Testing System and Testing Method for Power Semiconductor Devices

Abstract

The present invention relates to a test system and a test method for power semiconductor devices, which include a main current circuit and / or a surge test circuit and / or a thermal test circuit and / or a high-voltage circuit and a control module. Among them, the main current circuit is adapted to provide a half-wave conduction current for the device under test, and the control module is adapted to perform a surge test on the device under test during the positive half-wave of the sine wave and perform a forward or reverse high-voltage test on the device under test during the negative half-wave. The present invention has reasonable design, compact structure and convenient use.

Description

Technical Field

[0001] The present invention relates to the technical field of power device testing, and in particular to a testing system and a testing method for power semiconductor devices. Background Art

[0002] With the development of high-power power electronic devices, power electronic devices based on power diodes, thyristors, MOSFETs or IGBTs have been increasingly widely used. The voltage and current withstand capabilities of power electronic devices are their most important parameters. To ensure the effectiveness, reliability, stability and safety of the devices, it is necessary to test their various characteristic parameters. Since power electronic devices in the power system need to withstand surge currents with higher peaks and longer durations, it is necessary to detect their surge currents. And when the current value flowing through a power electronic device in the conducting state is large, it will cause an increase in the junction temperature and damage the device. Therefore, it is necessary to perform on-line detection of its junction temperature. Existing power electronic device testing instruments have problems such as a small rated test current, a narrow test voltage range, inability to perform full dynamic testing and low efficiency, inability to directly observe test results, and inability to achieve independent operation between test modules.

[0003] CN102156271B - Detection method of semiconductor parameter measurement system cannot perform parameter testing during normal operation. CN102944824B - A testing method for transient high-temperature reverse leakage current of a rectifier diode also cannot perform comprehensive measurement.

[0004] Therefore, there is a need for a testing system for power semiconductor devices that can simultaneously perform high-voltage testing, junction temperature testing and surge testing on devices under different working conditions, improving the accuracy and efficiency of power semiconductor device testing. Summary of the Invention

[0005] In order to adapt to the performance characteristics of semiconductor devices such as high voltage, high frequency and high temperature resistance, the present invention provides a testing system for power semiconductor devices that overcomes or at least partially solves the above problems, can perform various tests, and improves the efficiency of semiconductor device testing.

[0006] Existing test benches can only perform single-item tests and cannot comprehensively reflect the working state, that is, they cannot test the actual working state of the device, so the actual working parameters of the device under test cannot be obtained, and it is impossible to more scientifically judge whether the device is qualified; the present invention cleverly realizes that after connecting to the power grid, through single-phase half-wave rectification by a diode, testing under normal power-on conditions can be achieved, and the reproduction of the true working conditions of the device can be realized.

[0007] In order to improve the accuracy of testing, reduce impedance interference, quickly remove the generated heat through circulating water, enhance the heat dissipation effect, eliminate the fan, reduce noise, and increase the service life, fix the resistor through pipe clamps to achieve adjustable resistance values. The present invention innovates on the resistor to meet the above-mentioned testing requirements.

[0008] Regarding the problem of phase synchronization, the applicant uses a comparator circuit to compare with the zero-crossing point of the power supply sine wave to obtain a synchronization signal, thereby achieving waveform synchronization without hysteresis or delay.

[0009] The system includes a main current circuit and / or a surge test circuit and / or a thermistor test circuit and / or a high-voltage circuit and a control module. Among them, the main current circuit is suitable for providing a half-wave conduction current for the device under test. The control module includes an electronic switch circuit, and the electronic switch circuit is suitable for synchronous triggering of the surge or rectifier circuit and synchronous display on the oscilloscope, so as to trigger the conduction of the device under test during the sine half-wave of the main current or surge current test circuit.

[0010] In the method of the present invention, first, connect the anode and cathode of the device under test to the positive and negative connection terminals of the main current circuit respectively, adjust the magnitude of the main current to make the device under test conduct, and measure the forward peak voltage and average voltage drop of the device under test; when performing reverse voltage testing, switch the polarity switching module of the high-voltage circuit to the reverse, adjust the output voltage of the high-voltage power supply through the high-voltage regulator, and measure the reverse voltage and reverse leakage current of the device under test; when testing the thermistor voltage, connect the devices to be tested in series to the heating module, heat the device under test to different temperatures through the heating module, adjust the magnitude of the thermistor current through the thermistor current regulator, and test the thermistor voltage corresponding to the thermistor current at different temperatures; finally, connect the surge test circuit, adjust the magnitude of the surge current to a predetermined multiple of the main current through the surge current regulator, connect the high-voltage power supply, switch the polarity of the polarity switching module to the reverse, and perform surge testing on the device under test based on the preset number of surge pulses and surge pulse time intervals.

[0011] In summary, the present invention uses a step-down transformer to step down the voltage, generates an electronic switch signal synchronized with the power grid sine wave through zero-crossing comparison by a comparator, switches the voltage drop waveform, main current waveform, surge waveform, thermistor voltage waveform, thermistor comparison, and surge comparison waveforms through an electronic switch and a band switch, and presents the measured waveforms on the oscilloscope.

[0012] The present invention can simultaneously perform thermal, surge, and full dynamic parameter tests on a device under test during the half-wave conduction stage of the device under test. Each test circuit can be combined or used independently, improving the efficiency of device testing. The output voltage or current of each test circuit can be adjusted according to the rated parameter values of the device under test, enabling it to adapt to the characteristics of semiconductor devices with high voltage, high temperature resistance, and high switching frequencies, and improving the accuracy of device testing.

[0013] Among them, for a. Vf (thermal) test, the device is heated using the main current, and the change in its Vf (thermal) can be observed and read on an oscilloscope and can also be directly read on a digital voltmeter;

[0014] b. Full dynamic surge: The main current and reverse (positive) voltage are applied simultaneously. A timer and a counter are used to determine the surge interval time and the number of surges, and it automatically stops when the specified number of times is reached. Although the surge disappears instantaneously, the surge waveform on the main current can be observed on an oscilloscope, and the proportional relationship between the surge and the main current is clear at a glance. For the device under test, not only can the main current be applied to measure the average voltage drop and peak voltage across the device, but also the reverse voltage can be applied to measure the reverse leakage current of the device, simulating the normal operating state of the device;

[0015] c. Water-cooled resistor: This equipment has a large power, the surge current can reach 3000A, and the main current is 200A. The resistance of the circuit, the connection contact resistance, and the internal resistance of the transformer are difficult to calculate. At the same time, when a large current passes through the current-limiting resistor, a large amount of heat is generated. The present invention uses a stainless steel pipe as the current-limiting resistor to achieve two points. One is that its resistance size can be adjusted through a wiring card. The second is that the heat is removed by circulating water. The third is that compared with the air-cooling method, the area of the radiator used is much smaller, and the influence of hot air on the test equipment and the influence of resistor heating on the equipment are reduced. The fourth is that the fan is omitted to achieve noise reduction;

[0016] d. Surge waveform: The prior art uses an LC energy storage type to simulate and generate a surge waveform for cooling. This waveform is not a standard sine half-wave. Most of them do not apply the main current and only apply the reverse voltage, which can only be called a semi-dynamic surge and there is attenuation. The present invention is a full dynamic surge, completely simulating the working state in the power grid. Its surge waveform, main current waveform, and sine half-wave waveform of the power supply grid are completely consistent, truly simulating the working mode of the device in the power grid, with controllable temperature and the ability to apply reverse voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a schematic diagram of a preferred test system 100 for power semiconductor devices. Figure 2 It is a schematic circuit diagram of a preferred control module 150. Figure 3 It is the left half part diagram after the circuit of the control module 150 is optimized. Figure 4 It is the right half part diagram after the circuit of the control module 150 is optimized. Figure 5Schematic diagram of the preferred main current circuit 110 / surge current circuit 120. Figure 6 Schematic diagram of the main current circuit 110. Figure 7 Schematic diagram of the surge current circuit 120. Figure 8 Schematic diagram of the preferred high-voltage circuit 130. Figure 9 Schematic diagram of the process of the preferred test method 001. Figure 10 Schematic diagram of the voltage drop of the device under test and the comparison voltage waveform. Figure 11 Schematic diagram of the preferred surge current waveform. Figure 12 Schematic diagram of the thermistor voltage waveform under the preferred normal test conditions. Figure 13 Schematic diagram of the thermistor voltage waveform under the preferred hot test conditions. Figure 14 Schematic diagram of the simplified physical structure of the preferred liquid load. Figure 15 Schematic diagram of the deformed structure of the preferred liquid-cooled resistor. Specific implementation mode

[0018] Such as Figures 1-15 All kinds of power electronic devices have two working states: conduction and blocking, including power semiconductor devices. When a power semiconductor device works, it will heat up and increase in temperature due to power loss. If the device temperature is too high, its service life will be shortened. From the research and development, production, use and maintenance of semiconductor power devices, corresponding electrical parameter tests are required, including static parameter tests (breakdown voltage, leakage current, conduction voltage drop, etc.), dynamic parameter tests, ultimate capacity tests (surge current test, etc.), reliability life tests (high-temperature storage test, temperature cycle test, high-temperature reverse bias test, etc.). In order to test various performance parameters of power semiconductor devices under working conditions, this solution provides a test system and method capable of real-time measuring the performance of power electronic devices.

[0019] Figure 1 In the illustrated embodiment, the system 100 includes a main current circuit 110, a surge test circuit 120, a high-voltage circuit 130, a thermistor test circuit 140, and a control module 150, and can perform full dynamic surge tests, full dynamic tests, and thermistor tests simultaneously during the half-wave conduction stage of the device under test. The measurement results include surge current, hot and cold state thermistor voltage, average voltage drop, peak voltage, positive and negative peak voltages, positive and negative leakage currents, maximum junction temperature, etc.

[0020] Generally speaking, the main current circuit 110 can provide a half-wave conduction current for the device under test. The control module 150 includes several electronic switch circuits. The electronic switch circuit can control the output of the surge test circuit 120 when detecting that the half-wave conduction current is at a high level, and the output of the high-voltage circuit 130 when at a low level, so that the surge pulse output by the surge test circuit 120 is triggered at the sine half-wave synchronization stage of the device under test. The control module 150, which can be a thyristor, a relay, and / or a combination thereof, etc., can adjust the output voltage or current of each circuit according to the rated value of the device under test.

[0021] As Figures 5-7 shown in the embodiment, a schematic structural diagram of the main current circuit 110 and the surge test circuit 120. The main current circuit 110 and the surge test circuit 120 are externally connected to an AC power supply; the AC power supply is mains power or industrial power;

[0022] After the main current circuit 110 steps down the voltage, it realizes unidirectional half-wave rectification output through a diode. The surge test circuit 120 steps up the voltage and realizes unidirectional half-wave rectification output through a diode.

[0023] Among them, the main current circuit 110 can provide a conduction voltage and current for the device under test to test its conduction voltage drop. The waveform of the device conduction voltage can be observed through an oscilloscope as the voltage drop waveform of the device under test. The forward peak voltage VFM / VTM and the forward average voltage drop Vavg in the waveform diagram can be read through an ammeter.

[0024] The main current circuit 110 includes a main current regulator 111, a first trigger circuit 112, and a first air-cooling module D1. The main current regulator 111 can adjust the magnitude of the main current output by the main circuit according to the rated value of the device under test, and the adjustment range is 1A - 200A. The first air-cooling module D1 is used to dissipate heat from the high-power diode and thyristor radiators.

[0025] The main current regulator 111 has a main current isolation transformer TC11, 30V / 300A; a main current voltage regulator T10 for voltage division is electrically connected to the main coil of the main current isolation transformer TC11, and a main current AC meter Y11 matching the main current voltage regulator T10 is shunted on the main coil of the main current isolation transformer TC11 to display the input electrical parameters, which is convenient for operation and to judge the position of the main current voltage regulator T10;

[0026] The gear of the main current and the main current voltage regulator T10 cooperate with each other to be able to adjust the magnitude of the main current output by the main current circuit according to the rated value of the device under test, and the adjustment range is 1A - 200A; when the current flowing through the device under test is greater than 50A, the first air-cooling module D1 can be turned on to ventilate and dissipate heat from components such as the main current isolation transformer TC11.

[0027] The main current circuit 110 further includes a band switch connected to the main current loop. The band switch includes a plurality of adjustable main current limiting resistors R111. By connecting in series main current load resistors with gradually increasing resistance values, the step-by-step corresponding reduction of the output current is achieved. Preferably, there are six of them. The main current limiting resistors R111 include a first resistor R11, a second resistor R12, a third resistor R13, a fourth resistor R14, a fifth resistor R15, and a sixth resistor R16.

[0028] One end of the first resistor R11 is connected to the main current regulator 111 loop, and the other end is divided into two paths. One path is connected to the 200A main current shift switch, and the other path is connected to one end of the second resistor R12. The second resistor R12, the third resistor R13, the fourth resistor R14, the fifth resistor R15, and the sixth resistor R16 are connected in sequence and correspondingly connected to the 100A, 50A, 20A, 5A, and 1A main current shift switches. The main current shift switch is connected to the device under test through the K terminal.

[0029] The main current controls the operation of 6 relays through the band switch, and outputs the main currents of 200A, 100A, 50A, 20A, 5A, and 1A with the main current correspondingly decreasing in sequence. In this embodiment, preferably six gears are adopted to adapt to the tests of different current devices. Using one or other quantities constitutes an equivalent, and the current values and resistance values are for distinction and not for limitation.

[0030] The band switch is equipped with 6 current gears, which respectively correspond to shunts of different current gears, and can switch the AC contactor and the shunts of the corresponding current gears. The magnitude of the main current is displayed through the main ammeter. For example Figures 14-15 , among them, the resistors R11-14, R21-23 can be liquid-cooled resistors. The liquid-cooled resistor includes a coiled pipe 20, and an insulating cooling medium circulates in the coiled pipe 20; connectors 21 are arranged at both ends of the coiled pipe 20 for externally connecting a water circuit. The coiled pipe 20 is equipped with a first electrical connection end 29 and an adjustable second electrical connection end 28 for externally connecting a circuit. By adjusting the position of the second electrical connection end 28 on the coiled pipe 20, the resistance value of the liquid-cooled resistor is adjusted; the coiled pipe 20 is equipped with a fixed support portion 22 for fixing the coiled pipe 20 on the test bench.

[0031] When the coiled pipe 20 is a spiral pipe, the water circuit enters from the lower connector 21 and exits from the upper connector 21 to realize water circulation; a toggle rod 27 and several rotating brackets 23 are arranged on the fixed support portion 22 at the lower end of the coiled pipe 20, and slip rings 26 are arranged on the rotating brackets 23. The first electrical connection end 29 is at one end of the coiled pipe 20, and the second electrical connection end 28 has an external electrical connection end 30 for externally connecting a circuit.

[0032] The external water circuit includes a water pump 31 and a refrigerator 32 connected in series. A thermometer 33 is provided on the water flow circuit. An adjusting sliding sleeve 24 is slidably sleeved on the coil 20, and an articulated connecting portion 25 is electrically connected between the adjusting sliding sleeve 24 and the slip ring 26. A toggle lever 27 is used to toggle the articulated connecting portion 25, so that the adjusting sliding sleeve 24 slides up and down on the coil 20 to achieve a change in the lead distance, realizing fine adjustment of the resistance value. By adjusting the height of the rotating bracket 23, multi-lead adjustment is achieved. The conduction angle of the current waveform passing through the device under test is made greater than 170 degrees.

[0033] The coil can be spiral (such as Figure 15 the solution to be protected for the next improvement), serpentine (such as Figure 14 the solution adopted for the test) or other tortuous structures. The material can be materials such as aluminum and copper, preferably 304 stainless steel. The insulating cooling medium can be oil, air flow, ethanol, etc., but preferably pure water or deionized water. The water circuit of the coil is externally connected to a refrigerator and a water pump, so as to realize the circulation of water flow and temperature control. Using pure water or deionized water as the medium can avoid scaling and corrosion. The spiral tube can generate an electromagnetic effect to magnetize the water and reduce scaling.

[0034] The output end of the main current regulator 111 is output to node A through the main current diode D11, 2CZ500 / 1600V and the main current thyristor Q11, 3CT500\3000V, so as to be connected to the device under test for normal measurement.

[0035] When testing the conduction voltage of the device under test, when the device under test is a diode, the anode of the diode is connected to the positive pole of the main current circuit, that is, node A, and the cathode of the diode is connected to the negative pole of the main current circuit, that is, node K. When the device under test is a thyristor, the anode of the thyristor is connected to the positive pole A of the main current circuit, the cathode of the thyristor is connected to the negative pole K of the main current circuit, and the control electrode of the thyristor is connected to the control electrode g of the main current circuit.

[0036] Since the main current thyristor Q11 needs a trigger signal to conduct, in order to provide a trigger voltage and current for the main current thyristor Q11, the main current circuit 110 includes a first trigger circuit 112, which is used to synchronously trigger the on-off of the main current thyristor Q11 and adjust the current magnitude. The synchronous trigger signal is taken out by using the in-phase half-wave when the main current thyristor Q11 conducts, and the main current thyristor Q11 is synchronously triggered, that is, the thyristor conducts in the positive half-wave and blocks in the negative half-wave. In this way, when a high voltage is applied in the negative half-wave of the main current, the thyristor blocks, playing an isolation role to prevent the high-voltage transformer and the diode from forming a loop and causing a short circuit.

[0037] During the main current test, the mains power passes through the fuse BZ of the power switch to the main current regulator T10 with high power, and then is isolated by the main current isolation transformer TC11 with high power for step-down. The secondary of the main current isolation transformer TC11 outputs a low-voltage and high-current power supply, which then passes through the high-power main current diode D11 and the high-power unidirectional main current thyristor Q11 to perform half-wave rectification on the output of the high-power step-down transformer. The main current is generated through the device under test and the load resistors R11 - R16.

[0038] The functions of the main current are as follows: a. Test the average voltage drop and peak voltage drop of the device (without applying reverse voltage at this time). When a specified current passes through, the device under test generates a half-wave voltage drop. The size of the average voltage drop is measured by a voltmeter, and the voltage drop waveform is observed through an oscilloscope. The comparison voltage and the peak of the voltage waveform can be made horizontal by adjusting the corresponding comparison voltage potentiometer, and the peak voltage drop is read through the voltmeter. See Figure 10 ; b. When testing Vf(thermal), pass the main current to heat up the device under test and measure the case temperature of the device under test with a temperature probe. Read Vf(thermal) through an oscilloscope and a voltmeter; c. Conduct a basic comparison waveform during the surge test. See Figure 11 ; d. Apply a specified main current to the device under test, and then apply a specified reverse (the thyristor can be forward or reverse) voltage for full dynamic testing.

[0039] Figure 10 In the illustrated embodiment, a schematic diagram of the main current waveform and the peak voltage waveform. The comparison line of the oscilloscope can be made level with the top of the sine wave, and the peak voltage value is measured by a voltmeter. In an embodiment of the present invention, the reading on the voltmeter is "0.987" at this time, which is the forward peak voltage value of the device.

[0040] The general architecture of the surge test circuit 120 is basically the same as that of the main current circuit, including a surge current regulator 121, a pulse counting and timing module 123, a second trigger circuit 122, and a second air-cooling module D2. The main current regulator 121 can adjust the magnitude of the surge current output by the main circuit according to the rated value of the device under test. The second air-cooling module D2 is used to dissipate heat from the high-power diode and thyristor heat sinks.

[0041] Surge reliability is one of the device reliability indicators, which refers to the ability of the device to withstand surge current. Surge current refers to the peak current or overload current (sharp pulse interference) that is much larger than the steady-state current when the power supply is turned on instantaneously or when an abnormal situation occurs in the circuit. The device may be burned out in an instant during the surge, and the PN junction breakdown may occur. Therefore, the purpose of the surge test is to test the maximum surge current that the power semiconductor can withstand and the characteristic changes shown under the surge current.

[0042] During the inrush current test, the commercial power passes through the fuse BL of the power switch to the main current regulator T20 with high power, and then is isolated by the main current transformer TC12 with high power step-down. The secondary of the main current transformer TC12 outputs a low-voltage and high-current power supply, which then passes through the main current diode D12 with high power and the main current thyristor Q12 with high power and unidirectional main current to perform half-wave rectification on the output of the high-power step-down transformer. The inrush current is generated through the device under test and the load resistors R21 - R26.

[0043] After the inrush current regulator 121, there is an inrush current isolation transformer TC12, with an output of 60V / 600A. An AC voltmeter Y12 is connected to the secondary coil of the inrush current transformer TC12 to display the input voltage parameters, facilitating operation and judging the position of the main current regulator T20. The output end of the secondary coil of the inrush transformer TC12 is connected to the output node A through the series-connected inrush diode D12, 2CZ800 / 1600V and the inrush thyristor Q12, 3CT800 / 3000V, which is controlled by the second trigger circuit 122 to open and close and serves as the electronic switch of the inrush.

[0044] The control module 150 uses a step-down transformer for voltage reduction, compares with a comparison voltage through a comparator, generates an electronic switch signal synchronized with the sine wave of the power grid, and switches the main current waveform, inrush waveform, and inrush comparison waveform of the device through the electronic switch and the band switch, presenting the measured waveform on the oscilloscope.

[0045] After the power supply is stepped down by the transformer TC51, it is rectified and filtered and regulated by U541 to obtain a regulated power supply of 5V. The 5V power supply supplies power to the operational amplifier U52, the comparator U51, and the electronic switch integrated circuit U54. A bias voltage is obtained by dividing the voltage through the adjustable potentiometer R59 and the potentiometer R58, and a comparison voltage of Vf(thermal)VTM is obtained by dividing the voltage through R511 and the adjustable potentiometer R510. The magnitude of this comparison voltage can be adjusted by 510. The voltage at the secondary tap of the transformer TC51 is divided by R51 and R52 and applied to pin 2 of the comparator U51, and the bias voltage obtained by dividing the voltage through R58 and R59 is applied to pin 3 of the comparator U51. In this way, a rectangular pulse in the same phase as the secondary AC of the transformer TC51 is output at pin 1 of the comparator U51, and the pulse width can be adjusted by R58. This pulse is followed and driven by U52 and applied to pin 6 of the electronic switch U54 to control the operation of the internal electronic switch of U54.

[0046] When the internal electronic switch of U54 operates, the output terminal pins 1 and 8 are conducted; its signal is output from pin 1; pin 1 of U54 is connected to the input terminal of the follower U56, and the output terminal of the follower U56 is connected to the oscilloscope through the band switches SB52 and SB53; the voltage signals at both ends of the device under test are added to pin 2 of U54 through the corresponding relays Jg4 at nodes a and K via the follower U53, and pin 1 is the common output terminal of the switch signal of the electronic switch U54; the electronic switch U54 then converts the signals at pins 8 and 2 through the electronic switch, outputs them from pin 1, follows through the electronic switch U54, and sends them to the oscilloscope through the band switch SB52 to display the voltage waveform at both ends of the device under test.

[0047] The surge current circuit 120 further includes a band switch connected to the surge current loop, corresponding to the surge current shift switches of 200A, 100A, 50A, 20A, 5A, and 1A. The surge loop includes a plurality of adjustable load resistors R122. By connecting load resistors with sequentially increasing resistance values in series, the current is gradually reduced correspondingly for output. Preferably, there are six. The main current limiting resistor R122 includes the first resistor R21, the second resistor R22, the third resistor R23, the fourth resistor R24, the fifth resistor R25, and the sixth resistor R26; the surge current is connected to the device under test through terminals A and K.

[0048] The 5V power supply is divided by the potentiometer W64 of R63, and a comparison voltage for the surge can be obtained by adjusting W64. This comparison voltage is mainly used to set the multiple between the surge current and the main current, so that the height of the surge waveform is equal to the set comparison voltage. This comparison voltage is added to pin 8 of U59 through isolation and following by U63.

[0049] The two contacts ①② are connected in parallel at both ends of the shunt. The main current and surge current signals on the shunts of each gear from 1 to 200A are at both ends. This signal is added to pin 2 of the electronic switch U59 through isolation and following by U61. Pin 1 is the common switch signal output terminal. In this way, the electronic switch follows and buffers the comparison voltage signal at pin 8 and the voltage signal on the shunt at pin 2 through U62 and sends them to the oscilloscope through the band switches SB52 and SB54. In this way, the main current, surge current signals, and surge comparison signals on the shunt are displayed on the oscilloscope.

[0050] The switch signal of the surge uses an external single-chip microcomputer PLC. The single-chip microcomputer PLC obtains a trigger pulse with the same phase as the current to trigger the thyristor to conduct and generate a surge. The surge signal is obtained from both ends of the shunts of each gear, passes through the band conversion switch to the potentiometer. It is adjusted by the potentiometer and sent to the function conversion and electronic switch, and is converted by the electronic switch to the oscilloscope to display the surge waveform.

[0051] The pulse counting and timing module 123 includes a timing module and a counting module, which are used to control the number of surges and the time interval between surges. The number of surges is set by the counter according to requirements, and the time interval between surges is set by the cyclic timer according to requirements. When the number of surges set in the experiment is reached, the device automatically stops working, and the surge waveform can be observed on the oscilloscope. The current phase of the surge is in the same phase as the main current phase, and the surge is controlled by the surge thyristor Q12 and the pulse counting and timing module 123.

[0052] During the surge test, on the one hand, the surge impact can be carried out alone without applying the main current and reverse voltage; second, the main current and surge can be applied without applying the reverse voltage; third, the main current, surge, and reverse voltage can be all applied for the full dynamic surge test. The present invention can carry out the surge test alone, perform a single surge impact test on the device under test; semi-dynamic surge test, apply the surge test when applying the main current to the device under test; full dynamic surge test, apply the surge test when applying the main current and (positive) reverse high voltage to the device under test at the same time, and the phase of the (positive) reverse high voltage is opposite to the main current of the surge).

[0053] Connect the surge test circuit during the half-wave conduction stage of the device under test, adjust the magnitude of the surge current to a predetermined multiple of the main current through the surge current regulator, turn on the high-voltage power supply, switch the polarity of the polarity switching module to the reverse, and perform the surge test on the device under test based on the pre-set number of surge pulses and the time interval between surge pulses.

[0054] The phase of the high voltage is opposite to the main current of the surge, such as Figure 8 .

[0055] The high-voltage circuit 130 includes a high-voltage switching module, a high-voltage regulator 131, a high-voltage intermediate module 132, a polarity switching module 133, and an overload protection module 134.

[0056] This circuit is used to apply a high voltage to the device under test in the opposite phase to the main current and the surge, for testing the withstand voltage value of the device, or applying a high voltage during dynamic testing.

[0057] The power supply is connected to the voltage regulator of the high-voltage regulation through the normally closed contact JB4 of the high-voltage switch SB4-1 and the overcurrent protection relay JB4. After the voltage regulator, a step-up transformer Tc4-1 is connected. The step-up transformer outputs two gears of 100OV and 2000V, and the gear switching is controlled by the switch SB4-2 to control the relay JZ4. The voltage regulator can adjust the magnitude of the high voltage.

[0058] The high voltage is generated by half-wave rectifying the alternating current through the 1000V or 2000V tap of TC4-1 via current-limiting resistors R4-3 and R4-2 by rectifying diode D4-2. D4-2 applies its reverse voltage to D4-1 during the negative half-wave of the alternating current to prevent the reverse voltage from being applied to the device under test. D4-3 to D4-6 and C4-1 rectify and filter the half-wave of the alternating current to obtain the peak value of the half-wave voltage on capacitor C4-1, and then the voltage is divided by Rz4-6 and adjustable potentiometer Rz4-4 and sent to the peak voltage meter head to display the peak voltage value. The adjustable potentiometer Rz4-4 is used for peak voltage calibration. The half-wave voltage is divided by R4-5, R4-7 (R4-8) and sent to the oscilloscope to display the dynamic curve. A DC ammeter is connected in series in the circuit to display the leakage current during testing in the circuit. R4-9 is an overcurrent protection sampling resistor.

[0059] There is a polarity conversion switch SB4-3 in the high voltage output circuit. Through the conversion of this switch, the positive and negative polarities of the output high voltage can be converted according to the test requirements.

[0060] In addition, a protection relay Jg4 is also connected in the high voltage circuit. Jg4 is energized and attracted when the high voltage switch is closed, and the high voltage is applied to the device under test through the corner contacts of Jg4. When the high voltage switch is opened, Jg4 is not attracted, and the high voltage circuit is in an open state from other external circuits through the normally open contacts of Jg4.

[0061] The high voltage switch SB4-1 is a single-pole double-throw switch. One end supplies power for high voltage testing, and the other end supplies power for thermal sensitivity testing. When switched to high voltage, the thermal sensitivity voltage has no voltage and cannot work. When switched to thermal sensitivity, the high voltage has no power and cannot work. The purpose is that high voltage and thermal sensitivity cannot be powered simultaneously to avoid mutual influence during testing and prevent misoperation from damaging the circuit.

[0062] The phase of the high voltage half-wave is 180 degrees out of phase with the main current and surge phase, so as to ensure that the main current and surge are conducted during one half-wave and (positive) reverse voltage is applied during the other half-wave. The functions of the high voltage circuit are as follows:

[0063] ①. The high voltage circuit can conduct independent withstand voltage testing on devices and can test the non-repetitive and repetitive withstand voltage values of diodes and thyristors.

[0064] ②. (Positive) reverse voltage can be applied during full dynamic main current testing.

[0065] ③. (Positive) reverse voltage can be applied during surge, semi-dynamic surge, and full dynamic testing.

[0066] An overcurrent and overload protection circuit 134 is also provided in this high voltage circuit. When the loop is overcurrent or overloaded, the high voltage power supply is cut off to protect the circuit.

[0067] The overcurrent protection circuit is stepped down by transformer Tc4-2, rectified by D4-4, filtered by C4-4, and stabilized by U4-1 to obtain a 12V DC power supply. This 12V power supply supplies power to comparator U4-2 and overload protection relay JB4. At the same time, an overcurrent protection threshold voltage is obtained through R4-11 and adjustable potentiometer R4-13 and added to pin 2 of U4-2. The threshold voltage is adjusted and set by R4-13.

[0068] R4-9 is the overcurrent protection sampling resistor. The current sampling voltage on R4-9 is limited by R4-10 through the voltage regulator D4-5, filtered by C4-6, and added to the 3rd pin of U4-2. When the overcurrent and overvoltage exceed the set protection value, the U-21 pin outputs a high level to drive the thyristor Q4 to conduct, and the relay JB4 is attracted. The normally closed point JB4 is disconnected, cutting off the high voltage power supply, so that the high voltage has no output, and protecting the components of the high voltage circuit.

[0069] At the same time, the overload protection relay JB4 is also connected in parallel with a light-emitting diode. When the overload protection is activated, the light-emitting diode lights up to show that the circuit is in a protection state and there is no high-voltage output. A reset switch SB-4 is also connected in series with the JB4 coil. Pressing this switch can release the protection and retest.

[0070] In the thermistor test 140 in the example of the present invention, the thermistor test includes a normal thermistor test and a hot thermistor test. The resistivity of the semiconductor will change significantly with temperature. Due to the thermistor characteristics of the semiconductor device, the stability of the semiconductor device will be affected when the ambient temperature changes. During the normal thermistor test, firstly, according to the rated current of the device under test, the thermistor current regulator is used to adjust the thermistor current. Generally, 1%-10% of the rated current of the device is selected. For example, for a diode with a rated average current of 70A, 70A×5%=3.5A is generally taken as the thermistor test current; then, heating is performed, and the thermistor voltage of each device passing through the thermistor current at different temperatures (50°C, 80°C, 110°C, 140°C, 150°C, 170°C) is tested in turn. At the same time, the thermistor voltage Vf waveform under the normal thermistor test can be observed with an oscilloscope.

[0071] In the thermistor voltage test, the diode or thyristor can be passed through the specified thermistor current with a regulated current-stabilized power supply. Detect the thermistor voltage at different ambient temperatures. The thermistor voltage can be read on the instrument on the device or on an oscilloscope, which is Vf; or a small hole of a certain depth can be drilled on the base of the device and a temperature control probe can be inserted. Then the device is added with the specified main current and thermistor current, and the main current is used to heat the device to the required temperature. The temperature is kept constant for a certain period of time, and the waveform on the oscilloscope is used to compare the voltage adjustment, and the thermistor voltage value is read on the digital meter or oscilloscope. This is Vf (thermal);

[0072] like Figure 5, the thermal test circuit includes a thermal current regulator and a heating module. Specifically, the thermal test circuit 140 includes a thermal constant voltage and constant current source U31. The input terminal of the thermal constant voltage and constant current source U31 is connected to the power supply. A control coil of a thermal isolation relay Jr is provided between the input terminals of the thermal constant voltage and constant current source U31. The thermal constant voltage and constant current source U31 is electrically connected to a thermal current regulator for adjusting the magnitude of the thermal current. The thermal constant voltage and constant current source outputs through a thermal isolation diode. One path outputs the 5A gear through the adjustable thermal resistor 1R, and one path outputs the 1A gear through the adjustable thermal resistor 5R. Then, after passing through the single-pole double-throw switch SB31, it is connected to the device under test through the normally open execution switch of the thermal isolation relay Jr, so as to achieve normally open isolation and energized conduction. It has two-stage control, adjustable current, and constant current output. Its output current is not affected by the magnitude of the external contact resistance and wire resistance. The thermal voltage drop is read by the digital voltmeter on the device. The relay Jr is an isolation relay, and its power supply and constant current power supply are powered in parallel. Jr is attracted when performing thermal tests and disconnected during other function tests to prevent affecting the constant current power supply. In addition, the thermal power supply is interlocked with the high-voltage test power switch. When performing high-voltage tests, the constant current power supply is not powered, and Jr is disconnected to avoid the high voltage affecting the constant current circuit.

[0073] When measuring Vf, first, heat the device under test to different set temperatures through an oven or a hot stage, such as 50 °C, 80 °C, 110 °C, 140 °C, 150 °C, 170 °C; then, measure its thermal voltage drop through the set thermal current.

[0074] When measuring Vf(thermal), drill a test hole on the base of the device under test and insert a temperature control probe to monitor its temperature, and apply the specified main current and thermal current. In this way, two currents, the main current and the thermal current, pass through the device. The waveforms of the main current and the thermal voltage drop can be observed on the oscilloscope, and the dynamic process of the thermal voltage drop changing with temperature can be observed. When the device under test reaches the specified temperature and time, the magnitude of its thermal voltage can be adjusted by adjusting the comparison voltage potentiometer to make the comparison voltage and the thermal voltage drop curve on a horizontal line. The thermal voltage can be read on the digital meter on the panel or read on the oscilloscope using the scale of the oscilloscope.

[0075] When the current value passing through the semiconductor in the conduction state is relatively large, it will cause the increase of the junction temperature, thus damaging the device. Therefore, it is necessary to test its junction temperature. By testing the thermal voltage of the device passing through the thermal current at multiple different temperatures, draw a thermal curve, and calculate the thermal slope and the highest junction temperature of the device. The breakdown voltage of the diode or thyristor can be tested through positive and reverse high voltages. When performing full dynamic application of the main current, apply a reverse voltage; when performing full dynamic surge, apply a reverse voltage. When testing thyristor devices, both positive and negative voltages are applied.

[0076] Figure 12 , the schematic diagram of the thermal-sensitive voltage waveform under the hot-state thermal-sensitive test in the illustrated embodiment.

[0077] The temperature rise of the device can be calculated by the following formula: △Tj = (Vf - Vf(thermal)) / M

[0078] In the formula: △Tj represents the junction temperature rise of the device under test, Vf is the thermal-sensitive voltage at the lowest test temperature under normal conditions, Vf(thermal) represents the thermal-sensitive voltage at 150 °C in the hot state, and M represents the thermal-sensitive slope.

[0079] The highest junction temperature of the device TjM = △Tj + T0. In the formula, TjM represents the highest junction temperature of the device, and T0 = the lowest test temperature.

[0080] The control module 150 includes a high-voltage single-pole double-throw switch SB4-1 (such as Figure 8 ), one end supplies power to the high-voltage circuit 130, and the other end supplies power to the thermal-sensitive test circuit 140. When the high voltage is turned on or off, the thermal-sensitive voltage is turned off or on to perform switching conduction, avoid double connection, avoid mutual influence during testing, prevent misoperation, and damage the circuit.

[0081] The control module 150 uses a step-down transformer to step down the voltage, compares it with a comparison voltage through a comparator, generates an electronic switch signal synchronized with the power grid sine wave, and switches the voltage drop waveform, main current waveform, surge waveform, thermal-sensitive voltage waveform, thermal-sensitive comparison, and surge comparison waveforms through an electronic switch and a band switch, and presents the measured waveforms on an oscilloscope.

[0082] The control module 150 is also electrically connected to processors such as PLC and MCU for data processing.

[0083] Figures 2-4 In the illustrated embodiment, the control module 150 is used for a function conversion and waveform display module, and includes a first control unit and a surge control unit. The first control unit includes a first voltage comparison circuit, a thermal-sensitive comparison circuit, and a first electronic switch; it is used to control the function conversion, testing, oscilloscope display, and voltage reading of the thermal-sensitive voltage drop Vf, average voltage drop VT, peak voltage drops VTM, and Vf(thermal). The surge control unit includes a surge comparison circuit and a second electronic switch, and is used to control the conversion of surges and the oscilloscope display of surges.

[0084] In the first control unit, the power supply has two inputs. One output is given to the first voltage comparison circuit, and the other output is given to the thermal-sensitive comparison circuit. The first voltage comparison circuit controls the on-off of the thermal-sensitive comparison circuit by triggering the first electronic switch, realizes the synchronous switching of the main current circuit 110, the thermal-sensitive test circuit 140, and the first voltage comparison circuit, and displays them on a digital meter and an oscilloscope.

[0085] Such as Figures 3-4, the first voltage comparison circuit includes a comparator U51, an operational amplifier U52, and a variable resistor R58. The variable resistor R58 is used to adjust the duty cycle of the corresponding first electronic switch U54;

[0086] When performing the VTVTMVfVf (thermal) test, the power supply is stepped down, rectified, filtered by the transformer TC51, and regulated by U54 to obtain a 5V regulated power supply. The 5V power supply supplies power to the operational amplifier U52, the comparator U51, and the electronic switch integrated circuit U54. A bias voltage is obtained by dividing the voltage through the adjustable potentiometer R59 and the variable resistor R58, and a comparison voltage of Vf (thermal) VTM is obtained by dividing the voltage through R511 and the adjustable potentiometer R510. The magnitude of this comparison voltage can be adjusted by 510. The voltage at the secondary tap of the transformer TC51 is applied to pin 2 of the comparator U51 through R51 and R52, and the bias voltage obtained by dividing the voltage through R58 and R59 is applied to pin 3 of the comparator U51. In this way, a rectangular pulse in the same phase as the secondary AC of the transformer TC51 is output at pin 1 of the comparator U51. Its pulse width can be adjusted by R58. This pulse is followed and driven by U52 and applied to pin 6 of the electronic switch U54 to control the operation of the internal electronic switch of U54.

[0087] Contact point small a and the main circuit K terminal are actually connected to both ends of the device under test. In this way, the voltage signal at both ends of the device under test is applied to pin 2 of the electronic switch U54 through the relay contact Jg4 and the resistor R57 by following through U53. Pin 1 is the common terminal for the switch signal output of the electronic switch U54. In this way, the electronic switch U54 converts the signals at pins 8 and 2 through the electronic switch and outputs them from pin 1. After following through U54, it is sent to the oscilloscope through the band switch SB52. In this way, the voltage waveform at both ends of the device under test is displayed on the oscilloscope. The band switch SB51 is for the function test conversion of Vf VT and VTM Vf (thermal). When switched to VfVT, the voltage at both ends of the device under test is applied to the digital voltmeter through SB51 and SB61. At this time, the Vf and VT of the device under test can be read through the digital meter. When switched to VTMVf (thermal), the comparison voltage is applied to the digital meter. Adjust the comparison voltage potentiometer V510 and observe the waveform on the oscilloscope to make the comparison voltage waveform and the peak of the voltage drop waveform on the same horizontal line or form a horizontal line with the waveform of Vf (thermal). At this time, the voltage of the digital meter is VTMVf (thermal).

[0088] SB52, SB54, SB61, and SB62 are four-pole double-throw band switches used for the test function conversion of thermal voltage drop and surge. Jg4 is a high-voltage isolation relay. When performing a high-voltage test, Jg4 is disconnected to avoid the impact of high voltage on this part of the circuit.

[0089] As Figure 13 shown, thermal testing, surge testing, and full dynamic testing can be performed simultaneously.

[0090] When performing a surge test on the device under test, the control module 150 can control the main current circuit, the surge test circuit, and the high-voltage circuit to conduct in sequence, so as to perform a surge test on the device under test based on the preset number of surge pulses and the time interval between surge pulses; when performing a thermal sensitivity test on the device under test, the control module 150 can control the thermal sensitivity test circuit to conduct, and test the thermal sensitivity voltage corresponding to the thermal sensitivity current at different temperatures by adjusting the magnitude of the thermal sensitivity current and the temperature at which the device under test is heated; when performing a full dynamic test on the device under test, the control module 150 can control the main current circuit and the high-voltage circuit to conduct in sequence, so as to test the forward and reverse peak voltages and the forward and reverse leakage currents of the device under test. Among them, during the full dynamic test, a half-wave current is applied to the device under test within a power frequency half-cycle, and the average value of the current is determined by the rated current value of the device, while a forward or reverse sine half-wave blocking voltage is applied within the other half-cycle to measure the dynamic blocking volt-ampere characteristics of the device. The indicators of the full dynamic test mainly include the average current, the average voltage drop, the forward and reverse non-repetitive peak voltages, the forward and reverse peak leakage currents, etc.

[0091] Figure 9 In the illustrated embodiment, the test sequence can be adjusted according to actual needs, and the main current waveform, the peak voltage waveform, and the surge waveform can be observed through an oscilloscope to ensure that the main circuit loop and the surge test loop are normally conducting before the test.

[0092] According to the solution of the present invention, by controlling the conduction or cut-off of different test circuits, it is possible to simultaneously perform thermal sensitivity, surge, and full dynamic parameter tests on the device under test during the half-wave conduction stage of the device under test. Each test circuit can be combined or used independently, improving the efficiency of device testing; the output voltage or current magnitude of each test circuit can be adjusted according to the rated parameter value of the device under test, which can adapt to the characteristics of high voltage, high temperature resistance, and high switching frequency of power semiconductor devices, and can improve the accuracy of device testing.

Claims

1. A test system for a power semiconductor device, characterized in that: it includes a main current circuit (110); the main current circuit (110) provides a half-wave conduction current for the device under test; the test system further includes: a control module (150), a surge test circuit (120), a high-voltage circuit (130) and / or a thermal test circuit (140), which are used to respectively perform full-dynamic surge tests, full-dynamic main current tests and / or thermal tests on the device under test during the half-wave conduction stage; the control module (150) is adapted to control a surge test on the device under test during the positive half-wave of the sine wave and / or the control module (150) controls a forward or reverse high-voltage test on the device under test during the negative half-wave; the control module (150) includes a first voltage comparison circuit, a thermal comparison circuit, a first electronic switch U54, a second voltage comparison circuit, a surge comparison circuit and a second electronic switch U59; after the main current circuit (110) is stepped down, it realizes unidirectional half-wave rectification output through a diode D11 and / or a main current thyristor Q11. After the surge test circuit (120) is stepped down, it realizes unidirectional half-wave rectification output through a diode D12 and / or a surge current thyristor Q12; the surge test circuit (120) includes a surge current regulator (121) for adjusting the peak value of the surge current; a pulse counting timing module (123) for setting the number of surges and the surge time interval; a second air-cooling module D2 for dissipating heat from the rectifier diodes and thyristors in the circuit; the high-voltage circuit (130) includes a high-voltage switching module, a high-voltage regulator (131), a high-voltage intermediate module (132), a polarity switching module (133) and an overload protection module (134) which are electrically connected; and / or, the thermal test circuit (140) adds a thermal current to the device under test through a thermal isolation diode and a thermal isolation relay JR.

2. The test system for a power semiconductor device according to claim 1, characterized in that: the control module (150) steps down the voltage using a step-down transformer, compares it with a comparison voltage through a comparator, generates an electronic switch signal synchronized with the grid sine wave, switches the main current waveform, surge waveform and / or surge comparison waveform of the device under test through an electronic switch and a band switch, and presents the measured waveform on an oscilloscope; the power supply outputs two paths, one path is output to the first voltage comparison circuit, and the other path is output to the thermal comparison circuit; the first voltage comparison circuit controls the thermal comparison circuit by triggering the first electronic switch U54, realizes the switching between the main current circuit (110), the thermal test circuit (140) and the first voltage comparison circuit and displays it on a digital meter and / or an oscilloscope; the second voltage comparison circuit controls the surge comparison circuit by triggering the second electronic switch U59, realizes the switching between the main current circuit (110), the surge test circuit (120) and the second voltage comparison circuit, and displays it on an oscilloscope; When testing the on-state voltage drop of the device under test, when the device under test is a diode, connect the anode of the diode to the positive pole of the main current circuit, i.e., node A, and the cathode of the diode to the negative pole of the main current circuit, i.e., node K; when the device under test is a thyristor, connect the anode of the thyristor to the positive pole of the main current circuit, the cathode of the thyristor to the negative pole of the main current circuit, and the control electrode to the g pole of the test bench; The high-voltage switching module outputs two paths. One path passes through the high-voltage regulator (131) and the high-voltage intermediate module (132) in sequence, and then the output terminal of the polarity switching module (133) is connected to node A and node K. The other path of the high-voltage switching module bypasses the overload protection module (134) to sample the signal output by the high-voltage intermediate module (132); The high-voltage switching module is used to perform high-voltage forward or reverse tests, and apply high voltage during the negative half-wave of the main current circuit test to achieve full dynamic testing; the high-voltage regulator (131) is used to adjust the voltage output; The polarity switching module (133) is used to control the reversal of the high-voltage polarity applied to the device under test, so that when performing thyristor tests, the forward peak voltage and forward leakage current value of the device are measured during forward testing, and the reverse peak voltage and reverse leakage current of the device are measured during reverse testing; when testing a diode, the reverse peak voltage and reverse leakage current are tested; The overload protection module (134) is used to detect the current of the high-voltage circuit (130). When a short circuit or overload occurs in the high-voltage circuit, it indicates whether there is overload through an indicator light, and disconnects the high-voltage power supply when overloaded; The thermal test circuit (140) includes a thermal voltage-stabilized and current-stabilized power supply U31 and adjustable thermal resistors 1R and 5R corresponding to the 1A and 5A gears. The thermal test circuit (140) has a thermal current potentiometer set on the panel for adjusting the thermal current magnitude. The provided current is a constant current, and its current is not affected by the magnitude of the external contact resistance and wire resistance. The thermal voltage drop is read by a digital voltmeter on the device; the thermal isolation relay JR is powered in parallel with the thermal voltage-stabilized and current-stabilized power supply U31. The thermal isolation relay JR is closed during thermal testing, otherwise it is open to prevent affecting the current-stabilized power supply; When measuring Vf, first, heat the device under test to different set temperatures through an oven or a hot stage; then, test its thermal voltage drop through the set thermal current; Measuring Vf (热) When measuring Vf, first, drill a test hole on the base of the device under test and insert a temperature control probe to monitor its temperature; Then, apply the main current and thermal current to the device under test, observe the waveforms of the main current and thermal voltage drop through an oscilloscope, and observe the dynamic process of the thermal voltage changing with temperature; secondly, when the device under test reaches the set temperature and time, adjust the thermal comparison voltage potentiometer R510 so that the comparison voltage and the thermal voltage curves are on a horizontal line, and the thermal voltage is read through a digital meter and / or an oscilloscope.

3. The test system for power semiconductor devices according to claim 1, characterized in that: a) In the control module (150), a first voltage comparison circuit includes a comparator U51, an operational amplifier U52, and a variable resistor R58. The variable resistor R58 is used to adjust the duty cycle corresponding to the first electronic switch U54. The power supply is stepped down, rectified, filtered by a transformer TC51 and then regulated by a voltage regulator U541 to obtain a 5V power supply. The 5V power supply supplies power to the operational amplifier U52, the comparator U51, and the first electronic switch U54. A bias voltage is obtained by dividing the voltage through the resistor R59 and the variable resistor R58, and a comparison voltage Vf and the comparison voltage of VTM are obtained by dividing the voltage through the resistor R511 and the comparison voltage potentiometer R510. The comparison voltage is adjusted by the adjustable potentiometer R510. The voltage of the secondary tap of the transformer TC51 is applied to the 2nd pin of the comparator U51 through the resistors R51 and R52. The bias voltage obtained by dividing the voltage through the variable resistor R58 and the resistor R59 is applied to the 3rd pin of the comparator U51. A rectangular pulse in the same phase as the secondary alternating current of the transformer TC51 is output at the 1st pin of the comparator U51. The pulse width of the rectangular pulse is adjusted by the variable resistor R58 and is applied to the 6th pin of the first electronic switch U54 through the follow-up drive of the operational amplifier U52 to control the operation of the internal electronic switch of the first electronic switch U54; (热) and the comparison voltage of VTM. The comparison voltage is adjusted by the adjustable potentiometer R510. The voltage of the secondary tap of the transformer TC51 is applied to the 2nd pin of the comparator U51 through the resistors R51 and R52. The bias voltage obtained by dividing the voltage through the variable resistor R58 and the resistor R59 is applied to the 3rd pin of the comparator U51. A rectangular pulse in the same phase as the secondary alternating current of the transformer TC51 is output at the 1st pin of the comparator U51. The pulse width of the rectangular pulse is adjusted by the variable resistor R58 and is applied to the 6th pin of the first electronic switch U54 through the follow-up drive of the operational amplifier U52 to control the operation of the internal electronic switch of the first electronic switch U54; The contact point small a and the K end of the main circuit are used to be connected to both ends of the device under test. The voltage signal at both ends of the device under test is added through the contacts of the high-voltage isolation relay Jg4 and the resistor R57 and followed by U53 to the 2nd pin of the first electronic switch U54. The 1st pin is the common terminal for the switch signal output of the first electronic switch U54. The first electronic switch U54 then converts the signals at the 8th and 2nd pins and outputs them from the 1st pin, which is followed by the first electronic switch U54 and sent to the oscilloscope through the band switch SB52 for displaying the voltage waveform at both ends of the device under test; The band switch SB51 is for Vf, VT, VTM, and / or Vf (热) Function test conversion; when switched to Vf or VT, the voltage across the device under test is applied to the digital voltmeter through switches SB51 and SB61, and the Vf and VT of the device under test are read through the digital meter; when switched to VTM or Vf (热) , the comparison voltage is applied to the digital meter. Adjust the comparison voltage potentiometer R510 and observe the waveform on the oscilloscope to make the peak of the comparison voltage waveform and the voltage drop waveform on the same horizontal line or make the waveform of the comparison voltage and the Vf (热) waveform form a horizontal line. The voltage shown on the digital meter is VTM and Vf (热) ; Four-pole double-throw band switches SB52, SB54, SB61, and SB62 are used for the test function conversion of thermal voltage drop and surge; when performing high-voltage tests, the high-voltage isolation relay Jg4 is disconnected to avoid the influence of high voltage; b), The main current circuit (110) includes a main current regulator (111), a first trigger circuit (112) and a first air-cooling module D1. The main current regulator (111) adjusts the magnitude of the main current output by the main circuit according to the rated value of the device under test. When the rated current flowing through the device under test is greater than 50A, the first air-cooling module D1 starts ventilation and heat dissipation; The main current regulator (111) has a main current isolation transformer TC11. A main current AC meter Y11 is connected to the secondary coil of the main current isolation transformer TC11 to display the input electrical parameters and judge the position of the main current voltage regulator T10; According to the rated value of the device under test, adjust the gear of the main current, and use the main current voltage regulator T10 to adjust the magnitude of the rated current output by the main current circuit; c), The main current circuit (110) includes a plurality of adjustable main current load resistors R111 connected in the main current loop, and the resistance values increase in sequence to achieve a step-by-step corresponding reduction in current output. The main current load resistors R111 include a first resistor R11, a second resistor R12, a third resistor R13, a fourth resistor R14, a fifth resistor R15, and a sixth resistor R16, which respectively correspond to the main current gears of 200A, 100A, 50A, 20A, 5A, and 1A. The main current is connected to the device under test through the A and K ends; d), During the surge current test, the commercial power is connected to the main current voltage regulator T20 through the power switch fuse BL, and then isolated by the step-down main current transformer TC12. The secondary of the main current transformer TC12 outputs power, which is then half-wave rectified through the main current diode D12 and the unidirectional main current thyristor Q12, and a surge current is generated through the device under test and the load resistors R21 - R26; The surge current circuit (120) includes a main current regulator (111), a second trigger circuit (122), and a second air-cooling module D2. The main current regulator (111) adjusts the magnitude of the surge current output by the main circuit according to the rated value of the device under test; the second air-cooling module D2 is used to dissipate heat from the main current diode D12 and the unidirectional main current thyristor Q12 when the rated current of the device under test is greater than 50A; The inrush current regulator (121) includes an inrush current isolation transformer TC12 with a rated output of 60V / 600A. An AC voltmeter Y12 is connected to the secondary coil of the inrush current transformer TC12 to display the input voltage parameter and judge the position of the main current regulator T20. The output end of the secondary coil of the inrush transformer TC12 is connected to the output node A through a series-connected inrush diode D12 and an inrush thyristor Q12 which is controlled by the second trigger circuit (122) to open and close and serves as an inrush electronic switch. The pulse counting timing module (123) includes a timing module and a counting module, which are used to control the number of inrushes and the time interval between inrushes. The number of inrushes is set by the counting module, and the inrush time interval is set by a cyclic timer. When the set number of inrushes is reached, the inrush waveform is displayed on the oscilloscope. The inrush current phase and the main current phase are in the same phase, and the inrush is controlled through the inrush thyristor Q12 and the pulse counting timing module (123). And / or e), a high-voltage circuit (130), when it is out of phase with the main current and the inrush, applies a high voltage to the device under test to test the withstand voltage value of the device, or applies a high voltage during dynamic testing. In the high-voltage circuit (130), a rectifying and filtering circuit (132) includes a plurality of diodes D4-1 connected in series in the forward direction on the high-voltage output line, a plurality of rectifying diodes D4-2 connected in series in the reverse direction between the high-voltage output line and the high-voltage loop, and a plurality of series-connected diodes D4-3, a capacitor C4-1, and a resistor R4-6 electrically connected between the output line and the loop. The plurality of series-connected diodes D4-3 are divided into two paths. One path is connected to the loop through the capacitor C4-1, and the other path is connected to the return through the resistor R4-6 and the adjustable potentiometer Rz4-4. A peak voltmeter Y4-2 is connected in parallel to the adjustable potentiometer Rz4-4. The power supply is applied to the voltage regulator RZ4-1 through the normally closed contact JB4 of the high-voltage switch SB4-1 of the single-pole double-throw switch and the overcurrent protection relay JB4. After the voltage regulator RZ4-1, there is a step-up transformer TC4-1. The step-up transformer outputs two gears of 1000V and 2000V, and the gear switching is controlled by the switch SB4-2 to control the relay JZ4. The voltage regulator adjusts the magnitude of the high voltage. The high voltage is generated by half-wave rectifying the AC through the 1000V or 2000V tap of the step-up transformer TC4-1 through the current-limiting resistors R4-3 and R4-2 by the rectifying diode D4-2. D4-2 applies its reverse voltage to D4-1 during the negative half-wave of the AC to prevent the reverse voltage from being applied to the device under test. D4-3 to D4-6 and C4-1 rectify and filter the half-wave of the AC, and the peak value of the half-wave voltage is obtained on the capacitor C4-1. Then, it is divided by the adjustable resistor Rz4-6 and the adjustable potentiometer Rz4-4 and sent to the peak voltmeter head to display the peak voltage value. The adjustable potentiometer Rz4-4 is used for peak voltage calibration. A DC ammeter is connected in series in the circuit to display the leakage current during the test in the circuit. The high-voltage circuit (130) includes a polarity conversion switch SB4-3 to convert the output high-voltage polarity according to the test requirements. The high-voltage circuit (130) also has a protection relay JB4, which is energized and attracted when the high-voltage switch is closed. The high voltage is applied to the device under test through the normally open contact of the protection relay Jg4. When the high-voltage switch is opened, the protection relay JB4 is not attracted, and the high-voltage circuit is disconnected from other external circuits through the normally open contact of the protection relay JB4 to prevent other circuits from affecting the high-voltage circuit. One end of the high-voltage switch SB4-1 supplies power to the high-voltage circuit, and the other end supplies power to the thermal test circuit. When switched to the high-voltage circuit, the thermal test circuit is open; when switched to the thermal mode, the high-voltage circuit is open, so as to avoid simultaneous power supply of high voltage and heat, prevent misoperation and damage the circuit. The phase of the high-voltage half-wave is opposite to that of the main current and the surge phase by 180 degrees, so as to ensure that the main current and the surge are conducted in one half-wave, and positive / negative voltage is applied in the other half-wave.

4. The test system for a power semiconductor device according to claim 3, characterized in that: In the main current circuit (110), the main current load resistor R111 includes a coil (20) as a resistor, and deionized water circulates in the coil (20). Connectors (21) are provided at both ends of the coil (20) for external connection of a water circuit. The coil (20) is equipped with a first electrical connection end (29) and an adjustable second electrical connection end (28) for external connection of a circuit. By adjusting the position of the second electrical connection end (28) on the coil (20), the resistance value of the liquid-cooled resistor is adjusted. The external water circuit includes a water pump (31) and a refrigerator (32) connected in series.

5. The test system for a power semiconductor device according to claim 3, characterized in that: The main current shift switch includes a multi-position main current switch knob; the main current switch knob and the surge switch knob are coaxially linked to realize the same-position current transmission of the main circuit and the surge circuit. In the thermal test circuit (140), Calculate the temperature rise of the device: ΔTj = (Vf - Vf (热) ) / M; Where: △Tj represents the junction temperature rise of the device under test, Vf is the thermal voltage at the lowest test temperature under normal conditions, Vf (热) represents the thermal voltage at 150°C in the hot state, and M represents the thermal slope; The maximum junction temperature TjM of the device = △Tj + T0, where TjM represents the maximum junction temperature of the device, and T0 = the lowest test temperature.

6. The test system for a power semiconductor device according to claim 3, characterized in that: In the main current circuit (110), the output end of the main current regulator (111) is output to node A through the main current diode D11 and the main current thyristor Q11, so as to be connected to the device under test for measurement. The main current circuit (110) includes a first trigger circuit (112) for synchronously triggering the on / off of the main current thyristor Q11 and adjusting the current magnitude.

7. The test system for a power semiconductor device according to claim 3, characterized in that: The overload protection circuit (134) includes an ammeter Y4-3 for displaying the leakage current and a sampling resistor R4-8. In the overcurrent protection circuit (134), the circuit is stepped down by the TC4-2 transformer, rectified by the full-wave rectification module D4-4, filtered by the filter capacitor C4-4, and regulated by the voltage regulator U4-1 to obtain a 12V DC power supply. The 12V power supply supplies power to the comparator U4-2 and the overload protection relay JB4. At the same time, the threshold voltage for overcurrent protection is obtained through the resistor R4-11 and the adjustable potentiometer R4-13 and applied to pin 2 of the comparator U4-2. The magnitude of the threshold voltage is adjusted and set by R4-13. At the comparator U4-2, an overcurrent protection sampling resistor R4-9 is electrically connected. The current sampling voltage on the overcurrent protection sampling resistor R4-9 is limited by the resistor R4-10 and the zener diode D4-5, and the noise is filtered by C4-6 and then applied to pin 3 of the comparator U4-2. When the overcurrent and overvoltage exceed the set protection threshold, the output of pin 1 of U4-2 is at a high level to drive the thyristor Q4 to conduct, and the relay JB4 will be attracted. The normally closed point of the relay JB4 is disconnected, cutting off the high-voltage power supply, so that there is no high-voltage output, protecting the devices in the high-voltage circuit. At the same time, the overload protection relay JB4 is connected in parallel with the light-emitting diode D4-6. When the overload protection action occurs, the light-emitting diode D4-6 lights up to indicate that the circuit is in the protection state at this time and there is no high-voltage output. A reset switch SB-4 is also connected in series on the coil of the relay JB4. When it is pressed, the protection state is released and the test is retested.

8. A test method for a power semiconductor device, characterized in that: With the system described in claim 1, the method includes the following steps; S010, Connect the device under test to the positive and negative connection terminals of the main current circuit, adjust the magnitude of the main current to turn on the device under test, and measure the forward peak voltage and average voltage drop of the device under test. S020, Switch the polarity switching module of the high-voltage circuit to the reverse direction, adjust the output voltage of the high-voltage power supply through the high-voltage regulator, and measure the reverse voltage and reverse leakage current of the device under test. S030, Connect the devices to be tested in series to the heating module, heat the device under test to different temperatures through the heating module, adjust the magnitude of the thermistor current through the thermistor current regulator, and test the thermistor voltage corresponding to the thermistor current at different temperatures. S040, Connect the surge test circuit during the half-wave conduction stage of the device under test, adjust the magnitude of the surge current to a predetermined multiple of the main current through the surge current regulator, turn on the high-voltage power supply, switch the polarity of the polarity switching module to the reverse direction, and perform a surge test on the device under test based on the pre-set number of surge pulses and the surge pulse time interval.

9. The test method for a power semiconductor device according to claim 8, characterized in that: wherein, When performing a full dynamic surge test on the device under test, the control module controls the main current circuit, the surge test circuit, and the high-voltage circuit to conduct in sequence, so as to perform a surge test on the device under test based on the pre-set number of surge pulses and the surge pulse time interval. When performing a thermal sensitivity test on the device under test, the control module controls the conduction of the thermal sensitivity test circuit, and tests the thermal sensitivity voltage corresponding to the thermal sensitivity current at different temperatures by adjusting the magnitude of the thermal sensitivity current and the temperature at which the device under test is heated; when performing a full dynamic test on the device under test, the control module controls the sequential conduction of the main current circuit and the high-voltage circuit to test the forward and reverse peak voltages and the forward and reverse leakage currents of the device under test. The main current circuit includes a main current regulator, a drive circuit, and a plurality of current-limiting resistors. The main current regulator is used to adjust the magnitude of the main current according to the rated value of the device under test, and the drive circuit is adapted to control the gate voltage in the loop or of the device under test to control the conduction and cut-off of the device. The surge test circuit includes a surge current regulator, a counting module, and a timing module. The surge current regulator is adapted to adjust the surge current to a predetermined multiple of the main current. The counting module is adapted to set the number of times of surge pulse triggering during the surge test process, and the timing module is adapted to set the time interval between surge pulses; the thermal sensitivity test circuit includes a thermal sensitivity current regulator and a heating module. The thermal sensitivity current regulator is adapted to adjust the magnitude of the thermal sensitivity current according to the specified rated current, and the heating module is adapted to heat the device under test to different temperature values. The high-voltage circuit includes a high-voltage regulator, a polarity switching module, and an overload protection circuit. The high-voltage regulator is adapted to adjust the voltage value applied to both ends of the device under test by the high-voltage power supply. The polarity switching module is adapted to adjust the polarity applied to the device under test so as to measure the forward peak voltage and the forward leakage current value of the device during the forward test, and measure the reverse peak voltage and the reverse leakage current of the device during the reverse test. The over-current and overload protection circuit cuts off the high-voltage power supply protection circuit when the loop current is overloaded or short-circuited, and gives an overload prompt through the overload indicator light.

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