.

[0067] In this embodiment, the stator current cycle refers to the time required for the current in the stator winding to complete a complete sinusoidal waveform change in a three-phase AC motor. This cycle usually corresponds to the frequency of the power supply. For example, if the power supply frequency is 50 Hz, then the stator current cycle is 1 / 50 second, that is, 20 milliseconds. For the power devices in the three-phase two-level motor controller, they will experience multiple switching actions in one stator current cycle, and each switch is accompanied by power loss.

[0068] In this embodiment, by correcting the switching loss of the insulated gate bipolar transistor and the turn-off loss of the diode, a corrected switching loss of the insulated gate bipolar transistor and a corrected turn-off loss of the diode are obtained, and then the average loss of the power device can be obtained by combining the conduction loss of the insulated gate bipolar transistor and the conduction loss of the diode.

[0069] In an embodiment of the present application, by obtaining a correction coefficient for the switching frequency of the power device in the overmodulation zone, the original switching frequency of the power device is corrected as the actual switching frequency of the power device in the overmodulation zone, and the actual switching frequency is used to calculate the average loss of the power device, so that the calculated average loss can be guaranteed to be the same as the actual loss of the power device in the overmodulation zone, thereby ensuring the accuracy of the average loss calculation. By using the corrected average loss of the power device, the junction temperature estimation of the motor controller in the overmodulation zone is closer to the actual junction temperature, thereby improving the accuracy of the junction temperature estimation. This avoids the problem that the SVPWM modulation frequency is used to calculate the average loss in the overmodulation zone because the SVPWM modulation frequency is necessarily greater than the actual switching frequency of the power device, resulting in the problem that the average loss calculated in the end is too large.

[0070] Figure 3 A schematic diagram of a process for obtaining a second switch power correction coefficient according to an embodiment of the present application. Figure 3 As shown, after establishing Figure 1 After the MATLAB script shown, the MATLAB script will perform the following steps to obtain the second switch power correction factor:

[0071] Step S310: obtaining the duty cycle output by the power device in the overmodulation region at each set modulation ratio.

[0072] Step S320: Determine the number of target duty cycles that meet the set conditions among the output duty cycles.

[0073] Step S330: determining a first switching frequency correction coefficient corresponding to each set modulation ratio according to the number of target duty cycles.

[0074] In this embodiment, the setting condition may refer to a duty cycle of 100%, which means that in a pulse width modulation cycle, the time that a power device (such as an IGBT or a diode) is in a conducting state is equal to the entire cycle length. Intuitively, this means that in a complete waveform, the high level portion occupies the entire time and there is no low level portion.

[0075] For example, in some other embodiments, the setting condition may also refer to the output voltage reaching the maximum possible value under the duty cycle. When the output voltage reaches the maximum possible value once, the corresponding duty cycle is the target duty cycle. Each time the output voltage reaches the maximum possible value, the number of target duty cycles is increased by one, thereby obtaining the number of target duty cycles.

[0076] In this embodiment, the target duty cycle number can be determined by simulation or experimental measurement. When performing simulation, a Simulink model of the SVPWM overmodulation algorithm can be established. Then, different set modulation ratios M and current frequencies fe are configured as input parameters, and the simulation is run to record the output duty cycle under each set modulation ratio and save it in the MATLAB Workspace for subsequent processing and analysis.

[0077] In this embodiment, the Nth set modulation ratio and the corresponding first switching frequency correction coefficient Coff can be saved in arrays DATA1 and DATA2, that is, DATA1 = [M1, M2, ..., MN], DATA2 = [Coff1, Coff2, ..., CoffN], for subsequent retrieval and use.

[0078] For example, in some implementations, the first switching frequency correction coefficient may be calculated using the following formula:

[0079] Coff=(1–T / X) (Formula 5)

[0080] In the above formula, Coff represents the first switching frequency correction coefficient, T represents the number of target duty cycles, and X is a constant. For example, X can be 500.

[0081] In the embodiment of the present application, the first switching frequency correction coefficient corresponding to each set modulation ratio is calculated based on the number of target duty cycles. These first switching frequency correction coefficients can be used to correct the SVPWM modulation frequency in the overmodulation region in the future to make it closer to the actual switching frequency of the power device, thereby improving the calculation accuracy of the average loss.

[0082] The following describes how to obtain the above arrays DATA1 and DATA2 through simulation through some embodiments. Figure 4 The following is a schematic diagram of the simulation process provided by the embodiment of the present application. Figure 4 As shown, the method comprises the following steps:

[0083] Step S410: Obtain the initial value of the modulation ratio, the first step length and the initialized current frequency. The initial value of the modulation ratio is greater than or equal to 1.

[0084] Step S420: According to the initial value of the modulation ratio and the first step length, N set modulation ratios are determined, and the last set modulation ratio is the difference between the next set modulation ratio and the first step length. Wherein N is a positive integer;

[0085] Step S430: Determine the simulation step size and simulation time of the simulation model according to the current frequency.

[0086] Step S440: using the current frequency and the Nth set modulation ratio as inputs of the simulation model, starting the simulation model to perform simulation according to the simulation step length and simulation time, and outputting the duty cycle under the Nth set modulation ratio.

[0087] Step S450: When the value of the Nth set modulation ratio is less than the set threshold, continue to use the current frequency and the N+1th set modulation ratio as inputs to the simulation model to obtain the duty cycle under the N+1th set modulation ratio, until the value of the set modulation ratio input into the simulation model is equal to the set threshold, and obtain the duty cycle output by the power device under each set modulation ratio.

[0088] In this embodiment, the current frequency fe is initialized first, and then the flag value k of the number of simulation cycles is set. For example, it is assumed that k is assigned a value of 1, and the kth set modulation ratio M is configured at the same time. For example, the kth set modulation ratio M can be set to 1. After completing the above settings, the simulation step size and simulation time of the simulation model need to be set according to the current frequency fe. Then proceed to the following steps:

[0089] (1) Start the simulation model;

[0090] (2) Read the result output by the simulation model. For example, the output result may be the U-phase duty cycle DutyU.

[0091] (3) Calculate the number of duty cycles of 100% in the U-phase duty cycle DutyU, that is, find the number of target duty cycles;

[0092] (4) Calculate the first switching frequency correction coefficient Coff = (1-T / X) under the current modulation ratio;

[0093] (5) The kth set modulation ratio M and the corresponding first switching frequency correction coefficient Coff are stored in arrays DATA1 and DATA2 respectively;

[0094] (6) The modulation ratio M is set to increase by a step of 0.01, the flag value k is increased by a step of 1, and the loop end condition is set: if the kth modulation ratio M is greater than the overmodulation limit (i.e., the set threshold value, such as 1.1), the loop ends; otherwise, go to (1) and continue to repeat (1)-(6). Thus, two 1*11 arrays DATA1 and DATA2 are obtained.

[0095] Among them, array DATA1 = [M1, M2, ..., MN], array DATA2 = [Coff1, Coff2, ..., CoffN].

[0096] For example, Figure 5 The following is a schematic diagram of the automatic execution flow of the MATLAB script provided in the embodiment of the present application, such as Figure 5 As shown, it can be divided into the following steps:

[0097] Step S510: Set the current frequency fe, the standard value k=1, and the kth set modulation ratio=1.

[0098] Step S520: configure the simulink model simulation step size to 0.001 / fe and the simulation time to 1 / fe.

[0099] Step S530: Run the Simulink model.

[0100] Step S540: Read the model output result, ie, the U-phase duty cycle.

[0101] Step S550: Calculate the number T of the U-phase duty cycles with a duty cycle of 100%.

[0102] Step S560: Calculate the first switching frequency correction coefficient Coff=(1-T / X).

[0103] Step S570: Save arrays DATA1 and DATA2.

[0104] Step S580: Let k=k+1, and the kth set modulation ratio=1+0.01.

[0105] Step S590: Determine whether the kth modulation ratio is greater than 1.1. If so, the process ends. If not, the process continues to execute step S530 and subsequent steps.

[0106] In the embodiment of the present application, through the Simulink simulation experiment, the output duty cycle of the power device under different set modulation ratios can be accurately obtained. This provides basic data for the subsequent calculation of the second switching frequency correction coefficient. At the same time, through the above Simulink simulation, it can be found that the calculated second switching frequency correction coefficient is only related to the overmodulation algorithm, so it can be applied to motor controllers of different powers and different voltage levels without frequent modifications. The method for realizing average loss correction in the motor controller is simple, and the chip resources of the motor controller are less occupied.

[0107] The following embodiments describe in detail how to obtain the second switching frequency correction coefficient.

[0108] In some embodiments, the second switching frequency correction coefficient may be obtained by the following steps:

[0109] Step 11: Determine a first set modulation ratio and a second set modulation ratio in the set modulation ratio according to the current modulation ratio;

[0110] Step 12: determining a correction coefficient corresponding to the first set modulation ratio and a correction coefficient corresponding to the second set modulation ratio according to the first switching frequency correction coefficient corresponding to each set modulation ratio;

[0111] Step 13: Determine the second switching frequency correction coefficient according to the correction coefficient corresponding to the first set modulation ratio, the correction coefficient corresponding to the second set modulation ratio, the current modulation ratio, the first set modulation ratio, and the second set modulation ratio.

[0112] Among them, it has been mentioned above that two arrays DATA1 and array DATA2 are obtained after simulation. Array DATA1 = [M1, M2, ..., MN], array DATA2 = [Coff1, Coff2, ..., CoffN]. DATA1 stores N set modulation ratios, and DATA2 stores the first switching frequency correction coefficients corresponding to the N set modulation ratios. Exemplarily, assuming that the first set modulation ratio is M2, then the correction coefficient corresponding to the first set modulation ratio M2 is the first switching frequency correction coefficient Coff2 in array DATA2.

[0113] Among them, when determining the first set modulation ratio and the second set modulation ratio, the following method can be used to determine: ① Take the two set modulation ratios located on both sides of the current modulation ratio in the array DATA1. For example, assuming that the current modulation ratio is M3, the first set modulation ratio can be M2, and the second set modulation ratio can be M4. The correction coefficient corresponding to the first set modulation ratio is the first switching frequency correction coefficient Coff2, and the correction coefficient corresponding to the second set modulation ratio is the first switching frequency correction coefficient Coff4. ② Two set modulation ratios close to the current modulation ratio can be selected from the array DATA1 as the first set modulation ratio and the second set modulation ratio.

[0114] In this embodiment, after the first set modulation ratio and the second set modulation ratio are determined from the array DATA1, the first switching frequency correction coefficient corresponding to the first set modulation ratio and the second switching frequency correction coefficient corresponding to the second set modulation ratio are selected from the array DATA2.

[0115] Furthermore, in some embodiments, the second switching frequency correction coefficient may be determined in the following manner:

[0116]

[0117] In the above formula, C fswcoff represents the second switching frequency correction coefficient, DATA1[Index1] represents the first set modulation ratio, DATA2[Index1] represents the correction coefficient corresponding to the first set modulation ratio, DATA1[Index2] represents the second set modulation ratio, DATA2[Index2] represents the correction coefficient corresponding to the second set modulation ratio, and M represents the current modulation ratio.

[0118] In this embodiment, M can be used as an input of a binary table lookup to determine the first set modulation ratio and the second set modulation ratio in the array DATA1. After the first set modulation ratio and the second set modulation ratio are determined by the binary table lookup, a more accurate second switching frequency correction coefficient can be calculated by the above formula (6).

[0119] In the embodiment of the present application, by introducing a second switching frequency correction coefficient on the basis of the first switching frequency correction coefficient, an additional degree of freedom is provided for the frequency correction of the power device. This multi-level correction mechanism can more comprehensively consider various influencing factors, such as load changes, temperature fluctuations, etc., thereby achieving a more accurate correction of the switching frequency and further improving the accuracy of the calculation of the average loss.

[0120] After calculating the second switching frequency correction coefficient, the switching loss of the insulated gate bipolar transistor and the turn-off loss of the diode can be corrected by the following embodiments. First, in the development environment corresponding to the main control chip, C language can be used to encode according to the following logic, and after compilation, it can be burned into the main control chip, so that when the motor controller is in the overmodulation area, the average loss of the power device can be corrected in real time.

[0121] The correction method for switching loss of insulated gate bipolar transistor is as follows:

[0122] 1. Obtain the turn-on energy and turn-off energy of the insulated gate bipolar transistor in the power device.

[0123] 2. Since the switching frequency of the power device in the overmodulation area is set to the SVPWM modulation frequency, the SVPWM modulation frequency is directly corrected using the second switching frequency correction coefficient, and then the corrected SVPWM modulation frequency is used as the actual switching frequency of the power device in the overmodulation area.

[0124] Exemplarily, the specific calculation formula is as follows:

[0125]

[0126] In the above formula, P IGBT_AvgSW is the corrected insulated gate bipolar transistor switching loss, E on is the conduction energy of the insulated gate bipolar transistor, E off is the turn-off energy of the insulated gate bipolar transistor, f sw is the switching frequency, C fswcoff is the second switching frequency correction coefficient.

[0127] The diode turn-off loss correction method is as follows:

[0128] 1. Obtain the diode turn-off energy of the power device.

[0129] 2. According to the diode turn-off energy and the above-mentioned corrected SVPWM modulation frequency, the diode turn-off loss is corrected.

[0130] Exemplarily, the specific calculation formula is as follows:

[0131]

[0132] In the above formula, P Diode_AvgSW is the corrected diode turn-off loss E rr is the diode turn-off energy, f sw is the switching frequency, C fswcoff is the second switching frequency correction coefficient.

[0133] After obtaining the above-mentioned corrected IGBT switching loss and corrected diode turn-off loss, the final average loss is calculated by combining the diode conduction loss and IGBT conduction loss mentioned above.

[0134] In an embodiment of the present application, by correcting the switching loss of the insulated gate bipolar transistor and the turn-off loss of the diode, and then calculating the average loss of the power device based on the corrected data, the junction temperature of the motor controller can be estimated in the overmodulation area, which is closer to the actual junction temperature. At the same time, it can avoid false alarms of excessive junction temperature, which causes the motor controller to limit the output power; finally, the switching frequency of the power device in the overmodulation area can be increased, the current control effect can be improved, and the noise, vibration, and harshness (NVH) noise can be reduced.

[0135] The following is an embodiment of the device of the present application, which can be used to execute the embodiment of the method of the present application. For details not disclosed in the embodiment of the device of the present application, please refer to the embodiment of the method of the present application.

[0136] Figure 6 This is a schematic diagram of the structure of the average loss determination device provided in the embodiment of the present application. Figure 6 As shown, the average loss determination device 600 includes a first coefficient acquisition module 610 , a second coefficient acquisition module 620 , a loss correction module 630 , a loss acquisition module 640 and an average loss determination module 650 .

[0137] The first coefficient acquisition module 610 is used to acquire the first switching frequency correction coefficient corresponding to each set modulation ratio. The set modulation ratio is greater than or equal to 1, and the first switching frequency correction coefficient is determined by the duty cycle output by the power device in the overmodulation region under the set modulation ratio.

[0138] The second coefficient acquisition module 620 is used to determine the second switching frequency correction coefficient according to the current modulation ratio of the power device and the first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio.

[0139] The loss correction module 630 is used to correct the switching loss of the insulated gate bipolar transistor and the turn-off loss of the diode of the power device according to the second switching frequency correction coefficient.

[0140] The loss acquisition module 640 is used to acquire the conduction loss of the insulated gate bipolar transistor and the conduction loss of the diode of the power device.

[0141] The average loss determination module 650 is used to determine the average loss of the power device according to the IGBT conduction loss, the diode conduction loss, the corrected IGBT switching loss and the corrected diode turn-off loss.

[0142] In an example, the first coefficient acquisition module may be specifically used for:

[0143] Obtaining the duty cycle output by the power device in the overmodulation region at each set modulation ratio;

[0144] Determining the number of target duty cycles that meet set conditions among the output duty cycles;

[0145] According to the number of target duty cycles, a first switching frequency correction coefficient corresponding to each set modulation ratio is determined.

[0146] In an example, the first coefficient acquisition module may be specifically used for:

[0147] Get the initial value of the modulation ratio, the first step length and the current frequency after initialization. The initial value of the modulation ratio is greater than or equal to 1.

[0148] According to the initial value of the modulation ratio and the first step length, N set modulation ratios are determined, the last set modulation ratio is the difference between the next set modulation ratio and the first step length, and N is a positive integer;

[0149] According to the current frequency, the simulation step size and simulation time of the simulation model are determined;

[0150] Taking the current frequency and the Nth set modulation ratio as the input of the simulation model, starting the simulation model to simulate according to the simulation step size and simulation time, and outputting the duty cycle under the Nth set modulation ratio;

[0151] When the value of the Nth set modulation ratio is less than the set threshold, the current frequency and the N+1th set modulation ratio continue to be used as inputs to the simulation model to obtain the duty cycle under the N+1th set modulation ratio, until the value of the set modulation ratio input into the simulation model is equal to the set threshold, and the duty cycle output by the power device under each set modulation ratio is obtained.

[0152] In an example, the first coefficient acquisition module may be specifically configured to calculate the first switching frequency correction coefficient using the following formula:

[0153] Coff=(1–T / X)

[0154] In the above formula, Coff represents the first switching frequency correction coefficient, T represents the number of target duty cycles, and X is a constant.

[0155] In one example, the second coefficient acquisition module may be specifically used for:

[0156] According to the current modulation ratio, determining a first set modulation ratio and a second set modulation ratio in the set modulation ratio;

[0157] Determine, according to the first switching frequency correction coefficient corresponding to each set modulation ratio, a correction coefficient corresponding to the first set modulation ratio and a correction coefficient corresponding to the second set modulation ratio;

[0158] The second switching frequency correction coefficient is determined according to the correction coefficient corresponding to the first set modulation ratio, the correction coefficient corresponding to the second set modulation ratio, the current modulation ratio, the first set modulation ratio, and the second set modulation ratio.

[0159] In an example, the second coefficient acquisition module may be specifically configured to calculate the second switching frequency correction coefficient using the following formula:

[0160]

[0161] In the above formula, C fswcoff represents the second switching frequency correction coefficient, DATA1[Index1] represents the first set modulation ratio, DATA2[Index1] represents the correction coefficient corresponding to the first set modulation ratio, DATA1[Index2] represents the second set modulation ratio, DATA2[Index2] represents the correction coefficient corresponding to the second set modulation ratio, and M represents the current modulation ratio.

[0162] In one example, the loss correction module may be specifically used to:

[0163] According to the second switching frequency correction coefficient, the switching frequency of the power device is corrected, and the switching frequency is the space vector pulse width modulation frequency;

[0164] The switching loss of the insulated gate bipolar transistor of the power device is corrected according to the turn-on energy of the insulated gate bipolar transistor, the turn-off energy of the insulated gate bipolar transistor and the corrected switching frequency in the power device.

[0165] In one example, the loss correction module can be specifically used to calculate the corrected insulated gate bipolar transistor switching loss through the following formula:

[0166]

[0167] In the above formula, P IGBT_AvgSW is the corrected insulated gate bipolar transistor switching loss, E on is the conduction energy of the insulated gate bipolar transistor, E off is the turn-off energy of the insulated gate bipolar transistor, f sw is the switching frequency, C fswcoff is the second switching frequency correction coefficient.

[0168] In an example, the loss correction module may be specifically used to correct the diode turn-off loss according to the diode turn-off energy of the power device and the corrected switching frequency.

[0169] In one example, the loss correction module can be specifically used to calculate the corrected diode turn-off loss through the following formula:

[0170]

[0171] In the above formula, P Diode_AvgSW is the corrected diode turn-off loss, E rr is the diode turn-off energy, f sw is the switching frequency, C fswcoff is the second switching frequency correction coefficient.

[0172] The device provided in the embodiment of the present application can be used to execute the method in the above-mentioned embodiment. Its implementation principle and technical effect are similar and will not be repeated here.

[0173] It should be noted that it should be understood that the division of the various modules of the above device is only a division of logical functions. In actual implementation, they can be fully or partially integrated into one physical entity, or they can be physically separated. And these modules can all be implemented in the form of software calling through processing elements; they can also be all implemented in the form of hardware; some modules can also be implemented in the form of software calling through processing elements, and some modules can be implemented in the form of hardware. For example, the first coefficient acquisition module can be a separately established processing element, or it can be integrated in a chip of the above device. In addition, it can also be stored in the memory of the above device in the form of program code, and called and executed by a processing element of the above device. The implementation of other modules is similar. In addition, these modules can be fully or partially integrated together, or they can be implemented independently. The processing element here can be an integrated circuit with signal processing capabilities. In the implementation process, each step of the above method or each module above can be completed by an integrated logic circuit of hardware in the processor element or instructions in the form of software.

[0174] Figure 7 The hardware structure diagram of the electronic device provided in the embodiment of the present application is as follows: The electronic device 700 may include a processor 701 and a memory 702 storing computer program instructions.

[0175] Specifically, the processor 701 may include a central processing unit (CPU), or an application specific integrated circuit (ASIC), or may be configured to implement one or more integrated circuits of the embodiment of the present invention.

[0176] The memory 702 may include a large capacity memory for data or instructions. By way of example and not limitation, the memory 702 may include a hard disk drive (HDD), a floppy disk drive, a flash memory, an optical disk, a magneto-optical disk, a magnetic tape, or a universal serial bus (USB) drive or a combination of two or more of these. In one example, the memory 702 may include a removable or non-removable (or fixed) medium, or the memory 702 is a non-volatile solid-state memory. The memory 702 may be inside or outside the integrated gateway disaster recovery device.

[0177] In one example, the memory 702 may be a read-only memory (ROM). In one example, the ROM may be a mask-programmed ROM, a programmable ROM (PROM), an erasable PROM (EPROM), an electrically erasable PROM (EEPROM), an electrically rewritable ROM (EAROM), or a flash memory, or a combination of two or more of these.

[0178] The memory 702 may include a read-only memory (ROM), a random access memory (RAM), a magnetic disk storage medium device, an optical storage medium device, a flash memory device, an electrical, optical or other physical / tangible memory storage device. Thus, in general, the memory includes one or more tangible (non-transitory) computer-readable storage media (e.g., a memory device) encoded with software including computer-executable instructions, and when the software is executed (e.g., by one or more processors), it is operable to perform the operations described with reference to the method according to an aspect of the present disclosure.

[0179] The processor 701 implements the method in the above embodiment by reading and executing the computer program instructions stored in the memory 702 .

[0180] In one example, the electronic device may further include a communication interface 703 and a bus 704. Figure 7 As shown, the processor 701, the memory 702, and the communication interface 703 are connected via a bus 704 and communicate with each other.

[0181] The communication interface 703 is mainly used to implement the communication between the modules, devices, units and / or equipment in the embodiment of the present invention.

[0182] Bus 704 includes hardware, software or both, and the components of online data flow billing equipment are coupled to each other. For example, but not limitation, the bus may include Accelerated Graphics Port (AGP) or other graphics bus, Enhanced Industry Standard Architecture (EISA) bus, Front Side Bus (FSB), Hyper Transport (HT) interconnection, Industry Standard Architecture (ISA) bus, InfiniBand interconnection, Low Pin Count (LPC) bus, Memory bus, Micro Channel Architecture (MCA) bus, Peripheral Component Interconnect (PCI) bus, PCI-Express (PCI-X) bus, Serial Advanced Technology Attachment (SATA) bus, Video Electronics Standards Association Local (VLB) bus or other suitable bus or two or more of these combinations. In appropriate cases, bus 704 may include one or more buses. Although the embodiments of the present invention describe and illustrate specific buses, the present invention considers any suitable bus or interconnection.

[0183] In addition, in combination with the method in the above embodiment, the embodiment of the present invention can provide a computer storage medium for implementation. The computer storage medium stores computer program instructions; when the computer program instructions are executed by a processor, any one of the methods in the above embodiment is implemented.

[0184] An embodiment of the present application also provides a computer program product, including a computer program, which implements any one of the methods in the above embodiments when the computer program is processed and executed.

[0185] The embodiment of the present application also provides a motor controller, which may be a three-phase two-level motor controller. The motor controller includes at least: a processing chip and a power device, the processing chip may refer to a main control chip in the motor controller, and the processing chip is used to execute the above method to determine the average loss of the power device in the motor controller.

[0186] It should be clear that the present invention is not limited to the specific configuration and processing described above and shown in the figures. For the sake of simplicity, a detailed description of the known method is omitted here. In the above embodiments, several specific steps are described and shown as examples. However, the method process of the present invention is not limited to the specific steps described and shown, and those skilled in the art can make various changes, modifications and additions, or change the order between the steps after understanding the spirit of the present invention.

[0187] The functional blocks shown in the above structural block diagram can be implemented as hardware, software, firmware or a combination thereof. When implemented in hardware, it can be, for example, an electronic circuit, an application specific integrated circuit (Application Specific Integrated Circuit, ASIC), appropriate firmware, plug-in, function card, etc. When implemented in software, the elements of the present invention are programs or code segments used to perform the required tasks. The program or code segment can be stored in a machine-readable medium, or transmitted on a transmission medium or communication link by a data signal carried in a carrier. "Machine-readable medium" can include any medium capable of storing or transmitting information. Examples of machine-readable media include electronic circuits, semiconductor memory devices, read-only memory (Read-Only Memory, ROM), flash memory, erasable read-only memory (Erasable ReadOnly Memory, EROM), floppy disks, compact disc read-only memory (Compact Disc Read-Only Memory, CD-ROM), optical discs, hard disks, optical fiber media, radio frequency (Radio Frequency, RF) links, etc. The code segment can be downloaded via a computer network such as the Internet, an intranet, etc.

[0188] It should also be noted that the exemplary embodiments mentioned in the present invention describe some methods or systems based on a series of steps or devices. However, the present invention is not limited to the order of the above steps, that is, the steps can be performed in the order mentioned in the embodiments, or in a different order from the embodiments, or several steps can be performed simultaneously.

[0189] Aspects of the present disclosure are described above with reference to the flowchart and / or block diagram of the method, device (system) and computer program product according to the embodiment of the present disclosure. It should be understood that each box in the flowchart and / or block diagram and the combination of each box in the flowchart and / or block diagram can be implemented by computer program instructions. These computer program instructions can be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device to produce a machine so that these instructions executed by the processor of the computer or other programmable data processing device enable the implementation of the function / action specified in one or more boxes of the flowchart and / or block diagram. Such a processor can be, but is not limited to, a general-purpose processor, a special-purpose processor, a special application processor, or a field programmable logic circuit. It can also be understood that each box in the block diagram and / or flowchart and the combination of boxes in the block diagram and / or flowchart can also be implemented by dedicated hardware that performs a specified function or action, or can be implemented by a combination of dedicated hardware and computer instructions.

[0190] The above is only a specific implementation of the present invention. Those skilled in the art can clearly understand that for the convenience and simplicity of description, the specific working process of the system, module and unit described above can refer to the corresponding process in the aforementioned method embodiment, and will not be repeated here. It should be understood that the protection scope of the present invention is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed by the present invention, and these modifications or replacements should be covered within the protection scope of the present invention.

Claims

1. A method for determining average loss, characterized in that: include: Obtaining a first switching frequency correction coefficient corresponding to each set modulation ratio, wherein the set modulation ratio is greater than or equal to 1, and the first switching frequency correction coefficient is determined by a duty cycle output by a power device in an overmodulation region under the set modulation ratio; Determine a second switching frequency correction coefficient according to a current modulation ratio of the power device and a first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio; According to the second switching frequency correction coefficient, correcting the insulated gate bipolar transistor switching loss and the diode turn-off loss of the power device; Obtaining the insulated gate bipolar transistor conduction loss and the diode conduction loss of the power device; The average loss of the power device is determined based on the IGBT conduction loss, the diode conduction loss, the corrected IGBT switching loss and the corrected diode turn-off loss.

2. The method according to claim 1, characterized in that The obtaining of the first switching frequency correction coefficient corresponding to each set modulation ratio includes: Obtaining a duty cycle output by the power device in the overmodulation region at each set modulation ratio; Determining the number of target duty cycles that meet set conditions among the output duty cycles; According to the number of the target duty cycles, a first switching frequency correction coefficient corresponding to each set modulation ratio is determined.

3. The method according to claim 2, characterized in that The obtaining of the duty cycle output by the power device in the overmodulation region at each set modulation ratio comprises: Obtaining an initial value of the modulation ratio, a first step length, and an initialized current frequency, wherein the initial value of the modulation ratio is greater than or equal to 1, Determine N set modulation ratios according to the initial value of the modulation ratio and the first step length, where the last set modulation ratio is the difference between the next set modulation ratio and the first step length, and N is a positive integer; Determining the simulation step size and simulation time of the simulation model according to the current frequency; Taking the current frequency and the Nth set modulation ratio as inputs of the simulation model, starting the simulation model to perform simulation according to the simulation step size and simulation time, and outputting the duty cycle under the Nth set modulation ratio; When the value of the Nth set modulation ratio is less than the set threshold, continue to use the current frequency and the N+1th set modulation ratio as inputs to the simulation model to obtain the duty cycle at the N+1th set modulation ratio, until the value of the set modulation ratio input into the simulation model is equal to the set threshold, and then obtain the duty cycle output by the power device at each set modulation ratio.

4. The method according to claim 2, characterized in that: Determining the first switching frequency correction coefficient corresponding to each set modulation ratio according to the number of the target duty cycles includes: Coff=(1–T / X) In the above formula, Coff represents the first switching frequency correction coefficient, T represents the number of the target duty cycles, and X is a constant.

5. The method according to claim 1, characterized in that The determining the second switching frequency correction coefficient according to the current modulation ratio of the power device and the first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio includes: According to the current modulation ratio, determining a first set modulation ratio and a second set modulation ratio from the set modulation ratios; According to the first switching frequency correction coefficient corresponding to each set modulation ratio, determining the correction coefficient corresponding to the first set modulation ratio and the correction coefficient corresponding to the second set modulation ratio; The second switching frequency correction coefficient is determined according to the correction coefficient corresponding to the first set modulation ratio, the correction coefficient corresponding to the second set modulation ratio, the current modulation ratio, the first set modulation ratio and the second set modulation ratio.

6. The method according to claim 5, characterized in that The determining of the second switching frequency correction coefficient according to the correction coefficient corresponding to the first set modulation ratio, the correction coefficient corresponding to the second set modulation ratio, the current modulation ratio, the first set modulation ratio and the second set modulation ratio includes: In the above formula, C fswcoff represents the second switching frequency correction coefficient, DATA1[Index1] represents the first set modulation ratio, DATA2Index1 represents the correction coefficient corresponding to the first set modulation ratio, DATA1Index2 represents the second set modulation ratio, DATA2Index2 represents the correction coefficient corresponding to the second set modulation ratio, and M represents the current modulation ratio.

7. The method according to claim 1, characterized in that The step of correcting the switching loss of the insulated gate bipolar transistor of the power device according to the second switching frequency correction coefficient includes: According to the second switching frequency correction coefficient, the switching frequency of the power device is corrected, the switching frequency being a space vector pulse width modulation frequency; The switching loss of the insulated gate bipolar transistor of the power device is corrected according to the turn-on energy of the insulated gate bipolar transistor, the turn-off energy of the insulated gate bipolar transistor and the corrected switching frequency in the power device.

8. The method according to claim 7, characterized in that The method of correcting the switching loss of the insulated gate bipolar transistor of the power device according to the turn-on energy of the insulated gate bipolar transistor, the turn-off energy of the insulated gate bipolar transistor and the corrected switching frequency in the power device comprises: In the above formula, P IGBT_AvgSW is the corrected insulated gate bipolar transistor switching loss, E on is the conduction energy of the insulated gate bipolar transistor, E off is the turn-off energy of the insulated gate bipolar transistor, f sw is the switching frequency, C fswcoff is the second switching frequency correction coefficient.

9. The method according to claim 7, characterized in that: Correcting the diode turn-off loss of the power device according to the second switching frequency correction coefficient includes: The diode turn-off loss is corrected according to the diode turn-off energy of the power device and the corrected switching frequency.

10. The method according to claim 9, characterized in that The step of correcting the diode turn-off loss according to the diode turn-off energy of the power device and the corrected switching frequency includes: In the above formula, P Diode_AvgSW is the corrected diode turn-off loss, E rr is the diode turn-off energy, f sw is the switching frequency, C fswcoff is the second switching frequency correction coefficient.

11. An average loss determination device, characterized in that: include: A first coefficient acquisition module, used to acquire a first switching frequency correction coefficient corresponding to each set modulation ratio, the set modulation ratio is greater than or equal to 1, and the first switching frequency correction coefficient is determined by the duty cycle output by the power device in the overmodulation region under the set modulation ratio; A second coefficient acquisition module, used to determine a second switching frequency correction coefficient according to a current modulation ratio of the power device and a first switching frequency correction coefficient corresponding to the switching frequency of the power device under each set modulation ratio; A loss correction module, used to correct the insulated gate bipolar transistor switching loss and diode turn-off loss of the power device according to the second switching frequency correction coefficient; A loss acquisition module, used to acquire the conduction loss of the insulated gate bipolar transistor and the conduction loss of the diode of the power device; The average loss determination module is used to determine the average loss of the power device according to the conduction loss of the insulated gate bipolar transistor, the conduction loss of the diode, the corrected switching loss of the insulated gate bipolar transistor and the corrected turn-off loss of the diode.

12. A motor controller, characterized in that: The motor controller comprises at least: a processing chip and a power device, wherein the processing chip is used to execute the method according to any one of claims 1 to 10 to determine the average loss of the power device.

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