Method for monitoring power module losses, smart device and medium

Abstract

The application provides a power module loss monitoring method, intelligent equipment and a medium, comprising: determining the initial loss of the power module under ideal conditions based on a loss algorithm under an SPWM control signal; and determining the actual loss of the power module under the ideal conditions under an actual control signal based on a preset loss correlation relationship and the initial loss. In this way, when the power module is controlled by an SVPWM control signal or a DPWM control signal, the calculation amount is small when determining the actual loss of the power module under the ideal conditions, the calculation result is relatively accurate, the memory consumption is small, and real-time loss calculation in an embedded device is easy.

Description

Technical Field

[0001] This application relates to the field of power electronics technology, specifically providing a method for monitoring power module losses, an intelligent device, and a medium. Background Technology

[0002] Accurate calculation of power module losses within the inverter is a crucial prerequisite for estimating junction temperature, input power, bus current, and even torque.

[0003] Depending on the application of the inverter, the controlled object, and the control objective, different Pulse Width Modulation (PWM) control strategies can be adopted. Commonly used PWM control strategies include Sinusoidal Pulse Width Modulation (SPWM), Space Vector Pulse Width Modulation (SVPWM), and Discrete Pulse Width Modulation (DPWM). Among them, SPWM, because its modulation wave only contains the fundamental wave and is symmetrical, has simple and convenient loss calculation, is easy to embed in real-time calculation, and does not require a lot of computing power and memory, making it widely used in the industry. However, due to the limitations of the modulation method, SPWM has low DC-side voltage utilization. The most widely used in practice are SVPWM / DPWM, which can allow a certain range of overmodulation to improve DC-side voltage utilization. DPWM, because one-third of its output phase voltage is discontinuously clamped, has lower losses than SVPWM and is more suitable for high-power / ultra-high-power inverter equipment.

[0004] However, SVPWM and DPWM have complex harmonic components in their modulation waves, which makes the power module loss calculation cumbersome and complicated, and consumes a lot of memory, making them unsuitable for real-time calculation in embedded devices. Summary of the Invention

[0005] To overcome the aforementioned deficiencies, this application is made to provide a power module loss monitoring method, intelligent device, and medium that solves, or at least partially solves, the technical problem of complex loss calculation for power modules under SVPWM and DPWM control.

[0006] In a first aspect, this application provides a method for monitoring power module losses, the method comprising:

[0007] Based on the loss algorithm under the SPWM control signal, the initial loss of the power module under ideal conditions is determined; the ideal conditions include that the SPWM control signal is a symmetrical signal, and / or that the fundamental frequency of the phase voltage is always greater than the preset frequency.

[0008] Based on the preset loss correlation, the actual loss of the power module under the ideal conditions is determined using the initial loss and the actual control signal; the loss correlation is the loss correlation between different control signals and the SPWM control signal.

[0009] Furthermore, in the power module loss monitoring method described above, if the actual control signal is a DPWM control signal, the loss correlation includes correcting the initial loss;

[0010] Based on a preset loss correlation, using the initial loss, the actual loss of the power module under the actual control signal and the ideal conditions is determined, including:

[0011] Based on a preset loss correction strategy, the initial loss is corrected to obtain the actual loss.

[0012] Furthermore, in the power module loss monitoring method described above, the initial loss is corrected based on a preset loss correction strategy to obtain the actual loss, including:

[0013] If the initial loss includes the initial conduction loss, the initial conduction loss is corrected based on the first correction coefficient to obtain the actual conduction loss in the actual loss; wherein, the first correction coefficient is determined based on the modulation ratio of the power module and the power factor angle of the power module;

[0014] If the initial loss includes the initial switching loss, the initial switching loss is corrected based on the second correction factor to obtain the actual switching loss in the actual loss; wherein the second correction factor is determined based on the power factor angle.

[0015] Furthermore, in the power module loss monitoring method described above, the first correction coefficient is determined based on the modulation ratio of the power module and the power factor angle of the power module, including:

[0016] If the power factor angle of the power module is less than the power angle threshold, the first correction coefficient is determined to decrease 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.

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

[0018] If the power factor angle of the power module is greater than the power angle threshold, the first correction coefficient is determined to increase as the modulation ratio increases; 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.

[0019] Furthermore, in the power module loss monitoring method described above, the second correction coefficient is determined based on the power factor angle, including:

[0020] The second correction coefficient is determined based on the cosine value of the power factor angle at 1 and a preset multiple.

[0021] Furthermore, in the power module loss monitoring method described above, if the actual control signal is an SVPWM control signal, the loss correlation includes not correcting the initial loss;

[0022] Based on a preset loss correlation, using the initial loss, the actual loss of the power module under the actual control signal and the ideal conditions is determined, including:

[0023] The initial loss is taken as the actual loss.

[0024] Furthermore, in the power module loss monitoring method described above, 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:

[0025] The loss algorithm is determined based on the type of power devices in the power module.

[0026] In a second aspect, this application provides an intelligent device, the target detection device including a processor and a storage device, the storage device being adapted to store a plurality of program codes, the program codes being adapted to be loaded and run by the processor to perform the target detection method described in any of the preceding claims.

[0027] In a third aspect, a computer-readable storage medium is provided that stores a plurality of program codes adapted to be loaded and run by a processor to perform the target detection method described in any of the preceding claims.

[0028] The above-described technical solutions of this application have at least one or more of the following beneficial effects:

[0029] In implementing the technical solution of this application, a loss algorithm based on SPWM control signals is used to determine the initial loss of the power module under ideal conditions. Then, 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 actual control signals under the same ideal conditions. Thus, when the power module is controlled by either SVPWM or DPWM control signals, determining the actual loss of the power module under ideal conditions involves minimal computation, yields relatively accurate results, consumes little memory, and is easily performed in real-time loss calculations within embedded devices. Attached Figure Description

[0030] The disclosure of this application will become more readily understood with reference to the accompanying drawings. It will be readily understood by those skilled in the art 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 drawings are used to denote similar components, wherein:

[0031] Figure 1 This is a schematic diagram showing the relationship between the on-resistance of a SiC-based MOSFET and the current at different junction temperatures.

[0032] Figure 2 This is a schematic flowchart of the main steps of a target detection method according to an embodiment of this application;

[0033] Figure 3 These are waveforms of the duty cycle functions of SPWM, SVPWM, and DPWM at different power factor angles phi and different modulation ratios m.

[0034] Figure 4 This is a schematic diagram showing the conduction loss of a power module controlled by SVPWM and SPWM signals under different modulation ratios at the same power factor angle.

[0035] Figure 5 This is a schematic diagram showing the conduction loss of a power module controlled by SVPWM and SPWM signals under the same modulation ratio but different power factor angles.

[0036] Figure 6 This is a schematic diagram showing the conduction loss of the power module under the control of DPWM and SPWM control signals at different modulation ratios for the same power factor angle.

[0037] Figure 7 This is a schematic diagram showing the conduction loss of the power module under the control of DPWM and SPWM control signals at different power factor angles with the same modulation ratio.

[0038] Figure 8This is a schematic diagram of the switching losses of the power module under the control of DPWM and SPWM control signals at different power factor angles with the same modulation ratio.

[0039] Figure 9 This is a schematic diagram showing the switching losses of a power module controlled by a DPWM control signal and an SPWM control signal that performs power factor correction, under the same modulation ratio but different power factor angles.

[0040] Figure 10 This is a main structural block diagram of a smart device according to an embodiment of this application. Detailed Implementation

[0041] Some embodiments of this application are described below with reference to the accompanying drawings. Those skilled in the art should understand that these embodiments are merely illustrative of the technical principles of this application and are not intended to limit the scope of protection of this application.

[0042] In the description of this application, "module" and "processor" can include hardware, software, or a combination of both. A module can include hardware circuitry, various suitable sensors, communication ports, memory, and can also include software components, such as program code, or a combination of software and hardware. A processor can be a central processing unit, microprocessor, image processor, digital signal processor, or any other suitable processor. The processor has data and / or signal processing capabilities. The processor can be implemented in software, in hardware, or a combination of both. Non-transitory computer-readable storage media includes 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" means all possible combinations of A and B, such as only A, only B, or A and B. The terms "at least one A or B" or "at least one of A and B" have a similar meaning to "A and / or B" and can include only A, only B, or A and B. The singular terms "a" or "this" can also include plural forms.

[0043] Power modules include IGBT power devices, SiC power devices, GaN power devices, etc. Regardless of the type of power device, power modules in power conversion electronic devices such as inverters will generate conduction losses and switching losses during operation. Different types of power devices have different distributions of conduction and switching losses across the switching devices and their parallel diodes, mainly manifested in two types of differences: silicon-based IGBTs and SiC-based MOSFETs.

[0044] For SiC-based MOSFET modules, taking a single phase of a SiC power device as an example, when a positive current is applied, the upper-bridge MOSFET switches. When the upper-bridge MOSFET is on, current flows through the MOSFET wafer. Due to the on-state voltage drop of the MOSFET wafer, conduction losses occur. When the upper-bridge MOSFET is off, current flows through the lower-bridge MOSFET wafer, not the lower-bridge diode, resulting in conduction losses. This is the main difference between MOSFETs and IGBTs. The same principle applies when a negative current is applied. During the switching process of the MOSFET wafer, corresponding switching losses are generated.

[0045] For silicon-based IGBTs, taking a single phase as an example, when a positive current is applied, the upper-bridge IGBT switches. When the upper-bridge IGBT is on, current flows through the IGBT wafer. Due to the on-state voltage drop of the IGBT wafer, conduction losses occur. When the upper-bridge IGBT is off, current flows through the lower-bridge diode wafer. Due to the on-state voltage drop of the diode wafer, conduction losses occur. The same applies when a negative current is applied. Corresponding switching losses are generated during the switching process of the IGBT wafer or diode wafer.

[0046] When using SPWM control signals to control power modules, the modulation wave of the SPWM control signal contains only the fundamental wave and is symmetrical, making its loss calculation simple, convenient, and easy to perform in embedded real-time calculations without consuming a lot of computing power and memory. It is widely used in the industry.

[0047] Specifically, the average conduction loss of a certain half-bridge of SiC-based MOSFETs under the control of the SPWM control signal is calculated as follows:

[0048] Since the MOSFET carries current in both positive and negative current cycles, the conduction loss is calculated as shown in equation (1):

[0049]

[0050] For SiC-based MOSFETs, the voltage-current curve between the drain and source terminals crosses zero, indicating the absence of an initial turn-on voltage. Therefore, the following calculation formula (2) applies:

[0051]

[0052] However, the on-resistance of a SiC-based MOSFET is a current- and temperature-sensitive value. The measured relationship between the on-resistance of a certain SiC-based MOSFET and the current flowing through it at different junction temperatures is as follows: Figure 1 As shown. Figure 1 This is a schematic diagram showing the relationship between the on-resistance of a SiC-based MOSFET and the current at different junction temperatures. Figure 1 As shown, the on-resistance and current can be approximated as linear: rMos =k*I+b, where k and b are the on-resistance properties of the SiC-based MOSFET at a certain junction temperature, and are fixed values. Figure 1 The neutral line a1 is the actual curve showing the relationship between on-resistance and current when the junction temperature is 175℃. Figure 1 The middle line a2 is the fitted curve of the relationship between the on-resistance and the current when the junction temperature is 175℃. Figure 1 The midline b1 is the actual curve showing the relationship between on-resistance and current when the junction temperature is 125℃. Figure 1 The midline b2 is the fitted curve of the relationship between on-resistance and current when the junction temperature is 125℃. Figure 1 The neutral line c1 is the actual curve showing the relationship between the on-resistance and the current when the junction temperature is 25℃. Figure 1 The midline c2 is the fitted curve of the relationship between on-resistance and current when the junction temperature is 25℃.

[0053] It should be noted that the y in the equations for the various curves in the figure is related to the r mentioned earlier. Mos Both have the same meaning, representing on-resistance; x and I have the same meaning, representing current.

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

[0055]

[0056] The MOSFET body diode only experiences conduction losses during the dead time. During the dead time, the MOSFET body diode performs freewheeling. When the dead time ends, the MOSFET turns on, and the current switches to the MOSFET channel. Since the MOSFET dead time is extremely short, the diode conduction losses can be ignored.

[0057] Based on the above calculation formulas (2) and (3), integrating calculation formula (1) yields the calculation formula (4) for the conduction loss of the SiC-based MOSFET:

[0058]

[0059] The conduction loss of the diode is calculated using formula (5):

[0060] P loss,diode,cond ≈0(5)

[0061] Under the control of the SPWM control signal, the average switching loss of a certain half-bridge of SiC-based MOSFETs is calculated as follows:

[0062] Switching loss refers to the energy loss generated during the instantaneous turn-on and turn-off of a MOSFET. Although a MOSFET can conduct bidirectionally, no switching loss is generated during natural commutation. That is, the average switching loss of a MOSFET is the same as the average switching loss of a MOSFET wafer under SPWM control. Therefore, the switching loss of a MOSFET is calculated as shown in formula (6).

[0063]

[0064] The diode switching loss is calculated using formula (7):

[0065] P loss,diode,swi ≈0(7)

[0066] Among them, P loss,Mos,cond P is the wafer conduction loss of a certain half-bridge MOSFET. loss,diode,cond For the conduction loss of a certain half-bridge diode wafer, I m r is the peak current flowing through the MOSFET half-bridge. Mos φ is the on-resistance of the MOSFET wafer, φ is the power factor angle, i.e., the angle between the voltage vector and the current vector, and m is the modulation ratio.

[0067] P loss,Mos,swi For the wafer switching loss of a certain half-bridge MOSFET, P loss,diode,swi For the switching loss of a certain half-bridge digitizer wafer, f PWM E is the switching frequency. on E represents the energy consumed by a MOSFET wafer during each turn-on under specific conditions. off U represents the energy consumed by a MOSFET wafer during each turn-off under specific conditions. ds I represents the actual voltage between the MOSFET's drain and source terminals. n U is the test current value given in the datasheet. n The test voltage value given in the datasheet.

[0068] Taking a single-phase or three-phase SiC-based MOSFET inverter as an example, the total loss calculation formula (8) is as follows:

[0069]

[0070] The above method for calculating the losses of SiC-based MOSFET power modules controlled by SPWM control signals is simple, convenient, and easy to perform in embedded real-time calculations without consuming a lot of computing power and memory.

[0071] Specifically, the average conduction loss of a silicon-based IGBT half-bridge under the control of the SPWM control signal is calculated as follows:

[0072] The formula (9) for calculating the conduction loss of an IGBT is as follows:

[0073]

[0074] The formula (10) for calculating the conduction loss of a diode is as follows:

[0075]

[0076] The formula (11) for calculating the switching loss of IGBT is as follows:

[0077]

[0078] The formula (12) for calculating the switching loss of a diode is as follows:

[0079]

[0080] Among them, P loss,igbt,cond For the conduction loss of a certain half-bridge IGBT wafer, P loss,diode,cond For the conduction loss of a certain half-bridge diode wafer, I m V is the peak current flowing through this half-bridge of the IGBT. ce0 V represents the initial on-state voltage of the IGBT wafer. f0 r is the initial on-state voltage of the diode wafer. igbt r is the on-resistance of the IGBT wafer. diode φ is the on-resistance of the diode wafer, φ is the power factor angle, i.e., the angle between the voltage vector and the current vector, and m is the modulation ratio.

[0081] P loss,igbt,swi For the switching loss of a certain half-bridge IGBT wafer, P loss,diode,swi For the switching loss of a certain half-bridge digitizer wafer, f PWM E is the switching frequency. on E represents the energy consumed by an IGBT wafer during each turn-on under specific conditions. off E represents the energy consumed by an IGBT wafer during each turn-off under specific conditions. rec U represents the energy consumed by a diode wafer during each rectification under specific conditions. ce I represents the actual voltage value between the collector and emitter of the IGBT. n U is the test current value given in the datasheet. n The test voltage value given in the datasheet.

[0082] The above method for calculating the losses of IGBT power modules based on SPWM control signals is simple, convenient, and easy to perform in real-time embedded calculations without requiring a large amount of computing power or memory.

[0083] However, due to the limitations of the modulation method, the SPWM control signal has low DC-side voltage utilization. The most widely used control signals in the industry are SVPWM and DPWM, which can allow a certain range of overmodulation and improve DC-side voltage utilization. The DPWM control signal has lower losses than the SVPWM control signal because one-third of its output phase voltage is in a discontinuous clamping state, making it more suitable for high-power / ultra-high-power inverter equipment.

[0084] However, SVPWM and DPWM control signals contain complex harmonic components in their modulation waves, making the power module loss calculation cumbersome and complex, and resulting in high memory consumption. They are not suitable for accurate and real-time calculation in embedded devices.

[0085] Specifically, the conduction loss, switching loss, and total loss of the power module under the control of SVPWM and DPWM control signals can be calculated using either numerical or analytical methods. The following explanation uses the numerical method:

[0086] The numerical calculation of power module losses under SVPWM control is as follows:

[0087] The SVPWM modulation wave can be simplified to the form of fundamental wave plus third harmonic, and the specific calculation formula (13) is as follows:

[0088]

[0089] The following calculation procedure can be used to numerically calculate the conduction loss and switching loss of the power module under SVPWM control signal:

[0090] %%matlab

[0091] %a = w*t

[0092] Freq = 100;

[0093] w = 2 * pi * Freq;

[0094] delta_t = 0.0001;

[0095] delta_a = w * delta_t;

[0096] a=0:delta_a:(2*pi-delta_a);

[0097] I = Imax * sin(a);

[0098] r_mos = k*I + b;

[0099] Vds = r_mos * I;

[0100] %SVPWM(Space Vector Pulse Width Modulation)duty;

[0101] SVPWM=(1+m*(sin(a+phi)+3*sqrt(3) / 8 / pi*sin(3*(a+phi)))) / 2;

[0102] %Conduction loss of SVPWM;

[0103] Loss_CD_SVPWM_Mos=sum(I.*Vds.*SVPWM*delta_a.*(a>=0&a<2*pi)) / 2 / pi;

[0104] Loss_CD_SVPWM_Diode = 0;

[0105] Loss_CD_SVPWM=6*(Loss_CD_SVPWM_Mos+Loss_CD_SVPWM_Diode);

[0106] %halfduty MOSFET switch, the other halfcommutate naturally;

[0107] Loss_SW_SVPWM_Mos=sum(Imax*sin(a) / In*HvDc / Un*(E_total_Mos).*((a>=0&a <pi))) / (2*pi / w);

[0108] Loss_SW_SVPWM_Diode = 0;

[0109] Loss_SW_SVPWM=6*(Loss_SW_SVPWM_Mos+Loss_SW_SVPWM_Diode).

[0110] The loss of the power module under DPWM control signal is calculated using a numerical method as follows:

[0111] There are 6 pattern types for DPWM, and we commonly use DPWM1, whose modulation wave can be represented by a piecewise function (14) within one period:

[0112]

[0113] The following calculation procedure can be used to numerically calculate the conduction loss and switching loss of the power module under DPWM control:

[0114]

[0115]

[0116] Based on the above description, it can be seen that SVPWM control signals and DPWM control signals contain complex harmonic components in their modulation waves, which makes the power module loss calculation cumbersome and complex, and consumes a lot of memory. Therefore, they are not suitable for accurate and real-time calculation in embedded devices.

[0117] Therefore, in order to solve the above-mentioned technical problems, this application provides the following technical solution:

[0118] See appendix Figure 2 , Figure 2 This is a schematic flowchart illustrating the main steps of a target detection method according to an embodiment of this application. Figure 2 As shown, the target detection method in this application embodiment mainly includes the following steps 201-202.

[0119] Step 201: Determine the initial loss of the power module under ideal conditions based on the loss algorithm under SPWM control signal;

[0120] In a specific implementation, the modulation ratios of both SVPWM and DPWM control signals can reach a maximum of 1.1547. However, the modulation ratio of the SPWM control signal can only reach a maximum of 1. Since the power module loss calculation under SPWM control is relatively simple, the initial loss of the power module under ideal conditions can be determined based on the loss algorithm described above. That is, when calculating the loss, the value of m>1 can be substituted into the loss algorithm under SPWM control to obtain the initial loss of the power module under ideal conditions. However, the actual inverter control still uses SVPWM / DPWM control signals. After calculating the inverter conduction loss using the loss algorithm under SPWM control, the power factor angle φ and modulation ratio m are adjusted or not adjusted according to the actual situation. Ideal conditions include that the SPWM control signal is a symmetrical signal, and / or that the fundamental frequency of the phase voltage is always greater than a preset frequency.

[0121] It should be noted that, based on the aforementioned description of SiC-based MOSFETs and silicon-based IGBTs, it is known that their loss algorithms under SPWM control signals are different. Therefore, before executing step 201, the loss algorithm can be determined based on the type of power device in the power module.

[0122] Step 202: Based on the preset loss correlation, using the initial loss, determine the actual loss of the power module under the ideal conditions under the actual control signal; the loss correlation is the loss correlation between different control signals and the SPWM control signal.

[0123] In a specific implementation, under ideal conditions, loss calculations can be performed using the complex algorithm for calculating power module losses under the conventional SVPWM control signal, yielding the first loss of the power module under the SVPWM control signal. Similarly, using the complex algorithm for calculating power module losses under the conventional DPWM control signal, a second loss of the power module under the DPWM control signal can be calculated. Then, the first and second losses are analyzed with the initial loss of the power module under ideal conditions to obtain the loss correlation between different control signals and the SVPWM 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 based on the loss correlation between different control signals and the SVPWM control signal, yielding the actual loss of the power module under the actual control signal of the inverter under the stated ideal conditions.

[0124] The process of obtaining the loss correlation between different control signals and the SPWM control signal is explained in detail below:

[0125] Specifically, Figure 3 These are waveforms of the duty cycle functions of SPWM, SVPWM, and DPWM at different power factor angles phi and different modulation ratios m.

[0126] in, Figure 3 (1) is the waveform diagram of 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. Figure 3 (2) is the waveform diagram of 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. Figure 3 (3) is the waveform diagram of 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. Figure 3 (4) is the waveform diagram of 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.

[0127] Based on the waveforms corresponding to the duty cycle functions of the SPWM, SVPWM, and DPWM control signals mentioned above, we can further obtain the conduction losses of the power modules controlled by the SVPWM and SPWM control signals under different modulation ratios at the same power factor angle, and the conduction losses of the power modules controlled by the SVPWM and SPWM control signals under different power factor angles at the same modulation ratio.

[0128] Specifically, Figure 4 This diagram illustrates the conduction losses of a power module controlled by SVPWM and SPWM signals at different modulation ratios for the same power factor angle. Figure 4 As shown, Figure 4 (1) is a comparison of the conduction losses of the power module controlled by the SVPWM control signal and the SPWM control signal under different modulation ratios when the power factor angle φ = 0.1π. Figure 4 (2) shows the comparison of the conduction losses of the power module controlled by the SVPWM control signal and the SPWM control signal under different modulation ratios when the power factor angle φ = 0.9π. Figure 4 As shown, regardless of the modulation ratio, under ideal conditions, the difference between the actual conduction loss of the power module under SVPWM control signal control and the initial conduction loss of the power module under SPWM control signal control is small. Therefore, the two can be approximately equal.

[0129] Figure 5 This diagram illustrates the conduction losses of a power module controlled by SVPWM and SPWM signals at different power factor angles with the same modulation ratio. Figure 5 As shown, Figure 5 (1) is a comparison of the conduction losses of the power module controlled by the SVPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m = 1. Figure 5 (2) shows the comparison of the conduction losses of the power module controlled by the SVPWM control signal and the SPWM control signal at different power factor angles when the modulation ratio m = 1.1547. Figure 5 As shown, regardless of the power factor angle, under ideal conditions, the difference between the actual conduction loss of the power module under SVPWM control signal control and the initial conduction loss of the power module under SPWM control signal control is small. Therefore, the two can be approximately equal.

[0130] Therefore, it can be approximated that the conduction loss of the power module under the SVPWM control signal is equal to that under the SPWM control signal. This applies to any modulation ratio and any power factor angle without sacrificing calculation accuracy.

[0131] Furthermore, compared to the power module under SPWM control signal, the power module under SVPWM control signal does not change the phase current and has the same number of switching operations. Therefore, the switching loss of the power module under SVPWM control signal is equal to that of the power module under SPWM control signal.

[0132] Based on this, the loss correlation between the SVPWM control signal and the SPWM control signal can be obtained as follows: no correction is made to the initial loss.

[0133] Similarly, based on the waveforms corresponding to the duty cycle functions of the SPWM, SVPWM, and DPWM control signals mentioned above, we can further obtain the conduction losses of the power module under different modulation ratios of the DPWM and SPWM control signals at the same power factor angle, as well as the conduction losses under different power factor angles of the DPWM and SPWM control signals at the same modulation ratio.

[0134] Specifically, Figure 6 This diagram illustrates the conduction losses of a power module under DPWM and SPWM control signals at different modulation ratios for the same power factor angle. Figure 6 As shown, Figure 6 (1) is a comparison of the conduction loss of the power module under the control of DPWM and SPWM control signals when the power factor angle φ = 0.1π and the modulation ratio is different. Figure 6 (2) shows the comparison of the conduction losses of the power module under the control of DPWM and SPWM signals at different modulation ratios when the power factor angle φ = 0.9π. Figure 6 As shown in (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. Figure 6 As shown in (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.

[0135] Figure 7 This diagram illustrates the conduction losses of a power module under DPWM and SPWM control signals at different power factor angles with the same modulation ratio. Figure 7 As shown, Figure 7 (1) is a comparison of the conduction losses of the power module under the control of the DPWM control signal and the SPWM control signal when the modulation ratio m = 1 and the power factor angle is different. Figure 7(2) shows the comparison of the conduction losses of the power module under the control of the DPWM and SPWM control signals at different power factor angles when the modulation ratio m = 1.1547. Figure 7 As shown, regardless of the power factor angle, under ideal conditions, the difference between the actual conduction loss of the power module under DPWM control signal control and the initial conduction loss of the power module under SPWM control signal control is small. Therefore, the two can be approximately equal.

[0136] Therefore, it can be approximated that the conduction loss of the power module under DPWM control signal needs to be corrected for modulation ratio based on the conduction loss calculated under SPWM control signal, and the correction coefficient is linearly related to the modulation ratio. If the conduction loss of the power module under DPWM control signal is approximated by the conduction loss calculated under SPWM control signal, there is no need to correct for the influence of power factor angle.

[0137] Furthermore, based on the waveforms corresponding to the duty cycle functions of the aforementioned SPWM, SVPWM, and DPWM control signals, we can further obtain the switching losses of the power module under the control of the DPWM and SPWM control signals at different modulation ratios under the same power factor angle, and the switching losses of the power module under the control of the DPWM and SPWM control signals at different power factor angles under the same modulation ratio.

[0138] Specifically, Figure 8 This diagram illustrates the conduction losses of a power module under DPWM and SPWM control signals at different power factor angles with the same modulation ratio. Figure 8 As shown, Figure 8 (1) is a comparison of the conduction losses of the power module under the control of the DPWM control signal and the SPWM control signal when the modulation ratio m = 1 and the power factor angle is different. Figure 8 (2) shows the comparison of the conduction losses of the power module under the control of the DPWM and SPWM control signals at different power factor angles when the modulation ratio m = 1.1547. Figure 8 As shown in (1) and (2), under 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.

[0139] Figure 9 This diagram illustrates the conduction losses of a power module controlled by a DPWM control signal and an SPWM control signal for power factor correction, at different power factor angles and with the same modulation ratio. Figure 9 As shown, Figure 9(1) is a comparison of the conduction losses under the control of the DPWM control signal and the SPWM control signal with power factor correction when the modulation ratio m = 1 and the power factor angle is different. Figure 9 (2) shows the comparison of conduction losses 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. Figure 9 As shown, after power factor correction of the switching losses under SPWM control signal, the actual conduction loss of the power module under DPWM control signal is equal to the initial conduction loss of the power module under SPWM control signal, and the two have coincided into a single line.

[0140] Therefore, the switching loss of the power module under the DPWM control signal can be considered equal to the switching loss of the power module under the SPWM control signal multiplied by a coefficient (1-0.5|cosφ|), and is independent of the modulation ratio.

[0141] based on Figures 6 to 9 It can be seen that the loss correlation between the DPWM control signal and the SPWM control signal is: the initial loss is corrected.

[0142] In a specific implementation process, based on the above Figures 3 to 9 The loss correlation between the different control signals and the SPWM control signal is obtained. 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 the DPWM control signal, the initial loss can be corrected based on the preset loss correction strategy to obtain the actual loss.

[0143] Specifically, the process of correcting the initial loss to obtain the actual loss can be achieved by following these steps:

[0144] a1. If the initial loss includes the initial conduction loss, the initial conduction loss is corrected based on the first correction coefficient to obtain the actual conduction loss in the actual loss.

[0145] In one specific implementation, the first correction coefficient is determined based on the modulation ratio of the power module and the power factor angle of the power module.

[0146] Specifically, see Figure 6As shown in (1), in the driving mode (the power factor angle 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; and when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

[0147] See Figure 6 As shown in (2), in power generation mode (power factor angle 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; and when the modulation ratio is equal to the modulation ratio threshold, the first correction coefficient is equal to 1.

[0148] a2. If the initial loss includes the initial switching loss, the initial switching loss is corrected based on the second correction coefficient to obtain the actual switching loss in the actual loss.

[0149] In one specific implementation, the second correction coefficient is determined based on the power factor angle.

[0150] Specifically, see Figure 9 Multiplying the switching loss of the power module under the SPWM control signal by a coefficient (1-0.5|cosφ|) makes 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 the cosine value of the power factor angle at 1 and a preset multiple; where the preset multiple can be equal to 0.5.

[0151] The power module loss monitoring method in this embodiment is based on a loss algorithm under SPWM control signals. It determines the initial loss of the power module under ideal conditions and, based on the loss correlation between different control signals and the SPWM control signal, uses the initial loss to determine the actual loss of the power module under actual control signals under the same ideal conditions. Thus, when the power module is controlled by either SVPWM or DPWM control signals, determining the actual loss of the power module under ideal conditions involves minimal computation, yields relatively accurate results, consumes little memory, and is easily implemented in real-time loss calculations within embedded devices.

[0152] In a specific implementation, the aforementioned power module loss monitoring method primarily addresses ideal conditions. When the power module is controlled by an SVPWM or DPWM control signal, a simple loss algorithm under SVPWM control can be used to obtain the initial loss, which in turn leads to the actual loss, simplifying the process of determining the power module's loss. However, in reality, the power module is affected by various factors during actual control, resulting in a difference between the actual loss under ideal and non-ideal conditions. If it is necessary to determine the actual loss under non-ideal conditions, the actual loss under ideal conditions can be further corrected 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 related to 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 related to the AC current frequency of the power module. Further examples are omitted here; please refer to existing related technologies for details.

[0153] It should be noted that although the 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 this application, different steps do not necessarily have to be executed in such an order. They can be executed simultaneously (in parallel) or in other orders, and these variations are all within the scope of protection of this application.

[0154] Those skilled in the art will understand that all or part of the processes in the method of the above-described embodiment can also be implemented by a computer program instructing related hardware. The computer program can be stored in a computer-readable storage medium, and when executed by a processor, it can implement the steps of the various method embodiments described above. The computer program includes computer program code, which can be in the form of source code, object code, executable file, or some intermediate form. The computer-readable storage medium can include any entity or device capable of carrying the computer program code, a medium, a USB flash drive, a portable hard drive, a magnetic disk, an optical disk, a computer memory, a read-only memory, a random access memory, an electrical carrier signal, a telecommunication signal, and a software distribution medium, etc. It should be noted that the content included in the computer-readable storage medium can be appropriately added or removed according to the requirements of legislation and patent practice in the jurisdiction. For example, in some jurisdictions, according to legislation and patent practice, the computer-readable storage medium does not include electrical carrier signals and telecommunication signals.

[0155] Furthermore, this application also provides a target detection device.

[0156] See appendix Figure 10 , Figure 10 This is a main structural block diagram of a smart device according to an embodiment of this application. Figure 10 As shown, the smart device in this embodiment may include a processor 10 and a storage device 20.

[0157] The storage device 20 can be configured to store a program for executing the target detection method of the above-described method embodiments, and the processor 10 can be configured to execute the program in the storage device 20, which includes, but is not limited to, a program for executing the target detection method of the above-described method embodiments. For ease of explanation, only the parts related to the embodiments of this application are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of this application. The target detection device can be a control device comprising various electronic devices.

[0158] In a specific implementation, there can be multiple storage devices 20 and processors 10. The program executing the target detection method of the above method embodiments can be divided into multiple subroutines, each of which can be loaded and run by the processor 10 to perform different steps of the target detection method of the above method embodiments. Specifically, each subroutine can be stored in different storage devices 20, and each processor 10 can be configured to execute programs in one or more storage devices 20 to jointly implement the target detection method of the above method embodiments; that is, each processor 10 executes different steps of the target detection method of the above method embodiments to jointly implement the target detection method of the above method embodiments.

[0159] The aforementioned 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 that high-performance device. Alternatively, the aforementioned 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 within the server cluster.

[0160] In a clustering process, the intelligent device may specifically include driving equipment, autonomous vehicles, intelligent cars, robots, drones, etc.

[0161] In some embodiments of this application, the smart device further includes at least one sensor for sensing information. The sensor is communicatively connected to any type of processor mentioned in this application. Optionally, the smart device further includes an autonomous driving system for guiding the smart device to drive autonomously or assisting in driving. The processor communicates with the sensor and / or the autonomous driving system to perform the methods described in any of the above embodiments.

[0162] Furthermore, this application also provides a computer-readable storage medium. In one embodiment of the computer-readable storage medium according to this application, the computer-readable storage medium can be configured to store a program that performs the target detection method of the above-described method embodiments. This program can be loaded and run by a processor to implement the above-described target detection method. For ease of explanation, only the parts related to the embodiments of this application are shown; for specific technical details not disclosed, please refer to the method section of the embodiments of this application. The computer-readable storage medium can be a storage device device comprising various electronic devices. Optionally, in the embodiments of this application, the computer-readable storage medium is a non-transitory computer-readable storage medium.

[0163] Furthermore, it should be understood that since the various modules are only provided to illustrate the functional units of the device described in this application, the physical devices corresponding to these modules may be the processor itself, or a part of the processor's software, hardware, or a combination of both. Therefore, the number of modules shown in the figures is merely illustrative.

[0164] Those skilled in the art will understand that the various modules in the device can be adaptively split or combined. Such splitting or combining of specific modules will not cause the technical solution to deviate from the principles of this application; therefore, the technical solutions after splitting or combining will fall within the protection scope of this application.

[0165] It should be noted that the relevant user personal information involved in the various embodiments of this application is processed in strict accordance with the requirements of laws and regulations, following the principles of legality, legitimacy, and necessity, based on the reasonable purpose of the business scenario, and is personal information that users actively provide or generate during the use of the product / service, as well as personal information obtained with user authorization.

[0166] The personal information processed in this application will vary depending on the specific product / service scenario and will be subject to the specific scenario in which the user uses the product / service. It 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 the utmost diligence.

[0167] This application attaches great importance to the security of users' personal information and has taken reasonable and feasible security protection measures that comply with industry standards to protect users' information and prevent unauthorized access, disclosure, use, modification, damage or loss of personal information.

[0168] The technical solution of this application has been described in conjunction with the embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of this application is obviously not limited to these specific embodiments. Without departing from the principles of this application, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of this application.

Claims

1. A method of monitoring power module losses, characterized by, The method comprises: determining an initial loss of the power module under ideal conditions based on a loss algorithm under an SPWM control signal; the ideal conditions include that the SPWM control signal is a symmetrical signal, and / or a fundamental frequency of a phase voltage is always greater than a preset frequency; determining an actual loss of the power module under the ideal conditions under an actual control signal based on the initial loss and a preset loss correlation; and the loss correlation is a loss correlation between different control signals and the SPWM control signal; if the actual control signal is a DPWM control signal, the loss correlation includes modifying the initial loss; the determining of the actual loss of the power module under the ideal conditions under the actual control signal based on the initial loss and the preset loss correlation includes modifying the initial loss based on a preset loss modification strategy to obtain the actual loss; the modifying of the initial loss based on the preset loss modification strategy to obtain the actual loss includes: if the initial loss includes an initial conduction loss, modifying the initial conduction loss based on a first modification coefficient to obtain an actual conduction loss in the actual loss; wherein the first modification coefficient is determined based on a modulation ratio of the power module and a power factor angle of the power module.

2. The method of claim 1, wherein, the modifying of the initial loss based on the preset loss modification strategy to obtain the actual loss includes: if the initial loss includes an initial switching loss, modifying the initial switching loss based on a second modification coefficient to obtain an actual switching loss in the actual loss; wherein the second modification coefficient is determined based on the power factor angle.

3. The method of claim 1, wherein, the first modification coefficient is determined based on the modulation ratio of the power module and the power factor angle of the power module, including: if the power factor angle of the power module is less than a power angle threshold, it is determined that the first modification coefficient decreases with the increase of the modulation ratio; and when the modulation ratio is less than a modulation ratio threshold, the first modification coefficient is greater than 1, when the modulation ratio is greater than the modulation ratio threshold, the first modification coefficient is less than 1; when the modulation ratio is equal to the modulation ratio threshold, the first modification coefficient is equal to 1.

4. The method of claim 1, wherein the first modification coefficient is determined based on the modulation ratio of the power module and the power factor angle of the power module, including: if the power factor angle of the power module is greater than a power angle threshold, it is determined that the first modification coefficient increases with the increase of the modulation ratio; and when the modulation ratio is less than a modulation ratio threshold, the first modification coefficient is less than 1, when the modulation ratio is greater than the modulation ratio threshold, the first modification coefficient is greater than 1; when the modulation ratio is equal to the modulation ratio threshold, the first modification coefficient is equal to 1.

5. The method of claim 2, wherein, the second modification coefficient is determined based on the power factor angle, including: the second modification coefficient is determined based on the cosine value of the power factor angle under 1 and a preset multiple.

6. The method of claim 1, wherein, if the actual control signal is an SVPWM control signal, the loss correlation does not include modifying the initial loss. Based on the preset loss correlation relationship, the initial loss is used to determine the actual loss of the power module under the actual control signal in the ideal condition, comprising: The initial loss is used as the actual loss.

7. The method of claim 6, wherein, Before determining the initial loss of the power module under the SPWM control signal in the ideal condition, further comprising: Based on the type of power device in the power module, the loss algorithm is determined.

8. A smart device, comprising: A processor and a storage device are included, and the storage device is adapted to store a plurality of program codes, which are adapted to be loaded and run by the processor to execute the power module loss monitoring method of any one of claims 1 to 7.

9. A computer readable storage medium characterized by, A plurality of program codes are stored, which are adapted to be loaded and run by the processor to execute the power module loss monitoring method of any one of claims 1 to 7.

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