Over-current reliability test circuit of SiIGBT and SiC MOSFET hybrid device and method thereof

Abstract

The invention discloses an over-current reliability test circuit and method for a Si IGBT and SiC MOSFET hybrid device, and belongs to the technical field of power system automation control, and the over-current reliability test circuit comprises a high-voltage power supply circuit, a test circuit and a driving module. One end of the test circuit is connected with the high-voltage power supply circuit, and the other end is connected with the driving module; the test circuit comprises an inductive load L1, a fly-wheel diode D2 and a hybrid device, the hybrid device comprises a Si IGBT and a SiC MOSFET, and the Si IGBT and the SiC MOSFET are connected in parallel; the fly-wheel diode D2 is connected in series with the hybrid device; two ends of the inductive load L1 are connected with a cathode and an anode of the fly-wheel diode D2; the driving module comprises a signal generator, a first driver and a second driver; the method has the advantages that the reliability of the Si IGBT and SiC MOSFET parallel hybrid device under the overcurrent condition can be systematically tested, powerful support is provided for application of the hybrid device, and the purposes of high performance and low cost of a power device are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of power system automation control, and more specifically, to an overcurrent reliability test circuit and method for a Si IGBT and SiC MOSFET hybrid device. Background Art

[0002] With the rapid progress of new energy electric vehicles and photovoltaic industries, the performance requirements for power devices are becoming increasingly stringent, especially in terms of switching speed and loss. Si IGBT refers to Silicon Insulated Gate Bipolar Transistor. It is a composite fully controlled voltage-driven power semiconductor device composed of a bipolar junction transistor (BJT) and an insulated gate field effect transistor (MOSFET). SiC MOSFET refers to Silicon Carbide Metal-Oxide-Semiconductor Field-Effect Transistor. It is a power semiconductor device based on silicon carbide SiC material and is part of the third generation of semiconductor technology. The third generation semiconductor device SiC MOSFET exhibits higher operating temperature, faster switching speed and lower switching loss due to its wide bandgap characteristics and high electron mobility, making the inverter based on SiC MOSFET superior to the traditional IGBT inverter in terms of volume, power density and efficiency.

[0003] As a wide bandgap material, SiC has extremely high electron mobility, which enables SiC-based MOSFET devices to operate at higher operating temperatures, with faster switching speeds and lower switching losses. Therefore, inverters built with SiC MOSFETs are significantly superior to traditional IGBT inverters in terms of volume, power density and efficiency. However, due to factors such as basic material quality, technology maturity, crystal size and cost, the manufacturing cost of SiC MOSFET is still high. In order to find a balance between cost and performance, the industry has proposed a solution to connect Si IGBT and SiC MOSFET in parallel to form a hybrid device. In this hybrid device, Si IGBT plays a leading role under high current conditions, while SiC MOSFET plays a major role under low current conditions. By precisely controlling the switching timing, zero voltage shutdown of the IGBT can be achieved, thereby significantly reducing switching losses, making the switching losses of the hybrid device close to the level of pure SiC MOSFET, while greatly reducing costs.

[0004] Although hybrid devices have many advantages, research on their safety and reliability is still insufficient. Especially before hybrid devices are applied to key fields such as new energy vehicles and photovoltaics, comprehensive testing of their safety and reliability is particularly important. Since the IGBT in the hybrid device is responsible for the large current part and the SiC MOSFET is responsible for the small current part, and the IGBT is usually turned off first in order to reduce losses during the shutdown process, the SiC MOSFET needs to withstand a large current shock after the IGBT is turned off, which may even exceed 2-3 times its rated current. Therefore, it is urgent to propose an overcurrent reliability test method for SiCMOSFET during the shutdown process of the hybrid device to ensure the safety and reliability of the hybrid device in practical applications. Summary of the invention

[0005] In order to overcome the shortcomings of the prior art, an overcurrent reliability test circuit and method for a Si IGBT and SiC MOSFET hybrid device are proposed, which can systematically test the reliability of a Si IGBT and SiC MOSFET parallel hybrid device under overcurrent conditions, provide strong support for the application of hybrid devices, and achieve the goal of high performance and low cost of power devices.

[0006] The invention solves the technical problem by adopting a technical solution: an overcurrent reliability test circuit for a Si IGBT and SiC MOSFET hybrid device, wherein the improvement is that the overcurrent reliability test circuit comprises a high-voltage power supply circuit, a test circuit and a drive module; one end of the test circuit is connected to the high-voltage power supply circuit, and the other end of the test circuit is connected to the drive module; The test circuit includes an inductive load L1, a freewheeling diode D2, and a hybrid device, wherein the hybrid device includes a Si IGBT and a SiC MOSFET, wherein the Si IGBT and the SiC MOSFET are connected in parallel; the freewheeling diode D2 and the hybrid device are connected in series, and both ends of the inductive load L1 are connected to the cathode and anode of the freewheeling diode D2; The driving module includes a signal generator, a first driver and a second driver; the first driver is connected to SiC MOSFET for driving SiC MOSFET, the second driver is connected to Si IGBT for driving SiIGBT, and the output end of the signal generator is connected to the first driver and the second driver.

[0007] In the above structure, the high-voltage power supply circuit includes a high-voltage power supply, a busbar capacitor C, a diode D1, an air switch S1 and a discharge resistor R; the air switch S1 and the discharge resistor R are connected in series and connected in parallel with the busbar capacitor C, the high-voltage power supply is connected in series with the diode D1 and the positive electrode of the diode D1 is connected to the positive electrode of the high-voltage power supply, the negative electrode of the diode D1 is connected to one end of the busbar capacitor C, and the positive electrode of the high-voltage power supply is connected to the other end of the busbar capacitor C.

[0008] In the above structure, the signal generator can output two separately editable drive signals based on FPGA control to achieve independent drive control of Si IGBT and SiC MOSFET.

[0009] In the above structure, the signal generator can output two separately editable drive signals based on DSP control to achieve independent drive control of Si IGBT and SiC MOSFET.

[0010] The present invention also discloses an overcurrent reliability test method for a Si IGBT and SiC MOSFET hybrid device, the improvement of which is that it comprises the following steps: S10: Ensure that the bus voltage is stable and set the inductance value of inductor L1. At time t0, drive the Si IGBT to turn on, so that the bus capacitor, inductor L1 and Si IGBT form a loop and start charging the inductor L1. The current of Si IGBT Start to rise; S20: In the first pulse, the inductor current is increased to the overcurrent test current through the Si IGBT, which is recorded as time t1; the Si IGBT is turned off, so that the current forms a freewheeling loop in the inductor L1 and the diode D2; S30: At time t2, the Si IGBT is reopened to allow the current to flow from the freewheeling loop to the Si IGBT again; S40: After the Si IGBT is fully turned on, which is recorded as time t3, the SiC MOSFET in the hybrid device is turned on, so that the current starts to flow from the Si IGBT to the SiC MOSFET; S50: After the SiC MOSFET is fully turned on, recorded as time t4, the Si IGBT is turned off. At this time, the current completely flows through the SiC MOSFET and enters the overcurrent test stage; S60: Continue the overcurrent test until the end of time t5.

[0011] Furthermore, the method also includes a multi-pulse test, repeating the process from step S30 to step S60 to perform multiple over-current tests on the hybrid device to accelerate the test process.

[0012] Furthermore, during multiple pulse tests, a heat sink is installed to dissipate the accumulated heat of the test device and maintain a consistent junction temperature for the device test.

[0013] Furthermore, in step S10, the calculation formula of the current of the Si IGBT is: ; Among them, U is the bus voltage, T is the conduction time, and L is the inductance value of inductor L1.

[0014] The beneficial effect of the present invention is that the reliability of a Si IGBT and SiC MOSFET parallel hybrid device under overcurrent conditions can be systematically tested, providing strong support for the application of the hybrid device and achieving the goal of high performance and low cost of power devices. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 A circuit schematic diagram of an overcurrent reliability test circuit for a Si IGBT and SiC MOSFET hybrid device of the present invention; Figure 2 It is a flow chart of an overcurrent reliability test method of a Si IGBT and SiC MOSFET hybrid device of the present invention; Figure 3 A shutdown waveform diagram of a hybrid device under a shutdown delay time in an overcurrent reliability test method of a hybrid device of Si IGBT and SiC MOSFET of the present invention; Figure 4 A waveform diagram of a multi-pulse test method for an overcurrent reliability test method of a Si IGBT and SiC MOSFET hybrid device of the present invention; Figure 5 This is an experimental waveform diagram of an overcurrent reliability test method for a Si IGBT and SiC MOSFET hybrid device of the present invention; Figure 6 The figure is a waveform diagram of an accelerated test scheme of an overcurrent reliability test method for a Si IGBT and SiC MOSFET hybrid device of the present invention. DETAILED DESCRIPTION

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] The following will clearly and completely describe the concept, specific structure and technical effects of the present invention in combination with the embodiments and drawings, so as to fully understand the purpose, characteristics and effects of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, other embodiments obtained by technicians in this field without creative work are all within the scope of protection of the present invention. In addition, all the connection / connection relationships involved in the patent do not refer to the direct connection of components, but refer to the formation of a better connection structure by adding or reducing connection accessories according to the specific implementation situation. The various technical features in the invention can be combined interchangeably without conflicting with each other.

[0018] It should be noted that if the embodiments of the present invention involve directional indications (such as up, down, left, right, front, back...), the directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0019] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. Secondly, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0020] See also Figure 1 As shown, the present invention provides an overcurrent reliability test circuit for a Si IGBT and SiC MOSFET hybrid device, the overcurrent reliability test circuit comprising a high-voltage power supply circuit, a test circuit and a drive module; one end of the test circuit is connected to the high-voltage power supply circuit, and the other end of the test circuit is connected to the drive module; The test circuit includes an inductive load L1, a freewheeling diode D2 and a hybrid device, wherein the hybrid device includes a Si IGBT and a SiC MOSFET, wherein the Si IGBT and the SiC MOSFET are connected in parallel; the freewheeling diode D2 and the hybrid device are connected in series, and the two ends of the inductive load L1 are connected to the cathode and the anode of the freewheeling diode D2; when the inductive load L1 releases energy, the freewheeling diode D2 provides a freewheeling path to prevent the device from being subjected to excessive voltage stress at the moment of shutdown, thereby protecting the safety of the test circuit.

[0021] In order to reduce the turn-off loss, the hybrid device of Si IGBT and SiC MOSFET in parallel is turned off with a delay. The Si IGBT is turned off first to achieve zero voltage turn-off of the Si IGBT. At this time, the current of the Si IGBT is commutated to the SiC MOSFET, and the SiC MOSFET is subjected to overcurrent conduction stress. After a certain delay time, the SiC MOSFET is turned off and subjected to overcurrent turn-off stress. The waveform is shown in the figure. Figure 3 shown.

[0022] The driving module includes a signal generator, a first driver and a second driver; the first driver is connected to SiC MOSFET for driving SiC MOSFET, the second driver is connected to Si IGBT for driving SiIGBT, and the output end of the signal generator is connected to the first driver and the second driver. The driving module is designed with an independent driver so that the driving signals of the two devices can be controlled separately. In conjunction with the signal generator, various working conditions can be simulated by adjusting the duty cycle, frequency and other parameters of the driving signal, such as low frequency, high current and high frequency, low current. This independent drive design enhances the flexibility of circuit testing.

[0023] Si IGBT: It has the characteristics of low on-state voltage, low cost, and is suitable for high current, but the switching speed is slow, and there is tail current when it is turned on. SiC MOSFET: It has the characteristics of fast switching speed, low switching loss, and good high-temperature performance. Under the condition of the same on-resistance, the cost of SiC MOSFET chips is higher than that of Si IGBT chips; using Si IGBT and SiCMOSFET in parallel can fully utilize the advantages of both devices in fields such as new energy vehicles and photovoltaics: when working at low frequency or high current, Si IGBT mainly works; in high frequency or fast switching scenarios, SiC MOSFET plays a role. This achieves performance optimization while effectively reducing power loss.

[0024] Furthermore, the high-voltage power supply circuit includes a high-voltage power supply, a busbar capacitor C, a diode D1, an air switch S1, and a discharge resistor R; the air switch S1 and the discharge resistor R are connected in series and then connected in parallel with the busbar capacitor C, the high-voltage power supply is connected in series with the diode D1, and the positive electrode of the diode D1 is connected to the positive electrode of the high-voltage power supply, the negative electrode of the diode D1 is connected to one end of the busbar capacitor C, and the positive electrode of the high-voltage power supply is connected to the other end of the busbar capacitor C. The busbar capacitor C is used to store electrical energy and plays a role in filtering and energy support; the air switch S1 closes the circuit after the test is completed, connects the discharge resistor R1 and the busbar capacitor C in parallel, so that the energy of the busbar capacitor C is consumed through the resistor R1 to ensure safety.

[0025] In order to meet the different driving requirements of Si IGBT and SiC MOSFET devices, the optimal control effect is achieved through flexible parameter adjustment. The signal generator can output two separately editable driving signals based on FPGA control to achieve independent driving control of the Si IGBT and SiC MOSFET. FPGA stands for Field-Programmable Gate Array, which is a highly integrated programmable hardware device. Unlike traditional ASIC chips, it does not have fixed functions, but can be programmed according to user needs to realize various digital circuits and system functions. The core of FPGA is configurable logic units, which can be configured according to programming instructions to realize different logic functions, such as AND gates, OR gates, XOR gates, adders, counters, etc. In addition to logic units, FPGA also contains a large number of connection resources, which can connect different logic units to form a complex circuit system.

[0026] Furthermore, in order to meet the different driving requirements of Si IGBT and SiC MOSFET devices, the signal generator can also output two separately editable driving signals based on DSP control to achieve independent driving control of Si IGBT and SiC MOSFET. DSP, the full name of Digital Signal Processor, is a microprocessor specially used for processing digital signals. It has powerful data processing capabilities and high-speed computing speed, and can quickly process various complex digital signals, such as audio, video, images, etc. DSP can generate various waveform signals with high precision. DSP can integrate data acquisition functions, monitor the status of output signals and the working conditions of devices in real time, and provide feedback to optimize driving strategies. Through real-time monitoring, DSP can detect abnormal situations in time and handle them, thereby improving the safety and reliability of the system.

[0027] like Figure 2-Figure 6 As shown, the present invention also provides an overcurrent reliability test method for a Si IGBT and SiC MOSFET hybrid device, comprising the following steps: S10: Ensure that the bus voltage is stable and set the inductance value of the inductor L1. At time t0, drive the Si IGBT to turn on, so that the bus capacitor, inductor L1 and Si IGBT form a loop, start charging the inductor L1, and the current I of the Si IGBT starts to rise; S20: In the first pulse, the inductor current is increased to the overcurrent test current through the Si IGBT, which is recorded as time t1; the Si IGBT is turned off, so that the current forms a freewheeling loop in the inductor L1 and the diode D2; S30: At time t2, the Si IGBT is reopened to allow the current to flow from the freewheeling loop to the Si IGBT again; S40: After the Si IGBT is fully turned on, which is recorded as time t3, the SiC MOSFET in the hybrid device is turned on, so that the current starts to flow from the Si IGBT to the SiC MOSFET; S50: After the SiC MOSFET is fully turned on, recorded as time t4, the Si IGBT is turned off. At this time, the current completely flows through the SiC MOSFET and enters the overcurrent test stage; S60: Continue the overcurrent test until the end of time t5.

[0028] This method completely simulates the commutation process of Si IGBT and SiC MOSFET under overcurrent conditions, and can accurately evaluate the dynamic response capability and coordination effect of the two devices. This test method simulates the dynamic commutation process and long-term operation of Si IGBT and SiC MOSFET under overcurrent conditions by precisely controlling current and timing, and can comprehensively evaluate the reliability, shutdown delay impact, and overcurrent capability of hybrid devices.

[0029] Furthermore, in step S10, the current of the Si IGBT The calculation formula is: ; Among them, U is the bus voltage, T is the conduction time, and L is the inductance value of the inductor L1. In the first pulse, when the inductor current is increased to the overcurrent test current through the IGBT, it is t1. At this time, the Si IGBT is turned off, and the current is freewheeling in the loop composed of the inductor L1 and the diode D2. At t2, the Si IGBT is turned on to make the Si IGBT bear the turn-on stress, and the current flows back to the Si IGBT from the freewheeling loop. When the Si IGBT is fully turned on, it is t3. At this time, the SiC MOSFET in the hybrid device is turned on, and the current begins to commutate from the Si IGBT to the SiC MOSFET. When the SiC MOSFET is fully turned on, it is t4. At this time, the Si IGBT is turned off, and the current flows completely from the SiC MOSFET and enters the overcurrent test. At t5, the overcurrent test ends. During the test, the SiC MOSFET in the hybrid device is subjected to overcurrent conduction stress and overcurrent turn-off stress, but not to turn-on overcurrent stress, which is consistent with the stress borne by the SiC MOSFET in the hybrid device during the turn-off delay. Through this experimental method, the influence of the hybrid device turn-off delay on the hybrid device life can be tested and the reliability of the hybrid device can be studied.

[0030] A single overcurrent test may take a long time to accumulate enough data and waveforms. Through multi-pulse testing, the overcurrent operation can be repeated in a short time, and more test data can be quickly collected. Therefore, the method also includes a multi-pulse test, repeating the process of step S30 to step S60 to perform multiple overcurrent tests on the hybrid device to speed up the test process. A single overcurrent test may not be able to fully reflect the behavior of the device under different load and operating conditions, especially the slight changes that may occur during overcurrent and switching. Through multiple tests, the stability and overcurrent resistance of the device can be more fully reflected. The test waveform is as follows: Figure 5 As shown, the test from t0 to t5 is Figure 3 From t5 to t6, when the inductor current consumption is consistent with the current at t2, repeat the test from t2 to t5, and perform a second overcurrent test on the hybrid device. This can be repeated to achieve multiple tests and shorten the test cycle. However, this solution will cause heat accumulation in the device, and a heat sink needs to be installed to dissipate the accumulated heat of the test device in time to keep the junction temperature of the device test consistent.

[0031] Furthermore, the performance of power devices is often affected by temperature, especially under high current and high frequency operation, where temperature changes may cause changes in device parameters such as on-resistance and switching loss. During multiple pulse tests, by installing a heat sink to dissipate the accumulated heat of the test device and keep the junction temperature of the device test consistent, not only can the reliability and consistency of the test results be improved, but it can also effectively evaluate the thermal management capabilities of the device, promote thermal characteristics research, and ensure the safety of the test process.

[0032] The above is a specific description of the preferred implementation of the present invention, but the invention is not limited to the embodiments. Those skilled in the art can make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An overcurrent reliability test circuit for a Si IGBT and SiC MOSFET hybrid device, characterized in that: The overcurrent reliability test circuit comprises a high-voltage power supply circuit, a test circuit and a drive module; one end of the test circuit is connected to the high-voltage power supply circuit, and the other end of the test circuit is connected to the drive module; The test circuit includes an inductive load L1, a freewheeling diode D2 and a hybrid device, wherein the hybrid device includes a Si IGBT and a SiC MOSFET, wherein the Si IGBT and the SiC MOSFET are connected in parallel; the freewheeling diode D2 and the hybrid device are connected in series, and both ends of the inductive load L1 are connected to the cathode and anode of the freewheeling diode D2; The driving module includes a signal generator, a first driver and a second driver; the first driver is connected to SiCMOSFET for driving SiC MOSFET, the second driver is connected to Si IGBT for driving Si IGBT, and the output end of the signal generator is connected to the first driver and the second driver.

2. The overcurrent reliability test circuit of a Si IGBT and SiC MOSFET hybrid device according to claim 1, characterized in that: The high-voltage power supply circuit includes a high-voltage power supply, a busbar capacitor C, a diode D1, an air switch S1 and a discharge resistor R; the air switch S1 and the discharge resistor R are connected in series and then connected in parallel with the busbar capacitor C, the high-voltage power supply is connected in series with the diode D1 and the positive electrode of the diode D1 is connected to the positive electrode of the high-voltage power supply, the negative electrode of the diode D1 is connected to one end of the busbar capacitor C, and the positive electrode of the high-voltage power supply is connected to the other end of the busbar capacitor C.

3. The overcurrent reliability test circuit of a Si IGBT and SiC MOSFET hybrid device according to claim 1, characterized in that: The signal generator can output two separately editable drive signals based on FPGA control to achieve independent drive control of Si IGBT and SiC MOSFET.

4. The overcurrent reliability test circuit of a Si IGBT and SiC MOSFET hybrid device according to claim 1, characterized in that: The signal generator can output two separately editable drive signals based on DSP control to achieve independent drive control of SiIGBT and SiC MOSFET.

5. A test method for an overcurrent reliability test circuit of a Si IGBT and SiC MOSFET hybrid device based on any one of claims 1 to 4, characterized in that: The following steps are involved: S10: Ensure that the bus voltage is stable and set the inductance value of the inductor L1. At time t0, drive the Si IGBT to turn on, so that the bus capacitor, inductor L1 and Si IGBT form a loop, start charging the inductor L1, and the current I of the Si IGBT starts to rise; S20: In the first pulse, the inductor current is increased to the overcurrent test current through the Si IGBT, which is recorded as time t1; the Si IGBT is turned off, so that the current forms a freewheeling loop in the inductor L1 and the diode D2; S30: At time t2, the Si IGBT is reopened to allow the current to flow from the freewheeling loop to the Si IGBT again; S40: After the Si IGBT is fully turned on, which is recorded as time t3, the SiC MOSFET in the hybrid device is turned on, so that the current starts to flow from the Si IGBT to the SiC MOSFET; S50: After the SiC MOSFET is fully turned on, recorded as time t4, the Si IGBT is turned off. At this time, the current completely flows through the SiC MOSFET and enters the overcurrent test stage; S60: Continue the overcurrent test until the end of time t5.

6. The test method of the overcurrent reliability test circuit of the Si IGBT and SiC MOSFET hybrid device according to claim 5, characterized in that: The method further comprises a multi-pulse test, in which the process from step S30 to step S60 is repeated to perform multiple over-current tests on the hybrid device, thereby accelerating the test process.

7. The test method of the overcurrent reliability test circuit of the Si IGBT and SiC MOSFET hybrid device according to claim 5, characterized in that: During multiple pulse tests, a heat sink is installed to dissipate the accumulated heat of the test device and keep the junction temperature of the device test consistent.

8. The test method of the overcurrent reliability test circuit of the Si IGBT and SiC MOSFET hybrid device according to claim 5, characterized in that: In step S10, the current of the Si IGBT The calculation formula is: ； Among them, U is the bus voltage, T is the conduction time, and L is the inductance value of inductor L1.

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