Testing device for NPC T-type three-level circuit

Abstract

The utility model belongs to the field of inverter circuits, and comprises an NPC T-type three-level circuit test device, which comprises an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, a test power supply VCC, a ground terminal GND, a first switch SW1, a third switch SW3, a fourth switch SW4, a sixth switch SW6, a second inductor L2 and a capacitor C, a capacitor C is arranged between the test power supply VCC and the grounding end GND; the capacitor C is used for filtering clutters of the test power supply VCC; the first switch SW1, the third switch SW3 and the sixth switch SW6 are all in a closed state, and the fourth switch SW4 is in an open state; the states of the first switch SW1, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 enable a first IGBT tube Q1 in the NPC T-type three-level circuit to be used for dipulse testing. The test system is simplified, the single power supply system can better perform control and debugging monitoring, power supply interference is reduced, and test accuracy is improved.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of inverter circuit, and particularly relates to a test device for NPC T-type three-level circuit. BACKGROUND

[0002] The NPC T-type three-level circuit is a kind of multi-level inverter topology structure. As shown in the figure, the T-type three-level circuit is composed of two half-bridge inverter units and a neutral point (usually coupled through a capacitor), forming a "T" shaped circuit topology. Each half-bridge contains two switching elements (such as IGBTs) and corresponding freewheeling diodes. The working principle of the T-type three-level inverter circuit is based on the principle of resonance and the principle of capacitor charging and discharging. By controlling the switching state of the two half-bridges, the T-type three-level circuit can generate a five-level line voltage waveform at the load end. The charging and discharging process of the capacitor and the cooperation of the switching state make the output voltage smoothly transition between three different levels, reducing the harmonic content caused by the staircase waveform in the traditional two-level inverter. The prior art performs double-pulse test on the T-NPC three-level module basic circuit, as shown in the figure, the positive power supply is connected between 1-0, the negative power supply inductor is connected between -1-0, the inductor is connected to the corresponding IGBT position by welding temporary parallel connection, and the inductor and the control power supply also need to be replaced when the test IGBT is replaced; the above operation will result in low test efficiency, high cost and time-consuming. Figure 1 The utility model discloses a test device for NPC T-type three-level circuit. Figure 1 The utility model discloses a test device for NPC T-type three-level circuit. Utility model content

[0003] In order to solve the above-mentioned problems of low test efficiency, high cost and time-consuming, the application provides a test device for NPC T-type three-level circuit.

[0004] In the first aspect, a test device for NPC T-type three-level circuit is provided, which comprises an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, and further comprises a test power supply VCC, a ground terminal GND, a first switch SW1, a third switch SW3, a fourth switch SW4, a sixth switch SW6, a second inductor L2 and a capacitor C.

[0005] The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter out the noise of the test power supply VCC.

[0006] The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC.

[0007] The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND.

[0008] The fourth switch SW4 is arranged between the emitter end of the second IGBT tube Q2 and the ground end GND.

[0009] One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector end of the fourth IGBT tube Q4.

[0010] The first switch SW1, the third switch SW3 and the sixth switch SW6 are in the closed state, and the fourth switch SW4 is in the open state; the states of the first switch SW1, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 enable the first IGBT tube Q1 in the NPC T-type three-level circuit to be used for double-pulse testing.

[0011] In a second aspect, a test device for an NPC T-type three-level circuit is provided, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, and further comprising: a test power supply VCC, a ground end GND, a second switch SW2, a third switch SW3, a fourth switch SW4, a sixth switch SW6, a second inductor L2 and a capacitor C.

[0012] The capacitor C is arranged between the test power supply VCC and the ground end GND; the capacitor C is used to filter out the noise of the test power supply VCC.

[0013] The second switch SW2 is arranged between the collector end of the fourth IGBT tube Q4 and the test power supply VCC.

[0014] The third switch SW3 is arranged between the collector end of the fourth IGBT tube Q4 and the ground end GND.

[0015] The fourth switch SW4 is arranged between the emitter end of the second IGBT tube Q2 and the ground end GND.

[0016] One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector end of the fourth IGBT tube Q4.

[0017] The second switch SW2, the fourth switch SW4 and the sixth switch SW6 are in the closed state, and the third switch SW3 is in the open state; the states of the second switch SW2, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 enable the second IGBT tube Q2 in the NPC T-type three-level circuit to be used for double-pulse testing.

[0018] The third aspect also provides a test device of an NPC T-type three-level circuit, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, and further comprising a test power supply VCC, a ground terminal GND, a first switch SW1, a third switch SW3, a fourth switch SW4, a fifth switch SW5, a first inductor L1 and a capacitor C.

[0019] The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter out the noise of the test power supply VCC.

[0020] The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC.

[0021] The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND.

[0022] The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND.

[0023] One end of the fifth switch SW5 is connected to the emitter terminal of the first IGBT tube Q1, and the other end of the fifth switch SW5 is connected to one end of the first inductor L1; the other end of the first inductor L1 is connected to the collector terminal of the first IGBT tube Q1.

[0024] The first switch SW1, the third switch SW3 and the fifth switch SW5 are in a closed state, and the fourth switch SW4 is in an open state; the states of the first switch SW1, the third switch SW3, the fourth switch SW4 and the fifth switch SW5 enable the third IGBT tube Q3 or the fourth IGBT tube Q4 in the NPC T-type three-level circuit to be used for double-pulse testing.

[0025] The fourth aspect also provides a test device of an NPC T-type three-level circuit, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, and further comprising a test power supply VCC, a ground terminal GND, a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a fifth switch SW5, a sixth switch SW6, a first inductor L1, a second inductor L2 and a capacitor C.

[0026] The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter out the noise of the test power supply VCC.

[0027] The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC.

[0028] The second switch SW2 is arranged between the collector terminal of the fourth IGBT tube Q4 and the test power supply VCC.

[0029] The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND.

[0030] The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND.

[0031] One end of the fifth switch SW5 is connected with the emitter terminal of the first IGBT tube Q1, and the other end of the fifth switch SW5 is connected with one end of the first inductor L1; the other end of the first inductor L1 is connected with the collector terminal of the first IGBT tube Q1.

[0032] One end of the sixth switch SW6 is connected with the collector terminal of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector terminal of the fourth IGBT tube Q4; according to the closing or opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, the fifth switch SW5 and the sixth switch SW6, the test device of the NPC T-type three-level circuit can be respectively used for the double-pulse test of the first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4.

[0033] In summary, the present application includes at least one of the following beneficial technical effects:

[0034] Simplify the test system, reduce the cost of test equipment, reduce the possibility of wiring error, improve the reliability and repeatability of test;

[0035] Single power supply system can better control and debug monitoring, reduce the power interference, improve the test accuracy;

[0036] Energy saving and environmental protection: single power supply system generates less heat, reduces cooling demand, improves the stability of the test environment;

[0037] 4, improve the test efficiency, reduce the cost. BRIEF DESCRIPTION OF DRAWINGS

[0038] Figure 1 It is the test basic circuit of the NPC T-type three-level circuit in the prior art;

[0039] Figure 2It is the device diagram for double pulse test of the first IGBT tube Q1 in the utility model;

[0040] Figure 3 It is the logic block diagram for double pulse test of the first IGBT tube Q1 in the utility model;

[0041] Figure 4 It is the device diagram for double pulse test of the second IGBT tube Q2 in the utility model;

[0042] Figure 5 It is the logic block diagram for double pulse test of the second IGBT tube Q2 in the utility model;

[0043] Figure 6 It is the device diagram for double pulse test of the third IGBT tube Q3 and the fourth IGBT tube Q4 in the utility model;

[0044] Figure 7 It is the logic block diagram for double pulse test of the third IGBT tube Q3 in the utility model;

[0045] Figure 8 It is the logic block diagram for double pulse test of the fourth IGBT tube Q4 in the utility model;

[0046] Figure 9 It is the device diagram for double pulse test of any one of the four IGBT tubes. DETAILED DESCRIPTION

[0047] TERMS EXPLANATION

[0048] NPC T-type three-level circuit: NPC (Neutral Point Clamped) is neutral point clamped circuit; It is the NPC circuit arranged in T type.

[0049] FRD: Fast Recovery Diode; Fast recovery diode.

[0050] The first aspect, as shown in Figure 2 , Figure 3 , provide a kind of test device of NPC T-type three-level circuit, including the NPC T-type three-level circuit being constituted by first IGBT tube Q1, second IGBT tube Q2, third IGBT tube Q3 and fourth IGBT tube Q4, it also includes: test power supply VCC, ground terminal GND, first switch SW1, third switch SW3, fourth switch SW4, sixth switch SW6, second inductance L2 and capacitor C;In prior art, two power supplies are often needed, increase test cost and the complexity of test device.

[0051] The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter the noise of the test power supply VCC.

[0052] The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC.

[0053] The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND.

[0054] The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND.

[0055] One end of the sixth switch SW6 is connected with the collector terminal of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector terminal of the fourth IGBT tube Q4.

[0056] The first switch SW1, the third switch SW3 and the sixth switch SW6 are in the closed state, and the fourth switch SW4 is in the open state; the states of the first switch SW1, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 enable the first IGBT tube Q1 in the NPC T-type three-level circuit to be used for double-pulse testing. In the technical solution, only one test power supply and a plurality of switches are needed to realize the testing work of the NPC T-type three-level circuit. The double-pulse testing does not need to change the connection mode of the IGBT tube, and the double-pulse testing of different IGBT tubes can be realized by closing or opening of the plurality of switches. In the technical solution, the object of the test is the performance of the first IGBT tube Q1 under the double-pulse condition, that is, the parameter item of the double-pulse test of the test loop at this time is the turn-on and turn-off parameters of the first IGBT tube Q1; the reverse recovery parameters of the diode FRD in parallel with the third IGBT tube Q3 are also tested when the double-pulse is added to the first IGBT tube Q1.

[0057] The test device of the NPC T-type three-level circuit, the gate of the first IGBT tube Q1 is connected with the double-pulse generator, the gate of the third IGBT tube Q3 is connected with the low-level signal generator, and the gate of the fourth IGBT tube Q4 is connected with the high-level signal generator.

[0058] In the second aspect, as Figure 4 , Figure 5As shown, a test device of an NPC T-type three-level circuit is provided, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, further comprising: a test power supply VCC, a ground terminal GND, a second switch SW2, a third switch SW3, a fourth switch SW4, a sixth switch SW6, a second inductor L2 and a capacitor C;

[0059] The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter out the noise of the test power supply VCC;

[0060] The second switch SW2 is arranged between the collector terminal of the fourth IGBT tube Q4 and the test power supply VCC;

[0061] The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND;

[0062] The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND;

[0063] One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector terminal of the fourth IGBT tube Q4;

[0064] The second switch SW2, the fourth switch SW4 and the sixth switch SW6 are in a closed state, and the third switch SW3 is in an open state; the states of the second switch SW2, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 enable the second IGBT tube Q2 in the NPC T-type three-level circuit to be used for double-pulse testing. In the technical solution, only one test power supply and a plurality of switches are needed to realize the test work of the NPC T-type three-level circuit. The double-pulse testing does not need to change the connection mode of the IGBT tube, and the double-pulse testing of different IGBT tubes can be realized by closing or opening the plurality of switches. In the technical solution, the object of the test is the performance of the second IGBT tube Q2 under double-pulse conditions, i.e., the parameter items of the double-pulse test of the test loop at this time are the turn-on and turn-off parameters of the second IGBT tube Q2; the reverse recovery parameters of the diode FRD in parallel with the fourth IGBT tube Q4 when the second inductor L2 releases the freewheeling current under the double-pulse added to the second IGBT tube Q2 are also tested.

[0065] The test device of the NPC T-type three-level circuit, a gate of the second IGBT tube Q2 is connected with a double-pulse generator, a gate of the third IGBT tube Q3 is connected with a high-level signal generator, and a gate of the fourth IGBT tube Q4 is connected with a low-level signal generator.

[0066] In a third aspect, as shown in Figure 6 、 Figure 7 、 Figure 8 The test device of the NPC T-type three-level circuit further comprises a test power supply VCC, a ground terminal GND, a first switch SW1, a third switch SW3, a fourth switch SW4, a fifth switch SW5, a first inductor L1 and a capacitor C.

[0067] The capacitor C is arranged between the test power supply VCC and the ground terminal GND, and is used for filtering out noise of the test power supply VCC.

[0068] The first switch SW1 is arranged between a collector terminal of the first IGBT tube Q1 and the test power supply VCC.

[0069] The third switch SW3 is arranged between a collector terminal of the fourth IGBT tube Q4 and the ground terminal GND.

[0070] The fourth switch SW4 is arranged between an emitter terminal of the second IGBT tube Q2 and the ground terminal GND.

[0071] One end of the fifth switch SW5 is connected with an emitter terminal of the first IGBT tube Q1, and the other end of the fifth switch SW5 is connected with one end of the first inductor L1; the other end of the first inductor L1 is connected with a collector terminal of the first IGBT tube Q1.

[0072] The first switch SW1, the third switch SW3 and the fifth switch SW5 are in a closed state, and the fourth switch SW4 is in an open state; the states of the first switch SW1, the third switch SW3, the fourth switch SW4 and the fifth switch SW5 enable the third IGBT tube Q3 or the fourth IGBT tube Q4 in the NPC T-type three-level circuit to be used for double-pulse testing. In the technical solution, only one test power supply and a plurality of switches are needed to realize the test work on the NPC T-type three-level circuit. The double-pulse testing does not need to change the connection mode of the IGBT tube, and the double-pulse testing of different IGBT tubes can be realized by closing or opening the plurality of switches. In the technical solution, as shown in Figure 7As shown, the tested object is the performance of the third IGBT tube Q3 under the double pulse condition, that is, the parameter item of the double pulse test of the test circuit at this time is the turn-on and turn-off parameters of the third IGBT tube Q3; also tested is the reverse recovery parameter of the diode FRD connected in parallel with the first IGBT tube Q1 when the freewheeling current released by the first inductor L1 under the double pulse applied to the third IGBT tube Q3. And, as shown, the tested object is the performance of the fourth IGBT tube Q4 under the double pulse condition, that is, the parameter item of the double pulse test of the test circuit at this time is the turn-on and turn-off parameters of the fourth IGBT tube Q4; also tested is the reverse recovery parameter of the diode FRD connected in parallel with the first IGBT tube Q1 when the freewheeling current released by the first inductor L1 under the double pulse applied to the fourth IGBT tube Q4. Figure 8

[0073] The first IGBT tube Q1, the gate of the third IGBT tube Q3 is connected with a high double pulse generator, and the gate of the fourth IGBT tube Q4 is connected with a high level signal generator.

[0074] The first IGBT tube Q1, the gate of the third IGBT tube Q3 is connected with a high double pulse generator, and the gate of the fourth IGBT tube Q4 is connected with a high level signal generator.

[0075] The fourth aspect, as shown, Figure 9 As shown, a test device for an NPC T-type three-level circuit is also provided, which comprises an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3 and a fourth IGBT tube Q4, and further comprises a test power supply VCC, a ground terminal GND, a first switch SW1, a second switch SW2, a third switch SW3, a fourth switch SW4, a fifth switch SW5, a sixth switch SW6, a first inductor L1, a second inductor L2 and a capacitor C.

[0076] The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter out the noise of the test power supply VCC;

[0077] The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC;

[0078] The second switch SW2 is arranged between the collector terminal of the fourth IGBT tube Q4 and the test power supply VCC;

[0079] The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND;

[0080] ​The fourth switch SW4 is arranged between the emitter end of the second IGBT tube Q2 and the ground end GND.

[0081] One end of the fifth switch SW5 is connected with the emitter of the first IGBT tube Q1, and the other end of the fifth switch SW5 is connected with one end of the first inductor L1; the other end of the first inductor L1 is connected with the collector end of the first IGBT tube Q1.

[0082] One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector end of the fourth IGBT tube Q4; according to the closing or opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, the fifth switch SW5 and the sixth switch SW6, the test device of the NPC T-type three-level circuit can be respectively used for the double-pulse test of the first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4.

[0083] The first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4 can be replaced by MOSFET tubes; the MOSFET tubes can be SiC or / and GaN.

[0084] The first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4 can be SiC or / and GaN.

[0085] In summary, the present application includes at least one of the following beneficial technical effects:

[0086] The test system is simplified, the cost of test equipment is reduced, the possibility of wiring error is reduced, and the reliability and repeatability of the test are improved.

[0087] The single power supply system can be better controlled and debugged, the power supply interference is reduced, and the test accuracy is improved.

[0088] Energy saving and environmental protection: the single power supply system generates less heat, reduces cooling demand, and improves the stability of the test environment.

[0089] 4. Improve test efficiency and reduce cost.

[0090] The above are preferred embodiments of the present application, and do not limit the protection scope of the present application. Any feature disclosed in the specification (including the abstract and the drawings) can be replaced by other equivalent or similar features, unless specifically stated. That is, each feature is only an example of a series of equivalent or similar features, unless specifically stated.

Claims

1. A test device of an NPC T-type three-level circuit, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3, and a fourth IGBT tube Q4, characterized in that, Also include: Test power supply VCC, ground terminal GND, first switch SW1, third switch SW3, fourth switch SW4, sixth switch SW6, second inductor L2 and capacitor C; The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter the spurs of the test power supply VCC; The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC; The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND; The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND; One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector terminal of the fourth IGBT tube Q4; The first switch SW1, the third switch SW3 and the sixth switch SW6 are all in the closed state, and the fourth switch SW4 is in the open state; the state of the first switch SW1, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 makes the first IGBT tube Q1 in the NPC T-type three-level circuit can be used for double pulse test.

2. The test apparatus of the NPC T-type three-level circuit according to claim 1, characterized by, The gate of the first IGBT tube Q1 is connected with a double pulse generator, the gate of the third IGBT tube Q3 is connected with a low level signal generator, and the gate of the fourth IGBT tube Q4 is connected with a high level signal generator.

3. A test device of an NPC T-type three-level circuit, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3, and a fourth IGBT tube Q4, characterized in that, Also include: Test power supply VCC, ground terminal GND, second switch SW2, third switch SW3, fourth switch SW4, sixth switch SW6, second inductor L2 and capacitor C; The capacitor C is arranged between the test power supply VCC and the ground terminal GND; the capacitor C is used to filter the spurs of the test power supply VCC; The second switch SW2 is arranged between the collector terminal of the fourth IGBT tube Q4 and the test power supply VCC; The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND; The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND; One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector terminal of the fourth IGBT tube Q4; The second switch SW2, the fourth switch SW4 and the sixth switch SW6 are all in the closed state, and the third switch SW3 is in the open state; the state of the second switch SW2, the third switch SW3, the fourth switch SW4 and the sixth switch SW6 makes the second IGBT tube Q2 in the NPC T-type three-level circuit can be used for double pulse test.

4. The test apparatus of the NPC T-type three-level circuit according to claim 3, characterized by The gate of the second IGBT tube Q2 is connected with a double pulse generator, the gate of the third IGBT tube Q3 is connected with a high level signal generator, and the gate of the fourth IGBT tube Q4 is connected with a low level signal generator.

5. A test device of an NPC T-type three-level circuit, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3, and a fourth IGBT tube Q4, characterized in that, Also include: The test power supply VCC, the ground terminal GND, the first switch SW1, the third switch SW3, the fourth switch SW4, the fifth switch SW5, the first inductor L1 and the capacitor C are connected in series. The capacitor C is arranged between the test power supply VCC and the ground terminal GND, and is used for filtering the noise of the test power supply VCC. The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC. The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND. The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND. One end of the fifth switch SW5 is connected with the emitter of the first IGBT tube Q1, and the other end of the fifth switch SW5 is connected with one end of the first inductor L1; the other end of the first inductor L1 is connected with the collector terminal of the first IGBT tube Q1. The first switch SW1, the third switch SW3 and the fifth switch SW5 are in the closed state, and the fourth switch SW4 is in the open state; the state of the first switch SW1, the third switch SW3, the fourth switch SW4 and the fifth switch SW5 enables the third IGBT tube Q3 or the fourth IGBT tube Q4 in the NPC T-type three-level circuit to be used for double-pulse testing.

6. The test apparatus of the NPC T-type three-level circuit according to claim 5, characterized by The gate of the first IGBT tube Q1 is connected with a low-level signal generator, the gate of the third IGBT tube Q3 is connected with a high double-pulse generator, and the gate of the fourth IGBT tube Q4 is connected with a high-level signal generator.

7. The test apparatus of the NPC T-type three-level circuit according to claim 5, characterized by The gate of the first IGBT tube Q1 is connected with a low-level signal generator, the gate of the third IGBT tube Q3 is connected with a high double-pulse generator, and the gate of the fourth IGBT tube Q4 is connected with a high-level signal generator.

8. A test device of an NPC T-type three-level circuit, comprising an NPC T-type three-level circuit composed of a first IGBT tube Q1, a second IGBT tube Q2, a third IGBT tube Q3, and a fourth IGBT tube Q4, characterized in that, Further comprising: The test power supply VCC, the ground terminal GND, the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, the fifth switch SW5, the sixth switch SW6, the first inductor L1, the second inductor L2 and the capacitor C are connected in series. The capacitor C is arranged between the test power supply VCC and the ground terminal GND, and is used for filtering the noise of the test power supply VCC. The first switch SW1 is arranged between the collector terminal of the first IGBT tube Q1 and the test power supply VCC. The second switch SW2 is arranged between the collector terminal of the fourth IGBT tube Q4 and the test power supply VCC. The third switch SW3 is arranged between the collector terminal of the fourth IGBT tube Q4 and the ground terminal GND. The fourth switch SW4 is arranged between the emitter terminal of the second IGBT tube Q2 and the ground terminal GND. One end of the fifth switch SW5 is connected with the emitter of the first IGBT tube Q1, and the other end of the fifth switch SW5 is connected with one end of the first inductor L1; the other end of the first inductor L1 is connected with the collector terminal of the first IGBT tube Q1. One end of the sixth switch SW6 is connected with the collector of the third IGBT tube Q3, and the other end of the sixth switch SW6 is connected with one end of the second inductor L2; the other end of the second inductor L2 is connected with the collector of the fourth IGBT tube Q4; the test device of the NPC T-type three-level circuit can be respectively used for the double-pulse test of the first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4 according to the closing or opening of the first switch SW1, the second switch SW2, the third switch SW3, the fourth switch SW4, the fifth switch SW5 and the sixth switch SW6.

9. The test apparatus of any one of claims 1 to 8, wherein, The first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4 can be replaced by MOSFET tubes; the MOSFET tubes can be SiC or / and GaN.

10. The test apparatus of any one of claims 1-8, wherein, The first IGBT tube Q1, the second IGBT tube Q2, the third IGBT tube Q3 or the fourth IGBT tube Q4 can be SiC or / and GaN.

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