CN115327332A

CN115327332A - Test system and test method of power semiconductor device

Info

Publication number: CN115327332A
Application number: CN202210925620.0A
Authority: CN
Inventors: 于波; 于丽丽
Original assignee: Qingdao Haiyifeng Power Electronics Co ltd
Current assignee: Qingdao Haiyifeng Power Electronics Co ltd
Priority date: 2022-08-03
Filing date: 2022-08-03
Publication date: 2022-11-11

Abstract

The invention relates to a test system and a test method of a power semiconductor device, which comprises a main current circuit and/or a surge test circuit and/or a heat-sensitive test circuit and/or a high-voltage circuit and a control module, wherein the main current circuit is suitable for providing half-wave conduction current for a tested device, the control module is suitable for carrying out surge test on the tested device in sine positive half-wave and carrying out forward or reverse high-voltage test on the tested device in negative half-wave. The invention has reasonable design, compact structure and convenient use.

Description

Test system and test method of power semiconductor device

Technical Field

The invention relates to the technical field of power device testing, in particular to a testing system and a testing method of a power semiconductor device.

Background

With the development of high-power electronic devices, power electronic devices based on power diodes, thyristors, MOSFETs or IGBTs are increasingly widely used. The ability of power electronic devices to withstand voltage and current is the most important parameter, and in order to ensure the effectiveness, reliability, stability and safety of the devices, various characteristic parameters of the devices need to be tested. Since power electronics in a power system need to withstand surge currents with higher peak values and longer durations, surge current detection is needed. When the current value flowing through the power electronic device in the on state is large, the junction temperature is increased, and the device is damaged, so that the junction temperature of the power electronic device needs to be detected on line. The existing power electronic device testing instrument has the problems of small rated testing current, narrow testing voltage range, incapability of carrying out full dynamic testing, low efficiency, incapability of visually observing testing results, incapability of achieving independent operation among testing modules and the like.

CN 102156271B-detection method of the semiconductor parameter measurement system, can't realize the parameter test while working normally. CN 102944824B-a method for testing transient high temperature reverse leakage current of rectifier diode, is also unable to realize comprehensive measurement.

Therefore, a testing system for a power semiconductor device is needed, which can perform high-voltage testing, junction temperature testing and surge testing on the device at the same time under different working conditions, and improve the accuracy and efficiency of testing the power semiconductor device.

Disclosure of Invention

In order to adapt to the performance characteristics of high voltage, high frequency and high temperature resistance of the semiconductor device, the invention provides a test system of the power semiconductor device, which overcomes the problems or at least partially solves the problems, can carry out various tests and improves the test efficiency of the semiconductor device.

The existing test board can only carry out single test and cannot comprehensively reflect the working state, namely the actual working state of the device cannot be tested, so that the actual working parameters of the device to be tested cannot be obtained, and whether the device is qualified or not cannot be judged more scientifically; the invention ingeniously realizes the test under the normal power-on condition by the unidirectional half-wave rectification of the diode after the power grid is accessed, and can realize the reappearance of the real working condition of the device.

In order to improve the test accuracy, reduce impedance interference, quickly take away the generated heat through circulating water, increase the heat dissipation effect, save a fan, reduce noise and prolong the service life, and the resistance is fixed through a pipe clamp to realize adjustable resistance, the invention innovates the resistor so as to meet the test requirements.

Aiming at the problem of phase synchronization, the applicant adopts a comparator circuit to compare with a power supply sine wave zero crossing point to obtain a synchronous signal, thereby realizing the synchronization of waveforms without generating hysteresis or delay.

The system comprises a main current circuit and/or a surge test circuit and/or a thermosensitive test circuit and/or a high-voltage circuit and a control module, wherein the main current circuit is suitable for providing half-wave conduction current for a tested device, and the control module comprises an electronic switch circuit which is suitable for synchronous triggering of a surge or rectification circuit and synchronous display of an oscilloscope. In order to cause the device under test to trigger conduction when the main current or the sine half wave of the inrush current test circuit.

In the method, firstly, an anode and a cathode of a tested device are respectively connected to a positive terminal and a negative terminal of a main current circuit, the magnitude of the main current is adjusted to conduct the tested device, and the positive peak voltage and the average voltage drop of the tested device are measured; when a reverse voltage test is carried out, a polarity switching module of a high-voltage circuit is switched to be reverse, the output voltage of a high-voltage power supply is regulated through a high-voltage regulator, and the reverse voltage and the reverse leakage current of a tested device are measured; when testing the thermosensitive voltage, connecting the device to be tested to the heating module after being connected in series, respectively heating the device to be tested to different temperatures through the heating module, adjusting the size of the thermosensitive current through the thermosensitive current regulator, and testing the thermosensitive voltage corresponding to the thermosensitive current at different temperatures; and finally, switching on a surge test circuit, adjusting the magnitude of surge current to be a preset multiple of the main current through a surge current regulator, switching on a high-voltage power supply, switching the polarity of the polarity switching module to be reverse, and carrying out surge test on the device to be tested based on the preset surge pulse quantity and the preset surge pulse time interval.

In summary, the invention utilizes the step-down transformer to reduce voltage, generates an electronic switch signal synchronous with the sine wave of the power grid through zero-crossing comparison of the comparator, and displays the voltage-drop waveform, the main current waveform, the surge waveform, the thermosensitive voltage waveform and the thermosensitive comparison of the components, wherein the waveform of the surge comparison is switched by the electronic switch and the band switch, and the measured waveform is displayed on the oscilloscope.

The invention can utilize the half-wave conduction stage of the tested device to simultaneously carry out heat-sensitive, surge and full-dynamic parameter testing on the tested device, and each testing circuit can be combined or independently used, thereby improving the efficiency of device testing; the output voltage or current of each test circuit can be adjusted according to the rated parameter value of the tested device, the characteristics of high voltage, high temperature resistance and high switching frequency of the semiconductor device can be adapted, and the accuracy of device test can be improved. .

The a and Vf (thermal) tests utilize main current to heat the device, the change of Vf (thermal) can be observed and read on oscillography, and can be directly read on a digital voltmeter;

b. the full dynamic surge is added with main current and reverse (forward) voltage, the interval time of surge and the number of surge are determined by a timer and a counter, and the surge is automatically stopped when the specified number of times is reached. Although the surge disappears instantly, the surge waveform on the main current can be observed on an oscilloscope, the proportional relation between the surge and the main current is clear at a glance, the main current can be added to a device to be tested, the average voltage drop and the peak voltage at the two ends of the device can be tested, reverse voltage can also be added, the reverse leakage current of the device can be tested, and the normal working state of the device can be simulated;

c. the water-cooled resistor has high power, the surge current can reach 3000A, and the main current is 200A. The resistance of the loop is connected with the contact resistance, the internal resistance of the transformer is difficult to calculate, and meanwhile, the heat productivity of a large current passing through the current limiting resistance is high;

the invention relates to a full-dynamic surge, which completely simulates the working state in a power grid, wherein the surge waveform, the main current waveform and the sine half-wave waveform of a power supply grid are completely consistent, the working mode of a device in the power grid is truly simulated, the temperature is controllable, and reverse voltage can be added.

Drawings

Fig. 1 is a schematic diagram of a preferred power semiconductor device testing system 100. Fig. 2 is a circuit schematic of a preferred control module 150. Fig. 3 is a diagram of the optimized left half of the control module 150 circuit. Fig. 4 is a diagram of the right half of the control module 150 after circuit optimization. Fig. 5 is a schematic diagram of a preferred main current circuit 110/inrush current circuit 120. Fig. 6 is a schematic diagram of main current circuit 110. Fig. 7 is a schematic diagram of inrush current circuit 120. Fig. 8 is a schematic diagram of a preferred high voltage circuit 130. FIG. 9 is a schematic flow chart of a preferred test method 001. FIG. 10 is a graph of voltage drop versus comparative voltage waveforms for a preferred device under test. Fig. 11 is a schematic diagram of a preferred inrush current waveform. FIG. 12 is a schematic diagram of the thermosensitive voltage waveform under the preferred normal test conditions. FIG. 13 is a schematic diagram of a thermosensitive voltage waveform under preferred thermal state test conditions. Fig. 14 is a simplified schematic diagram of a preferred liquid loading object. FIG. 15 is a schematic diagram of a preferred liquid-cooled resistance deformation configuration.

Detailed Description

As shown in fig. 1-15, various power electronic devices have both on and off states of operation, including power semiconductor devices. When the power semiconductor device works, heat and temperature rise can be caused by power loss, and the service life of the power semiconductor device can be shortened due to overhigh temperature of the power semiconductor device. Corresponding electrical parameter tests are required from research, development, production, use and maintenance of semiconductor power devices, and the tests comprise static parameter tests (breakdown voltage, leakage current, conduction voltage drop and the like), dynamic parameter tests, limit capability tests (surge current tests and the like), reliability life tests (high-temperature storage tests, temperature cycle tests, high-temperature reverse bias tests and the like) and the like. In order to test various performance parameters of a power semiconductor device under working conditions, the scheme provides a test system and a test method capable of measuring the performance of a power electronic device in real time.

In the embodiment shown in fig. 1, the system 100 includes a main current circuit 110, a surge test circuit 120, a high voltage circuit 130, a thermal test circuit 140, and a control module 150, and is capable of performing a full dynamic surge test, a full dynamic test, and a thermal test simultaneously at a half-wave conduction stage of a device under test, where the measurement results include a surge current, a thermal voltage in a cold or hot state, an average voltage drop, a peak voltage in a forward or reverse direction, a leakage current in the forward or reverse direction, a highest junction temperature, and the like.

In general, main current circuit 110 may provide half-wave conduction current for the device under test, and control module 150 includes several electronic switching circuits. The electronic switching circuit may correspondingly control the output of the surge testing circuit 120 when detecting that the half-wave conduction current is at a high level, and control the output of the high-voltage circuit 130 when detecting that the half-wave conduction current is at a low level, so as to trigger the surge pulse output by the surge testing circuit 120 at the sine half-wave synchronization stage of the device under test. The control module 150, which may be a thyristor, a relay, and/or a combination thereof, may adjust the output voltage or current of each circuit according to the rating of the device under test.

As shown in fig. 5-7, the main current circuit 110 and the surge test circuit 120 are structurally schematic, and the main current circuit 110 and the surge test circuit 120 are externally connected with an ac power supply; the alternating current power supply is mains supply or industrial electricity;

after the main current circuit 110 is stepped down, unidirectional half-wave rectification output is realized through a diode, the surge test circuit 120 is stepped up, and unidirectional half-wave rectification output is realized through a diode.

The main current circuit 110 may provide a conduction voltage and a current for the device under test to test a conduction voltage drop thereof, the waveform of the conduction voltage of the device under test may be observed by an oscilloscope as a voltage drop waveform of the device under test, and the positive peak voltage VFM/VTM and the positive average voltage drop V in the waveform diagram may be read by an ammeter.

The main current circuit 110 comprises a main current regulator 111, a first trigger circuit 112 and a first air-cooling module D1, wherein the main current regulator 111 can regulate the magnitude of the main current output by the main circuit according to the rated value of the device to be tested, and the regulation range is 1A-200A. The first air cooling module D1 is used for radiating heat of the high-power diode and the controllable silicon radiator.

The main current regulator 111 has a main current isolation transformer TC11,30V/300A; a main coil of a main current isolation transformer TC11 is electrically connected with a main current voltage regulator T10 for voltage division, a main current AC meter Y11 matched with the main current voltage regulator T10 is connected beside a main coil of the main current isolation transformer TC11 so as to display input electric parameters, facilitate operation and judge the position of the main current voltage regulator T10;

the gear of the main current is matched with the main current voltage regulator T10, so that the size of the main current output by the main current circuit can be regulated according to the rated value of a tested device, and the regulation range is 1A-200A; when the current flowing through the tested device is larger than 50A, the first air cooling module D1 can be started to ventilate and radiate the main current isolation transformer TC11 and other components.

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, and the output of the current is correspondingly reduced step by connecting main current load resistors whose resistance values are sequentially increased in series, preferably six, and 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 R15,1, and a sixth resistor R16;

one end of a first resistor R11 is connected with a main current regulator 111 loop, the other end of the first resistor R11 is divided into two paths, one path of the first resistor R11 is connected with a 200A main current gear shift switch, the other path of the first resistor R11 is connected with one end of a second resistor R12, the second resistor R12, a third resistor R13, a fourth resistor R14, a fifth resistor R15 and a sixth resistor R16 are connected step by step and correspondingly connected with main current gear shift switches of 100A, 50A, 20A, 5A and 1A, and the main current gear shift switch is connected into a tested device through a K end;

the main current is converted by the band switch to control the action of 6 relays, and the main current is correspondingly reduced in sequence and output as the main currents of 200A, 100A, 50A, 20A, 5A and 1A. It is made equivalent by one or other numbers, and the current value and the resistance value are for distinction and not limitation.

The wave band switch is provided with 6 current gears which respectively correspond to the current dividers of different current gears, the alternating current contactor and the current divider corresponding to the current gears can be switched, and the size of the main current is displayed through the main ammeter. Referring to fig. 14-15, wherein the resistors R11-14, R21-23 may be liquid-cooled resistors, including a coil 20, with an insulating cooling medium circulating in the coil 20; the two ends of the coil 20 are provided with connectors 21 for externally connecting a water path, the coil 20 is provided with a first electric connection end 29 and an adjustable second electric connection end 28 for externally connecting a circuit, and the resistance value of the liquid cooling resistor is adjusted by adjusting the position of the second electric connection end 28 on the coil 20; the coil 20 is fitted with a fixed support 22 for fixing the coil 20 in the test stand,

when the coil pipe 20 is a spiral pipe, the waterway takes in water from the joint 21 at the lower end and takes out water from the joint 21 at the upper end, so that water circulation is realized; a poke rod 27 and a plurality of rotary brackets 23 are arranged on a fixed supporting part 22 at the lower end of the coil pipe 20, a collecting ring 26 is arranged on each rotary bracket 23, a first electric connection end 29 is arranged at one end of the coil pipe 20, and a second electric connection end 28 is provided with an external electric connection end 30 for external circuit;

the external waterway comprises a water pump 31 and a refrigerator 32 which are connected in series, and a thermometer 33 is arranged on a water flow loop; an adjusting sliding sleeve 24 is sleeved on the coil pipe 20 in a sliding manner, and a hinged connection part 25 is electrically connected between the adjusting sliding sleeve 24 and a collecting ring 26; the poke rod 27 is used for poking the hinged connection part 25, so that the adjusting sliding sleeve 24 can slide and lift on the coil pipe 20 to realize the change of a lead distance, the fine adjustment of the resistance value is realized, and the adjustment of multiple leads is realized by adjusting the height of the rotating bracket 23. The conduction angle of the current waveform through the device under test is made greater than 170 degrees.

The coil may be spiral (fig. 15 is a scheme for further improvement and protection), serpentine (fig. 14 is a scheme for experiment) or other winding structure, and the material may be aluminum, copper, etc., preferably 304 stainless steel. The insulating cooling medium can be oil, air flow, ethanol and the like, but is preferably pure water or deionized water, a water channel of the coil pipe is externally connected with a refrigerator and a water pump, so that circulation and temperature control of water flow are realized, and the pure water or the deionized water is used as a medium, so that scaling and corrosion resistance are avoided. The spiral pipe can generate an electromagnetic effect, magnetization of water is realized, and scaling is reduced.

The output of the main current regulator 111 is output to node A through main current diodes D11,2CZ500/1600V and main current thyristors Q11,3CT500 \/3000V to access the device under test for normal measurement.

When the tested device is a diode, the anode of the diode is connected with the anode of the main current circuit, namely node A, and the cathode of the diode is connected with the cathode of the main current circuit, namely node K. When the device to be tested is a thyristor, the anode of the thyristor is connected with the anode A of the main current circuit, the cathode of the thyristor is connected with the cathode K of the main current circuit, and the control electrode of the thyristor is connected with the control electrode g of the main current circuit.

Since the main current thyristor Q11 needs a trigger signal to be turned on, in order to provide a trigger voltage and a current to the main current thyristor Q11, the main current circuit 110 includes a first trigger circuit 112 for synchronously triggering on/off of the main current thyristor Q11 to adjust the current. The synchronous trigger signal is taken out by utilizing the same-phase half wave when the main current controlled silicon Q11 is conducted, and the main current controlled silicon Q11 is synchronously triggered, namely, the controlled silicon is conducted when the positive half wave is conducted, and the controlled silicon is blocked when the negative half wave is conducted, so that the controlled silicon is blocked when the negative half wave of the main current is added with high voltage, an isolation effect is achieved, and the high-voltage transformer and the two poles are prevented from forming a loop to cause short circuit.

During main current testing, commercial power is transmitted to a high-power main current voltage regulator T10 through a power switch fuse BZ, then is isolated by a high-power step-down main current isolation transformer TC11, a low-voltage high-current power supply is output by the secondary side of the main current isolation transformer TC11, then is subjected to half-wave rectification by a high-power main current diode D11 and a high-power one-way main current controllable silicon Q11, and generates main current through a tested device and load resistors R11-R16.

The main current has the following functions that a, the mean voltage drop and the peak voltage drop of the device are tested (no reverse voltage is added at the moment), when the specified current passes, the device to be tested generates half-wave voltage drop, the mean voltage drop of the device to be tested is tested through a voltmeter, the voltage drop waveform of the device to be tested is observed through an oscilloscope, the peak values of the voltage waveform and the comparative voltage waveform are in a horizontal line through a corresponding comparative voltage potentiometer, and the peak voltage drop of the voltage waveform is read through the voltmeter, which is shown in figure 10; b, when testing Vf (heat), supplying main current to make the tested device raise temperature and heat, using temperature probe to test the shell temperature of tested device, using oscillograph and voltmeter to read Vf (hot horizontal and vertical), c, making basic comparison waveform in surge test, as shown in fig. 11 d, adding defined main current to tested device, then adding defined reverse (both positive and negative of thyristor) voltage to make full dynamic test.

FIG. 10 is a schematic diagram of a main current waveform and a peak voltage waveform for the embodiment. The oscilloscope comparison line may be made to be level with the top of the sine wave and the peak voltage value measured by the voltmeter, which in one embodiment of the invention reads "0.987" on the voltmeter, which is the forward peak voltage value of the device.

The surge test circuit 120 is substantially the same in structure as the main current circuit, and includes a surge current regulator 121, a pulse count timing module 123, a second trigger circuit 122, and a second air-cooling module D2, where the main current regulator 121 can regulate the magnitude of the surge current output by the main circuit according to the rating of the device under test. The second air cooling module D2 is used for radiating the high-power diode and the silicon controlled radiator.

Surge reliability is one of the indexes of device reliability, and refers to the ability of a device to withstand surge current, which refers to the peak current or overload current (spike interference) generated in the instant of power-on or in the abnormal condition of a circuit and far greater than the steady-state current. The device may burn out at a moment of surge, and PN junction breakdown occurs, so the purpose of surge test is to test the maximum surge current that the power semiconductor can bear, and the characteristic change exhibited under the surge current.

During surge current testing, commercial power passes through a power switch fuse BL to a high-power main current voltage regulator T20, is isolated by a high-power step-down main current transformer TC12, a low-voltage large-current power supply is output by the secondary side of the main current transformer TC12, then the output of the high-power step-down transformer is subjected to half-wave rectification through a high-power main current diode D12 and a high-power unidirectional main current thyristor Q12, and surge current is generated through a tested device and load resistors R21-R26.

The back of the surge current regulator 121 is connected with a surge current isolation transformer TC12, the output is 60V/600A, and an alternating current voltmeter Y12 is connected on a secondary coil of the surge current transformer TC12 to display input voltage parameters, facilitate operation and judge the position of a main current regulator T20. The output end of the secondary coil of the surge transformer TC12 is connected with an output node A through a series surge diode D12 and 2CZ800/1600V and a surge controllable silicon Q12 and 3CT800/3000V which is controlled by a second trigger circuit 122 to be started and stopped and is used as an electronic switch of a surge.

The control module 150 reduces the voltage by using a step-down transformer, compares the voltage with a comparison voltage by a comparator, generates an electronic switching signal synchronous with the sine wave of the power grid, switches the main current waveform and the surge waveform of the device and the compared waveform of the surge by an electronic switch and a band switch, and displays the measured waveform on an oscilloscope.

After the power supply is stepped down by the transformer TC51, the rectifying filter is stabilized by the U541 to obtain a 5V stabilized power supply, and 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 through voltage division of an adjustable potentiometer R58 of R59, a comparison voltage of Vf (thermal) VTM is obtained through voltage division of R511 and the adjustable potentiometer R510, the magnitude of the comparison voltage can be adjusted through 510, voltage of a secondary tap of a transformer TC51 is divided by R51 and R52 and is added to a pin 2 of the comparator U51, the bias voltage obtained through voltage division of R58 and R59 is added to a pin 3 of the comparator U51, therefore, a rectangular pulse which is in the same phase with alternating current of a secondary side of the transformer TC51 is output at a pin 1 of the comparator U51, the pulse width can be adjusted through R58, and the pulse is driven to be added to a pin 6 of an electronic switch U54 through U52 to control the action of an internal electronic switch of the U54.

When the electronic switch in the U54 acts, the output terminal pin 1 is conducted with the pin 8; its signal is output from pin 1; a pin 1 of the U54 is connected with the input end of a follower U56, and the output end of the follower U56 is connected with an oscilloscope through band switches SB52 and SB 53; the nodes a and K respectively follow the voltage signals at two ends of the tested device to the pin 2 of the U54 through the corresponding relays Jg4, and the pin 1 is the common output end of the switch signal of the electronic switch U54; the electronic switch U54 converts the signals of the 8 pin and the 2 pin through the electronic switch, and the signals are output by the 1 pin, follow the signals through the electronic switch U54 and the band switch SB52 and are sent to the oscilloscope so as to display the voltage waveform at two ends to be measured.

The inrush current circuit 120 further includes a band switch connected to the inrush current loop, and corresponding to the inrush current shift switches 200A, 100A, 50A, 20A, 5A, and 1A. The surge loop comprises a plurality of adjustable load resistors R122, the output of the current is correspondingly reduced step by connecting the load resistors with sequentially increased resistance values in series, preferably six, and the main current limiting resistor R122 comprises a first resistor R21, a second resistor R22, a third resistor R23, a fourth resistor R24, a fifth resistor R25 and a sixth resistor R26; the surge current passes through the A and K ends and is connected to a device to be tested;

the 5V power supply is divided by a R63 potentiometer W64, and a surge comparison voltage can be obtained by W64 regulation, and the comparison voltage is mainly used for setting a multiple between a surge current and a main current so as to enable the height of a surge waveform to be equal to the set comparison voltage. This comparison voltage follows the 8 pin applied to U59 via U63 isolation.

(1) And (2) two contacts are arranged at two ends of the current divider, the two ends are main current and surge current signals on the current divider of 1-200A grades, the signals are isolated by a U61 and are applied to a pin 2 of an electronic switch U59, the pin 1 is a common switch signal output end, so that the electronic switch sends a comparison voltage signal of a pin 8 and a voltage signal on the current divider of the pin 2 to an oscilloscope through a U62 following buffer and band switches SB52 and SB54, and the main current, the surge current signals and the surge comparison signals on the current divider are displayed on the oscilloscope.

The switching signal of the surge adopts an external singlechip PLC, and the singlechip PLC acquires trigger pulse with the same current phase to trigger the thyristor to be conducted to generate the surge. The surge signal is obtained from two ends of each shunt and is transmitted to the potentiometer through the wave band change-over switch. Regulated by a potentiometer, sent to a function conversion and electronic switch, and converted to an oscilloscope by the electronic switch to display surge waveform.

The pulse counting timing module 123 comprises a timing module and a counting module, and is used for controlling the number of times of surge and the time interval of surge, the number of times of surge is set by a counter according to requirements, the time interval of surge is set by a cycle timer according to requirements, and when the experiment reaches the set number of times of surge, the device automatically stops working on the oscilloscope and can observe the surge waveform. The current phase of the surge and the main current phase are in the same phase, and the surge is controlled by the surge controllable silicon Q12 and the pulse counting timing module 123.

During surge test, on one hand, surge impact can be independently carried out without adding main current and reverse voltage; secondly, main current and surge can be applied, and reverse voltage is not applied; thirdly, the full dynamic surge test can be carried out by fully adding the main current, the surge and the reverse voltage. The invention can independently carry out surge test and independent surge impact test on the tested device; semi-dynamic surge test, adding surge test when the tested device applies main current; the full dynamic surge test is carried out, wherein the main current is applied to the tested device at the same time, and the surge test is carried out when the (positive) reverse high voltage is applied, wherein the phase of the (positive) reverse high voltage is opposite to the surge main current).

And switching on a surge test circuit at the half-wave conduction stage of the device to be tested, adjusting the magnitude of surge current to be a preset multiple of main current through a surge current regulator, switching on a high-voltage power supply, switching the polarity of the polarity switching module to be reverse, and carrying out surge test on the device to be tested based on the preset surge pulse quantity and the preset surge pulse time interval.

The phase of the high voltage is opposite to the surge main current as in fig. 8.

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.

The circuit is used for applying high voltage to a device to be tested in a phase opposite to a main current and a surge to test the withstand voltage value of the device, or applying high voltage during dynamic test.

The power supply is added to a high-voltage regulating voltage regulator through a high-voltage switch SB4-1 and a normally closed contact JB4 of an overcurrent protection relay JB 4. The booster is connected to a step-up transformer Tc4-1, and the step-up transformer outputs two steps of 100OV and 2000V, and the relay JZ4 is controlled by a switch SB4-2 to switch the steps. The voltage regulator can regulate the high voltage.

The high voltage is generated by half-wave rectification of an alternating current by a 1000V or 2000V tap of TC4-1 through a current limiting resistor R4-3 and a current limiting resistor R4-2, the D4-2 is that a reverse voltage is applied to the D4-1 when a negative half wave of the alternating current is generated, the reverse voltage is prevented from being applied to a tested device, the D4-3 to the D4-6 and the C4-1 are used for rectifying and filtering the half wave of the alternating current, a peak value of the half-wave voltage is obtained on a capacitor C4-1, then the half-wave voltage is divided through an Rz4-6 and an adjustable potentiometer Rz4-4 and sent to a peak voltage meter head to display a peak voltage value, the adjustable potentiometer Rz4-4 is used for peak voltage calibration, and the half-wave voltage is divided through R4-5 and R4-7 (R4-8) and sent to an oscilloscope to display a dynamic curve: a direct current ammeter is connected in series in the circuit to display leakage current in the circuit during testing. R4-9 is an overcurrent protection sampling resistor.

The high-voltage output circuit is provided with a polarity conversion switch SB4-3, and the positive and negative polarities of the output high-voltage output can be converted according to test requirements through the conversion of the switch.

In addition, protective relays Jg4 and Jg4 are connected in the high-voltage circuit, and are electrically attracted when the high-voltage switch is closed, and high voltage is applied to a device to be tested through a corner contact of the Jg 4. When the high-voltage switch is switched off, the Jg4 is not attracted, the high-voltage circuit is in a disconnected state with other external circuits through the normally open contact of the Jg4,

the high-voltage switch SB4-1 is a single-pole double-throw switch, one end of the high-voltage switch is used for supplying power for high-voltage testing, the other end of the high-voltage switch is used for supplying power for thermosensitive testing, when a high voltage is applied, a thermosensitive voltage does not have a voltage and cannot work, when the thermosensitive voltage is applied, the high voltage does not have a voltage and cannot work, the purpose is that the high voltage and the thermosensitive voltage cannot supply power simultaneously, the influence of the high voltage and the thermosensitive voltage during testing is avoided, and misoperation and circuit damage are prevented.

The phase of the high-voltage half wave is 180 degrees different from the phase of the main current and the surge so as to ensure that the main current and the surge are passed through when half wave is carried out, and the reverse voltage is added to the other half wave. The high-voltage circuit has the following functions:

(1) the high-voltage circuit can carry out independent withstand voltage test on the device, and can test the unrepeated and repeated withstand voltage values of the diode and the silicon controlled rectifier.

(2) A (positive) reverse voltage can be applied at the time of the full dynamic main current test.

(3) The (positive) reverse voltage can be applied during surge, semi-dynamic surge and full-dynamic test.

An overcurrent and overload protection circuit 134 is also arranged in the high-voltage circuit, and the high-voltage power supply protection circuit is cut off when the circuit is subjected to overcurrent and overload.

The over-current protection circuit is characterized in that a 12V direct-current power supply is obtained by voltage reduction of a Tc4-2 transformer, rectification of D4-4, filtering of C4-4 and voltage stabilization of U4-1, the 12V power supply supplies power to a comparator U4-2 and an overload protection relay JB4, an over-current protection threshold voltage is obtained through R4-11 and an adjustable potentiometer R4-13 and is added to 2 pins of U4-2, and the threshold voltage is adjusted and set through R4-13.

R4-9 is an overcurrent protection sampling resistor, the current sampling voltage on R4-9 is limited by R4-10 through a voltage regulator tube D4-5, noise waves are filtered by C4-6 and are added to 3 pins of U4-2, when overcurrent and overvoltage exceed a set protection value, the U-21 pin outputs high level to drive a silicon controlled rectifier Q4 to be conducted, and a relay JB4 is attracted. And the normally-off point JB4 is disconnected, and the high-voltage power supply is cut off, so that the high voltage has no output, and the devices of the high-voltage circuit are protected.

And meanwhile, the overload protection relay JB4 is also connected with a light emitting diode in parallel, when overload protection acts, the light emitting diode is lightened to display that the circuit is in a protection state at the moment, no high-voltage output exists, and a reset switch SB-4 is also connected in series with the coil JB4, and the protection can be released by pressing the switch, and the test can be carried out again.

In the thermal test 140 in the embodiment of the present invention, the thermal test includes a normal thermal test and a thermal test, the resistivity of the semiconductor changes significantly with the temperature, and the operation stability of the semiconductor device is affected when the environmental temperature changes due to the thermal characteristics of the semiconductor device. When in normal thermal test, firstly, a thermal current regulator is used for regulating a thermal current according to the rated current of a tested device, generally 1% -10% of the rated current of the device is selected, for example, a diode with the rated average current of 70A is selected, and generally 70A multiplied by 5% =3.5A is taken as the thermal test current; then heating, sequentially testing the thermosensitive voltage of each device passing the thermosensitive current at different temperatures (50 ℃, 80 ℃, 110 ℃, 140 ℃, 150 ℃ and 170 ℃), and simultaneously observing the thermosensitive voltage Vf waveform under the normal thermosensitive test by using an oscilloscope.

In the thermal voltage test, a diode or a thyristor can be electrified with specified thermal current by using a current-regulated power supply. The temperature-sensitive voltages at different ambient temperatures are detected. The thermosensitive voltage can be read on a meter or an oscilloscope on the equipment, and the thermosensitive voltage is Vf; or a small hole with a certain depth is drilled on the device base, and the temperature control probe is inserted. Then, the device is added with the specified main current and the thermal current, the main current is utilized to heat the device to the required temperature, the temperature is kept constant for a certain time, the waveform on an oscilloscope is utilized to compare the voltage for regulation, and the thermal voltage value is read on a digital meter or the oscilloscope, wherein the value is Vf (heat);

as shown in FIG. 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 constant-current source U31, an input end of the thermal constant-voltage constant-current source U31 is connected to a power supply, a control coil of a thermal isolation relay Jr is arranged between the input ends of the thermal constant-current source U31, the thermal constant-current source U31 is electrically connected to a thermal current regulator for regulating the magnitude of a thermal current, the thermal constant-current source is output through a thermal isolation diode, a 5A gear is output through an adjustable thermistor 1R, a 1A gear is output through an adjustable thermistor 5R, and a tested device is connected through a normally open execution switch of the thermal isolation relay Jr after passing through a single-pole double-throw switch SB31, so that normally open isolation and conduction are realized. The output current is not affected by the external contact resistance and the wire resistance, and the thermosensitive voltage drop is read by a digital voltmeter on the equipment. The relay Jr is an isolation relay, the power supply of the isolation relay is connected with the current stabilizing power supply in parallel to supply power, the Jr is closed when a heat-sensitive test is carried out, and the Jr is disconnected when other functions are tested, so that the current stabilizing power supply is prevented from being influenced. In addition, the thermosensitive power supply is interlocked by a high-voltage test power switch, the current-stabilizing power supply does not supply power when the high-voltage test is carried out, and Jr is disconnected to avoid the influence of the high voltage on the current-stabilizing circuit.

When measuring Vf, firstly, the device to be measured is heated to different set temperatures, such as 50 ℃, 80 ℃, 110 ℃, 140 ℃, 150 ℃ and 170 ℃ through an oven or a hot bench; then, testing the thermosensitive voltage drop of the circuit board through the set thermosensitive current;

when measuring Vf (heat), a test hole is made on the base of the device to be measured, a temperature control probe is inserted into the test hole to monitor its temperature, and a prescribed main current and a thermosensitive current are applied. Thus, two currents, namely the main current and the thermosensitive current, are passed through the device, the waveforms of the main current and the thermosensitive voltage drop can be observed on an oscilloscope, and the dynamic process of the thermosensitive voltage drop along with the temperature change can be observed. When the tested device reaches the specified temperature and time, the magnitude of the thermosensitive voltage can be adjusted through the comparative voltage potentiometer, so that the comparative voltage and the thermosensitive voltage drop curve are on the same horizontal line, and the thermosensitive voltage can be read out on a digital meter on a panel or on an oscilloscope by utilizing the scale of the oscilloscope.

When the current value passing through the semiconductor in the on state is large, junction temperature is increased, and thus, the device is damaged. Therefore, the junction temperature of the device needs to be tested, a thermal sensitive curve is drawn through the thermal sensitive voltage of the test device passing through the thermal sensitive current at a plurality of different temperatures, and the thermal sensitive slope and the highest junction temperature of the device are calculated. The withstand voltage value of a diode or controllable silicon can be tested through forward and reverse high voltage, and reverse voltage is applied when full-dynamic main current application is carried out; when the thyristor is tested, the positive and negative voltages are applied.

FIG. 12 is a diagram of a thermal voltage waveform under a thermal state thermal test according to an embodiment.

The device temperature rise can be calculated by the following equation: Δ Tj = (Vf-Vf (hot))/M

In the formula: Δ Tj represents junction temperature rise of the device under test, vf (thermal) represents thermosensitive voltage at the lowest test temperature in normal state, vf (thermal) represents thermosensitive voltage at 150 ℃ in thermal state, and M represents thermosensitive slope.

The highest junction temperature of the device TjM = Δ Tj + T0, where TjM represents the highest junction temperature of the device, and T0= the lowest test temperature.

The control module 150 includes a high voltage single pole double throw switch SB4-1 (see fig. 8), one end of which supplies power to the high voltage circuit 130, and the other end of which 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 switch on, thereby avoiding double connection, avoiding mutual influence during testing, and preventing misoperation and circuit damage.

The control module 150 reduces the voltage by using a step-down transformer, compares the voltage with a comparison voltage by a comparator, generates an electronic switch signal synchronous with the sine wave of the power grid, compares the voltage drop waveform, the main current waveform, the surge waveform, the thermosensitive voltage waveform and the thermosensitive comparison of the voltage drop waveform and the main current waveform of the device, switches the waveform of the surge comparison by the electronic switch and the band switch, and displays the measured waveform on the oscilloscope.

The control module 150 is also electrically connected to a processor such as a PLC, an MCU, etc., for data processing.

In the embodiment shown in fig. 2-4, the control module 150, which is used for the function conversion and waveform display module, includes a first control unit and a surge control unit. The first control unit comprises a first voltage comparison circuit, a thermosensitive comparison circuit and a first electronic switch; the device is used for controlling the function conversion, the test, the oscillography display and the voltage reading of the thermosensitive voltage drop Vf, the average voltage drop VT and the peak voltage drop VTM, vf (heat). The surge control unit comprises a surge comparison circuit and a second electronic switch and is used for controlling the conversion of surge and the display of surge oscillography.

In the first control unit, the power supply inputs two paths, one path is output to the first voltage comparison circuit, the other path is output to the thermal sensitive comparison circuit, the first voltage comparison circuit realizes on-off control of the thermal sensitive comparison circuit by triggering the first electronic switch, realizes synchronous switching of the main current circuit 110, the thermal sensitive test circuit 140 and the first voltage comparison circuit, and displays the synchronous switching on a digital watch and an oscilloscope.

As shown in fig. 3-4, the first voltage comparing circuit includes a comparator U51, an operational amplifier U52 and an adjustable resistor R58, wherein the adjustable resistor R58 is used for adjusting the duty ratio of the corresponding first electronic switch U54;

when the VTVTVTMVfVf (thermal) test is carried out, a 5V stabilized power supply is obtained by voltage stabilization of a power supply through a transformer TC51 voltage reduction rectification filter and U54 voltage stabilization, and 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 through voltage division of an R59 adjustable potentiometer R58, a comparison voltage of Vf (thermal) VTM is obtained through voltage division of R511 and an adjustable potentiometer R510, the magnitude of the comparison voltage can be adjusted through 510, voltage of a secondary tap of a transformer TC51 is divided by R51 and R52 and is added to a pin 2 of the comparator U51, the bias voltage obtained through voltage division of R58 and R59 is added to a pin 3 of the comparator U51, therefore, a rectangular pulse which is in the same phase with alternating current of a secondary side of the transformer TC51 is output at a pin 1 of the comparator U51, the pulse width can be adjusted through R58, the pulse is driven to be added to a pin 6 of an electronic switch U54 through U52, and electronic switching action inside the U54 is controlled.

The small contact point a and the end K of the main loop are actually connected to two ends of a tested device, so that voltage signals at two ends of the tested device are added to a pin 2 of an electronic switch U54 through a relay contact Jg4 and a resistor R57, the pin 1 serves as a common output end of a switch signal of the electronic switch U54, signals of the pin 8 and the pin 2 are converted through the electronic switch by the electronic switch U54, the signals are output through the pin 1, and are sent to an oscilloscope through a band switch SB52 through the U54, and voltage waveforms at two ends to be tested are displayed on the oscilloscope. The band switch SB51 switches for Vf VT and VTM Vf (thermal) function test when vfVT is reached, the voltage across the device under test is added to the digital voltmeter through SB51 and SB61, at which time Vf and VT of the device under test can be read through the digital voltmeter. When the voltage is applied to VTMVf (heat), the comparison voltage is added to a digital table, a comparison voltage potentiometer V510 is adjusted, the waveform on an oscilloscope is observed, the comparison voltage waveform and the peak value of the voltage drop waveform are on the same horizontal line or are in a horizontal line with the waveform of Vf (heat), and the voltage of the digital table is VTMVf (heat).

SB52, SB54, SB61 and SB62 are four-pole double-throw band switches used for testing function conversion of thermal drop and surge. Jg4 is a high-voltage isolation relay, and when high-voltage testing is carried out, jg4 is disconnected to avoid influence of high voltage on the part of circuit.

As shown in fig. 13, the heat-sensitive test, the surge test, and the full-dynamic test can be performed simultaneously.

When performing the surge test on the device under test, the control module 150 may control the main current circuit, the surge test circuit, and the high voltage circuit to be sequentially turned on, so as to perform the surge test on the device under test based on the preset surge pulse number and the surge pulse time interval; when the device to be tested is subjected to heat-sensitive test, the control module 150 can control the conduction of the heat-sensitive test circuit, and the heat-sensitive voltages corresponding to the heat-sensitive currents at different temperatures are tested by adjusting the magnitude of the heat-sensitive current and the heated temperature of the device to be tested; when the device under test is fully dynamically tested, the control module 150 may control the main current circuit and the high voltage circuit to be turned on in sequence, so as to test the forward and reverse peak voltages and the forward and reverse leakage currents of the device under test. During full dynamic test, half-wave current is applied to a tested device in one power frequency half cycle, the average value of the current is determined by the rated current value of the device, and forward or reverse sine half-wave blocking voltage is applied in the other half cycle to measure the dynamic blocking volt-ampere characteristic of the device. The indexes of the full-dynamic test mainly comprise average current, average voltage drop, forward and reverse non-repetitive peak voltage, forward and reverse peak leakage current and the like.

In the embodiment shown in fig. 9, the steps may be to adjust the test sequence according to actual needs, and the main current waveform, the peak voltage waveform and the surge waveform may be observed through an oscilloscope, so as to ensure that the main circuit loop and the surge test loop are normally conducted before the test.

According to the scheme of the invention, through controlling the on-off of different test circuits, the device to be tested can be subjected to thermal sensitivity, surge and full dynamic parameter test at the half-wave on-stage of the device to be tested, and the test circuits can be combined and can be used independently, so that the efficiency of device test is improved; the output voltage or current of each test circuit can be adjusted according to the rated parameter value of the tested device, the characteristics of high voltage, high temperature resistance and high switching frequency of the power semiconductor device can be adapted, and the accuracy of device test can be improved.

Claims

1. A test system for a power semiconductor device, characterized by: comprises a main current circuit (110); the main current circuit (110) provides half-wave conduction current for the device under test.

2. The power semiconductor device test system of claim 1, wherein: the test system also comprises a control module (150) which comprises a surge test circuit (120), a high-voltage circuit (130) and/or a heat-sensitive test circuit (140) and is used for respectively carrying out full-dynamic surge test, full-dynamic main current test and/or heat-sensitive test on the tested device in a half-wave conduction stage;

the control module (150) is adapted to control the surge test on the device under test on a sinusoidal positive half-wave and/or the control module (150) controls the forward or reverse high voltage test on the device under test on a negative half-wave.

3. The test system for a power semiconductor device according to claim 2, wherein:

a) The control module (150) comprises a first voltage comparison circuit, a thermosensitive comparison circuit, a first electronic switch U54, a second voltage comparison circuit, a surge comparison circuit and a second electronic switch U59;

the control module (150) reduces the voltage by using a step-down transformer, compares the voltage with a comparison voltage by a comparator, generates an electronic switch signal synchronous with the sine wave of the power grid, switches the main current waveform, the surge waveform and/or the compared surge waveform of the tested device by an electronic switch and a band switch, and displays 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 thermosensitive comparison circuit;

the first voltage comparison circuit controls the thermosensitive comparison circuit by triggering the first electronic switch U54, so that the switching of the main current circuit (110), the thermosensitive test circuit (140) and the first voltage comparison circuit is realized and displayed on a digital watch and/or an oscilloscope;

the second voltage comparison circuit controls the surge comparison circuit by triggering the second electronic switch U59, realizes the switching of the main current circuit (110), the surge test circuit (120) and the second voltage comparison circuit, and displays the switching on an oscilloscope;

b) After the voltage of the main current circuit (110) is reduced, unidirectional half-wave rectification output is realized through the diode D11 and/or the main current controllable silicon Q11, and after the voltage of the surge test circuit (120) is reduced, unidirectional half-wave rectification output is realized through the diode D12 and/or the surge current controllable silicon Q12;

c) When the conduction voltage drop of the device to be tested is tested, when the device to be tested is a diode, the anode of the diode is connected with the anode of the main current circuit, namely node A, and the cathode of the diode is connected with the cathode of the main current circuit, namely node K; when the tested device is a thyristor, the anode of the thyristor is connected with the anode of the main current circuit, the cathode of the thyristor is connected with the cathode of the main current circuit, and the control electrode is connected with the g electrode of the test board;

d) The surge test circuit (120) comprises a surge current regulator (121) for regulating the peak value of the surge current; the pulse counting timing module (123) is used for setting the number of times of surge and the surge time interval; the second air cooling module D2 is used for dissipating heat of a rectifier diode and a controllable silicon in the loop;

e) The high-voltage circuit (130) comprises a high-voltage switching module, a high-voltage regulator (131), a high-voltage middle module (132), a polarity switching module (133) and an overload protection module (134) which are electrically connected;

the high-voltage switching module outputs two paths, one path of the signal passes through the high-voltage regulator (131) and the high-voltage intermediate module (132) in sequence, the output end of the polarity switching module (133) is connected with the node A and the node K, and the other path of the high-voltage switching module is connected with the overload protection module (134) in a bypass mode to sample the signal output by the high-voltage intermediate module (132);

the high-voltage switching module is used for carrying out high-voltage forward or reverse test and adding high voltage to realize full-dynamic test when the negative half wave of the main current circuit is tested;

the polarity switching module (133) is used for controlling the high-voltage polarity applied to the tested device to be switched, so that when the silicon controlled rectifier test is carried out, the forward peak voltage and the forward leakage current value of the device are measured during the forward test, and the reverse peak voltage and the reverse leakage current of the device are measured during the reverse test; when testing the diode, testing reverse peak voltage and reverse leakage current;

the overload protection module (134) is used for detecting the current of the high-voltage circuit (130), prompting whether the high-voltage circuit is overloaded or not through an indicator lamp when the high-voltage circuit is short-circuited or overloaded, and disconnecting the high-voltage power supply when the high-voltage circuit is overloaded;

and/or f), the heat sensitive test circuit (140), including heat sensitive voltage regulation and current stabilization power U31 and adjustable heat sensitive resistance 1R, 5R correspond to 1A, 5A gear, through the heat sensitive isolating diode, heat sensitive isolating relay JR adds the heat sensitive current to the device under test, the heat sensitive test circuit (140) has heat sensitive current potentiometer set in faceplate, used for regulating the heat sensitive current magnitude, the current provided is the constant current, its current is not influenced by external contact resistance and size of wire resistance, the heat sensitive voltage drop is read out by the digital voltmeter on the apparatus; the heat-sensitive isolation relay JR is connected with the heat-sensitive voltage-stabilizing current-stabilizing power supply U31 in parallel for supplying power, the heat-sensitive isolation relay JR is closed when heat-sensitive testing is carried out, and otherwise, the heat-sensitive isolation relay JR is disconnected to prevent the current-stabilizing power supply from being influenced;

when measuring Vf, firstly, heating a device to be measured to different set temperatures through an oven or a hot table; then, testing the thermosensitive voltage drop of the circuit board through a set thermosensitive current;

when measuring Vf (heat), firstly, a testing hole is made on the base of the device to be tested and a temperature control probe is inserted in the testing hole so as to monitor the temperature of the device to be tested; then, electrifying the tested device with a main current and a thermosensitive current, observing the waveforms of the main current and the thermosensitive voltage drop through an oscilloscope, and observing the dynamic process of the thermosensitive voltage changing along with the temperature; secondly, when the tested device reaches the set temperature and time, the size of the thermosensitive voltage is adjusted by adjusting a thermosensitive comparison voltage potentiometer R510, so that the comparison voltage and the thermosensitive voltage curve are on the same horizontal line, and the thermosensitive voltage is read by a digital meter and/or an oscilloscope.

4. The test system for a power semiconductor device according to claim 3, wherein:

a) In the control module (150), the first voltage comparison circuit comprises a comparator U51, an operational amplifier U52 and an adjustable resistor R58, wherein the adjustable resistor R58 is used for adjusting the duty ratio of the corresponding first electronic switch U54;

the power supply is subjected to voltage drop rectification and filtration by a transformer TC51 and then is subjected to voltage stabilization by a voltage stabilizer U541 to obtain a 5V power supply; the 5V power supply supplies power to an operational amplifier U52, a comparator U51 and a first electronic switch U54, a bias voltage is obtained through voltage division of a resistor R59 and an adjustable potentiometer R58, a comparison voltage of Vf (heat) and VTM is obtained through voltage division of a resistor R511 and an adjustable potentiometer R510, the comparison voltage is adjusted through the adjustable potentiometer 510, voltage of a secondary tap of a transformer TC51 is divided by the resistors R51 and R52 and added to a pin 2 of the comparator U51, the bias voltage obtained through voltage division of the resistors R58 and R59 is added to a pin 3 of the comparator U51, a rectangular pulse with the same phase as alternating current of a secondary side of the transformer TC51 is output at a pin 1 of the comparator U51, the pulse width of the rectangular pulse is adjusted through the adjustable potentiometer R58 and is added to a pin 6 of the first electronic switch U54 through follow-driving of the resistor U52, and the action of an internal electronic switch of the first electronic switch U54 is controlled;

the small contact a and the main loop K end are used for connecting to two ends of a tested device, voltage signals at two ends of the tested device are added to a pin 2 of a first electronic switch U54 through a contact of a high-voltage isolating relay Jg4 and a resistor R57, the pin 1 is a switch signal output common end of the first electronic switch U54, the first electronic switch U54 converts signals of the pin 8 and the pin 2, the 1 pin outputs the signals, the signals are sent to an oscilloscope through a first electronic switch U54 and a band switch SB52, and the voltage waveforms at two ends of the tested device are displayed;

the band switch SB51 is used for Vf, VT, VTM and/or Vf (thermal) function test conversion; when Vf and VT are applied, the voltage across the tested device is added to the digital voltmeter through the switches SB51 and SB61, and Vf and VT of the tested device are read through the digital voltmeter; when VTM, vf (heat) is reached, the comparison voltage is added to the digital table, the comparison voltage potentiometer R510 is regulated to observe the waveform on the oscilloscope, so that the comparison voltage waveform and the peak value of the voltage drop waveform are on the same horizontal line or are in a horizontal line with the waveform of Vf (heat), and the voltage of the digital table is VTM, vf (heat);

the four-pole double-throw band switches SB52, SB54, SB61 and SB62 are used for testing function conversion of heat-sensitive voltage drop and surge; when a high-voltage test is carried out, the high-voltage isolation relay Jg4 is switched off to avoid the influence of high voltage;

b) The main current circuit (110) comprises a main current regulator (111), a first trigger circuit (112) and a first air-cooling module D1, wherein the main current regulator (111) regulates the magnitude of main current output by the main circuit according to the rated value of the device to be tested, and when the rated current flowing through the device to be tested is larger than 50A, the first air-cooling module D1 starts ventilation and heat dissipation;

the main current regulator (111) is provided with a main current isolation transformer TC11, and an alternating current voltmeter Y11 is connected to a secondary coil of the main current isolation transformer TC11 so as to display input electric parameters and judge the position of a main current voltage regulator T10;

adjusting the gear of the main current according to the rated value of the tested device, and adjusting the output rated current of the main current circuit by using a main current voltage regulator T10;

c) The main current circuit (110) comprises a plurality of adjustable main current load resistors R111 connected to a main current loop, the resistance values are sequentially increased, and the step-by-step corresponding reduction output of current is realized, the main current load resistors R111 comprise 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 are respectively correspondingly connected with main current gears of 200A, 100A, 50A, 20A, 5A and 1A, and main current passes through the A and K ends and is connected to a device to be tested;

d) During surge current testing, commercial power is connected to a main current voltage regulator T20 through a power switch fuse BL, and is isolated through a main current transformer TC12 for voltage reduction, a secondary output power supply of the main current transformer TC12 is subjected to half-wave rectification through a main current diode D12 and a unidirectional main current silicon controlled rectifier Q12, and surge current is generated through a tested device and load resistors R21-R26;

the surge current circuit (120) comprises a main current regulator (121), a second trigger circuit (122) and a second air-cooling module D2, wherein the main current regulator (121) regulates the magnitude of the surge current output by the main circuit according to the rated value of the tested device; the second air cooling module D2 is used for dissipating heat of the main current diode D12 and the unidirectional main current controllable silicon Q12 when the rated current of the tested device is larger than 50A;

the surge current regulator (121) comprises a surge current isolation transformer TC12 with rated output of 60V/600A, and an alternating current voltmeter Y12 is connected on a secondary coil of the surge current isolation transformer TC12 to display input voltage parameters and judge the position of a main current voltage regulator T20; the output end of a secondary coil of the surge transformer TC12 is connected to an output node A through a surge diode D12 connected in series and a surge controllable silicon Q12 which is controlled to be turned on and turned off by a second trigger circuit (122) and serves as an electronic switch of a surge;

the pulse counting timing module (123) comprises a timing module and a counting module, is used for controlling the number of times of surge and the time interval of the surge, the number of times of the surge is set by the counting module, the time interval of the surge is set by a circulating timer, and when the set number of times of the surge is reached, the surge waveform is displayed on the oscilloscope; the surge current phase and the main current phase are in the same phase, and the surge is controlled by a surge silicon controlled rectifier Q12 and a pulse counting timing module (123);

and/or e), a high voltage circuit (130) for applying a high voltage to the device under test in a phase opposite to the main current and surge for testing the withstand voltage of the device, or for applying a high voltage in a dynamic test;

in the high-voltage circuit (130), the rectifying and filtering circuit (132) comprises a plurality of diodes D4-1 which are connected in series in the forward direction on a high-voltage output circuit, a plurality of rectifying diodes D4-2 which are connected in series in the reverse direction between the high-voltage output circuit and a high-voltage loop, and a plurality of diodes D4-3 which are connected in series, a capacitor C4-1 and a resistor R4-6 which are connected in series electrically between the output circuit and the loop;

the series-connected diodes D4-3 are divided into two paths, one path is connected with a loop through a capacitor C4-1, the other path is connected with a backflow through a resistor R4-6 and an adjustable resistor Rz4-4, and a peak voltmeter Y4-2 is connected to the adjustable resistor Rz4-4 in a bypassing manner;

a power supply is added to a voltage regulator RZ4-1 through a high-voltage switch SB4-1 of the single-pole double-throw switch and a normally closed contact JB4 of an overcurrent protection relay JB 4; the voltage regulator RZ4-1 is connected with a step-up transformer TC4-1, the step-up transformer outputs two gears of 100OV and 2000V, and a relay JZ4 is controlled by a switch SB4-2 to switch the gears; the voltage regulator regulates the high voltage;

high voltage is generated by half-wave rectification of an alternating current by a 1000V or 200OV tap of TC4-1 through a current limiting resistor R4-3 and a current limiting resistor R4-2 through a rectifier diode D4-2, the reverse voltage of the D4-2 is applied to the D4-1 when the alternating current is in a negative half wave, the reverse voltage is prevented from being applied to a tested device, the D4-3 to the D4-6 and the C4-1 carry out rectification filtering on the alternating half wave, the peak value of the half-wave voltage is obtained on a capacitor C4-1, then the half-wave voltage is divided by Rz4-6 and an adjustable potentiometer Rz4-4 and sent to a peak voltage meter head to display the peak voltage value, and the adjustable potentiometer Rz4-4 is used for peak voltage calibration; a direct current ammeter is connected in series in the circuit to display the leakage current in the circuit during testing;

the high-voltage circuit (130) comprises a polarity conversion switch SB4-3, so that the polarity of the output high voltage is converted according to the test requirement;

the high-voltage circuit (130) is also provided with a protective relay Jg4, when the high-voltage switch is closed, the high-voltage switch is electrified and closed, and the high voltage is applied to a tested device through a normally open contact of the protective relay Jg 4; when the high-voltage switch is switched off, the protective relay Jg4 is not attracted, and the high-voltage circuit is in a disconnected state with other external circuits through a normally open contact of the protective relay Jg4, so that the influence of other circuits on the high-voltage circuit is prevented;

one end of the high-voltage switch SB4-1 supplies power to the high-voltage circuit, the other end supplies power to the heat-sensitive test circuit, when the high-voltage circuit is triggered, the heat-sensitive test circuit is disconnected, and when the heat-sensitive test circuit is triggered, the high-voltage circuit is disconnected, so that the high-voltage and heat-sensitive circuits are prevented from supplying power simultaneously, misoperation is prevented, and the circuits are damaged;

the phase of the high-voltage half-wave is opposite to the phase of the main current and the surge by 180 degrees, so that the main current and the surge are passed through when the half-wave is passed, and the reverse voltage is added to the other half-wave.

5. The system for testing a power semiconductor device according to claim 4, wherein: in the main current circuit (110), the main current load resistor R111 includes a coil (20) as a resistor, and deionized water is circulated in the coil (20); joints (21) are arranged at two ends of the coil (20) and used for externally connecting a water path, the coil (20) is provided with a first electric connection end (29) and an adjustable second electric connection end (28) in a matching way and used for externally connecting a circuit, and the resistance value of the liquid-cooling resistor is adjusted by adjusting the position of the second electric connection end (28) on the coil (20);

the external waterway comprises a water pump (31) and a refrigerator (32) which are connected in series.

6. The system for testing a power semiconductor device according to claim 4, wherein: the main current gear shifting switch comprises a main current switch knob with multiple gears; the main current switch knob and the surge switch knob are coaxially linked to realize the current transmission of the main circuit and the surge circuit at the same gear;

in a thermally-sensitive test circuit (140),

calculating the temperature rise of the device: Δ Tj = (Vf-Vf (hot))/M;

in the formula: Δ Tj represents junction temperature rise of the device under test, vf (thermal) represents thermosensitive voltage at the lowest test temperature in normal state, vf represents thermosensitive voltage at 150 ℃ in thermal state, and M represents thermosensitive slope;

7. The system for testing a power semiconductor device according to claim 4, wherein: in the main current circuit (110), the output end of the main current regulator (111) is output to a node A through a main current diode D11 and a main current controllable silicon Q11 so as to be connected into a device to be tested for measurement;

the main current circuit (110) comprises a first trigger circuit (112) which is used for synchronously triggering the on-off of the main current controllable silicon Q11 and adjusting the current.

8. The system for testing a power semiconductor device according to claim 4, wherein: the overload protection circuit (134) comprises an ammeter Y4-3 for displaying leakage current and a sampling resistor R4-8;

in the overcurrent protection circuit (134), a circuit is subjected to voltage reduction by a TC4-2 transformer and then is rectified by a full-wave rectification module D4-4, filtered by a filter capacitor C4-4 and stabilized by a voltage stabilizer U4-1 to obtain a 12V direct-current power supply, the 12V power supply supplies power to a comparator U4-2 and an overload protection relay JB4, meanwhile, the threshold voltage of overcurrent protection is obtained through a resistor R4-11 and an adjustable potentiometer R4-13 and is added to a pin 2 of the comparator U4-2, and the threshold voltage is adjusted and set through the resistor R4-13;

an overcurrent protection sampling resistor R4-9 is electrically connected to the comparator U4-2, the current sampling voltage on the overcurrent protection sampling resistor R4-9 is added to the 3 pins of the comparator U4-2 by a resistor R4-10, a voltage regulator tube D4-5 amplitude limiting and C4-6 noise wave filtering, when overcurrent and overvoltage exceed a set protection threshold value, the 1 pin of the U4-2 outputs a high level to drive a silicon controlled rectifier Q4 to be conducted, and a relay JB4 is attracted; the normally-closed point of the relay JB4 is disconnected, and the high-voltage power supply is cut off, so that the high voltage has no output, and the devices of the high-voltage circuit are protected;

meanwhile, the overload protection relay JB4 is also provided with a light emitting diode D4-6, when the overload protection acts, the light emitting diode D4-6 is lightened to display that the circuit is in a protection state at the moment and no high-voltage output exists, a reset switch SB-4 is also connected in series on the coil of the relay JB4, and when the overload protection relay is pressed down, the protection state is removed, and the overload protection relay is retested.

9. A method for testing a power semiconductor device, comprising: by means of the system of claim 1, the method comprising the steps of;

s010, connecting the tested device to a positive terminal and a negative terminal of a main current circuit, adjusting the magnitude of the main current to conduct the tested device, and measuring to obtain the forward peak voltage and the average voltage drop of the tested device;

s020, switching a polarity switching module of the high-voltage circuit into a reverse direction, regulating the output voltage of the high-voltage power supply through a high-voltage regulator, and measuring to obtain the reverse voltage and reverse leakage current of the device to be tested;

s030, connecting the device to be tested to a heating module after being connected in series, respectively heating the device to be tested to different temperatures through the heating module, adjusting the magnitude of thermosensitive current through a thermosensitive current regulator, and testing thermosensitive voltages corresponding to the thermosensitive current at different temperatures;

and S040, switching on a surge test circuit in the half-wave conduction stage of the device to be tested, adjusting the magnitude of surge current to be a preset multiple of main current through a surge current regulator, switching on a high-voltage power supply, switching the polarity of the polarity switching module to be reverse, and carrying out surge test on the device to be tested based on the preset surge pulse number and the preset surge pulse time interval.

10. The method for testing a power semiconductor device according to claim 9, wherein: when the device to be tested is subjected to full-dynamic surge test, the control module controls the main current circuit, the surge test circuit and the high-voltage circuit to be sequentially conducted so as to perform surge test on the device to be tested based on the preset surge pulse number and the preset surge pulse time interval;

when the device to be tested is subjected to heat-sensitive test, the control module controls the conduction of a heat-sensitive test circuit, and heat-sensitive voltages corresponding to heat-sensitive currents at different temperatures are tested by adjusting the magnitude of the heat-sensitive current and the heated temperature of the device to be tested; when the device to be tested is subjected to full-dynamic test, the control module controls the main current circuit and the high-voltage circuit to be sequentially conducted so as to test the forward and reverse peak voltage and the forward and reverse leakage current of the device to be tested;

the main current circuit comprises a main current regulator, a driving circuit and a plurality of current-limiting resistors, wherein the main current regulator is used for regulating the magnitude of the main current according to the rated value of the device to be tested, and the driving circuit is suitable for controlling the gate voltage in a control loop or the device to be tested so as to control the on and off of the device;

the surge testing circuit comprises a surge current regulator, a counting module and a timing module, wherein the surge current regulator is suitable for regulating surge current to be a preset multiple of main current, the counting module is suitable for setting the triggering times of surge pulses in the surge testing process, and the timing module is suitable for setting the time interval between the surge pulses; the heat-sensitive test circuit comprises a heat-sensitive current regulator and a heating module, wherein the heat-sensitive current regulator is suitable for adjusting the magnitude of heat-sensitive current according to specified rated current, and the heating module is suitable for heating a tested device to different temperature values;

the high-voltage circuit comprises a high-voltage regulator, a polarity switching module and an overload protection circuit, wherein the high-voltage regulator is suitable for regulating the voltage value of a high-voltage power supply applied to two ends of a tested device; the polarity switching module is suitable for adjusting the polarity applied to the device to be tested so as to measure the forward peak voltage and the forward leakage current value of the device during forward test and measure the reverse peak voltage and the reverse leakage current of the device during reverse test; the overcurrent and overload protection circuit cuts off the high-voltage power supply protection circuit when the loop current is overloaded or short-circuited, and carries out overload prompt through the overload indicator lamp;

when the device to be tested is subjected to full-dynamic surge test, the control module controls the main current circuit, the surge test circuit and the high-voltage circuit to be sequentially conducted so as to carry out surge test on the device to be tested based on the preset surge pulse number and the preset surge pulse time interval; when the device to be tested is subjected to heat-sensitive test, the control module controls the conduction of a heat-sensitive test circuit, and heat-sensitive voltages corresponding to heat-sensitive currents at different temperatures are tested by adjusting the magnitude of the heat-sensitive current and the heated temperature of the device to be tested; when the device to be tested is subjected to full-dynamic test, the control module controls the main current circuit and the high-voltage circuit to be sequentially conducted so as to test the forward and reverse peak voltage and the forward and reverse leakage current of the device to be tested;

the main current circuit comprises a main current regulator, a driving circuit and a plurality of current-limiting resistors, wherein the main current regulator is used for regulating the magnitude of the main current according to the rated value of the device to be tested, and the driving circuit is suitable for controlling the gate voltage in the loop or the device to be tested so as to control the on and off of the device;

the surge testing circuit comprises a surge current regulator, a counting module and a timing module, wherein the surge current regulator is suitable for regulating surge current to be a preset multiple of main current, the counting module is suitable for setting the triggering times of surge pulses in the surge testing process, and the timing module is suitable for setting the time interval between the surge pulses;

the heat-sensitive test circuit comprises a heat-sensitive current regulator and a heating module, wherein the heat-sensitive current regulator is suitable for adjusting the size of heat-sensitive current according to specified rated current, and the heating module is suitable for heating the tested device to different temperature values.