Control method and device for reducing IGBT (Insulated Gate Bipolar Translator) loss, electric drive system and vehicle

Abstract

The invention relates to a control method and device for reducing IGBT (Insulated Gate Bipolar Translator) loss, an electric drive system and a vehicle. The IGBT driving module is used for driving an IGBT device; the IGBT driving module comprises a positive voltage control unit, a negative voltage control unit and a control unit, the positive voltage control unit comprises a plurality of positive voltage gears used for conducting the IGBT device, and the plurality of positive voltage gears are respectively a positive voltage gear I to a positive voltage gear N; the negative pressure control unit comprises a plurality of negative pressure gears for turning off the IGBT device, and the plurality of negative pressure gears are respectively a negative pressure gear I to a negative pressure gear N; the voltage acquisition module is used for acquiring peak voltage of the IGBT device; and the analysis module is used for analyzing and controlling the gear adjustment of the IGBT driving module according to the collected peak voltage. Driving parameters are dynamically adjusted in real time, so that the driving system is kept in a working state with the lowest switching loss in the whole life cycle.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electric control system, and in particular to a control method and device for reducing IGBT loss, an electric drive system and a vehicle. BACKGROUND

[0002] The IGBT device loss mainly includes switching loss and conduction loss, and the conduction loss is determined by the IGBT device itself, and the external driving system generally has little effect. The switching loss is determined by the external driving circuit, and is an important factor affecting the switching loss. At present, the constant voltage driving mode is generally used. Generally speaking, the smaller the driving resistance, the faster the conduction speed, and the smaller the switching loss. However, due to the existence of stray inductance in the power path, V=L*di / dt, if the conduction speed is too fast, the voltage spike will be too large to damage the IGBT device.

[0003] The current method is to perform double-pulse debugging, select the maximum working voltage and working current, and try to reduce the driving resistance under the condition of meeting the safety margin of the voltage spike, so as to balance the voltage spike and the switching loss. However, since the driving resistance value is fixed after the double-pulse test is completed, the following problems exist: The voltage spike margin is too large at a small voltage, which causes the loss to be not at the lowest state, and the stray inductance changes due to system aging or product differences, so the current fixed driving parameters may not be able to guarantee that the switching loss of all IGBT devices can reach the optimal balance point.

[0004] Therefore, it is necessary to develop a new control method and device for reducing IGBT loss, an electric drive system and a vehicle. SUMMARY

[0005] The purpose of the present application is to provide a control method and device for reducing IGBT loss, an electric drive system and a vehicle, which dynamically adjusts the driving parameters in real time, so that the driving system can maintain the lowest switching loss state throughout the life cycle.

[0006] The control device for reducing IGBT loss according to the present application comprises: an IGBT device; an IGBT driving module connected to the gate of the IGBT device for driving the IGBT device; the IGBT driving module comprises a positive voltage control unit, a negative voltage control unit and a control unit for performing gear control, and the positive voltage control unit and the negative voltage control unit are respectively connected to the control unit; The positive voltage control unit comprises a plurality of positive voltage gears for turning on the IGBT device, and the plurality of positive voltage gears are respectively positive voltage gear one to positive voltage gear N, the higher the positive voltage gear, the shorter the conduction time of the IGBT device, and N is an integer and N>1; The negative voltage control unit comprises a plurality of negative voltage gears for turning off the IGBT device, and the plurality of negative voltage gears are respectively negative voltage gear one to negative voltage gear N, and the higher the negative voltage gear is, the shorter the turn-off time of the IGBT device is. The voltage acquisition module is connected with the IGBT device and is used for acquiring the peak voltage of the IGBT device. The analysis module is connected with the voltage acquisition module and the IGBT drive module, and is used for analyzing and controlling the gear adjustment of the IGBT drive module according to the acquired peak voltage.

[0007] Optionally, the positive voltage control unit comprises a first power supply V1, a first current-limiting resistor Rc, a first resistor Rd, a first transistor Q1, a first amplifier C1, a second power supply V2, a first switching switch G1 and N+1 positive voltage dividing resistors. The positive electrode of the first power supply V1, the first current-limiting resistor Rc and the drain of the first transistor Q1 are sequentially connected, the source of the first transistor Q1, the first resistor Rd and the negative electrode of the first power supply V1 are sequentially connected, and the connection node between the first resistor Rd and the negative electrode of the first power supply V1 is grounded. The connection node between the first current-limiting resistor Rc and the drain of the first transistor Q1 is connected with the non-inverting input terminal of the first amplifier C1, and the output terminal of the first amplifier C1 is connected with the gate of the first transistor Q1. The N+1 positive voltage dividing resistors are sequentially connected in series to form a first circuit, the positive electrode of the second power supply V2 is connected with a first end in the first circuit, the negative electrode of the second power supply V2 is connected with a second end in the first circuit and the connection node between the two is grounded. The first circuit comprises N first common nodes respectively located between adjacent two positive voltage dividing resistors, the first switching switch G1 comprises a first connection end and N second connection ends, the first connection end is connected with the inverting input terminal of the first amplifier C1, and the N second connection ends are respectively connected with the N first common nodes one by one. The first switching switch G1 is connected with the control unit, and the connection node between the source of the first transistor Q1 and the first resistor Rd is connected with the gate of the IGBT device. The N second connection ends are respectively positive voltage gear one to positive voltage gear N from the positive electrode to the negative electrode of the second power supply V2.

[0008] Optionally, the negative voltage control unit comprises a third power supply V3, a second current-limiting resistor Re, a second resistor Rf, a second transistor Q2, a second amplifier C2, a fourth power supply V4, a second switching switch G2 and N+1 negative voltage dividing resistors. The positive pole of the third power supply V3, the second current-limiting resistor Re and the drain of the second transistor Q2 are sequentially connected, the source of the second transistor Q2, the second resistor Rf and the negative pole of the third power supply V3 are sequentially connected, and the connection node between the second resistor Rf and the negative pole of the third power supply V3 is grounded. The connection node between the second current-limiting resistor Re and the drain of the second transistor Q2 is connected with the inverting input end of the second amplifier C2, and the output end of the second amplifier C2 is connected with the gate of the second transistor Q2. N+1 negative voltage dividing resistors are sequentially connected in series to form a second circuit, the positive pole of the fourth power supply V4 is connected with the first end in the second circuit, the negative pole of the fourth power supply V4 is connected with the second end in the second circuit, and the connection node between the two is grounded. The second circuit includes N second common nodes respectively located between adjacent two negative voltage dividing resistors, the second switching switch G2 includes a third connection end and N fourth connection ends, the third connection end is connected with the non-inverting input end of the second amplifier C2, and the N fourth connection ends are connected with the N second common nodes one by one. The second switching switch G2 is connected with the control unit, and the connection node between the source of the second transistor Q2 and the second resistor Rf is connected with the gate of the IGBT device. The N fourth connection ends are sequentially negative pressure gears one to N from the positive pole to the negative pole of the fourth power supply V4.

[0009] Optionally, the voltage acquisition module includes a transient voltage suppression diode TVS, a first voltage dividing resistor Ra, a sampling resistor Rb and a voltage acquisition unit for acquiring the voltage of the sampling resistor Rb. The negative pole of the transient voltage suppression diode TVS is connected with the collector of the IGBT device, the two ends of the first voltage dividing resistor Ra are respectively connected with the positive pole of the transient voltage suppression diode TVS and the first end of the sampling resistor Rb, and the second end of the sampling resistor Rb is connected with the emitter of the IGBT device. The first end and the second end of the sampling resistor Rb are also respectively connected with the voltage acquisition unit. The peak voltage of the IGBT device is estimated by the voltage acquisition unit to acquire the sampling voltage of the sampling resistor Rb.

[0010] Optionally, a load circuit is further included, the load circuit includes a fifth power supply V5, a parasitic inductance L1 and a load, the positive pole of the fifth power supply V5, the parasitic inductance L1 and the collector of the IGBT device are sequentially connected, the emitter of the IGBT device, the load and the negative pole of the fifth power supply V5 are sequentially connected, and the connection node between the load and the negative pole of the fifth power supply V5 is grounded.

[0011] In a second aspect, the application discloses a control method for reducing IGBT loss, which adopts the control device for reducing IGBT loss. S1, when powered on, the IGBT driving module starts to drive the IGBT device step by step from the positive voltage gear one and the negative voltage gear one; wherein, when reaching the gear N, the IGBT device is kept at the gear N; S2, whether the voltage collection module collects the peak voltage of the IGBT device, if yes, the peak voltage of the IGBT device is sent to the analysis module, and the step S3 is executed; otherwise, the IGBT driving module keeps the current output, and the step S2 is executed continuously; S3, the analysis module judges whether the peak voltage is higher than the maximum peak voltage threshold, if yes, the step S4 is executed, otherwise, the step S5 is executed; S4, the analysis module identifies the current gear X and judges whether the current gear X is the gear one, if yes, the output is stopped and an alarm is given, and the process is ended; otherwise, the IGBT driving module drives the IGBT device step by step after reducing the current gear X by one gear, and the step S2 is executed; S5, the analysis module judges whether the peak voltage is lower than the minimum peak voltage threshold, if yes, the step S6 is executed; otherwise, the IGBT driving module keeps the current output, and the step S2 is executed; S6, the analysis module identifies the current gear X and judges whether the current gear X is the gear N; if yes, the IGBT device is kept at the gear N, and the step S2 is executed; otherwise, the IGBT driving module drives the IGBT device step by step after increasing the current gear X by one gear or keeps the IGBT device at the gear N, and the step S2 is executed.

[0012] Optionally, the calculation formula of the turn-on time of each positive voltage gear is as follows: t1=(C2×(V1’-V4’)) / ((V1’-V2’×(r1+r2+…+rX) / (r1+r2+…+ri+…+rN)) / RC)+offset1; wherein, t1 is the turn-on time; r represents the positive voltage dividing resistor; X is the current gear; ri represents the resistance value of the positive voltage dividing resistor, i=1, 2, 3, …, N-1, N; N is the total number of the positive voltage dividing resistor; offset1 is the compensation correction time for exiting the constant current area, the value range of offset1 is [0.05us, 0.2us], C2 is the input capacitance of the IGBT device, RC is the resistance value of the first current limiting resistor Rc, V1’ is the voltage value of the first power supply V1, V2’ is the voltage value of the second power supply V2, and V4’ is the voltage value of the fourth power supply V4.

[0013] Optionally, the calculation formula of the turn-off time of each negative pressure gear is as follows: t2=(C2×(V1'-V4')) / ((V3'-(V4'×(r1+r2+…+rX) / (r1+r2+…+rj+…+rN))) / RE)+offset2; Wherein, t2 is the turn-off time; X is the current gear; rj represents the resistance value of the positive pressure dividing resistor, j=1, 2, 3, …, N-1, N; N is the total number of the negative pressure dividing resistor; offset2 is the compensation correction time for exiting the constant current area, the value range of offset2 is [0.05us, 0.2us]; C2 is the input capacitance of the IGBT device; RE is the resistance value of the second current limiting resistor Re; V1' is the voltage value of the first power supply V1, V3' is the voltage value of the third power supply V3, and V4' is the voltage value of the fourth power supply V4.

[0014] In a third aspect, the application provides an electric drive system, which comprises the control device for reducing IGBT loss.

[0015] In a fourth aspect, the application provides a vehicle, which comprises the electric drive system.

[0016] The application has the following advantages: (1) Dynamic adjustment, reduce loss: By real-time monitoring of the peak voltage and dynamically adjusting the driving gear, the problem of increased loss caused by excessive peak margin under small voltage is effectively avoided, and the change of stray inductance caused by system aging or product difference is adapted, so that the switching loss of the IGBT device is minimized throughout the life cycle.

[0017] (2) High flexibility, perfect protection: It has higher flexibility, can dynamically adjust the driving parameters according to the actual working conditions, effectively prevents the damage of IGBT device caused by abnormal stray inductance of the system, and improves the reliability and safety of the system.

[0018] (3) Simplify the process and improve the efficiency: No longer need to perform tedious double pulse test to adjust the driving parameters, simplify the test process, improve the development efficiency and reduce the cost.

[0019] In summary, the control method, device, electric drive system and vehicle for reducing IGBT loss of the application effectively reduce the switching loss of the IGBT device by dynamically adjusting the driving parameters, improve the reliability and safety of the system, simplify the development process, and have significant economic and social benefits. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1A schematic diagram of the control device for reducing IGBT loss in the embodiments of the present application; Figure 2 A schematic diagram of the IGBT driving module in the embodiments of the present application; Figure 3 A circuit diagram of the positive voltage control unit in the embodiments of the present application; Figure 4 A circuit diagram of the negative voltage control unit in the embodiments of the present application.

[0021] Figure 5 A flow chart of the control method for reducing IGBT loss in the embodiments of the present application; Figure 6 Simulation results of high peak voltage (TVS breakdown); Figure 7 Simulation results of low peak voltage (TVS not breakdown); Figure 8 Simulation results of positive voltage gear one driving IGBT capacitor charging curve; Figure 9 Simulation results of positive voltage gear two driving IGBT capacitor charging curve; Figure 10 Simulation results of positive voltage gear three driving IGBT capacitor charging curve; Figure 11 Simulation results of negative voltage gear one driving IGBT capacitor charging curve; Figure 12 Simulation results of negative voltage gear two driving IGBT capacitor charging curve; Figure 13 Simulation results of negative voltage gear three driving IGBT capacitor charging curve; Reference signs: 1-IGBT device; 2-IGBT driving module; 21-positive voltage control unit; 22-negative voltage control unit; 23-control unit, second switching switch; 3-voltage acquisition module; 31-voltage acquisition unit; 4-analysis module. DETAILED DESCRIPTION

[0022] The embodiments of the present application will be described below with reference to the accompanying drawings and preferred embodiments, and other advantages and effects of the present application can be understood by those skilled in the art from the disclosure in the specification. The present application can also be implemented or applied by other different specific embodiments, and each detail in the specification can be modified or changed based on different views and applications without departing from the spirit of the present application. It should be understood that the preferred embodiments are only for illustrating the present application, and are not intended to limit the protection scope of the present application.

[0023] As Figure 1 and Figure 2As shown, in the embodiments of the present application, a control device for reducing IGBT loss includes an IGBT device 1, an IGBT drive module 2, a voltage acquisition module 3 and an analysis module 4. The IGBT drive module 2 is connected to the gate of the IGBT device 1 for driving the IGBT device 1. The IGBT drive module 2 includes a positive voltage control unit 21, a negative voltage control unit 22 and a control unit 23 for performing gear control, and the positive voltage control unit 21 and the negative voltage control unit 22 are connected to the control unit 23. The positive voltage control unit 21 includes a plurality of positive voltage gears for turning on the IGBT device 1, and the plurality of positive voltage gears are respectively positive voltage gear one to positive voltage gear N. The higher the positive voltage gear, the shorter the turn-on time of the IGBT device 1, and N is an integer and N>1. The negative voltage control unit 22 includes a plurality of negative voltage gears for turning off the IGBT device 1, and the plurality of negative voltage gears are respectively negative voltage gear one to negative voltage gear N. The higher the negative voltage gear, the shorter the turn-off time of the IGBT device 1. The voltage acquisition module 3 is connected to the IGBT device 1 for acquiring the peak voltage of the IGBT device 1. The analysis module 4 is connected to the voltage acquisition module 3 and the IGBT drive module 2 for analyzing and controlling the gear adjustment of the IGBT drive module 2 according to the acquired peak voltage.

[0024] As shown in Figure 3 In a possible embodiment, the positive voltage control unit 21 includes a first power supply V1, a first current limiting resistor Rc, a first resistor Rd, a first transistor Q1, a first amplifier C1, a second power supply V2, a first switching switch G1 and N+1 positive voltage dividing resistors, and the connection relationship is as follows: The anode of the first power supply V1, the first current-limiting resistor Rc, and the drain of the first transistor Q1 are sequentially connected, the source of the first transistor Q1, the first resistor Rd, and the cathode of the first power supply V1 are sequentially connected, and the connection node between the first resistor Rd and the cathode of the first power supply V1 is grounded. The connection node between the first current-limiting resistor Rc and the drain of the first transistor Q1 is connected with the non-inverting input terminal of the first amplifier C1, and the output terminal of the first amplifier C1 is connected with the gate of the first transistor Q1. N+1 positive voltage dividing resistors are sequentially connected in series to form a first circuit, the anode of the second power supply V2 is connected with the first end in the first circuit, the cathode of the second power supply V2 is connected with the second end in the first circuit, and the connection node between the anode and the cathode of the second power supply V2 is grounded. The first circuit includes N first common nodes respectively located between adjacent two positive voltage dividing resistors, the first switching switch G1 includes one first connection end and N second connection ends, the first connection end is connected with the inverting input terminal of the first amplifier C1, and the N second connection ends are respectively and one-to-one connected with the N first common nodes. The first switching switch G1 is connected with the control unit 23, and the connection node between the source of the first transistor Q1 and the first resistor Rd is connected with the gate of the IGBT device 1. The N second connection ends are sequentially positive voltage gear one to positive voltage gear N from the anode to the cathode of the second power supply V2.

[0025] The first current-limiting resistor Rc functions to control the size of the constant-current-like output current, and can be combined with the gear to control the switching speed. The smaller the resistance is, the faster the switching speed is. The first switching switch G1 is used to switch different gears, and can adopt a mode including but not limited to digital switching. The first resistor Rd is used to prevent the IGBT from being misdirected. The circuits in the positive voltage control unit 21 and the negative voltage control unit 22 of the application are constant-current-like output circuits that can be automatically switched. The on and off time is controlled by controlling the current size. The lower the gear is, the smaller the current is, and the longer the time is. In the embodiment, the first power supply V1 and the second power supply V2 can be the same power supply. In order to reduce the power supply demand, the same power supply can be used. In order to consider the coverage of the scheme, the first power supply V1 and the second power supply V2 can also not be the same power supply, and can also have different voltages. According to the system voltage and the current dynamic adjustment driving current, the opening time is controlled, so that the switching loss is adapted to various working conditions to keep the lowest state.

[0026] In a possible embodiment, the first transistor Q1 is an NMOS.

[0027] As shown in Figure 4 In a possible embodiment, the negative voltage control unit 22 includes a third power supply V3, a second current-limiting resistor Re, a second resistor Rf, a second transistor Q2, a second amplifier C2, a fourth power supply V4, a second switching switch G2, and N+1 negative voltage dividing resistors, and the specific connection relationship is as follows: The positive pole of the third power supply V3, the second current-limiting resistor Re, and the drain of the second transistor Q2 are sequentially connected, the source of the second transistor Q2, the second resistor Rf, and the negative pole of the third power supply V3 are sequentially connected, and the connection node between the second resistor Rf and the negative pole of the third power supply V3 is grounded. The connection node between the second current-limiting resistor Re and the drain of the second transistor Q2 is connected with the inverting input terminal of the second amplifier C2, and the output terminal of the second amplifier C2 is connected with the gate of the second transistor Q2. N+1 negative voltage dividing resistors are sequentially connected in series to form a second circuit, the positive pole of the fourth power supply V4 is connected with the first end in the second circuit, the negative pole of the fourth power supply V4 is connected with the second end in the second circuit and the connection node between the two is grounded. The second circuit includes N second common nodes respectively located between adjacent two negative voltage dividing resistors, the second switching switch G2 includes a third connection end and N fourth connection ends, the third connection end is connected with the non-inverting input terminal of the second amplifier C2, and the N fourth connection ends are connected with the N second common nodes one by one. The second switching switch G2 is connected with the control unit 23, and the connection node between the source of the second transistor Q2 and the second resistor Rf is connected with the gate of the IGBT device 1. The N fourth connection ends are sequentially negative voltage gears one to N from the positive pole of the fourth power supply V4 to the negative pole.

[0028] In a possible embodiment, the second current-limiting resistor Re functions to control the size of the constant-like current output, and can be combined with the gear to control the switching speed. The smaller the resistance is, the faster the switching speed is. The first switching switch G1 is used to switch different gears, and can adopt a mode including but not limited to digital switching. The second resistor Rf is used to prevent the IGBT from being misdirected on. According to the dynamic adjustment of the driving current according to the system voltage and current, the turn-off time is controlled, so that the switching loss is adapted to various working conditions to keep the lowest state.

[0029] In a possible embodiment, the third power supply V3 and the fourth power supply V4 can be the same power supply. In order to reduce the power supply demand, the same power supply can be used. In order to consider the coverage of the scheme, the third power supply V3 and the fourth power supply V4 can also not be the same power supply, and can also have different voltages.

[0030] In a possible embodiment, the second transistor Q2 is a PMOS.

[0031] As shown in Figure 1 In a possible embodiment, the voltage acquisition module 3 includes a transient voltage suppression diode TVS, a first voltage dividing resistor Ra, a sampling resistor Rb, and a voltage acquisition unit 31 for acquiring the voltage of the sampling resistor Rb. The specific connection relationship is as follows: The negative electrode of the transient voltage suppression diode TVS is connected with the collector of the IGBT device 1, the two ends of the first voltage dividing resistor Ra are respectively connected with the positive electrode of the transient voltage suppression diode TVS and the first end of the sampling resistor Rb, and the second end of the sampling resistor Rb is connected with the emitter of the IGBT device 1. The first end and the second end of the sampling resistor Rb are also respectively connected with the voltage acquisition unit 31. The peak voltage of the IGBT device 1 is estimated by collecting the sampling voltage of the sampling resistor Rb through the voltage acquisition unit 31. Since the peak voltage is high voltage, general devices cannot collect high voltage, so the peak voltage is obtained by converting the sampling voltage through voltage division. The transient voltage suppression diode TVS will not be turned on without the peak voltage, and the function of the transient voltage suppression diode TVS is to avoid the working of the first voltage dividing resistor Ra and the sampling resistor Rb without the peak, so that the current time of the first voltage dividing resistor Ra and the sampling resistor Rb is greatly shortened, thereby avoiding the heating and loss of the bus voltage.

[0032] The transient voltage suppression diode TVS functions to avoid the working of the first voltage dividing resistor Ra and the sampling resistor Rb without the peak, so that the current time of the first voltage dividing resistor Ra and the sampling resistor Rb is greatly shortened, thereby avoiding the heating and loss of the bus voltage. Without the peak, the transient voltage suppression diode TVS is not turned on, and is not turned on in the non-switching time (i.e. the IGBT conduction time, which accounts for more than 90% of the time).

[0033] As shown in FIG. 1, Figure 1 As shown in FIG. 1,

[0034] In a possible embodiment, the resistances of the N+1 positive voltage dividing resistors and the N+1 negative voltage dividing resistors are equal, and the resistance values of the positive voltage dividing resistors and the negative voltage dividing resistors are in the range of [1K, 100K], which can reduce the current while keeping the voltage signal not easily disturbed.

[0035] As shown in FIG. 1, Figure 5 As shown in FIG. 1, S1, when powered on, the IGBT drive module 2 starts to drive the IGBT device 1 from the positive gear one and the negative gear one, and gradually increases the gear step by step; wherein when reaching the gear N, the gear N is kept to drive the IGBT device 1.

[0036] S2, whether the voltage acquisition module 3 collects the spike voltage of the IGBT device 1, if yes, the spike voltage of the IGBT device 1 is sent to the analysis module 4, and step S3 is executed; otherwise, the IGBT driving module 2 keeps the current output, and step S2 is continued to execute. The IGBT driving module 2 keeping the current output means that the current driving mode of the IGBT driving module 2 is not changed, and the execution is continued.

[0037] Specifically, the voltage acquisition module 3 collects signals of the IGBT device 1 according to a preset acquisition period, the preset acquisition period is a preset multiple of a switching period of the IGBT device 1, and the preset multiple is ≥1 and is an integer. The switching period is the time required for the IGBT device 1 to complete one cycle of action through positive voltage conduction and negative voltage turn-off, and one cycle of action is conducted, maintained, turned off and maintained off.

[0038] In the embodiment, the preset multiple is 1 or 2 or 3 or 4 or other values, the higher the sampling frequency, the higher the system load, and the actual system capacity needs to be confirmed. Optionally, the preset multiple is 1.

[0039] S3, the analysis module 4 judges whether the spike voltage is higher than the maximum spike voltage threshold, if yes, step S4 is executed; otherwise, step S5 is executed.

[0040] S4, the analysis module 4 identifies the current gear X and judges whether the current gear X is gear one, if yes, the output is stopped and an alarm is given, and the process is ended; otherwise, the IGBT driving module 2 reduces the current gear X by one gear and then gradually increases the gear to drive the IGBT device 1, and step S2 is executed.

[0041] The gear (X-1) increases the conduction or turn-off time, according to the spike voltage V=L*di / dt, the larger the dt, the smaller the spike voltage V, so that the spike voltage is reduced to a safe range, and the safety is ensured. If the current gear X is gear one, the output is stopped and an alarm is given, at this time, the lowest voltage spike of the gear exceeds the threshold, and it cannot be adjusted any more. If the current gear X is reduced by one gear, the gear is gradually increased according to the switching period. The above-mentioned gears include positive voltage gears and negative voltage gears, the type of the current gear X is determined according to the type of the current gear, and the current gear X can be a negative voltage gear X and a positive voltage gear X, which is determined according to the actual situation. If the current gear X is a positive voltage gear X, the adjusted gear is a positive voltage gear (X-1); if the current gear X is a negative voltage gear X, the adjusted gear is a negative voltage gear (X-1).

[0042] S5, the analysis module 4 judges whether the spike voltage is lower than the minimum spike voltage threshold, if yes, step S6 is executed; otherwise, the IGBT driving module 2 keeps the current output, and step S2 is executed. S6, the analysis module 4 identifies the current gear X and determines whether the current gear X is the gear N; if yes, the gear N drives the IGBT device 1 and the step S2 is performed; otherwise, the IGBT drive module 2 increases the current gear X by one gear and drives the IGBT device 1 step by step or keeps the gear N to drive the IGBT device 1, and the step S2 is performed.

[0043] The gear (X+1) reduces the on or off time, according to V=L*di / dt, the smaller the dt, the greater the peak voltage V, so as to increase the peak voltage to reduce the switching loss. When the current gear X is increased by one gear and equal to the gear N, the gear N drives the IGBT device 1; if the current gear X is increased by one gear and not equal to the gear N, the gear is increased step by step according to the switching period. Similarly, if the current gear X is a positive pressure gear X, the adjusted gear is a positive pressure gear (X+1); if the current gear X is a negative pressure gear X, the adjusted gear is a negative pressure gear (X+1).

[0044] The on time and the off time are controlled by the control method for reducing the IGBT loss disclosed in the application. The on time and the off time are flexibly controlled by the MCU according to the requirements of the control object. The peak voltage should be increased step by step to the next gear until the peak voltage is in the preset range of the peak voltage or has been increased to the maximum gear. The gears of the positive pressure control unit 21 and the gears of the negative pressure control unit 22 are independently controlled. The lowest gear is adopted to drive the IGBT device 1 when the power is on, which ensures the safety of the system. The MCU module sends high level to the IGBT drive module 2, that is, outputs positive pressure; the MCU module sends low level to the IGBT drive module 2, that is, outputs negative pressure. The on time of the IGBT device 1 is controlled by the positive pressure gear, and the off time of the IGBT device 1 is controlled by the negative pressure gear. The IGBT device 1 works in four stages in one switching period, including on, keep on, off and keep off. When on, the on time of the IGBT device 1 is controlled by the positive pressure gear; when off, the off time of the IGBT device 1 is controlled by the negative pressure gear. The on, keep on, off and keep off actions are performed in turn according to the control of the MCU module and the gear switching time, and are periodically and continuously performed. For example, in the first switching period, the on selects the positive pressure gear one, the keep on, the off adopts the negative pressure gear one, and the keep off; in the second switching period, the on selects the positive pressure gear two, the keep on, the off adopts the negative pressure gear two, and the keep off; and so on.

[0045] In some embodiments, the peak voltage control range is, for example, 2V~3V, and in other embodiments, it is set according to the actual situation, which is not limited herein. For example, the peak voltage control range is 2V~3V, the minimum peak voltage threshold is 2V, and the minimum peak voltage threshold is 3V.

[0046] In this embodiment, the analysis module 4 determines whether the peak voltage is higher than the maximum peak voltage threshold, if yes, it goes to execute step S4; otherwise, it goes to execute step S5; including executing the following steps: The analysis module 4 determines whether the peak voltage is higher than the maximum peak voltage threshold and is continuously collected M times, M≥1 and is an integer; if yes, it goes to execute step S4; otherwise, it goes to execute step S5.

[0047] In this embodiment, the analysis module 4 determines whether the peak voltage is lower than the minimum peak voltage threshold, if yes, it goes to execute step S6; otherwise, it keeps the current gear X driving the IGBT device 1, and goes to execute step S2; including executing the following steps: The analysis module 4 determines whether the peak voltage is lower than the minimum peak voltage threshold and is continuously collected M times, M≥1 and is an integer; if yes, it goes to execute step S6; otherwise, it keeps the current gear X driving the IGBT device 1, and goes to execute step S2. The switching is based on the judgment of the peak voltage, considering the peak fluctuation to filter out interference, and M is greater than or equal to 2 times. Exemplarily, M=3, which is not limited here, and can be selected according to actual needs.

[0048] In a possible embodiment, the calculation formula of the peak voltage of the IGBT device 1 is as follows: V=Vsense1*(RB+RA) / RB+Vtvs+Offset3; Wherein, V is the peak voltage of the IGBT device 1, Vtvs is the TVS breakdown working voltage, offset3 is the calibration coefficient, RA is the resistance value of the first voltage dividing resistor Ra; RB is the resistance value of the sampling resistor Rb; Vsense1 is the sampling voltage of the sampling resistor Rb, which can obtain its upper and lower limit range according to the peak voltage control range and configure. offset3 is the TVS breakdown voltage calibration and system error calibration, generally the value range is [-60V, 60V], which can be calibrated according to the actual situation, and the value of offset3 is calibrated according to the difference between the actual test voltage peak (similar to double pulse) and the peak voltage read by the system during debugging. Refer to Figure 1 , Vsense1 is the low voltage obtained by voltage dividing of the first voltage dividing resistor Ra and the sampling resistor Rb.

[0049] In a possible embodiment, the calculation formula of the conduction time of each positive voltage gear is as follows: t1=(C2×(V1’-V4’)) / ((V1’-V2’×(r1+r2+…+rX) / (r1+r2+…+ri+…+rN)) / RC)+offset1; Wherein, t1 is the on time; r represents the positive voltage division resistance; X is the current gear; ri represents the resistance value of the positive voltage division resistance, i = 1, 2, 3, …, N-1, N; N is the total number of the positive voltage division resistance; offset1 is the compensation correction time for exiting the constant current area, the value range of offset1 is [0.05us, 0.2us], C2 is the input capacitance of the IGBT device, RC is the resistance value of the first current limiting resistor Rc, V1' is the voltage value of the first power supply V1, V2' is the voltage value of the second power supply V2, V4' is the voltage value of the fourth power supply V4.

[0050] In a possible embodiment, the calculation formula of the off time of each negative voltage gear is as follows: t2=(C2×(V1'-V4')) / ((V3'-(V4'×(r1+r2+…+rX) / (r1+r2+…+rj+…+rN))) / RE)+offset2; Wherein, t2 is the off time; X is the current gear; rj represents the resistance value of the positive voltage division resistance, j = 1, 2, 3, …, N-1, N; N is the total number of the negative voltage division resistance; offset2 is the compensation correction time for exiting the constant current area, the value range of offset2 is [0.05us, 0.2us]; C2 is the input capacitance of the IGBT device 1; RE is the resistance value of the second current limiting resistor Re; V3' is the voltage value of the third power supply V3, V1' is the voltage value of the first power supply V1, V4' is the voltage value of the fourth power supply V4.

[0051] As shown in Figure 6 , it is the simulation result of high peak voltage (TVS breakdown), when TVS breaks down, a voltage obviously greater than 0.5V can be detected, which can be used to determine whether it is a normal voltage or an interference voltage.

[0052] As shown in Figure 7 , it is the simulation result of low peak voltage (TVS not breakdown), when TVS does not break down, a voltage lower than 60mV can be detected, when a voltage obviously lower than 0.5V is detected, it can be used to determine whether it is a normal voltage or an interference voltage.

[0053] As shown in Figure 8 , it is the simulation result of the positive voltage gear one driving IGBT capacitor charging curve, the positive voltage charging time of the IGBT capacitor of the one gear resistance value is 1.7us.

[0054] As shown in Figure 9 , it is the simulation result of the positive voltage gear two driving IGBT capacitor charging curve, the positive voltage charging time of the IGBT capacitor of the two gear resistance value is 0.8us.

[0055] As shown in Figure 10As shown in the figure, it is a positive voltage gear three drive IGBT capacitor charging curve simulation result, and the positive voltage charging time of the three-gear resistance IGBT capacitor is 0.6us.

[0056] As shown in the figure, it is a positive voltage gear three drive IGBT capacitor charging curve simulation result, and the positive voltage charging time of the three-gear resistance IGBT capacitor is 0.6us. Figure 11 As shown in the figure, it is a negative voltage gear one drive IGBT capacitor charging curve simulation result, and the negative voltage charging time of the one-gear resistance IGBT capacitor is 1us.

[0057] As shown in the figure, it is a negative voltage gear two drive IGBT capacitor charging curve simulation result, and the positive voltage charging time of the two-gear resistance IGBT capacitor is 0.5us. Figure 12 As shown in the figure, it is a negative voltage gear three drive IGBT capacitor charging curve simulation result, and the negative voltage charging time of the three-gear resistance IGBT capacitor is 0.3us.

[0058] Figure 13 As shown in the figure, it is a negative voltage gear three drive IGBT capacitor charging curve simulation result, and the negative voltage charging time of the three-gear resistance IGBT capacitor is 0.3us.

[0059] In the embodiment of the application, an electric drive system adopts the control device for reducing IGBT loss in the embodiment of the application.

[0060] In the embodiment of the application, a vehicle adopts the electric drive system in the embodiment of the application.

[0061] The control method and device for reducing IGBT loss, the electric drive system and the vehicle can keep the switch loss of the driving system at the lowest working state in the whole life cycle by dynamically adjusting the driving parameters in real time, so as to improve the system utilization rate, have higher flexibility, can effectively protect the system stray inductance, and do not need to perform double pulse test to adjust the driving parameters, thereby simplifying the test process.

[0062] The above embodiments are the preferred embodiments of the application, but the embodiments of the application are not limited to the above embodiments, and any changes, modifications, substitutions, combinations and simplifications made without departing from the spirit and principles of the application shall be equivalent replacement modes and shall be included in the protection scope of the application.​

Claims

1. A control device for reducing IGBT losses, characterized in that, include: IGBT devices (1); IGBT drive module (2) is connected to the gate of the IGBT device (1) and is used to drive the IGBT device (1); the IGBT drive module (2) includes a positive pressure control unit (21), a negative pressure control unit (22) and a control unit (23) for performing gear control, wherein the positive pressure control unit (21) and the negative pressure control unit (22) are respectively connected to the control unit (23); The positive pressure control unit (21) includes multiple positive pressure positions for turning on the IGBT device (1). The multiple positive pressure positions are positive pressure position one to positive pressure position N. The higher the positive pressure position, the shorter the conduction time of the IGBT device (1). N is an integer and N>1. The negative pressure control unit (22) includes multiple negative pressure positions for turning off the IGBT device (1), and the multiple negative pressure positions are negative pressure position one to negative pressure position N. The higher the negative pressure position, the shorter the turn-off time of the IGBT device (1). The voltage acquisition module (3) is connected to the IGBT device (1) and is used to acquire the peak voltage of the IGBT device (1); The analysis module (4) is connected to the voltage acquisition module (3) and the IGBT drive module (2) and is used to analyze and control the gear adjustment of the IGBT drive module (2) based on the acquired peak voltage.

2. The control device for reducing IGBT losses according to claim 1, characterized in that, The positive pressure control unit (21) includes a first power supply V1, a first current limiting resistor Rc, a first resistor Rd, a first transistor Q1, a first amplifier C1, a second power supply V2, a first switching switch G1, and N+1 positive pressure divider resistors. The positive terminal of the first power supply V1, the first current limiting resistor Rc, and the drain of the first transistor Q1 are connected in sequence. The source of the first transistor Q1, the first resistor Rd, and the negative terminal of the first power supply V1 are connected in sequence. The connection node between the first resistor Rd and the negative terminal of the first power supply V1 is grounded. The connection node between the first current-limiting resistor Rc and the drain of the first transistor Q1 is connected to the non-inverting input terminal of the first amplifier C1, and the output terminal of the first amplifier C1 is connected to the gate of the first transistor Q1. N+1 positive voltage divider resistors are connected in series to form the first circuit. The positive terminal of the second power supply V2 is connected to the first terminal of the first circuit, and the negative terminal of the second power supply V2 is connected to the second terminal of the first circuit, with the connection node between the two grounded. The first line includes N first common nodes located between two adjacent positive voltage divider resistors. The first switching switch G1 includes a first connection terminal and N second connection terminals. The first connection terminal is connected to the inverting input terminal of the first amplifier C1, and the N second connection terminals are respectively connected to the N first common nodes one by one. The first switching switch G1 is connected to the control unit (23), and the connection node between the source of the first transistor Q1 and the first resistor Rd is connected to the gate of the IGBT device (1). The N second connection terminals are arranged sequentially from the positive terminal to the negative terminal of the second power supply V2, from positive pressure position one to positive pressure position N.

3. The control device for reducing IGBT losses according to claim 1, characterized in that, The negative voltage control unit (22) includes a third power supply V3, a second current-limiting resistor Re, a second resistor Rf, a second transistor Q2, a second amplifier C2, a fourth power supply V4, a second switching switch G2, and N+1 negative voltage divider resistors; The positive terminal of the third power supply V3, the second current-limiting resistor Re, and the drain of the second transistor Q2 are connected in sequence. The source of the second transistor Q2, the second resistor Rf, and the negative terminal of the third power supply V3 are connected in sequence. The connection node between the second resistor Rf and the negative terminal of the third power supply V3 is grounded. The connection node between the second current-limiting resistor Re and the drain of the second transistor Q2 is connected to the inverting input terminal of the second amplifier C2, and the output terminal of the second amplifier C2 is connected to the gate of the second transistor Q2. N+1 negative voltage divider resistors are connected in series to form a second circuit. The positive terminal of the fourth power supply V4 is connected to the first terminal in the second circuit, and the negative terminal of the fourth power supply V4 is connected to the second terminal in the second circuit, with the connection node between the two grounded. The second line includes N second common nodes located between two adjacent negative voltage divider resistors. The second switching switch G2 includes a third connection terminal and N fourth connection terminals. The third connection terminal is connected to the non-inverting input terminal of the second amplifier C2, and the N fourth connection terminals are connected to the N second common nodes one by one. The second switching switch G2 is connected to the control unit (23), and the connection node between the source of the second transistor Q2 and the second resistor Rf is connected to the gate of the IGBT device (1). The N fourth connection terminals are arranged sequentially from the positive to the negative terminal of the fourth power supply V4, from negative pressure level one to negative pressure level N.

4. The control device for reducing IGBT losses according to claim 1, characterized in that, The voltage acquisition module (3) includes a transient voltage suppression diode (TVS), a first voltage divider resistor Ra, a sampling resistor Rb, and a voltage acquisition unit (31) for acquiring the voltage of the sampling resistor Rb. The negative terminal of the transient voltage suppressor diode TVS is connected to the collector of the IGBT device (1), the two ends of the first voltage divider resistor Ra are respectively connected to the positive terminal of the transient voltage suppressor diode TVS and the first end of the sampling resistor Rb, and the second end of the sampling resistor Rb is connected to the emitter of the IGBT device (1). The first and second ends of the sampling resistor Rb are also connected to the voltage acquisition unit (31) respectively; The peak voltage of the IGBT device (1) is estimated by the sampling voltage of the sampling resistor Rb collected by the voltage acquisition unit (31).

5. The control device for reducing IGBT losses according to claim 1, characterized in that, It also includes a load line, which includes a fifth power supply V5, a parasitic inductance L1 and a load. The positive terminal of the fifth power supply V5 and the parasitic inductance L1 are connected to the collector of the IGBT device (1) in sequence. The emitter of the IGBT device (1), the load and the negative terminal of the fifth power supply V5 are connected in sequence. The connection node between the load and the negative terminal of the fifth power supply V5 is grounded.

6. A control method for reducing IGBT losses, characterized in that, The method of using the control device for reducing IGBT losses as described in any one of claims 1 to 5 includes the following steps: S1. When powered on, the IGBT drive module (2) drives the IGBT device (1) step by step from positive pressure position one and negative pressure position one; when it reaches position N, it maintains position N to drive the IGBT device (1). S2. Does the voltage acquisition module (3) acquire the peak voltage of the IGBT device (1)? If yes, send the peak voltage of the IGBT device (1) to the analysis module (4) and proceed to step S3; otherwise, the IGBT drive module (2) maintains the current output and continues to execute step S2. S3. The analysis module (4) determines whether the peak voltage is higher than the maximum peak voltage threshold. If so, proceed to step S4; otherwise, proceed to step S5. S4. The analysis module (4) identifies the current gear X and determines whether the current gear X is gear one. If it is, the output stops and an alarm is triggered, and the process ends. Otherwise, the IGBT drive module (2) lowers the current gear X by one gear and then increases the gear level by level to drive the IGBT device (1), and then proceeds to step S2. S5. The analysis module (4) determines whether the peak voltage is lower than the minimum peak voltage threshold. If so, proceed to step S6; otherwise, the IGBT drive module (2) maintains the current output and proceeds to step S2. S6. The analysis module (4) identifies the current gear X and determines whether the current gear X is gear N. If so, it keeps gear N driving the IGBT device (1) and proceeds to step S2. Otherwise, the IGBT driving module (2) increases the current gear X by one gear and drives the IGBT device (1) by increasing the gear level step by step, or keeps gear N driving the IGBT device (1) and proceeds to step S2.

7. The control method for reducing IGBT losses according to claim 6, characterized in that, The calculation formula for the conduction time of each positive pressure position is as follows: t1=(C2×(V1'-V4')) / ((V1'-V2'×(r1+r2+…+rX) / (r1+r2+…+ri+…+rN)) / RC)+offset1; Where t1 is the conduction time; r represents the positive voltage divider resistor; X is the current gear; ri represents the resistance value of the positive voltage divider resistor, i=1,2,3,...,N-1,N; N is the total number of positive voltage divider resistors; offset1 is the time to exit the constant current region compensation correction, the value range of offset1 is [0.05us, 0.2us], C2 is the input capacitor of the IGBT device, RC is the resistance value of the first current limiting resistor Rc, V1' is the voltage value of the first power supply V1, V2' is the voltage value of the second power supply V2, and V4' is the voltage value of the fourth power supply V4.

8. The control method for reducing IGBT losses according to claim 6, characterized in that, The calculation formulas for the shut-off time of each negative pressure setting are as follows: t2=(C2×(V1'-V4')) / ((V3'-(V4'×(r1+r2+…+rX) / (r1+r2+…+rj+…+rN))) / RE)+offset2; Where t2 is the turn-off time; X is the current gear; rj represents the resistance value of the positive voltage divider resistor, j=1,2,3,...,N-1,N; N is the total number of negative voltage divider resistors; offset2 is the time to exit the constant current region compensation correction, and the value range of offset2 is [0.05us, 0.2us]; C2 is the input capacitance of the IGBT device; RE is the resistance value of the second current limiting resistor Re; V1' is the voltage value of the first power supply V1, V3' is the voltage value of the third power supply V3, and V4' is the voltage value of the fourth power supply V4.

9. An electric drive system, characterized in that: The control device for reducing IGBT losses as described in any one of claims 1 to 5 is adopted.

10. A vehicle, characterized in that: The electric drive system as described in claim 9 is used.

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