Method for monitoring loss of power module, smart device, and medium

Abstract

The present application provides a method for monitoring the loss of a power module, a smart device, and a medium, the method comprising: on the basis of a loss algorithm under an SPWM control signal, determining an initial loss of a power module under ideal conditions; and, on the basis of a preset loss association, using the initial loss to determine, under an actual control signal, an actual loss of the power module under the ideal conditions. In this way, when the power module is controlled by an SVPWM control signal or a DPWM control signal, during determination of the actual loss of the power module under the ideal conditions, the amount of calculation is small, the calculation result is relatively accurate, the memory consumption is low, and real-time loss calculation can be easily performed in an embedded device.

Description

Power module loss monitoring method, intelligent device and medium

[0001] This application claims priority to Chinese patent application 202311770135.1 filed on December 20, 2023, entitled “Method, intelligent device and medium for monitoring power module loss”. The entire contents of the above Chinese patent application are incorporated into this application by reference. Technical Field

[0002] The present application relates to the field of power electronics technology, and specifically provides a method, intelligent device, and medium for monitoring power module loss. Background Art

[0003] Accurate calculation of power module losses within the inverter is an important prerequisite for junction temperature estimation, input power estimation, bus current estimation, and even torque estimation.

[0004] Different pulse width modulation (PWM) control strategies can be adopted depending on the inverter application, controlled object, and control objective. Common PWM control strategies include sinusoidal pulse width modulation (SPWM), space vector pulse width modulation (SVPWM), and discrete pulse width modulation (DPWM). SPWM, because its modulation wave consists only of the fundamental wave and is symmetrical, is simple and convenient to calculate losses. It is suitable for embedded real-time calculations and does not require significant computing power or memory, making it widely used in the industry. However, due to the limitations of SPWM's modulation method, its DC side voltage utilization is low. SVPWM / DPWM is the most widely used in the industry, allowing for a certain range of overmodulation, improving DC side voltage utilization. DPWM, due to its discontinuous clamping state in one-third of its output phase voltage, has lower losses than SVPWM, making it more suitable for high-power / ultra-high-power inverter equipment.

[0005] However, since the modulation waves of SVPWM and DPWM contain complex harmonic components, the loss calculation of the power module is cumbersome and complex, and the memory consumption is high, making them unsuitable for real-time calculation in embedded devices.

[0006] Summary of the Invention

[0007] In order to overcome the above-mentioned defects, the present application is proposed to provide a power module loss monitoring method, intelligent device and medium that solve or at least partially solve the technical problem of complex loss calculation of power modules under SVPWM and DPWM control.

[0008] In a first aspect, the present application provides a method for monitoring power module loss, the method comprising:

[0009] Determining the initial loss of the power module under ideal conditions based on a loss algorithm under an SPWM control signal; the ideal conditions include the SPWM control signal being a symmetrical signal and / or the fundamental frequency of the phase voltage being always greater than a preset frequency;

[0010] Based on a preset loss correlation relationship, the initial loss is used to determine the actual loss of the power module under the ideal conditions under the actual control signal; the loss correlation relationship is the loss correlation relationship between different control signals and the SPWM control signal.

[0011] Furthermore, in the above-mentioned method for monitoring power module loss, if the actual control signal is a DPWM control signal, the loss association relationship includes correcting the initial loss;

[0012] Based on a preset loss correlation relationship and using the initial loss, determining the actual loss of the power module under the ideal conditions under the actual control signal includes:

[0013] Based on a preset loss correction strategy, the initial loss is corrected to obtain the actual loss.

[0014] Furthermore, in the above-mentioned method for monitoring power module loss, based on a preset loss correction strategy, the initial loss is corrected to obtain the actual loss, including:

[0015] If the initial loss includes an initial conduction loss, the initial conduction loss is corrected based on a first correction coefficient to obtain an actual conduction loss in the actual loss; wherein the first correction coefficient is determined based on a modulation ratio of the power module and a power angle factor of the power module;

[0016] If the initial loss includes initial switching loss, the initial switching loss is corrected based on a second correction coefficient to obtain actual switching loss in the actual loss; wherein the second correction coefficient is determined based on the power angle factor.

[0017] Furthermore, in the above-mentioned method for monitoring power module loss, the first correction coefficient is determined based on the modulation ratio of the power module and the power angle factor of the power module, including:

[0018] If the power angle factor of the power module is less than the power angle threshold, it is determined that the first correction coefficient decreases as the modulation ratio increases; and when the modulation ratio is less than the modulation ratio threshold, the first correction coefficient is greater than 1; when the modulation ratio is greater than the modulation ratio threshold, the first correction coefficient is less than 1; when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

[0019] Furthermore, in the above-mentioned method for monitoring power module loss, the first correction coefficient is determined based on the modulation ratio of the power module and the power angle factor of the power module, including:

[0020] If the power angle factor of the power module is greater than the power angle threshold, it is determined that the first correction coefficient increases with the increase of the modulation ratio; and when the modulation ratio is less than the modulation ratio threshold, the first correction coefficient is less than 1; when the modulation ratio is greater than the modulation ratio threshold, the first correction coefficient is greater than 1; when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

[0021] Furthermore, in the above-mentioned method for monitoring power module loss, the second correction coefficient is determined based on the power angle factor, including:

[0022] The second correction coefficient is determined based on 1 and a cosine value of the power angle factor at a preset multiple.

[0023] Furthermore, in the above-mentioned method for monitoring power module loss, if the actual control signal is an SVPWM control signal, the loss association relationship includes not correcting the initial loss;

[0024] Based on a preset loss correlation relationship and using the initial loss, determining the actual loss of the power module under the ideal conditions under the actual control signal includes:

[0025] The initial loss is taken as the actual loss.

[0026] Furthermore, in the above-mentioned method for monitoring power module loss, before determining the initial loss of the power module under ideal conditions based on the loss algorithm under the SPWM control signal, the method further includes:

[0027] The loss algorithm is determined based on the type of power devices in the power module.

[0028] In a second aspect, the present application provides an intelligent device, which includes a processor and a storage device, wherein the storage device is suitable for storing multiple program codes, and the program codes are suitable for being loaded and run by the processor to execute any of the target detection methods described above.

[0029] In a third aspect, a computer-readable storage medium is provided, wherein the computer-readable storage medium stores a plurality of program codes, wherein the program codes are suitable for being loaded and run by a processor to execute any one of the target detection methods described above.

[0030] The above one or more technical solutions of this application have at least one or more of the following beneficial effects:

[0031] In the technical solution implementing the present application, the initial loss of the power module under ideal conditions is determined based on a loss algorithm under SPWM control signals. Based on the loss correlation between different control signals and the SPWM control signal, the initial loss is used to determine the actual loss of the power module under the ideal conditions under the actual control signal. Thus, when the power module is controlled by an SVPWM control signal or a DPWM control signal, the actual loss of the power module under ideal conditions is determined with minimal computational effort, relatively accurate results, and minimal memory consumption, making it easy to perform real-time loss calculations in embedded devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The disclosure of this application will be more easily understood with reference to the accompanying drawings. Those skilled in the art will readily appreciate that these drawings are for illustrative purposes only and are not intended to limit the scope of protection of this application. Furthermore, similar numbers in the figures represent similar components, where:

[0033] Figure 1 is a schematic diagram showing the relationship between the on-resistance and current of a SIC-based MOSFET at different junction temperatures;

[0034] FIG2 is a schematic flow chart of the main steps of a target detection method according to an embodiment of the present application;

[0035] Figure 3 is a waveform diagram of the duty cycle function of SPWM, SVPWM, and DPWM at different power factor angles phi and different modulation ratios m;

[0036] FIG4 is a schematic diagram showing the conduction loss of a power module under the control of an SVPWM control signal and an SPWM control signal at different modulation ratios under the same power factor angle;

[0037] FIG5 is a schematic diagram showing the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio;

[0038] FIG6 is a schematic diagram showing the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different modulation ratios under the same power factor angle;

[0039] FIG7 is a schematic diagram showing the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio;

[0040] FIG8 is a schematic diagram showing the switching loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio;

[0041] FIG9 is a schematic diagram showing the switching losses of a power module under the control of a DPWM control signal and an SPWM control signal for power factor correction at different power factor angles under the same modulation ratio;

[0042] FIG10 is a main structural block diagram of a smart device according to an embodiment of the present application. DETAILED DESCRIPTION

[0043] Some embodiments of the present application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are only used to explain the technical principles of the present application and are not intended to limit the scope of protection of the present application.

[0044] In the description of this application, "module" and "processor" may include hardware, software, or a combination of both. A module may include hardware circuitry, various suitable sensors, communication ports, and memory. It may also include software components, such as program code, or a combination of software and hardware. A processor may be a central processing unit, a microprocessor, an image processor, a digital signal processor, or any other suitable processor. A processor has data and / or signal processing capabilities. A processor may be implemented in software, hardware, or a combination of both. Non-transitory computer-readable storage media include any suitable medium capable of storing program code, such as magnetic disks, hard disks, optical disks, flash memory, read-only memory, random access memory, etc. The term "A and / or B" refers to all possible combinations of A and B, such as only A, only B, or both A and B. The terms "at least one of A or B" or "at least one of A and B" have similar meanings to "A and / or B" and may include only A, only B, or both A and B. The singular forms "a" and "the" may also include the plural forms.

[0045] Power modules include IGBTs, SiCs, and GaN devices. Regardless of the type of power device, power conversion electronics like inverters generate conduction and switching losses during operation. Different power device types have different distributions of conduction and switching losses across the switching device and its parallel diode. This is primarily reflected in the differences between silicon-based IGBTs and SiC-based MOSFETs.

[0046] For SIC-based MOSFET modules, taking a certain phase of the SIC power device as an example, when a positive current is applied, the upper bridge MOSFET performs a switching action. When the upper bridge MOSFET is turned on, current flows through the MOSFET wafer. Due to the conduction voltage drop of the MOSFET wafer, conduction loss is generated. When the upper bridge MOSFET is turned off, current flows through the lower bridge MOSFET wafer, rather than the lower bridge diode Diode, resulting in conduction loss. This is the main difference between MOSFET and IGBT. The same applies to applying a negative current. During the switching process of the MOSFET wafer, corresponding switching losses are generated.

[0047] For a silicon-based IGBT, taking a single IGBT phase as an example, when a forward current is applied, the upper IGBT switches. When the upper IGBT is turned on, current flows through the IGBT wafer, generating conduction losses due to the on-state voltage drop across the IGBT wafer. When the upper IGBT is turned off, current flows through the lower diode wafer, generating conduction losses due to the on-state voltage drop across the diode wafer. The same applies when a negative current is applied. During the switching process of the IGBT wafer or diode wafer, corresponding switching losses are generated.

[0048] When using SPWM control signals to control power modules, the modulation wave of the SPWM control signal only contains the fundamental wave and is symmetrical. Therefore, the loss calculation is simple and convenient, and it is easy to use for embedded real-time calculation. It does not require a lot of computing power and memory, and is widely used in the industry.

[0049] Specifically, the average conduction loss of a half-bridge of the SIC-based MOSFET under the control of the SPWM control signal is calculated as follows:

[0050] Since MOSFET conducts current in both positive and negative current cycles, the conduction loss is calculated as follows:

[0051] For SIC-based MOSFET, the voltage and current curves between the DS poles pass through the zero point, and there is no initial turn-on voltage value, that is, the following calculation formula (2) is used:

[0052] However, the on-resistance of a SIC-based MOSFET is a current- and temperature-sensitive value. The relationship between the on-resistance of a SIC-based MOSFET and the current flowing through it at different junction temperatures is shown in Figure 1. Figure 1 is a schematic diagram of the relationship between the on-resistance of a SIC-based MOSFET and the current at different junction temperatures. As shown in Figure 1, it can be approximately considered that the on-resistance and current are linear: r Mos=k*I+b, where k and b are fixed values ​​for the on-resistance property parameters of the SiC-based MOSFET at a certain junction temperature. Line a1 in Figure 1 shows the actual curve of the on-resistance versus current at a junction temperature of 175°C. Line a2 in Figure 1 shows the fitted curve of the on-resistance versus current at a junction temperature of 175°C. Line b1 in Figure 1 shows the actual curve of the on-resistance versus current at a junction temperature of 125°C. Line b2 in Figure 1 shows the fitted curve of the on-resistance versus current at a junction temperature of 125°C. Line c1 in Figure 1 shows the actual curve of the on-resistance versus current at a junction temperature of 25°C. Line c2 in Figure 1 shows the fitted curve of the on-resistance versus current at a junction temperature of 25°C.

[0053] It should be noted that the y in the relationship between the curves in the figure and the aforementioned r Mos They have the same meaning and both represent on-resistance. x and I have the same meaning and both represent current.

[0054] The duty cycle function of SPWM can be calculated as formula (3)

[0055] The MOSFET body diode conduction losses only during the dead time. During this period, the MOSFET body diode performs the freewheeling function. After the dead time, the MOSFET turns on, and the current switches to the MOSFET channel. Because the MOSFET dead time is extremely small, the diode conduction losses can be ignored.

[0056] According to the above calculation formulas (2) and (3), the calculation formula (1) is integrated to obtain the calculation formula (4) for the conduction loss of the SIC-based MOSFET:

[0057] The conduction loss of the diode is calculated as formula (5): loss,diode,cond ≈0 (5)

[0058] Under the control of the SPWM control signal, the average switching loss of a half-bridge of the SIC-based MOSFET is calculated as follows:

[0059] Switching loss refers to the energy loss generated when MOSFET is turned on and off. Although MOSFET can conduct in both directions, it does not generate switching loss during the natural commutation process. That is, the average switching loss of MOSFET is the same as the average switching loss of MOSFET wafer under SPWM control signal. Therefore, the switching loss of MOSFET is calculated as follows:

[0060] The diode switching loss is calculated as follows:

[0061] Ploss,diode,swi ≈0 (7)

[0062] Among them, P loss,Mos,cond is the conduction loss of a half-bridge MOSFET wafer, P loss,diode,cond is the conduction loss of a half-bridge diode wafer, I m is the peak current flowing through the MOSFET half bridge, r Mos is the on-resistance of the MOSFET wafer, φ is the power factor angle, that is, the angle between the voltage vector and the current vector, and m is the modulation ratio.

[0063] P loss,Mos,swi is the switching loss of a half-bridge MOSFET wafer, P loss,diode,swi is the switching loss of a half-bridge diode wafer, f PWM is the switching frequency, E on E is the energy consumed by the MOSFET wafer each time it is turned on under specific conditions. off U is the energy consumed by the MOSFET wafer each time it is turned off under specific conditions. ds is the actual voltage value between the DS poles of MOSFET, I n is the test current value given in the data sheet, U n This is the test voltage value given in the data sheet.

[0064] Taking a single three-phase SIC-based MOSFET inverter as an example, the total loss calculation formula (8) is as follows:

[0065] The above loss calculation method of the SIC-based MOSFET power module based on SPWM control signal control is simple, convenient, and easy to use for embedded real-time calculation without consuming a lot of computing power and memory.

[0066] Specifically, the average conduction loss of a half-bridge of a silicon-based IGBT under the control of the SPWM control signal is calculated as follows:

[0067] The calculation formula (9) of the IGBT conduction loss is as follows:

[0068] The calculation formula (10) for the conduction loss of the diode is as follows:

[0069] The calculation formula (11) of IGBT switching loss is as follows:

[0070] The switching loss of the diode is calculated as follows:

[0071] Among them, P loss,igbt,condis the conduction loss of a half-bridge IGBT wafer, P loss,diode,cond is the conduction loss of a half-bridge diode wafer, I m is the peak current flowing through the IGBT half bridge, V ce0 is the initial on-state voltage of the IGBT wafer, V f0 is the initial on-state voltage of the diode wafer, r igbt is the on-resistance of the IGBT wafer, r diode is the on-resistance of the diode wafer, φ is the power factor angle, that is, the angle between the voltage vector and the current vector, and m is the modulation ratio.

[0072] P loss,igbt,swi is the switching loss of a half-bridge IGBT wafer, P loss,diode,swi is the switching loss of a half-bridge diode wafer, f PWM is the switching frequency, E on E is the energy consumed by the IGBT wafer each time it is turned on under specific conditions. off E is the energy consumed by the IGBT wafer each time it is turned off under specific conditions. rec U is the energy consumed by the diode wafer for each rectification under specific conditions. ce is the actual voltage value between CE poles of IGBT, I n is the test current value given in the data sheet, U n This is the test voltage value given in the data sheet.

[0073] The above loss calculation method of the IGBT power module under the control of the SPWM control signal is simple, convenient, and easy to be embedded in real time, without consuming a lot of computing power and memory.

[0074] However, since the SPWM control signal is limited by the modulation method, the utilization rate of the DC side voltage is low. The most widely used in the industry is the SVPWM control signal / DPWM control signal, which can allow a certain range of overmodulation and improve the utilization rate of the DC side voltage. The DPWM control signal has a discontinuous clamping state in one-third of its output phase voltage, so its loss is lower than that of the SVPWM control signal, making it more suitable for high-power / ultra-high-power inverter equipment.

[0075] However, since the modulation waves of SVPWM control signals and DPWM control signals contain complex harmonic components, the loss calculation of the power module is cumbersome and complex, and the memory consumption is high, which is not suitable for accurate and real-time calculation in embedded devices.

[0076] Specifically, the conduction loss, switching loss, and total loss of the power module under the control of the SVPWM control signal and the DPWM control signal can be calculated by numerical calculation or analytical method. The following is an explanation of the numerical method calculation:

[0077] The numerical calculation method for the power module loss under SVPWM control is as follows:

[0078] The SVPWM modulation wave can be simplified into the form of fundamental wave plus third harmonic. The specific calculation formula (13) is as follows:

[0079] The numerical calculation of the conduction loss and switching loss of the power module under the control of the SVPWM control signal can refer to the following calculation program: %%matlab %a=w*t Freq=100; w=2*pi*Freq; delta_t=0.0001; delta_a=w*delta_t; a=0:delta_a:(2*pi-delta_a); I=Imax*sin(a); r_mos=k*I+b; Vds=r_mos*I; %SVPWM(Space Vector Pulse Width Modulation)duty; SVPWM=(1+m*(sin(a+phi)+3*sqrt(3) / 8 / pi*sin(3*(a+phi)))) / 2; %Conduction loss of SVPWM; Loss_CD_SVPWM_Mos=sum(I.*Vds.*SVPWM*delta_a.*(a>=0&a<2*pi)) / 2 / pi; Loss_CD_SVPWM_Diode=0; Loss_CD_SVPWM=6*(Loss_CD_SVPWM_Mos+Loss_CD_SVPWM_Diode); %half duty MOSFET switch, the other half commutate naturally; Loss_SW_SVPWM_Mos=sum(Imax*sin(a) / In*HvDc / Un*(E_total_Mos).*((a>=0 &a <pi))) / (2*pi / w); Loss_SW_SVPWM_Diode=0; Loss_SW_SVPWM=6*(Loss_SW_SVPWM_Mos+Loss_SW_SVPWM_Diode)。

[0080] The numerical calculation method for the loss of the power module under the control of the DPWM control signal is as follows:

[0081] There are six DPWM pattern types. The most commonly used one is DPWM1. Its modulation wave in one cycle can be represented by the piecewise function (14):

[0082] The numerical calculation of the conduction loss and switching loss of the power module under DPWM control can refer to the following calculation procedure:

[0083] Based on the above records, it can be seen that the SVPWM control signal and the DPWM control signal have complex harmonic components in their modulation waves, which makes the loss calculation of the power module cumbersome and complex, and consumes high memory, making them unsuitable for accurate and real-time calculation in embedded devices.

[0084] Therefore, in order to solve the above technical problems, this application provides the following technical solutions:

[0085] 2, which is a schematic flow chart of the main steps of a target detection method according to an embodiment of the present application. As shown in FIG2, the target detection method in the embodiment of the present application mainly includes the following steps 201-202.

[0086] Step 201: Determine the initial loss of the power module under ideal conditions based on a loss algorithm under an SPWM control signal;

[0087] In one specific implementation, the maximum modulation ratio of both the SVPWM control signal and the DPWM control signal can reach 1.1547. However, the maximum modulation ratio of the SPWM control signal can only reach 1. Since the calculation of power module losses under the SPWM control signal is relatively simple, the initial losses of the power module under ideal conditions can be determined based on the loss algorithm under the SPWM control signal described above. Specifically, when calculating the losses, a value m > 1 can be substituted into the loss algorithm under the SPWM control signal to obtain the initial losses of the power module under ideal conditions. However, the actual inverter control still uses the SVPWM / DPWM control signal. However, after the inverter conduction losses are calculated using the loss algorithm under the SPWM control signal, the relevant power factor angle φ and the modulation ratio m are adjusted or not adjusted based on the actual situation. Ideal conditions include the SPWM control signal being symmetrical and / or the fundamental frequency of the phase voltage being always greater than a preset frequency.

[0088] It should be noted that, based on the aforementioned description of the SIC-based MOSFET and the silicon-based IGBT, it can be seen that the loss algorithms of the two under the SPWM control signal are different. Therefore, before executing step 201, the loss algorithm can be determined based on the type of power device in the power module.

[0089] Step 202: Based on a preset loss correlation relationship, using the initial loss, determine the actual loss of the power module under the ideal conditions under the actual control signal; the loss correlation relationship is the loss correlation relationship between different control signals and the SPWM control signal.

[0090] In a specific implementation, under ideal conditions, a loss calculation can be performed according to the conventional algorithm for calculating the loss of the power module under the SVPWM control signal to obtain a first loss of the power module under the SVPWM control signal, and a loss calculation can be performed according to the conventional algorithm for calculating the loss of the power module under the DPWM control signal to obtain a second loss of the power module under the DPWM control signal. The first and second losses are then analyzed with the initial loss of the power module under ideal conditions to obtain a loss correlation between different control signals and the SPWM control signal. Thus, in subsequent calculations, after obtaining the initial loss of the power module under ideal conditions, the initial loss of the power module under ideal conditions can be corrected or not according to the loss correlation between different control signals and the SPWM control signal to obtain the actual loss of the power module under the ideal conditions under the actual control signal of the inverter.

[0091] The following is a detailed description of the process of obtaining the loss correlation relationship between different control signals and the SPWM control signal:

[0092] Specifically, FIG3 is a waveform diagram of the duty cycle function of SPWM, SVPWM, and DPWM at different power factor angles phi and different modulation ratios m.

[0093] Among them, (1) in Figure 3 is the waveform diagram corresponding to the duty cycle function of the SPWM control signal, SVPWM control signal, and DPWM control signal when the power factor angle φ = 0.1π and the modulation ratio m = 1. (2) in Figure 3 is the waveform diagram corresponding to the duty cycle function of the SPWM control signal, SVPWM control signal, and DPWM control signal when the power factor angle φ = 0.1π and the modulation ratio m = 1.1547. (3) in Figure 3 is the waveform diagram corresponding to the duty cycle function of the SPWM control signal, SVPWM control signal, and DPWM control signal when the power factor angle φ = 0.9π and the power factor m = 1. (4) in Figure 3 is the waveform diagram corresponding to the duty cycle function of the SPWM control signal, SVPWM control signal, and DPWM control signal when the power factor angle φ = 0.9π and the power factor m = 1.1547.

[0094] Based on the waveforms corresponding to the duty cycle functions of the above-mentioned SPWM control signal, SVPWM control signal, and DPWM control signal, the conduction losses of the power modules controlled by the SVPWM control signal and the SPWM control signal at different modulation ratios under the same power factor angle can be further obtained, as well as the conduction losses of the power modules controlled by the SVPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio.

[0095] Specifically, FIG4 is a schematic diagram of the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different modulation ratios under the same power factor angle. As shown in FIG4, FIG4 (1) is a comparison result of the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different modulation ratios when the power factor angle φ = 0.1π. FIG4 (2) is a comparison result of the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different modulation ratios when the power factor angle φ = 0.9π. As shown in FIG4, regardless of the modulation ratio, under ideal conditions, the difference between the actual conduction loss of the power module under the control of the SVPWM control signal and the initial conduction loss of the power module under the control of the SPWM control signal is small, so the two can be approximately equal.

[0096] FIG5 is a schematic diagram of the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio. As shown in FIG5, FIG5 (1) is a comparison result of the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m=1. FIG5 (2) is a comparison result of the conduction loss of the power module under the control of the SVPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m=1.1547. As shown in FIG5, regardless of the power factor angle, under ideal conditions, the difference between the actual conduction loss of the power module under the control of the SVPWM control signal and the initial conduction loss of the power module under the control of the SPWM control signal is small, so the two can be approximately equal.

[0097] Therefore, it can be approximately considered that the conduction loss of the power module under the SVPWM control signal is equal to the conduction loss of the power module under the SPWM control signal. This is applicable to any modulation ratio and any power factor angle without losing calculation accuracy.

[0098] In addition, compared with the power module under the SPWM control signal, the power module under the SVPWM control signal does not change the phase current and the switching times are the same, so the switching loss of the power module under the SVPWM control signal is equal to the switching loss of the power module under the SPWM control signal.

[0099] Based on this, the loss correlation relationship between the SVPWM control signal and the SPWM control signal can be obtained as follows: no correction is made to the initial loss.

[0100] Similarly, based on the waveforms corresponding to the duty cycle functions of the above-mentioned SPWM control signal, SVPWM control signal, and DPWM control signal, we can further obtain the conduction losses of the power module under the control of the DPWM control signal and the SPWM control signal at different modulation ratios under the same power factor angle, as well as the conduction losses under the DPWM and SPWM control at different power factor angles under the same modulation ratio.

[0101] Specifically, FIG6 is a schematic diagram of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different modulation ratios under the same power factor angle. As shown in FIG6, FIG6 (1) is a comparison result of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different modulation ratios when the power factor angle φ = 0.1π. FIG6 (2) is a comparison result of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different modulation ratios when the power factor angle φ = 0.9π. As shown in FIG6 (1), when the modulation ratio is small, the actual conduction loss of the power module under the control of the DPWM control signal is greater than the initial conduction loss of the power module under the control of the SPWM control signal, and the difference between the two is large. As shown in FIG6 (2), when the modulation ratio is small, the actual conduction loss of the power module under the control of the DPWM control signal is less than the initial conduction loss of the power module under the control of the SPWM control signal, and the difference between the two is large.

[0102] FIG7 is a schematic diagram of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio. As shown in FIG7, FIG7 (1) is a comparison result of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m=1. FIG7 (2) is a comparison result of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m=1.1547. As shown in FIG7, regardless of the power factor angle, under ideal conditions, the difference between the actual conduction loss of the power module under the control of the DPWM control signal and the initial conduction loss of the power module under the control of the SPWM control signal is small, so the two can be approximately equal.

[0103] Therefore, it can be roughly assumed that the conduction losses of the power module under DPWM control signals require a modulation ratio correction based on the conduction losses calculated under SPWM control signals. The correction factor is linearly related to the modulation ratio. If the conduction losses of the power module under DPWM control signals are approximated using the conduction losses calculated under SPWM control signals, there is no need to correct for the influence of the power factor angle.

[0104] Furthermore, based on the waveforms corresponding to the duty cycle functions of the above-mentioned SPWM control signal, SVPWM control signal, and DPWM control signal, the switching losses of the power modules under the control of the DPWM control signal and the SPWM control signal at different modulation ratios under the same power factor angle can be further obtained, as well as the switching losses of the power modules under the control of the DPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio can be obtained.

[0105] Specifically, FIG8 is a schematic diagram of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles under the same modulation ratio. As shown in FIG8, FIG8 (1) is a comparison result of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m=1. FIG8 (2) is a comparison result of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m=1.1547. As shown in FIG8 (1) and (2), at any power factor angle, the actual conduction loss of the power module under the control of the DPWM control signal is less than the initial conduction loss of the power module under the control of the SPWM control signal, and the difference between the two is large.

[0106] FIG9 is a schematic diagram of the conduction loss of the power module under the control of the DPWM control signal and the SPWM control signal with power factor correction at the same modulation ratio and different power factor angles. As shown in FIG9, FIG9 (1) is a comparison result of the conduction loss under the control of the DPWM control signal and the SPWM control signal with power factor correction at different power factor angles when the modulation ratio m=1. FIG9 (2) is a comparison result of the conduction loss under the control of the DPWM control signal and the SPWM control signal with power factor correction at different power factor angles when the modulation ratio m=1.1547. As shown in FIG9, after the power factor correction is performed on the switching loss under the SPWM control signal, the actual conduction loss of the power module under the control of the DPWM control signal is equal to the initial conduction loss of the power module under the control of the SPWM control signal, and the two have overlapped to form a single line.

[0107] Therefore, the switching loss of the power module under the DPWM control signal can be considered to be equal to the switching loss of the power module under the SPWM control signal multiplied by the coefficient (1-0.5|cosφ|), which is independent of the modulation ratio.

[0108] Based on FIG. 6 to FIG. 9 , it can be seen that the loss correlation relationship between the DPWM control signal and the SPWM control signal is: the initial loss is corrected.

[0109] In a specific implementation process, based on the loss correlation between different control signals and the SPWM control signal obtained in Figures 3 to 9 above, after determining the initial loss of the power module under ideal conditions using the loss algorithm under the SPWM control signal, if the actual control signal is detected to be a DPWM control signal, the initial loss can be corrected based on a preset loss correction strategy to obtain the actual loss.

[0110] Specifically, the process of correcting the initial loss to obtain the actual loss can be implemented according to the following steps:

[0111] a1. If the initial loss includes initial conduction loss, correct the initial conduction loss based on a first correction coefficient to obtain the actual conduction loss in the actual loss;

[0112] In a specific implementation process, the first correction coefficient is determined based on the modulation ratio of the power module and the power angle factor of the power module.

[0113] Specifically, referring to (1) in FIG6 , if it is a driving mode (the power angle factor of the power module is less than the power angle threshold), before the modulation ratio is equal to 1, the actual conduction loss of the power module under the control of the DPWM control signal is greater than the initial conduction loss of the power module under the control of the SPWM control signal, and the initial conduction loss of the power module under the control of the SPWM control signal needs to be increased; when the modulation ratio is equal to 1, the actual conduction loss of the power module under the control of the DPWM control signal is equal to the initial conduction loss of the power module under the control of the SPWM control signal, and there is no need to adjust the initial conduction loss of the power module under the control of the SPWM control signal; when the modulation ratio is greater than 1, the actual conduction loss of the power module under the control of the DPWM control signal is less than the initial conduction loss of the power module under the control of the SPWM control signal, and the initial conduction loss of the power module under the control of the SPWM control signal needs to be increased. Therefore, it can be determined that the first correction coefficient decreases as the modulation ratio increases, and the specific value of the first correction coefficient can be the ratio of the actual conduction loss of the power module under the control of the DPWM control signal to the initial conduction loss of the power module under the control of the SPWM control signal. Therefore, when the modulation ratio is less than the modulation ratio threshold, the first correction coefficient is greater than 1; when the modulation ratio is greater than the modulation ratio threshold, the first correction coefficient is less than 1; when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

[0114] As shown in (2) in FIG6 , if it is a power generation mode (the power angle factor of the power module is greater than the power angle threshold), when the modulation ratio is less than 1, the actual conduction loss of the power module under the control of the DPWM control signal is less than the initial conduction loss of the power module under the control of the SPWM control signal, and the initial conduction loss of the power module under the control of the SPWM control signal needs to be reduced; when the modulation ratio is equal to 1, the actual conduction loss of the power module under the control of the DPWM control signal is equal to the initial conduction loss of the power module under the control of the SPWM control signal, and there is no need to adjust the initial conduction loss of the power module under the control of the SPWM control signal; when the modulation ratio is greater than 1, the actual conduction loss of the power module under the control of the DPWM control signal is greater than the initial conduction loss of the power module under the control of the SPWM control signal, and the initial conduction loss of the power module under the control of the SPWM control signal needs to be increased. Therefore, it can be determined that the first correction coefficient increases with the increase of the modulation ratio, and the specific value of the first correction coefficient can be the ratio of the actual conduction loss of the power module under the control of the DPWM control signal to the initial conduction loss of the power module under the control of the SPWM control signal. Therefore, when the modulation ratio is less than the modulation ratio threshold, the first correction coefficient is less than 1; when the modulation ratio is greater than the modulation ratio threshold, the first correction coefficient is greater than 1; when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

[0115] a2. If the initial loss includes initial switching loss, the initial switching loss is corrected based on a second correction coefficient to obtain actual switching loss in the actual loss.

[0116] In a specific implementation process, the second correction coefficient is determined based on the power angle factor.

[0117] Specifically, referring to Figure 9 , the switching loss of the power module under the SPWM control signal is multiplied by the coefficient (1-0.5|cosφ|) to make the corrected switching loss equal to the switching loss of the power module under the DPWM control signal. Therefore, the second correction coefficient is (1-0.5|cosφ|). In other words, the second correction coefficient can be determined based on 1 and the cosine value of the power angle factor at a preset multiple; the preset multiple can be equal to 0.5.

[0118] The power module loss monitoring method of this embodiment determines the initial loss of the power module under ideal conditions based on a loss algorithm under SPWM control signals. Based on the loss correlation between different control signals and the SPWM control signal, the initial loss is used to determine the actual loss of the power module under the ideal conditions under the actual control signal. Thus, when the power module is controlled by an SVPWM control signal or a DPWM control signal, the actual loss of the power module under ideal conditions is determined with minimal computational effort, relatively accurate results, and minimal memory consumption, making real-time loss calculations easier to perform in embedded devices.

[0119] In a specific implementation, the above-described power module loss monitoring method is primarily targeted at ideal conditions. When the power module is controlled by an SVPWM control signal or a DPWM control signal, a simple loss algorithm under an SPWM control signal can be used to obtain initial loss, which can then be used to determine actual loss, thereby simplifying the process of determining power module loss. However, in practice, the actual loss of the power module under ideal conditions is affected by various factors, and there may be a certain difference between the actual loss of the power module under non-ideal conditions. If it is necessary to determine the actual loss of the power module under non-ideal conditions, a correction can be made based on the actual loss under ideal conditions to obtain the actual loss under non-ideal conditions. For example, the conduction loss of the first switching device in the power module can be corrected based on at least a third correction coefficient, where the third correction coefficient is associated with the modulation ratio of the power module. Alternatively, the conduction loss of the first switching device in the power module can be corrected based on at least a fourth correction coefficient, where the fourth correction coefficient is associated with the AC current frequency of the power module. Examples are not provided here one by one, and reference can be made to the existing related art, which will not be elaborated here.

[0120] It should be pointed out that although the various steps in the above embodiments are described in a specific order, those skilled in the art will understand that in order to achieve the effect of the present application, different steps do not have to be performed in such an order. They can be performed simultaneously (in parallel) or in other orders. These changes are within the scope of protection of the present application.

[0121] It will be understood by those skilled in the art that all or part of the processes in the method for implementing the above embodiment of the present application can also be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a computer-readable storage medium. When the computer program is executed by a processor, it can implement the steps of each of the above method embodiments. The computer program includes computer program code, which can be in source code form, object code form, executable file or some intermediate form. The computer-readable storage medium can include: any entity or device, medium, USB flash drive, mobile hard disk, magnetic disk, optical disk, computer memory, read-only memory, random access memory, electric carrier signal, telecommunication signal and software distribution medium that can carry the computer program code. It should be noted that the content contained in the computer-readable storage medium can be appropriately increased or decreased according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, computer-readable storage media do not include electric carrier signals and telecommunication signals.

[0122] Furthermore, the present application also provides a target detection device.

[0123] 10 , which is a block diagram of the main structure of a smart device according to an embodiment of the present application. As shown in FIG10 , the smart device in the embodiment of the present application may include a processor 10 and a storage device 20 .

[0124] The storage device 20 may be configured to store a program for executing the target detection method of the above-described method embodiment, and the processor 10 may be configured to execute the program in the storage device 20, including but not limited to a program for executing the target detection method of the above-described method embodiment. For ease of explanation, only the portion related to the embodiment of the present application is shown. For specific technical details not disclosed, please refer to the method section of the embodiment of the present application. The target detection device may be a control device formed by various electronic devices.

[0125] In a specific implementation process, the number of the storage device 20 and the processor 10 can be multiple. The program for executing the target detection method of the above method embodiment can be divided into multiple subroutines, and each subroutine can be loaded and run by the processor 10 to execute different steps of the target detection method of the above method embodiment. Specifically, each subroutine can be stored in a different storage device 20 respectively, and each processor 10 can be configured to execute the program in one or more storage devices 20 to jointly implement the target detection method of the above method embodiment, that is, each processor 10 executes different steps of the target detection method of the above method embodiment respectively to jointly implement the target detection method of the above method embodiment.

[0126] The multiple processors 10 may be processors deployed on the same device. For example, the device may be a high-performance device composed of multiple processors, and the multiple processors 10 may be processors configured on the high-performance device. Furthermore, the multiple processors 10 may be processors deployed on different devices. For example, the device may be a server cluster, and the multiple processors 10 may be processors on different servers in the server cluster.

[0127] In a clustering implementation process, the smart device may specifically include a driving device, an autonomous driving vehicle, a smart car, a robot, an unmanned aircraft, etc.

[0128] In some embodiments of the present application, the smart device further includes at least one sensor configured to sense information. The sensor is communicatively coupled to any of the processors described herein. Optionally, the smart device further includes an autonomous driving system configured to guide the smart device to autonomously drive or provide assisted driving. The processor communicates with the sensor and / or autonomous driving system to perform the method described in any of the above embodiments.

[0129] Furthermore, the present application also provides a computer-readable storage medium. In a computer-readable storage medium embodiment according to the present application, the computer-readable storage medium can be configured to store a program for executing the target detection method of the above-mentioned method embodiment, and the program can be loaded and run by the processor to implement the above-mentioned target detection method. For ease of explanation, only the parts related to the embodiment of the present application are shown. For specific technical details not disclosed, please refer to the method part of the embodiment of the present application. The computer-readable storage medium can be a storage device formed by various electronic devices. Optionally, the computer-readable storage medium in the embodiment of the present application is a non-transitory computer-readable storage medium.

[0130] Furthermore, it should be understood that since the configuration of each module is merely for the purpose of illustrating the functional units of the apparatus of the present application, the physical devices corresponding to these modules may be the processor itself, or a portion of the software in the processor, a portion of the hardware, or a combination of software and hardware. Therefore, the number of modules in the figure is merely illustrative.

[0131] Those skilled in the art will appreciate that the various modules in the device can be adaptively split or merged. Such splitting or merging of specific modules will not cause the technical solution to deviate from the principles of this application. Therefore, the technical solutions after splitting or merging will fall within the scope of protection of this application.

[0132] It should be noted that the relevant user personal information that may be involved in the various embodiments of this application is strictly in accordance with the requirements of laws and regulations, follows the principles of legality, legitimacy and necessity, and is based on the reasonable purposes of business scenarios to process personal information that users actively provide during the use of products / services or generated due to the use of products / services, as well as personal information obtained with the user's authorization.

[0133] The user personal information processed by this application will vary depending on the specific product / service scenario and must be based on the specific scenario in which the user uses the product / service. This may involve the user's account information, device information, driving information, vehicle information, or other related information. This application will treat the user's personal information and its processing with a high degree of diligence.

[0134] This application attaches great importance to the security of user personal information and has taken reasonable and feasible security protection measures that comply with industry standards to protect user information and prevent personal information from being accessed, disclosed, used, modified, damaged or lost without authorization.

[0135] Thus far, the technical solutions of the present application have been described in conjunction with the embodiments shown in the accompanying drawings. However, it is readily understood by those skilled in the art that the scope of protection of the present application is obviously not limited to these specific embodiments. Without departing from the principles of the present application, those skilled in the art may make equivalent changes or substitutions to the relevant technical features, and the technical solutions after such changes or substitutions will fall within the scope of protection of the present application.

Claims

1. A method for monitoring power module loss, characterized in that: include: Based on the loss algorithm under the SPWM control signal, determine the initial loss of the power module under ideal conditions; the ideal conditions include that the SPWM control signal is a symmetrical signal, and / or the fundamental frequency of the phase voltage is always greater than a preset frequency; Based on a preset loss correlation relationship, using the initial loss, determining the actual loss of the power module under the ideal conditions under the actual control signal; The loss correlation relationship is a loss correlation relationship between different control signals and the SPWM control signal.

2. The method for monitoring power module loss according to claim 1, characterized in that: If the actual control signal is a DPWM control signal, the loss association relationship includes correcting the initial loss; Based on the preset loss correlation relationship, using the initial loss, determining the actual loss of the power module under the ideal conditions under the actual control signal, including: Based on a preset loss correction strategy, the initial loss is corrected to obtain the actual loss.

3. The method for monitoring power module loss according to claim 2, characterized in that: Based on a preset loss correction strategy, the initial loss is corrected to obtain the actual loss, including: If the initial loss includes an initial conduction loss, the initial conduction loss is corrected based on a first correction coefficient to obtain an actual conduction loss in the actual loss; wherein the first correction coefficient is determined based on a modulation ratio of the power module and a power angle factor of the power module; If the initial loss includes initial switching loss, the initial switching loss is corrected based on a second correction coefficient to obtain actual switching loss in the actual loss; wherein the second correction coefficient is determined based on the power angle factor.

4. The method for monitoring power module loss according to claim 3, characterized in that: The first correction coefficient is determined based on the modulation ratio of the power module and the power angle factor of the power module, including: If the power angle factor of the power module is less than the power angle threshold, it is determined that the first correction coefficient decreases as the modulation ratio increases; and when the modulation ratio is less than the modulation ratio threshold, the first correction coefficient is greater than 1, and when the modulation ratio is greater than the modulation ratio threshold, the first correction coefficient is less than 1; when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

5. The method for monitoring power module loss according to claim 3, characterized in that: The first correction coefficient is determined based on the modulation ratio of the power module and the power angle factor of the power module, including: If the power angle factor of the power module is greater than the power angle threshold, it is determined that the first correction coefficient increases with the increase of the modulation ratio; and when the modulation ratio is less than the modulation ratio threshold, the first correction coefficient is less than 1, and when the modulation ratio is greater than the modulation ratio threshold, the first correction coefficient is greater than 1; when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is The first correction coefficient is equal to 1.

6. The method for monitoring power module loss according to claim 3, characterized in that: The second correction coefficient is determined based on the power angle factor, including: The second correction coefficient is determined based on 1 and a cosine value of the power angle factor at a preset multiple.

7. The method for monitoring power module loss according to claim 2, characterized in that: If the actual control signal is an SVPWM control signal, the loss association relationship includes not correcting the initial loss; Based on the preset loss correlation relationship, using the initial loss, determining the actual loss of the power module under the ideal conditions under the actual control signal, including: The initial loss is taken as the actual loss.

8. The method for monitoring power module loss according to claim 7, characterized in that: Before determining the initial loss of the power module under ideal conditions based on the loss algorithm under the SPWM control signal, the method further includes: The loss algorithm is determined based on the type of power devices in the power module.

9. A smart device, characterized in that: The method comprises a processor and a storage device, wherein the storage device is suitable for storing a plurality of program codes, and the program codes are suitable for being loaded and run by the processor to execute the method for monitoring power module loss according to any one of claims 1 to 8.

10. A computer-readable storage medium, characterized in that: A plurality of program codes are stored, and the program codes are suitable for being loaded and run by a processor to execute the method for monitoring power module loss according to any one of claims 1 to 8.

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