Test circuit and test method

Abstract

The invention relates to the technical field of circuits, and discloses a test circuit and a test method.The test circuit comprises a signal generator, an optocoupler driver, an oscilloscope, an inductor, a discharge capacitor, a Rogowski coil, a high-voltage differential probe, a low-voltage probe, a low-voltage power module, a high-voltage power module and a controller; the low-voltage power supply module is connected with the power supply end of the optocoupler driver, the signal transmitter is connected with the input end of the optocoupler driver, and the output end of the optocoupler driver is connected with the control end of the MCT; the first end of the inductor is connected with the first end of the MCT, the second end of the inductor is connected with the first end of the Rogowski coil, and the second end of the Rogowski coil is connected with the first end of the high-voltage power supply module; the second end of the MCT is connected with the second end of the high-voltage power supply module; the first end of the discharge capacitor is connected with the second end of the inductor, and the second end of the discharge capacitor is connected with the second end of the MCT; the first end of the high-voltage differential probe is connected with the first end of the MCT, and the second end of the high-voltage differential probe is connected with the second end of the MCT; the low-voltage probe is connected with the control end of the MCT.

Description

Technical Field

[0001] The present application relates to the technical field of circuits, and particularly relates to a test circuit and a test method. Background Art

[0002] At present, an MCT (Metal-Oxide-Semiconductor Controlled Thyristor) device is a composite power device that combines the advantages of a thyristor and a MOS field-effect transistor, and has a high input impedance, a low conduction voltage drop, and good blocking characteristics.

[0003] However, the electrical performance test of an MCT device requires high voltage and large current tests, and has high requirements for test equipment and the environment. At present, it is impossible to accurately test the dynamic electrical performance parameters of an MCT device. Summary of the Invention

[0004] The purpose of the embodiments of the present application is to provide a test circuit and a test method, so as to achieve accurate testing of the dynamic electrical performance parameters of an MCT device.

[0005] To solve the above technical problems, an embodiment of the present application provides a test circuit, including: a signal generator, an optocoupler driver, an oscilloscope, an inductor, a discharge capacitor, a Rogowski coil, a high-voltage differential probe, a low-voltage probe, a low-voltage power supply module, a high-voltage power supply module, and a controller; the low-voltage power supply module is connected to the power supply terminal of the optocoupler driver, the signal transmitter is connected to the input terminal of the optocoupler driver, and the output terminal of the optocoupler driver is connected to the control terminal of the MCT device; the first end of the inductor is connected to the first end of the MCT device, the second end of the inductor is connected to the first end of the Rogowski coil, and the second end of the Rogowski coil is connected to the first end of the high-voltage power supply module; the second end of the MCT device is connected to the second end of the high-voltage power supply module; the first end of the discharge capacitor is connected to the second end of the inductor, and the second end of the discharge capacitor is connected to the second end of the MCT device; the first end of the high-voltage differential probe is connected to the first end of the MCT device, and the second end of the high-voltage differential probe is connected to the second end of the MCT device; the low-voltage probe is connected to the control terminal of the MCT device; the oscilloscope is respectively connected to the Rogowski coil, the high-voltage differential probe, and the low-voltage probe; the oscilloscope is used to obtain the anode-cathode current waveform of the MCT device through the Rogowski coil, obtain the anode-cathode voltage waveform of the MCT device through the high-voltage differential probe, and obtain the gate voltage waveform of the MCT device through the low-voltage probe; the controller is connected to the oscilloscope, the signal generator, the low-voltage power supply module, and the high-voltage power supply module; the controller is used to control the on and off of the signal generator, the low-voltage power supply module, and the high-voltage power supply module, and the controller is further used to obtain the current change rate of the MCT device according to the anode-cathode current waveform obtained by the oscilloscope, and obtain the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

[0006] An embodiment of the present application further provides a test method, which is applied to the controller of the above test circuit. The test method includes: controlling the low-voltage power supply module and the high-voltage power supply module to turn on, so that the discharge capacitor is charged to the working voltage; controlling the signal generator to output a pulse square wave signal, so that the MCT device is turned on, and the oscilloscope obtains the anode-cathode current waveform of the MCT device through the Rogowski coil, obtains the anode-cathode voltage waveform of the MCT device through the high-voltage differential probe, and obtains the gate voltage waveform of the MCT device through the low-voltage probe; obtaining the current change rate of the MCT device according to the anode-cathode current waveform, and obtaining the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

[0007] In some embodiments, the low-voltage power supply module includes: a low-voltage power supply and an isolated power supply; an output end of the low-voltage power supply is connected to an input end of the isolated power supply, and an output end of the isolated power supply is connected to a power supply end of the opto-coupler driver; the signal generator is connected to an input end of the opto-coupler driver, a first output end of the opto-coupler driver is connected to a control end of the MCT device, and a second output end of the opto-coupler driver is grounded.

[0008] In some embodiments, the test circuit further includes: a filtering module and a transient voltage suppression module; the filtering module includes a first capacitor, a first resistor, and a second resistor; the transient voltage suppression module is a transient voltage suppression diode; the first resistor is disposed between the first output end of the opto-coupler driver and the control end of the MCT device, the first output end of the opto-coupler driver is connected to a first end of the first resistor, and a second end of the first resistor is connected to the control end of the MCT device; the second end of the first resistor is further respectively connected to a first end of the first capacitor, a first end of the second resistor, and a first end of the transient voltage suppression diode, and the second output end of the opto-coupler driver is connected to a second end of the first capacitor, a second end of the second resistor, and a second end of the transient voltage suppression diode.

[0009] In some embodiments, the high-voltage power supply module includes: a high-voltage DC power supply, a current-limiting resistor, and a discharging resistor; a first output end of the high-voltage DC power supply is connected to a first end of the current-limiting resistor, and a second end of the current-limiting resistor is connected to a second end of the Rogowski coil; a second output end of the high-voltage DC power supply is connected to a second end of the MCT device, and the second output end of the high-voltage DC power supply is grounded; a first end of the discharging resistor is connected to the second end of the current-limiting resistor, and a second end of the discharging resistor is connected to ground.

[0010] The technical solutions provided by the embodiments of the present application have at least the following advantages:

[0011] In the embodiments of the present application, by providing a Rogowski coil, a high-voltage differential probe, and a low-voltage probe in the test circuit, the anode and cathode current waveforms of the MCT device are obtained from the Rogowski coil through an oscilloscope, the anode and cathode voltage waveforms of the MCT device are obtained from the high-voltage differential probe, and the gate voltage waveform of the MCT device is obtained from the low-voltage probe, so as to obtain the current change rate of the MCT device according to the anode and cathode current waveforms, and obtain the delay time of the MCT device according to the anode and cathode voltage waveforms and the gate voltage waveform, thereby obtaining the dynamic electrical performance parameters of the MCT device through multiple waveform diagrams of the MCT device, and improving the accuracy of the test of the dynamic electrical performance parameters of the MCT device. Description of the Drawings

[0012] One or more embodiments are exemplarily illustrated by the pictures in the corresponding drawings. These exemplary illustrations do not constitute a limitation on the embodiments. Elements with the same reference numerals in the drawings represent similar elements. Unless otherwise stated, the drawings in the figures do not constitute a scale limitation.

[0013] Figure 1 is one of the schematic diagrams of the circuit structure of a test circuit according to an embodiment of the present application;

[0014] Figure 2 is the second schematic diagram of the circuit structure of a test circuit according to an embodiment of the present application;

[0015] Figure 3 is the schematic diagram of the anode and cathode current waveforms of the MCT device;

[0016] Figure 4 is the schematic diagram of the anode and cathode voltage waveforms and the gate voltage waveform of the MCT device;

[0017] Figure 5 is the schematic flowchart of a test method according to an embodiment of the present application;

[0018] Figure 6 is the schematic flowchart of a test method according to an embodiment of the present application. Detailed Embodiments

[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present application clearer, the following will elaborate on each embodiment of the present application with reference to the drawings. However, those of ordinary skill in the art can understand that in each embodiment of the present application, many technical details are provided to help readers better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical solutions claimed in the present application can still be implemented. The following division of each embodiment is for convenience of description and should not constitute any limitation on the specific implementation of the present application. Each embodiment can be combined and cross-referenced with each other on the premise of no contradiction.

[0020] An embodiment of the present application relates to a test circuit. As Figure 1 shown, it is one of the schematic diagrams of the circuit structure of the test circuit of this embodiment. As Figure 2 shown, it is the second schematic diagram of the circuit structure of the test circuit of this embodiment. The test circuit includes: a signal generator 100, an optocoupler driver 101, an oscilloscope 102, an inductor L, a discharge capacitor C, a Rogowski coil 103, a high-voltage differential probe 104, a low-voltage probe 105, a low-voltage power supply module 106, a high-voltage power supply module 107, and a controller (not labeled in the figure).

[0021] Specifically, the low-voltage power supply module 106 is connected to the power supply terminal of the optocoupler driver 101, the signal transmitter is connected to the input terminal of the optocoupler driver 101, and the output terminal of the optocoupler driver 101 is connected to the control terminal of the MCT device M; the first end of the inductor L is connected to the first end of the MCT device M, the second end of the inductor L is connected to the first end of the Rogowski coil 103, and the second end of the Rogowski coil 103 is connected to the first end of the high-voltage power supply module 107; the second end of the MCT device M is connected to the second end of the high-voltage power supply module 107; the first end of the discharge capacitor C is connected to the second end of the inductor L, and the second end of the discharge capacitor C is connected to the second end of the MCT device M; the first end of the high-voltage differential probe 104 is connected to the first end of the MCT device M, and the second end of the high-voltage differential probe 104 is connected to the second end of the MCT device M; the low-voltage probe 105 is connected to the control terminal of the MCT device M; the oscilloscope 102 is respectively connected to the Rogowski coil 103, the high-voltage differential probe 104, and the low-voltage probe 105; the oscilloscope 102 is used to obtain the anode-cathode current waveform of the MCT device M through the Rogowski coil 103, obtain the anode-cathode voltage waveform of the MCT device M through the high-voltage differential probe 104, and obtain the gate voltage waveform of the MCT device M through the low-voltage probe 105; the controller is connected to the oscilloscope 102, the signal generator 100, the low-voltage power supply module 106, and the high-voltage power supply module 107; the controller is used to control the opening and closing of the signal generator 100, the low-voltage power supply module 106, and the high-voltage power supply module 107, and the controller is also used to obtain the current change rate of the MCT device M according to the anode-cathode current waveform obtained by the oscilloscope 102, and obtain the delay time of the MCT device M according to the anode-cathode voltage waveform and the gate voltage waveform.

[0022] In this embodiment, by setting the Rogowski coil 103, the high-voltage differential probe 104, and the low-voltage probe 105 in the test circuit, the oscilloscope 102 obtains the anode-cathode current waveform of the MCT device M from the Rogowski coil 103, obtains the anode-cathode voltage waveform of the MCT device M from the high-voltage differential probe 104, and obtains the gate voltage waveform of the MCT device M from the low-voltage probe 105, so as to obtain the current change rate of the MCT device M according to the anode-cathode current waveform, and obtain the delay time of the MCT device M according to the anode-cathode voltage waveform and the gate voltage waveform, thereby obtaining the dynamic electrical performance parameters of the MCT device M through multiple waveform diagrams of the MCT device M, and improving the accuracy of testing the dynamic electrical performance parameters of the MCT device M.

[0023] Specifically, the control end of the MCT device M is the gate (gate) of the MCT device M. The first end of the MCT device M is the anode, and the second end of the MCT device M is the cathode. In this embodiment, a Rogowski coil 103 is disposed in the branch where the anode of the MCT device M is located. The Rogowski coil 103 can obtain the cathode and anode currents of the MCT device M. The high-voltage differential probe 104 is disposed at the first and second ends of the MCT device M, respectively, to obtain the cathode and anode voltages of the MCT device M. The low-voltage probe 105 obtains the gate voltage of the MCT device M. Finally, the cathode and anode current waveforms, cathode and anode voltage waveforms, and gate voltage waveforms are displayed on the oscilloscope 102. The controller obtains the current change rate of the MCT device M based on the cathode and anode current waveforms, and obtains the delay time of the MCT device M based on the cathode and anode voltage waveforms and the gate voltage waveforms, thereby obtaining the dynamic electrical performance parameters of the MCT device M through multiple waveforms of the MCT device M.

[0024] The low-voltage power supply module 106 of this embodiment includes: a low-voltage power supply 1061 and an isolated power supply 1062; the output end of the low-voltage power supply 1061 is connected to the input end of the isolated power supply, and the output end of the isolated power supply is connected to the power supply end of the optocoupler driver 101; the signal generator 100 is connected to the input end of the optocoupler driver 101, the first output end of the optocoupler driver 101 is connected to the control end of the MCT device M, and the second output end of the optocoupler driver 101 is grounded.

[0025] Specifically, the isolated power supply is a DC / DC isolated power supply that converts the DC power output by low-voltage power supply 1061 into DC power to power optocoupler driver 101. Simultaneously, the isolated power supply also provides isolation protection, effectively reducing common-mode interference in the circuit, improving the system's anti-interference capability, and ensuring stable and reliable operation of electronic equipment in complex electromagnetic environments. In practical applications, the output voltage of low-voltage power supply 1061 can be set to 5V. The isolated power supply directly converts the 5V output voltage of low-voltage power supply 1061 into a 5V voltage, equivalent to the isolated power supply not changing the output voltage of low-voltage power supply 1061 and serving only as an isolation device.

[0026] Specifically, signal generator 100 is used to drive optocoupler driver 101, which outputs an MCT drive signal to the control terminal of MCT device M. Optocoupler driver 101 is powered by a DC / DC isolated power supply. In actual applications, the DC / DC isolated power supply provides a 5V DC output, and signal generator 100 is used to generate a pulsed square wave signal with a pulse width of 5μs and an amplitude of 3.3V.

[0027] The high-voltage power supply module 107 of this embodiment includes: a high-voltage DC power supply 1071, a current-limiting resistor R3, and a discharging resistor R4; the first output terminal of the high-voltage DC power supply 1071 is connected to the first end of the current-limiting resistor R3, and the second end of the current-limiting resistor R3 is connected to the second end of the Rogowski coil 103; the second output terminal of the high-voltage DC power supply 1071 is connected to the second end of the MCT device M, and the second output terminal of the high-voltage DC power supply 1071 is grounded; the first end of the discharging resistor R4 is connected to the second end of the current-limiting resistor R3, and the second end of the discharging resistor R4 is grounded.

[0028] Specifically, in the pulse discharge test, the high-voltage DC power supply 1071 first charges the discharge capacitor C. After the discharge capacitor C is charged to the working voltage, the signal generator 100 drives the optocoupler driver 101 to operate. The optocoupler driver 101 outputs an MCT drive signal to the control terminal of the MCT device M. The MCT device M conducts, and then the transient current flowing through the anode and cathode of the MCT device M can be measured through the Rogowski coil 103. At the same time, the transient voltage across the anode and cathode of the MCT device M is obtained through the high-voltage differential probe 104, and the gate voltage of the MCT device M is obtained through the low-voltage probe 105.

[0029] The test circuit of this embodiment further includes: a filtering module 108 and a transient voltage suppression module 109; the filtering module 108 includes a first capacitor C1, a first resistor R1, and a second resistor R2; the transient voltage suppression module 109 is a transient voltage suppression diode TVS; the first resistor R1 is arranged between the first output terminal of the optocoupler driver 101 and the control terminal of the MCT device M. The first output terminal of the optocoupler driver 101 is connected to the first end of the first resistor R1, and the second end of the first resistor R1 is connected to the control terminal of the MCT device M; the second end of the first resistor R1 is also respectively connected to the first end of the first capacitor C1, the first end of the second resistor R2, and the first end of the transient voltage suppression diode TVS. The second output terminal of the optocoupler driver 101 is connected to the second end of the first capacitor C1, the second end of the second resistor R2, and the second end of the transient voltage suppression diode TVS. In this embodiment, by setting the filtering module 108, the noise and interference input to the MCT device M are filtered out. By setting the transient voltage suppression module 109, the transient voltage input to the MCT device M is suppressed, preventing the voltage at the control terminal of the MCT device M from being too high and improving the stability of the MCT device M.

[0030] Specifically, the test circuit of this embodiment is used to test the dynamic electrical performance of the MCT device M. The specifications of each device are set according to the specifications of the actual MCT device M. For example, the maximum current of the MCT device M to be tested is 3500A, and the blocking voltage is 1800V. Therefore, in the corresponding test circuit, the output voltage of the low-voltage power supply 1061 can be set to ±5V, the output current to ±200mA, the output voltage of the high-voltage power supply to 5KV, the output power to 2KW, the resistance value of the current-limiting resistor to 100KΩ, the resistance value of the discharge resistor to 10MΩ, the working voltage of the discharge capacitor C to 1700V, the capacitance to 1.5uF, the maximum output current of the two channels of the optocoupler driver 101 to 20mA, the working voltage to 20V, the maximum voltage of the transient voltage suppression diode to 20V, the bandwidth of the oscilloscope 102 to 200MHz, and the bandwidth of the signal generator 100 to 25MHz.

[0031] In practical applications, the controller can complete the test of the dynamic electrical performance parameters of the MCT device M by controlling the on / off of the signal generator 100, the low-voltage power supply module 106, and the high-voltage power supply module 107. Specifically, the controller can first control the low-voltage power supply module 106 to turn on, that is, control the low-voltage power supply 1061 to turn on, and detect the gate voltage amplitude of the control end of the MCT device M through the low-voltage probe 105. If the gate voltage amplitude of the MCT device M reaches the output voltage of the low-voltage power supply module 106 (i.e., the output voltage of the low-voltage power supply 1061), then control the high-voltage power supply module 107 to turn on, that is, control the high-voltage power supply to turn on, so that the discharge capacitor C is charged to the working voltage; then, control the signal generator 100 to output a pulsed square-wave signal to make the MCT device M conduct. Since the Rogowski coil 103 acquires the anode and cathode currents of the MCT device M, the high-voltage differential probe 104 acquires the anode and cathode voltages of the MCT device M, and the low-voltage probe 105 acquires the gate voltage of the MCT device M, the oscilloscope 102 can acquire the anode and cathode current waveforms of the MCT device M through the Rogowski coil 103, the anode and cathode voltage waveforms of the MCT device M through the high-voltage differential probe 104, and the gate voltage waveform of the MCT device M through the low-voltage probe 105.

[0032] As Figure 3 shown, it is a schematic diagram of the anode and cathode current waveforms of the MCT device M, where the abscissa is time and the ordinate is current. As Figure 4 shown, it is a schematic diagram of the anode and cathode voltage waveforms and the gate voltage waveform of the MCT device M, where the abscissa is time and the ordinate is voltage. The anode and cathode voltage waveform is L1, and the gate voltage waveform is L2; after the controller acquires the anode and cathode current waveforms, the anode and cathode voltage waveforms, and the gate voltage waveform, it can obtain the current change rate of the MCT device M according to the anode and cathode current waveforms, and can obtain the delay time of the MCT device M according to the anode and cathode voltage waveforms and the gate voltage waveform.

[0033] Specifically, the controller obtains the current change rate in the following manner: according to the anode and cathode current waveforms, the first moment t1 at which the current reaches the first current value I1 and the second moment t2 at which the current reaches the second current value I2 during the first rise process are obtained, and the first current value I1 is less than the second current value I2; the current difference di between the first current value I1 and the second current value I2 is obtained; the time difference dt between the first moment t1 and the second moment t2 is obtained; and the current change rate dt / di=(I2-I1) / (t2-t1) according to the ratio of the current difference di to the time difference dt; wherein the first current value I1 is 10% of the peak value of the anode and cathode current waveform, and the second current value I2 is 90% of the peak value I of the anode and cathode current waveform. ASM In other embodiments, the first current value I1 may be greater than or less than 10% of the peak value I of the anode and cathode current waveform. ASM The second current value I2 can be greater than or less than 90% of the peak value I of the anode and cathode current waveform. ASM , specifically set according to actual needs, for example, the first current value I1 is set to the peak value I of the anode and cathode current waveform ASM 8%, 9%, 11%, 12%, etc., the second current value I2 is set to the peak value I of the anode and cathode current waveform ASM 88%, 89%, 91%, 92%, etc.

[0034] Specifically, the controller obtains the delay time in the following manner: obtain the third moment t3 when the gate voltage first rises to the first voltage value V1 according to the gate voltage waveform; obtain the fourth moment t4 when the voltage drops to the second voltage value V2 according to the cathode and anode voltage waveforms; and obtain the delay time T according to the difference between the third moment t3 and the fourth moment t4. d(on) =t4-t3; wherein the first voltage value V1 is 10% of the peak value of the gate voltage waveform V GM The second voltage value V2 is 90% of the peak value of the cathode and anode voltage waveform V AK In other embodiments, the first voltage value V1 may also be greater than or less than 10% of the peak value V of the gate voltage waveform. GM The second voltage value V2 can be greater than or less than 90% of the peak value V of the cathode and anode voltage waveform. AK , specifically set according to actual needs, for example, the first voltage value V1 is set to the peak value V of the gate voltage waveform GM 8%, 9%, 11%, 12%, etc., the second voltage value V2 is set to the peak value V of the anode and cathode voltage waveform AK 88%, 89%, 91%, 92%, etc.

[0035] Another aspect of the present application embodiment further provides a test method, which is applied to the controller of the test circuit of the above embodiment, such asFigure 5 As shown in the figure, it is a schematic flow chart of the test method of this embodiment. The test method of this embodiment includes the following steps:

[0036] Step 201: Control the low-voltage power supply module and the high-voltage power supply module to turn on, so that the discharge capacitor is charged to the working voltage.

[0037] Step 202: Control the signal generator to output a pulsed square wave signal, so that the MCT device is turned on. The oscilloscope obtains the anode-cathode current waveform of the MCT device through the Rogowski coil, obtains the anode-cathode voltage waveform of the MCT device through the high-voltage differential probe, and obtains the gate voltage waveform of the MCT device through the low-voltage probe.

[0038] Step 203: Obtain the current change rate of the MCT device according to the anode-cathode current waveform, and obtain the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

[0039] Specifically, the controller can first control the low-voltage power supply module and the high-voltage power supply module to turn on, that is, control the low-voltage power supply and the high-voltage power supply to turn on, so that the discharge capacitor is charged to the working voltage; then, the controller controls the signal generator to output a pulsed square wave signal, so that the MCT device is turned on, obtains the anode-cathode current of the MCT device through the Rogowski coil, obtains the anode-cathode voltage of the MCT device through the high-voltage differential probe, and obtains the gate voltage of the MCT device through the low-voltage probe. The oscilloscope can obtain the anode-cathode current waveform of the MCT device through the Rogowski coil, can obtain the anode-cathode voltage waveform of the MCT device through the high-voltage differential probe, and can obtain the gate voltage waveform of the MCT device through the low-voltage probe; finally, the controller obtains the current change rate of the MCT device according to the anode-cathode current waveform, and can obtain the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

[0040] As Figure 3 shown, obtaining the current change rate of the MCT device according to the anode-cathode current waveform includes: obtaining the first time t1 when the current reaches the first current value I1 and the second time t2 when it reaches the second current value I2 during the first rising process according to the anode-cathode current waveform, where the first current value I1 is less than the second current value I2; obtaining the current difference di between the first current value I1 and the second current value I2; obtaining the time difference dt between the first time t1 and the second time t2; obtaining the current change rate according to the ratio of the current difference di to the time difference dt, dt / di = (I2 - I1) / (t2 - t1). Among them, the first current value I1 is 10% of the peak value of the anode-cathode current waveform, and the second current value I2 is 90% of the peak value I of the anode-cathode current waveform ASM . The first current value I1 can be greater than or less than 10% of the peak value I of the anode-cathode current waveform ASM, the second current value I2 can be greater than or less than 90% of the peak value I of the anode-cathode current waveform ASM , and it is specifically set according to actual requirements. For example, the first current value I1 is set to 8%, 9%, 11%, 12%, etc. of the peak value I of the anode-cathode current waveform ASM , and the second current value I2 is set to 88%, 89%, 91%, 92%, etc. of the peak value I of the anode-cathode current waveform ASM .

[0041] As Figure 4 shown, the delay time of the MCT device is obtained according to the anode-cathode voltage waveform and the gate voltage waveform, including: obtaining the third moment t3 when the gate voltage first rises to the first voltage value V1 according to the gate voltage waveform; obtaining the fourth moment t4 when the voltage drops to the second voltage value V2 according to the anode-cathode voltage waveform; obtaining the delay time T according to the difference between the third moment t3 and the fourth moment t4 d(on) = t4 - t3. Among them, the first voltage value V1 is 10% of the peak value V of the gate voltage waveform GM , and the second voltage value V2 is 90% of the peak value V of the anode-cathode voltage waveform AK . The first voltage value V1 can also be greater than or less than 10% of the peak value V of the gate voltage waveform GM , and the second voltage value V2 can be greater than or less than 90% of the peak value V of the anode-cathode voltage waveform AK , and it is specifically set according to actual requirements. For example, the first voltage value V1 is set to 8%, 9%, 11%, 12%, etc. of the peak value V of the gate voltage waveform, and the second voltage value V2 is set to 88%, 89%, 91%, 92%, etc. of the peak value V of the anode-cathode voltage waveform GM . AK

[0042] In this embodiment, a Rogowski coil, a high-voltage differential probe, and a low-voltage probe are set in the test circuit. During the test, the controller obtains the anode-cathode current waveform of the MCT device from the Rogowski coil, the anode-cathode voltage waveform of the MCT device from the high-voltage differential probe, and the gate voltage waveform of the MCT device from the low-voltage probe through the oscilloscope. Then, the controller obtains the current change rate of the MCT device according to the anode-cathode current waveform, and obtains the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform, so as to realize obtaining the dynamic electrical performance parameters of the MCT device through multiple waveform diagrams of the MCT device, and improve the accuracy of testing the dynamic electrical performance parameters of the MCT device.

[0043] It is not difficult to find that this embodiment is a method embodiment corresponding to the circuit embodiment, and this embodiment can be implemented in cooperation with the circuit embodiment. The relevant technical details mentioned in the circuit embodiment are still valid in this embodiment. To avoid repetition, they will not be elaborated here. Correspondingly, the relevant technical details mentioned in this embodiment can also be applied to the circuit embodiment.

[0044] The embodiment of the present application also provides a test method, which is applied to the controller of the test circuit in the above embodiment, as Figure 6 shown in the schematic flowchart of the test method in this embodiment. The test method in this embodiment includes the following steps:

[0045] Step 301, control the low-voltage power supply module to turn on.

[0046] Step 302, detect the gate voltage amplitude at the control end of the MCT device through a low-voltage probe.

[0047] Step 303, if the gate voltage amplitude reaches the output voltage of the low-voltage power supply module, control the high-voltage power supply module to turn on.

[0048] Specifically, steps 301 to 303 in this embodiment are specific limitations of step 201 in the above embodiment.

[0049] Step 304, control the signal generator to output a pulsed square wave signal to turn on the MCT device. The oscilloscope obtains the anode-cathode current waveform of the MCT device through a Rogowski coil, obtains the anode-cathode voltage waveform of the MCT device through a high-voltage differential probe, and obtains the gate voltage waveform of the MCT device through a low-voltage probe;

[0050] Step 305, obtain the current change rate of the MCT device according to the anode-cathode current waveform, and obtain the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

[0051] Steps 304 to 305 in this embodiment are substantially the same as steps 202 to 203 in the above embodiment. To avoid repetition, they will not be elaborated again.

[0052] Specifically, the controller of this embodiment first controls the low-voltage power supply module to turn on, that is, controls the low-voltage power supply to turn on, and detects the gate voltage amplitude of the control end of the MCT device through a low-voltage probe. If the gate voltage amplitude of the MCT device reaches the output voltage of the low-voltage power supply module (i.e., the output voltage of the low-voltage power supply), the controller then controls the high-voltage power supply module to turn on, that is, controls the high-voltage power supply to turn on, so that the discharge capacitor is charged to the working voltage; afterwards, the controller controls the signal generator to output a pulsed square-wave signal to turn on the MCT device. The oscilloscope can obtain the anode-cathode current waveform of the MCT device through a Rogowski coil, can obtain the anode-cathode voltage waveform of the MCT device through a high-voltage differential probe, and can obtain the gate voltage waveform of the MCT device through a low-voltage probe. After that, after the controller obtains the anode-cathode current waveform, the anode-cathode voltage waveform, and the gate voltage waveform, it obtains the current change rate of the MCT device according to the anode-cathode current waveform, and obtains the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

[0053] In practical applications, the MCT device can be replaced to complete the testing of multiple MCT devices according to the test circuit. Among them, when replacing the sample, electrostatic protection should be done, and anti-static gloves and bracelets should be worn; from a safety perspective, it is recommended that before each test, a voltage, such as 100V voltage, should be applied between the anode and cathode of the MCT device first. After confirmation, then turn on the high-voltage DC power supply to apply the anode-cathode voltage of the MCT device to the target voltage, such as 5KV; after each test is completed, the residual charge of the discharge capacitor needs to be discharged first, which can be completed by using a 10kV telescopic discharge rod, and then contact the test circuit to avoid electric shock. And if a short-circuit fault occurs during the sample discharge test, it is necessary to promptly turn off the output of the high-voltage DC power supply to avoid burning out the current-limiting resistor. At the same time, the output current of the high-voltage power supply can be limited within 3mA before the test, and it is recommended that the test operator wear 220V insulated electrician gloves.

[0054] In addition, in order to highlight the innovative part of this application, units that are not closely related to solving the technical problems proposed in this application are not introduced in this embodiment, but this does not mean that there are no other units in this embodiment.

[0055] Those of ordinary skill in the art can understand that the above embodiments are specific embodiments for implementing this application, and in practical applications, various changes can be made in form and details without departing from the spirit and scope of this application.

Claims

1. A test circuit, characterized in that, Including: A signal generator, an optocoupler driver, an oscilloscope, an inductor, a discharge capacitor, a Rogowski coil, a high-voltage differential probe, a low-voltage probe, a low-voltage power supply module, a high-voltage power supply module, and a controller; The low-voltage power supply module is connected to the power supply terminal of the optocoupler driver, the signal transmitter is connected to the input terminal of the optocoupler driver, and the output terminal of the optocoupler driver is connected to the control terminal of the MCT device; The first end of the inductor is connected to the first end of the MCT device, the second end of the inductor is connected to the first end of the Rogowski coil, and the second end of the Rogowski coil is connected to the first end of the high-voltage power supply module; The second end of the MCT device is connected to the second end of the high-voltage power supply module; the first end of the discharge capacitor is connected to the second end of the inductor, and the second end of the discharge capacitor is connected to the second end of the MCT device; The first end of the high-voltage differential probe is connected to the first end of the MCT device, and the second end of the high-voltage differential probe is connected to the second end of the MCT device; the low-voltage probe is connected to the control terminal of the MCT device; The oscilloscope is respectively connected to the Rogowski coil, the high-voltage differential probe, and the low-voltage probe; the oscilloscope is used to obtain the anode-cathode current waveform of the MCT device through the Rogowski coil, obtain the anode-cathode voltage waveform of the MCT device through the high-voltage differential probe, and obtain the gate voltage waveform of the MCT device through the low-voltage probe; The controller is connected to the oscilloscope, the signal generator, the low-voltage power supply module, and the high-voltage power supply module; the controller is used to control the on and off of the signal generator, the low-voltage power supply module, and the high-voltage power supply module, and the controller is also used to obtain the current change rate of the MCT device according to the anode-cathode current waveform obtained by the oscilloscope, and obtain the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

2. The test circuit according to claim 1, wherein The low-voltage power supply module includes: a low-voltage power supply and an isolated power supply; The output terminal of the low-voltage power supply is connected to the input terminal of the isolated power supply, and the output terminal of the isolated power supply is connected to the power supply terminal of the optocoupler driver; the signal generator is connected to the input terminal of the optocoupler driver, the first output terminal of the optocoupler driver is connected to the control terminal of the MCT device, and the second output terminal of the optocoupler driver is grounded.

3. The test circuit according to claim 2, characterized in that, The test circuit further includes: a filtering module and a transient voltage suppression module; the filtering module includes a first capacitor, a first resistor, and a second resistor; the transient voltage suppression module is a transient voltage suppression diode; The first resistor is disposed between the first output terminal of the optocoupler driver and the control terminal of the MCT device, the first output terminal of the optocoupler driver is connected to the first end of the first resistor, and the second end of the first resistor is connected to the control terminal of the MCT device; The second terminal of the first resistor is also respectively connected to the first terminal of the first capacitor, the first terminal of the second resistor, and the first terminal of the transient voltage suppression diode. The second output terminal of the optocoupler driver is connected to the second terminal of the first capacitor, the second terminal of the second resistor, and the second terminal of the transient voltage suppression diode.

4. The test circuit according to any one of claims 1 to 3, characterized in that, The high-voltage power supply module includes: a high-voltage DC power supply, a current-limiting resistor, and a discharging resistor; The first output terminal of the high-voltage DC power supply is connected to the first terminal of the current-limiting resistor, and the second terminal of the current-limiting resistor is connected to the second terminal of the Rogowski coil; the second output terminal of the high-voltage DC power supply is connected to the second terminal of the MCT device, and the second output terminal of the high-voltage DC power supply is grounded; The first terminal of the discharging resistor is connected to the second terminal of the current-limiting resistor, and the second terminal of the discharging resistor is connected to ground.

5. A testing method, characterized in that, For the controller applied to the test circuit according to any one of claims 1 to 4, the test method includes: Controlling the low-voltage power supply module and the high-voltage power supply module to be turned on so that the discharge capacitor is charged to the operating voltage; Controlling the signal generator to output a pulsed square-wave signal so that the MCT device is turned on. The oscilloscope obtains the anode-cathode current waveform of the MCT device through the Rogowski coil, obtains the anode-cathode voltage waveform of the MCT device through the high-voltage differential probe, and obtains the gate voltage waveform of the MCT device through the low-voltage probe; Obtaining the current change rate of the MCT device according to the anode-cathode current waveform, and obtaining the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform.

6. The test method according to claim 5, wherein The controlling the low-voltage power supply module and the high-voltage power supply module to be turned on includes: Controlling the low-voltage power supply module to be turned on; Detecting the gate voltage amplitude of the control terminal of the MCT device through the low-voltage probe; If the gate voltage amplitude reaches the output voltage of the low-voltage power supply module, then controlling the high-voltage power supply module to be turned on.

7. The testing method according to claim 5, wherein The obtaining the current change rate of the MCT device according to the anode-cathode current waveform includes: Obtaining, according to the anode-cathode current waveform, a first moment when the current reaches a first current value during the first rising process and a second moment when it reaches a second current value, where the first current value is less than the second current value; Obtaining the current difference between the first current value and the second current value; Obtaining the time difference between the first moment and the second moment; Obtaining the current change rate according to the ratio of the current difference to the time difference.

8. The test method according to claim 5, characterized in that The obtaining the delay time of the MCT device according to the anode-cathode voltage waveform and the gate voltage waveform includes: Obtaining, according to the gate voltage waveform, a third moment when the gate voltage first rises to a first voltage value; Obtaining, according to the anode-cathode voltage waveform, a fourth moment when the voltage drops to a second voltage value; Obtaining the delay time according to the difference between the third moment and the fourth moment.

9. The test method according to claim 7, characterized in that The first current value is 10% of the peak value of the anode-cathode current waveform, and the second current value is 90% of the peak value of the anode-cathode current waveform.

10. The test method according to claim 8, wherein, The first voltage value is the peak value of 10% of the gate voltage waveform, and the second voltage value is the peak value of 90% of the anode-cathode voltage waveform.

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