Double-pulse testing device for high-power turn-off device

Abstract

The invention relates to a double-pulse testing device for a high-power turn-off device, and belongs to the technical field of electric power testing. The measurement and control system of the testing device comprises a control system and a measuring system used for collecting voltage and current needed by the tested turn-off device during corresponding testing. The control system is used for receiving a remote control instruction and controlling the on-off of the tested turn-off device according to the remote control instruction. The testing device is also provided with a high-voltage power supply unit for providing voltage for the capacitor of the tested power module and an adjustable reactor for providing different load inductances for the tested turn-off device. When the test is carried out, the test device can effectively realize the double-pulse test of the high-power turn-off device through the obtained corresponding voltage and current.

Description

Technical Field

[0001] The invention relates to a double-pulse test device for a high-power switchable device, belonging to the technical field of power testing. Background Art

[0002] Dynamic parameter testing is primarily based on double-pulse test circuits. Existing equipment mostly tests traditional Si devices, typically targeting half-bridge structures. This double-pulse test method results in large parasitic parameters and is unsuitable for testing high-speed, wide-bandgap power devices. As flexible DC technology evolves toward higher voltages and larger capacities, the voltage and current requirements for high-voltage, high-power, turn-off devices are also increasing. Double-pulse testing methods can comprehensively reflect the operating characteristics of turn-off devices. However, current manufacturers developing dynamic test systems for power devices, both domestically and internationally, have failed to address the testing of turn-off devices in various packaging configurations, voltage and current levels, materials, and junction temperatures. Summary of the Invention

[0003] The purpose of the present invention is to provide a double-pulse test device for a high-power turn-off device, so as to solve the problem of how to perform a double-pulse test on a high-power turn-off device.

[0004] To achieve the above object, the solution of the present invention includes:

[0005] A double-pulse test device for a high-power switchable device of the present invention comprises a measurement and control system, which includes a measuring system and a control system. The control system is used to receive remote control instructions for controlling the on and off of the switchable device under test, and also controls the on and off of the switchable device under test according to the remote control instructions through a driver board of the switchable device under test; the control system also includes a high-voltage power supply unit for connecting to the capacitor of a power module where the switchable device under test is located, and an adjustable inductor for providing different load inductances for the switchable device under test; and the measurement system includes an oscilloscope for collecting current and voltage required for the corresponding test of the switchable device under test.

[0006] Furthermore, the oscilloscope includes several voltage probes and several current probes; the first current probe in the current probe and the first voltage probe in the voltage probe are used to be connected in series and in parallel with the upper switch tube in the power module where the tested turn-off device is located when performing a double pulse test, so as to collect its collector current and diode voltage; the second current probe in the current probe and the second voltage probe in the voltage probe are used to be connected in series and in parallel with the lower switch tube in the power module where the tested turn-off device is located when performing a double pulse test, so as to collect its emitter current and collector-emitter voltage.

[0007] Furthermore, it also includes a conductor for short circuit; the conductor is used to be connected in parallel with the upper tube switch tube when performing a short circuit test to achieve a short circuit in the bridge arm of the power module; the third voltage probe in the voltage probe is used to be connected in parallel with the lower tube switch tube when performing a short circuit test to collect its driving voltage; the second voltage probe in the voltage probe is used to be connected in parallel with the lower tube switch tube when performing a short circuit test to collect its collector-emitter voltage; the second current probe in the current probe is used to be connected in series with the lower tube switch tube when performing a short circuit test to collect its emitter current.

[0008] Furthermore, the invention also includes a temperature regulating system for maintaining the temperature of the switchable device under test at a set temperature.

[0009] Furthermore, the temperature regulation system includes a liquid heating main circuit having a heating interface for the inflow and outflow of the heating medium, and the heating interface is used to connect the liquid inlet and outlet of the liquid cooling circuit of the power module for cooling the shutoff device.

[0010] Furthermore, a flow control unit for regulating the flow of the heating medium into and out of the heating interface is provided on the liquid heating main circuit.

[0011] Furthermore, a temperature control unit for controlling the temperature of the heating medium is also provided on the liquid heating main circuit.

[0012] Furthermore, the control system includes an industrial computer and a system control unit. The industrial computer is used to receive remote control instructions for controlling the on and off of the tested switchable device and forward the instructions to the system control unit. The system control unit is used to send on and off instructions to the driver board of the tested switchable device according to the remote control instructions to realize the on and off of the tested switchable device.

[0013] Furthermore, it also includes a touch screen; remote control instructions are sent to the industrial computer through the touch screen; the industrial computer is also used to forward data sent by the oscilloscope to the touch screen, and the touch screen performs corresponding processing after receiving the data forwarded by the industrial computer to obtain the parameters required for the double pulse test.

[0014] The beneficial effects of the present invention are as follows: the present invention is a pioneering invention, and the measurement and control system of the test device of the present invention includes a control system and a measurement system for collecting the voltage and current required by the tested switchable device when performing corresponding tests. The control system is used to receive remote control instructions and control the switching of the tested switchable device according to the remote control instructions; the test device is also provided with a high-voltage power supply unit for providing voltage to the capacitor of the tested power module and an adjustable inductor for providing different load inductances to the tested switchable device, so that the double-pulse test of the high-power switchable device can be effectively realized through the test device. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1It is a schematic diagram of the principle of a double pulse test device of the present invention;

[0016] Figure 2 1. It is a tap schematic diagram of an adjustable reactor of the present invention;

[0017] Figure 3 This is a schematic diagram of a double-pulse test circuit for a half-bridge module of the present invention;

[0018] Figure 4 This is a schematic diagram of a short-circuit test circuit of the present invention. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clear, the present invention is further described in detail below with reference to the accompanying drawings and implementation methods.

[0020] The concept of the present invention is to match the requirements of different inductance values ​​with an adjustable inductor and set up a corresponding test system to complete the corresponding double pulse test.

[0021] Device implementation method:

[0022] This embodiment provides a double-pulse test device for high-power turn-off devices. The device has complete double-pulse test functions, including but not limited to testing and verifying the switching characteristics, switching losses, safe operating range, and busbar stray inductance of power devices and drive circuits; it has a heating function, and the liquid heating system can heat the device heat sink to a maximum temperature of 200°C (flexibly adjustable from room temperature to 200°C), with a temperature control accuracy of ±2K and a heating to thermal stability time of no more than 30 minutes; it can realize local and remote temperature control; it can realize flexible setting of parameters such as test voltage and current, and has It is equipped with a one-button automatic test function; it has intelligent functions, the minimum adjustable step length of the controller pulse is ≤1μs, the double pulse waveform read by the oscilloscope can be sent to the host computer, and the test waveform and data can be exported to the data processing software for processing and editing; it can realize the reading of parameters such as switching time and delay and online calculation of device switching loss; it can store device test data and export test results with one button; the host computer control system should adopt standard communication protocol; DC capacitor series and parallel connection loop inductance, series loop inductance ≤150nH, parallel loop inductance ≤100nH. Figure 1 As shown in the figure, the device consists of a high-voltage adjustable DC power supply, a busbar capacitor group, an adjustable reactor, a control system, a measurement system, a liquid heating system, an explosion-proof box and an operating table. The double-pulse test device is powered by an AC 380V power supply.

[0023] The busbar capacitor bank consists of three capacitors. In double-pulse testing, the DC voltage is supported by the busbar capacitor bank, and the energy for the load inductance also comes from the busbar capacitor bank. Therefore, the busbar capacitor bank's withstand voltage rating and capacitance value are key factors in determining the test capacity of the offline test platform. Since this test device covers a wide voltage and current test range, it is necessary to ensure that the capacitor bank has a sufficiently high withstand voltage rating and a sufficiently high capacitance value to minimize voltage drop under high currents. This requires a capacitor bank with higher capacitance values. As the test voltage level increases, the voltage drop of the busbar capacitor bank decreases at the same load current. Therefore, at higher voltage levels, a large capacitance value is not required; similarly, at lower voltage levels, a large number of capacitors in series are not necessary. To reduce the number of capacitors used, the various levels of turn-off devices can be tiered to achieve full-range testing. Therefore, the capacitor bank uses three capacitors welded in parallel or three capacitors in series. This three-capacitor series arrangement can test silicon carbide devices with higher voltage levels and offers specialized stacked arrangements for series or parallel connections to reduce parasitic inductance in the test circuit.

[0024] The load in a double-pulse test is usually an inductive load, and this load inductance forms a freewheeling loop with the diode during the turn-off period of the switchable device, facilitating the adjustment of the pulse width and intermediate energy storage. The load inductance in the test loop primarily affects the switching speed and switching loss in the dynamic characteristics of the switchable device. During dynamic testing of a switchable device, if the load current rises too quickly, the test accuracy will be reduced. The speed of current rise is affected by the size of the load inductance. Increasing the load inductance can reduce the rate of current change, thereby controlling the current. However, the characteristic impedance of the loop increases with the increase in inductance, resulting in a decrease in test capacity. Therefore, the load inductance selection range should be given according to the test capacity of the device test device. Therefore, this device automatically switches the DC contactor according to the control signal, and can connect different inductance values ​​separately, automatically connected by computer control; the automatic switching switch parameter performance requirements match the inductance requirements.

[0025] The control system consists of an industrial computer 2 and a system control unit. The backend interface of the industrial computer 2 displays the system's main circuit principles and the status of each switch. The control device can also connect to the industrial computer 2 via a communication interface. The industrial computer 2 features a charging settings interface for setting the capacitor's charging voltage rise rate, charging voltage amplitude, charging voltage protection value, and charging start soft switch. It also controls the contactor, automatically shutting down the device when the voltage reaches the set value and disconnecting the charging contactor. The industrial computer 2 has two control program settings interfaces: single-pulse test and double-pulse test. The test has both automatic and manual control modes. Upon receiving a stop command, the control device immediately stops charging and automatically discharges the device. From the start of charging until the end of discharging, a buzzer sounds and a red light remains on (the buzzer and red light are controlled by a single output interface).

[0026] The measurement system primarily consists of an 8-channel oscilloscope, a high-voltage differential probe, a Rogowski coil current probe, and a camera. The oscilloscope system boasts 12-bit analog-to-digital (A / D) hardware sampling accuracy, with up to 16-bit A / D in HDR mode. The oscilloscope features an industry-leading -55dB high signal-to-noise ratio (SNR) front-end input amplifier and a system architecture with a lower noise floor. This enables the acquisition of the current and voltage required for testing, ensuring cleaner voltage and current waveforms with minimal error.

[0027] The liquid heating system includes the necessary temperature control unit, flow control unit, heating equipment main circuit, piping (including hoses), interface converter, industrial computer, thermometer, and sensors. The liquid heating system heats the heat sink of the press-fit device under test (PUT) to a maximum temperature of 200°C (flexibly adjustable from room temperature to 200°C), with a temperature control accuracy of ±2K. Both local and remote temperature control is possible. An explosion-proof enclosure houses the PUT and contains a camera. An operating console provides operator control, monitoring, and control.

[0028] The system control unit is connected to the main control chip of the power module under test, so as to send corresponding control instructions to the driving board of the test switchable device (switch tube) of the power module under test to realize the on and off of the switch tube in the power module under test; the high-voltage power supply unit is connected to the capacitor in the power module under test to provide the capacitor with the corresponding required voltage.

[0029] Before performing the double pulse test, the set temperature is transmitted to the industrial computer 1 by operating the touch screen (display screen) background software on the test bench. The liquid heating system confirms the temperature of the tested switchable device of the power module under test through the temperature control unit. If the temperature of the tested switchable device is lower than the set temperature, the liquid heating main circuit starts to heat the tested switchable device through a liquid heating interface with a heating medium flowing in. If the temperature of the tested switchable device is higher than the set temperature, the liquid heating main circuit starts to cool the tested switchable device through a liquid heating interface with a heating medium flowing out. The tester can choose to perform an automatic test or a manual test by operating the display screen on the test bench. During actual use, the power module has a liquid cooling circuit inside, which realizes the cooling of the switchable device of the power module during use. The flow rate and temperature of the heating medium are respectively realized by the flow control unit and the temperature control unit. Therefore, the present invention connects the liquid heating interface of the liquid heating system to the liquid cooling circuit of the power module to achieve heating or cooling.

[0030] Manual test: The display screen transmits the corresponding remote control command to the industrial computer 2 through the network cable. The industrial computer 2 transmits the command to the system control unit. At this time, the double pulse test switch is started. The system control unit automatically switches the DC contactor according to the control signal, and can connect different inductance values ​​respectively. The automatic switching switch parameter performance requirements match the inductance requirements.

[0031] During the test, it is assumed that the bus capacitor voltage remains unchanged, so the on-state process of the turn-off device (for example, IGBT) can be expressed as:

[0032]

[0033] Therefore, the first pulse width approximately satisfies:

[0034]

[0035] When the test voltage is maximum and the test current is minimum, the pulse width is shortest;

[0036]

[0037] On the contrary, when the test voltage reaches the specified lower limit and the current reaches the maximum, the pulse width is the longest.

[0038]

[0039] The range of inductance values ​​is obtained:

[0040]

[0041] When testing devices that can be turned off at different voltage levels, inductors with different inductance values ​​need to be selected. Therefore, the load inductor is selected as a multi-tap inductor, such as Figure 2 shown.

[0042] like Figure 3As shown, the high-voltage power supply unit is controlled to charge the DC capacitor. After charging is complete, the system control unit issues a first trigger-on command to the driver board of the upper or lower IGBT in the power module under test. After the set on-time T1 is reached, a first pulse off-time command is issued. After the first pulse off-time delay T2 is reached, the system control unit issues a second pulse trigger-on command to the driver board of the upper or lower IGBT in the power module under test. As long as there is residual voltage in the capacitor, the double-pulse switch test can be repeatedly pressed. During the test, the system's off-zone double-pulse waveform is measured and the data is transmitted to the industrial computer 2, which then transmits the data to the display screen. The test waveform and data can be exported to the corresponding data processing software for processing and editing. This allows for reading parameters such as switching time and delay, as well as online calculation of device switching losses. Device test data can be stored and test results can be exported with one click. After the test is completed, the industrial computer 2 activates the stop button, and the control device controls the discharge contactor to discharge. When the discharge voltage falls below 30V, the red light turns off and the buzzer stops.

[0043] In automatic mode: When automatic test is selected, the display screen transmits the command to industrial computer 2 through the network cable, and industrial computer 2 transmits the command to the system control unit. At this time, the double pulse test switch is started. According to the control logic of the manual mode, after the test is completed (that is, the second off pulse is completed), there is a delay of 100ms, and the control device automatically controls the discharge contactor to discharge. When the discharge voltage is less than 30V, the red light goes out and the buzzer stops.

[0044] During the charging process, if the current exceeds the set value, the high-voltage power supply will stop outputting immediately after a delay of 50ms, the charging contactor will be disconnected, and the discharge switch will be closed at the same time. In any case, pressing the emergency stop button will immediately block the charging pulse, disconnect the charging contactor, and close the discharge switch at the same time.

[0045] The high-power switchable device double pulse tester can complete IGBT turn-on and turn-off time test, turn-off voltage spike test, IGBT turn-on and turn-off loss test Eon, IGBT turn-on and turn-off loss test Eoff, diode reverse recovery loss test Erec, stray inductance test, IGBT reverse bias safe operation curve test (RBSOA), diode reverse recovery safe operation curve test (SOA DIODE) and short circuit test. Figure 3As shown, corresponding oscilloscope probes and inductors are placed at corresponding locations on the power module under test to collect voltage and current, thereby obtaining the corresponding test parameters. For example, an adjustable reactor is connected in parallel to both the collector and emitter of the upper IGBT; a first Rogowski coil probe is connected in series with the collector of the upper IGBT to collect the current Ir (collector current) there; a first high-voltage differential probe is connected in parallel between the collector and emitter of the upper IGBT to collect the voltage Vr (diode voltage) there; a second Rogowski coil probe is connected in series with the emitter of the lower IGBT to collect the corresponding current Ic (emitter current); a second high-voltage differential probe is connected in parallel between the gate and emitter of the lower IGBT to collect the corresponding drive voltage Vge; and a third high-voltage differential probe is connected in parallel between the collector and emitter of the lower IGBT to collect the collector-to-emitter voltage Vce (collector-to-emitter voltage) there.

[0046] (1) IGBT turn-on and turn-off time test, such as Figure 3 As shown in the figure, connect the test circuit. After the wiring is completed, test according to the following test steps:

[0047] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0048] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0049] According to actual needs, the upper tube IGBT and lower tube IGBT can be tested separately, and the final results are displayed on the display.

[0050] (2) Turn-off voltage spike test, such as Figure 3 As shown in the figure, connect the test circuit. After the wiring is completed, test according to the following test steps:

[0051] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0052] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0053] 3) The upper IGBT and lower IGBT can be tested separately according to actual needs.

[0054] 4) Measure the peak value of Vce at the second turn-off moment.

[0055] The final result is shown on the display.

[0056] (3) IGBT turn-on and turn-off loss test Eon, Eoff, such as Figure 3As shown in the figure, connect the test circuit. After the wiring is completed, test according to the following test steps:

[0057] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0058] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0059] 3) According to actual needs, the upper tube IGBT and lower tube IGBT can be tested separately and the data recorded.

[0060] The final result is shown on the display.

[0061] (4) Diode reverse recovery loss test Erec, such as Figure 3 As shown in the figure, connect the test circuit. After the wiring is completed, test according to the following test steps:

[0062] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0063] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0064] 3) According to actual needs, the upper tube IGBT and lower tube IGBT can be tested separately and the data recorded.

[0065] The final result is shown on the display.

[0066] (5) Stray inductance test, such as Figure 3 As shown, connect the circuit and then test it according to the following steps:

[0067] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0068] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0069] 3) According to actual needs, the upper tube IGBT and lower tube IGBT can be tested separately and the data recorded.

[0070] The final result is shown on the display.

[0071] (6) IGBT reverse bias safe operation curve test (RBSOA), such as Figure 3 As shown in the figure, connect the test circuit. After the wiring is completed, test according to the following test steps:

[0072] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0073] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0074] 3) According to actual needs, the upper tube IGBT and lower tube IGBT can be tested separately and the data recorded.

[0075] 4) Obtain the Vce and Ic values ​​at the second turn-off time, draw a curve based on the recorded data, and compare it with the curve in the data sheet.

[0076] The final result is shown on the display.

[0077] (7) Diode reverse recovery safety operation curve test (SOA DIODE), such as Figure 3 As shown in the figure, connect the test circuit. After the wiring is completed, test according to the following test steps:

[0078] 1) First, carry out low voltage and low current tests to check whether there are any abnormalities in the waveform;

[0079] 2) Increase the voltage to the rated voltage and adjust the pulse width of the double-pulse generator to make the cut-off current reach the rated value;

[0080] 3) According to actual needs, the upper tube IGBT and lower tube IGBT can be tested separately and the data recorded.

[0081] 4) The background obtains the Vr and Ir values ​​at the second opening time, draws a curve based on the recorded data and compares it with the curve in the specification.

[0082] The final result is shown on the display.

[0083] (8) Short circuit test:

[0084] 1) If Figure 4 As shown, the circuit is connected, and the wave board adopts a single pulse 10us wave channel;

[0085] 2) The air-core inductor is replaced with a copper busbar, which is connected in parallel with the upper IGBT, thereby achieving a short circuit within the bridge arm of the power module, raising the bus voltage to the rated value, and emitting a wave to the lower IGBT;

[0086] 3) Record the waveforms and di / dt of Vge, Vce, and Ic;

[0087] 4) Considering that the short-circuit test may cause damage to the IGBT, the interval between short-circuit tests should be at least 10 minutes, and only two tests are required, one at 1000V and one at rated voltage.

[0088] The final result is shown on the display.

[0089] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to the above embodiments, ordinary technicians in the field should understand that the specific embodiments of the present invention can still be modified or replaced by equivalents. Any modification or equivalent replacement that does not depart from the spirit and scope of the present invention should be covered by the scope of protection of the claims of the present invention.

Claims

1. A double pulse test device for high-power turn-off devices, characterized in that: The device comprises a measurement and control system, which includes a measurement system and a control system. The control system is used to receive remote control instructions for controlling the on and off of the device under test that can be turned off, and also controls the on and off of the device under test according to the remote control instructions through a driver board of the device under test that can be turned off; the device also comprises a high-voltage power supply unit connected to the capacitor of the power module where the device under test can be turned off, and an adjustable inductor for providing different load inductances for the device under test; the measurement system includes an oscilloscope for collecting current and voltage required for the corresponding test of the device under test.

2. The double pulse test device for high-power turn-off devices according to claim 1, characterized in that: The oscilloscope includes several voltage probes and several current probes; the first current probe in the current probes and the first voltage probe in the voltage probes are used to be connected in series and in parallel with the upper tube switch tube in the power module where the tested turn-off device is located when performing a double pulse test, so as to collect its collector current and diode voltage; the second current probe in the current probe and the second voltage probe in the voltage probes are used to be connected in series and in parallel with the lower tube switch tube in the power module where the tested turn-off device is located when performing a double pulse test, so as to collect its emitter current and collector-emitter voltage.

3. The double pulse test device for high-power turn-off devices according to claim 2, characterized in that: It also includes a conductor for short circuit; the conductor is used to be connected in parallel with the upper tube switch tube when performing a short circuit test to achieve a short circuit within the bridge arm of the power module; the third voltage probe in the voltage probe is used to be connected in parallel with the lower tube switch tube when performing a short circuit test to collect its driving voltage; the second voltage probe in the voltage probe is used to be connected in parallel with the lower tube switch tube when performing a short circuit test to collect its collector-emitter voltage; the second current probe in the current probe is used to be connected in series with the lower tube switch tube when performing a short circuit test to collect its emitter current.

4. The double pulse test device for high-power turn-off devices according to claim 1, characterized in that: Also included is a temperature regulating system for maintaining the temperature of the switchable device under test at a set temperature.

5. The double pulse test device for high-power turn-off devices according to claim 4, characterized in that: The temperature regulation system includes a liquid heating main circuit having a heating interface for the inflow and outflow of a heating medium, and the heating interface is used to connect to the liquid inlet and outlet of the liquid cooling circuit of the power module for cooling the shutoff device.

6. The double pulse test device for high-power turn-off devices according to claim 5, characterized in that: The liquid heating main circuit is provided with a flow control unit for regulating the flow of heating medium into and out of the heating interface.

7. The double pulse test device for high-power turn-off devices according to claim 5, characterized in that: The liquid heating main circuit is also provided with a temperature control unit for controlling the temperature of the heating medium.

8. The double pulse test device for high-power turn-off devices according to claim 1, characterized in that: The control system includes an industrial computer and a system control unit. The industrial computer is used to receive remote control instructions for controlling the on and off of the tested switchable device and forward the instructions to the system control unit. The system control unit is used to issue on and off instructions to the driver board of the tested switchable device according to the remote control instructions to realize the on and off of the tested switchable device.

9. The double pulse test device for high-power turn-off devices according to claim 8, characterized in that: It also includes a touch screen; the remote control instructions are sent to the industrial computer through the touch screen; the industrial computer is also used to forward the data sent by the oscilloscope to the touch screen, and the touch screen performs corresponding processing after receiving the data forwarded by the industrial computer to obtain the parameters required for the double pulse test.

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