Chopped wave module and three-level module voltage drop testing device

Abstract

The utility model provides a voltage drop testing device for a chopper module and a three-level module, which relates to the technical field of voltage drop testing, and comprises a voltage adjustable power supply, two ends of which are connected to a voltage applying point of the chopper module or the three-level module; two ends of the adjustable current source are connected to a power supply input point of the chopping module or the three-level module; and two ends of the voltage drop detector are connected to voltage drop detection points of the chopping module or the three-level module, and a value measured by the voltage drop detector is a saturation voltage drop test value. The beneficial effects are that a collector and an emitter of a single IGBT in the chopper module and the three-level module are taken as a voltage application point and a voltage drop detection point, a power supply input point is respectively connected with a voltage adjustable power supply, a voltage drop detector and an adjustable current source, and current and voltage are adjusted to carry out voltage drop test; and a saturation voltage drop test value under a high-current condition can be accurately measured.

Description

TECHNICAL FIELD

[0001] The utility model relates to pressure drop test technical field especially, relate to a kind of chopping module and the pressure drop testing device of three-level module. BACKGROUND

[0002] Insulated Gate Bipolar Transistor (IGBT), as a composite full-control voltage-driven power semiconductor device integrated by bipolar transistor (BJT) and insulated gate field effect transistor (MOSFET), combines the two big advantages of low gate drive energy of MOSFET and low on-state loss of bipolar transistor, and avoids the secondary breakdown problem that bipolar transistor may encounter. The application range of this device is extremely wide, not only covers traditional industries such as industry, 4C field (i.e. communication, computer, consumer electronics, automotive electronics) and aerospace, national defense and military industry, but also penetrates into strategic emerging industries such as rail transit, new energy, smart grid and new energy vehicles. In these applications, each parameter of IGBT plays a crucial role, among which saturation voltage drop (Vcesat) as a key factor determining the forward characteristics of IGBT directly affects its conduction power consumption and has certain influence on switching loss, so accurate measurement of Vcesat parameter is particularly important.

[0003] The general method for measuring IGBT saturation voltage drop (Vcesat) at present is to apply a specific voltage condition between the gate and the emitter, set the collector current between the collector and the emitter, and measure the voltage between the two poles to obtain the Vcesat value. However, with the continuous change of application scenarios, the packaging form of IGBT module is also increasingly diversified. For single IGBT in chopping module and three-level module (including INPC, ANPC, TNPC), the collector and the emitter are not designed with multiple terminal leads, but with single terminal design, which limits the overcurrent capacity of the terminal. If you try to force a large current into the power terminal as a single terminal for testing, it may cause sparking phenomenon, thereby damaging the module terminal. Therefore, the traditional Vcesat test method cannot accurately measure the Vcesat value of single-terminal packaged IGBT module under high current condition. UTILITY MODEL CONTENTS

[0004] In view of the problems existing in the prior art, the utility model provides a kind of chopping module and the pressure drop testing device of three-level module, comprising:

[0005] Voltage adjustable power supply, the two ends of the voltage adjustable power supply are connected to the voltage application point of the chopping module or the three-level module;

[0006] Adjustable current source, the two ends of the adjustable current source are connected to the power input point of the chopping module or the three-level module.

[0007] a pressure drop detector, two ends of the pressure drop detector are connected to a pressure drop detection point of the chopper module or the three-level module, and a value measured by the pressure drop detector is a saturation pressure drop test value.

[0008] Preferably, the chopper module comprises:

[0009] a first diode, two ends of the first diode are connected to two ends of the pressure drop detector;

[0010] a first insulated gate bipolar transistor, a collector of the first insulated gate bipolar transistor is connected to a negative electrode of the first diode, and a gate and an emitter of the first insulated gate bipolar transistor are connected to two ends of the voltage adjustable power supply;

[0011] a positive electrode of the adjustable current source is connected to a positive electrode of the first diode, and a negative electrode of the adjustable current source is connected to the emitter of the first insulated gate bipolar transistor;

[0012] a value measured by the pressure drop detector is a forward conduction pressure drop test value of the first diode.

[0013] Preferably, two ends of the voltage adjustable power supply are connected to the gate and the emitter of the first insulated gate bipolar transistor, respectively;

[0014] a positive electrode of the adjustable current source is connected to a positive electrode of the first diode, and a negative electrode of the adjustable current source is connected to the emitter of the first insulated gate bipolar transistor;

[0015] two ends of the pressure drop detector are connected to the collector and the emitter of the first insulated gate bipolar transistor, respectively, and a value measured by the pressure drop detector is a saturation pressure drop test value of the first insulated gate bipolar transistor.

[0016] Preferably, the three-level module comprises:

[0017] a second insulated gate bipolar transistor, an emitter of the second insulated gate bipolar transistor is connected to a collector of a third insulated gate bipolar transistor, an emitter of the third insulated gate bipolar transistor is connected to a collector of a fourth insulated gate bipolar transistor, and an emitter of the fourth insulated gate bipolar transistor is connected to a collector of a fifth insulated gate bipolar transistor;

[0018] a second diode, a negative electrode of the second diode is connected to the emitter of the second insulated gate bipolar transistor, a positive electrode of the second diode is connected to a negative electrode of a third diode, and a positive electrode of the third diode is connected to the emitter of the fourth insulated gate bipolar transistor;

[0019] The voltage-adjustable power supply comprises a first voltage-adjustable power supply and a second voltage-adjustable power supply, the first voltage-adjustable power supply is connected between the gate and the emitter of the second insulated gate bipolar transistor, and the second voltage-adjustable power supply is connected between the gate and the emitter of the third insulated gate bipolar transistor;

[0020] The positive electrode of the adjustable current source is connected to the collector of the second insulated gate bipolar transistor, and the negative electrode of the adjustable current source is connected to the emitter of the third insulated gate bipolar transistor;

[0021] The voltage-adjustable power supply comprises a first voltage-adjustable power supply and a second voltage-adjustable power supply, the first voltage-adjustable power supply is connected between the gate and the emitter of the second insulated gate bipolar transistor, and the second voltage-adjustable power supply is connected between the gate and the emitter of the third insulated gate bipolar transistor;

[0022] The first voltage-adjustable power supply is connected between the gate and the emitter of the second insulated gate bipolar transistor, and the first voltage-adjustable power supply measures the saturation voltage drop test value of the second insulated gate bipolar transistor;

[0023] The second voltage-adjustable power supply is connected between the gate and the emitter of the third insulated gate bipolar transistor, and the second voltage-adjustable power supply measures the saturation voltage drop test value of the third insulated gate bipolar transistor.

[0024] The first voltage-adjustable power supply is connected between the gate and the emitter of the fourth insulated gate bipolar transistor, and the second voltage-adjustable power supply is connected between the gate and the emitter of the fifth insulated gate bipolar transistor;

[0025] The positive electrode of the adjustable current source is connected to the collector of the fourth insulated gate bipolar transistor, and the negative electrode of the adjustable current source is connected to the emitter of the fifth insulated gate bipolar transistor;

[0026] The first voltage-adjustable power supply is connected between the gate and the emitter of the fourth insulated gate bipolar transistor, and the first voltage-adjustable power supply measures the saturation voltage drop test value of the fourth insulated gate bipolar transistor;

[0027] The second voltage-adjustable power supply is connected between the gate and the emitter of the fifth insulated gate bipolar transistor, and the second voltage-adjustable power supply measures the saturation voltage drop test value of the fifth insulated gate bipolar transistor.

[0028] Preferably, a short-circuit protection circuit is arranged between the gate and the emitter of the second insulated gate bipolar transistor;

[0029] The positive electrode of the adjustable current source is connected to the positive electrode of the second diode, and the negative electrode of the adjustable current source is connected to the collector of the second insulated gate bipolar transistor;

[0030] The two ends of the first voltage drop detector are connected with the emitter of the second insulated gate bipolar transistor and the anode of the second diode respectively, and the value measured by the first voltage drop detector is the forward conduction voltage drop test value of the second diode.

[0031] Preferably, a short circuit protection circuit is arranged between the gate and the emitter of the fifth insulated gate bipolar transistor.

[0032] The anode of the adjustable current source is connected with the emitter of the fifth insulated gate bipolar transistor, and the cathode of the adjustable current source is connected with the cathode of the third diode.

[0033] The two ends of the second voltage drop detector are connected with the emitter of the fourth insulated gate bipolar transistor and the cathode of the third diode respectively, and the value measured by the second voltage drop detector is the forward conduction voltage drop test value of the third diode.

[0034] The above technical scheme has the following advantages or beneficial effects: the collector and the emitter of the single IGBT in the chopper module and the three-level module are used as voltage application points, voltage drop detection points and power input points, which are respectively connected with a voltage adjustable power source, a voltage drop detector and an adjustable current source, and the current and the voltage are adjusted to perform voltage drop test, and when facing a single-terminal packaged module, the saturated voltage drop test value of the module under high current condition can be accurately measured. BRIEF DESCRIPTION OF DRAWINGS

[0035] Figure 1 A structure schematic view for voltage drop detection of the first diode in the chopper module in the preferable embodiment of the utility model;

[0036] Figure 2 A structure schematic view for voltage drop detection of the first insulated gate bipolar transistor in the chopper module in the preferable embodiment of the utility model

[0037] Figure 3 A structure schematic view for voltage drop detection of the second insulated gate bipolar transistor and the third insulated gate bipolar transistor in the three-level module in the preferable embodiment of the utility model;

[0038] Figure 4 A structure schematic view for voltage drop detection of the fourth insulated gate bipolar transistor and the fifth insulated gate bipolar transistor in the three-level module in the preferable embodiment of the utility model;

[0039] Figure 5 A structure schematic view for voltage drop detection of the second diode in the three-level module in the preferable embodiment of the utility model;

[0040] Figure 6For the preferred embodiment of the utility model, the structure schematic diagram when detecting the voltage drop of the third diode in the three-level module. DETAILED DESCRIPTION

[0041] The utility model will be explained in detail below in combination with the drawings and specific embodiments. The utility model is not limited to the embodiment, and other embodiments can also belong to the scope of the utility model as long as they meet the main idea of the utility model.

[0042] In the preferred embodiment of the utility model, based on the above problems existing in the prior art, a voltage drop testing device of a chopper module and a three-level module is provided, which comprises:

[0043] A voltage adjustable power supply, the two ends of the voltage adjustable power supply are connected to the voltage application point of the chopper module or the three-level module;

[0044] An adjustable current source, the two ends of the adjustable current source are connected to the power input point of the chopper module or the three-level module;

[0045] A voltage drop detector, the two ends of the voltage drop detector are connected to the voltage drop detection point of the chopper module or the three-level module, and the value measured by the voltage drop detector is a saturation voltage drop test value.

[0046] Specifically, in the embodiment, the collector and the emitter of a single IGBT in the chopper module and the three-level module are connected to the voltage adjustable power supply, the voltage drop detector and the adjustable current source as the voltage application point, the voltage drop detection point and the power input point respectively, and the saturation voltage drop test value under the high current condition is accurately measured by adjusting the current and the voltage when facing the module with a single terminal package.

[0047] As shown in Figure 1 , the voltage adjustable power supply is represented by a variable resistor VGG in series with a resistor Rg, the adjustable current source is represented by a variable resistor VCC, and the voltage drop detector adopts a voltmeter V.

[0048] Embodiment one

[0049] In this example, as shown in Figure 1 , the chopper module comprises:

[0050] A first diode D1, the positive and negative electrodes of the first diode D1 are connected to the two ends of the voltage drop detector;

[0051] A first insulated gate bipolar transistor T1, the collector of the first insulated gate bipolar transistor T1 is connected to the negative electrode of the first diode D1, and the gate and the emitter of the first insulated gate bipolar transistor T1 are connected to the two ends of the voltage adjustable power supply;

[0052] The positive electrode of the adjustable current source is connected to the positive electrode of the first diode, and the negative electrode of the adjustable current source is connected to the emitter of the first insulated gate bipolar transistor.

[0053] The value measured by the voltage drop detector is the forward conduction voltage drop test value of the first diode D1.

[0054] Specifically, the gate (terminal No. 3) and the emitter (terminal No. 5) of the first insulated gate bipolar transistor T1 in the chopper module are respectively connected to the resistor Rg and the voltage adjustable power supply VGG.

[0055] The positive electrode of the adjustable current source VCC is connected to the positive electrode of the first diode, and the negative electrode of the adjustable current source VCC is connected to the emitter of the first insulated gate bipolar transistor T1.

[0056] Terminal No. 1 is a power terminal capable of passing large current.

[0057] Terminal No. 5 is a power terminal capable of passing large current.

[0058] Terminal No. 3 is a signal terminal incapable of passing large current.

[0059] Terminal No. 4 is a signal terminal incapable of passing large current.

[0060] The voltage drop detection process of the first diode D1 in the chopper module is as follows:

[0061] Using the test method of Vcesat, a voltage condition is applied between the gate and the emitter of the first insulated gate bipolar transistor T1 using the adjustable low-voltage source VGG to make the first insulated gate bipolar transistor T1 open. A large current is given by the adjustable current source VCC to flow from the positive electrode of the first diode D1, and the emitter of the first insulated gate bipolar transistor T1 flows out to form a loop, thereby turning on the first insulated gate bipolar transistor T1.

[0062] The voltage drop detection point is between the positive electrode of the first diode D1 and the positive electrode and the negative electrode of the negative electrode of the first diode D1. The value measured by the voltage drop detector is the forward conduction voltage drop test value of the first diode D1.

[0063] Embodiment Two:

[0064] In this embodiment, as shown in Figure 2 The two ends of the voltage adjustable power supply VGG are respectively connected to the gate and the emitter of the first insulated gate bipolar transistor T1.

[0065] The positive electrode of the adjustable current source VCC is connected to the positive electrode of the first diode D1, and the negative electrode of the adjustable current source VCC is connected to the emitter of the first insulated gate bipolar transistor T1.

[0066] The two ends of the voltage drop detector are connected with the collector and the gate of the first insulated gate bipolar transistor T1, and the measured value of the voltage drop detector is the saturation voltage drop test value of the first insulated gate bipolar transistor T1.

[0067] Specifically, the voltage drop detection process of the first insulated gate bipolar transistor T1 in the chopper module is as follows:

[0068] The two ends of the voltage drop detector are connected with the collector and the gate of the first insulated gate bipolar transistor T1;

[0069] A voltage condition is applied between the gate and the emitter of the first insulated gate bipolar transistor T1 by using the voltage adjustable power supply VGG, so that the first insulated gate bipolar transistor T1 is turned on. A large current is given to flow from the anode of the first diode D1 to the emitter of the first insulated gate bipolar transistor T1 to form a loop by using the adjustable current source VCC, so that the first insulated gate bipolar transistor T1 is turned on. The voltage drop detection points are the collector and the emitter of the first insulated gate bipolar transistor T1.

[0070] The measured value of the voltage drop detector is the saturation voltage drop test value of the first insulated gate bipolar transistor T1.

[0071] Embodiment Three:

[0072] In this embodiment, as shown in Figure 3 The three-level module includes:

[0073] The emitter of the second insulated gate bipolar transistor T2 is connected with the collector of the third insulated gate bipolar transistor T3, the emitter of the third insulated gate bipolar transistor T3 is connected with the collector of the fourth insulated gate bipolar transistor T4, and the emitter of the fourth insulated gate bipolar transistor T4 is connected with the collector of the fifth insulated gate bipolar transistor T5.

[0074] The negative electrode of the second diode D2 is connected with the emitter of the second insulated gate bipolar transistor T2, the positive electrode of the second diode D2 is connected with the negative electrode of the third diode D3, and the positive electrode of the third diode D3 is connected with the emitter of the fourth insulated gate bipolar transistor T4.

[0075] The voltage adjustable power supply VGG includes the first voltage adjustable power supply VGG1 and the second voltage adjustable power supply VGG2. The two ends of the first voltage adjustable power supply VGG1 are connected between the gate and the emitter of the second insulated gate bipolar transistor T2, and the two ends of the second voltage adjustable power supply VGG2 are connected between the gate and the emitter of the third insulated gate bipolar transistor T3.

[0076] The positive electrode of the adjustable current source VCC is connected with the collector of the second insulated gate bipolar transistor T2, and the negative electrode of the adjustable current source VCC is connected with the emitter of the third insulated gate bipolar transistor T3.

[0077] The voltage drop detectors include a first voltage drop detector V1 and a second voltage drop detector V2;

[0078] The two ends of the first voltage drop detector V1 are connected between the collector and emitter of the second insulated gate bipolar transistor T2. The value measured by the first voltage drop detector V1 is the saturation voltage drop test value of the second insulated gate bipolar transistor T2.

[0079] The second voltage drop detector V2 is connected between the collector and emitter of the third insulated gate bipolar transistor T3. The value measured by the second voltage drop detector V2 is the saturation voltage drop test value of the third insulated gate bipolar transistor T3.

[0080] Specifically, the voltage drop detection process for the second insulated-gate bipolar transistor T2 and the third insulated-gate bipolar transistor T3 in the three-level module is as follows:

[0081] Adjustable low-voltage sources VGG1 and VGG2 are used to apply voltages between the gate and emitter of the second insulated-gate bipolar transistor T2 and the third insulated-gate bipolar transistor T3, respectively, so that the two IGBTs, the second insulated-gate bipolar transistor T2 and the third insulated-gate bipolar transistor T3, are turned on simultaneously. An adjustable current source VCC is used to give the collector current between the collector of the second insulated-gate bipolar transistor T2 and the emitter of the third insulated-gate bipolar transistor T3, so that the two IGBTs, the second insulated-gate bipolar transistor T2 and the third insulated-gate bipolar transistor T3, are turned on.

[0082] A large current flows into the collector (capable of carrying a large current) of the second insulated-gate bipolar transistor T2 and flows out from the emitter (capable of carrying a large current) of the third insulated-gate bipolar transistor T3, forming a circuit.

[0083] The voltage drop detection points are the collector and emitter of the second insulated gate bipolar transistor T2, and the value measured by the first voltage drop detector V1 is the saturation voltage drop test value of the second insulated gate bipolar transistor T2.

[0084] The voltage drop detection points are the collector and emitter of the third insulated gate bipolar transistor T3, and the value measured by the second voltage drop detector V2 is the saturation voltage drop test value of the third insulated gate bipolar transistor T3.

[0085] Example 4:

[0086] In this embodiment, as Figure 4 As shown, the two ends of the first voltage adjustable power supply VGG1 are connected between the gate and emitter of the fourth insulated gate bipolar transistor T4, and the two ends of the second voltage adjustable power supply VGG2 are connected between the gate and emitter of the fifth insulated gate bipolar transistor T5.

[0087] The positive pole of the adjustable current source VCC is connected to the collector of the fourth insulated gate bipolar transistor T4, and the negative pole of the adjustable current source VCC is connected to the emitter of the fifth insulated gate bipolar transistor T5.

[0088] The first voltage drop detector V1 is connected between the collector and the emitter of the fourth insulated gate bipolar transistor T4, and the value measured by the first voltage drop detector V1 is the saturation voltage drop test value of the fourth insulated gate bipolar transistor T4.

[0089] The second voltage drop detector V2 is connected between the collector and the emitter of the fifth insulated gate bipolar transistor T5, and the value measured by the second voltage drop detector V2 is the saturation voltage drop test value of the fifth insulated gate bipolar transistor T5.

[0090] Specifically, the voltage drop detection process of the fourth insulated gate bipolar transistor T4 and the fifth insulated gate bipolar transistor T5 in the three-level module is as follows:

[0091] The adjustable low-voltage source VGG1 and VGG2 are used to apply voltages between the gate and the emitter of the fourth insulated gate bipolar transistor T4 and the fifth insulated gate bipolar transistor T5 respectively, so that the fourth insulated gate bipolar transistor T4 and the fifth insulated gate bipolar transistor T5 are simultaneously turned on, and the adjustable current source VCC is used to give a collector current between the collector of the fourth insulated gate bipolar transistor T4 and the emitter of the fifth insulated gate bipolar transistor T5 to turn on the fourth insulated gate bipolar transistor T4 and the fifth insulated gate bipolar transistor T5.

[0092] A large current flows from the collector of the fourth insulated gate bipolar transistor T4 (which can pass a large current) and flows out from the emitter of the fifth insulated gate bipolar transistor T5 (which can pass a large current) to form a loop.

[0093] The voltage drop detection point is the collector and the emitter of the fourth insulated gate bipolar transistor T4, and the value measured by the first voltage drop detector V1 is the saturation voltage drop test value of the fourth insulated gate bipolar transistor T4.

[0094] The voltage drop detection point is the collector and the emitter of the fifth insulated gate bipolar transistor T5, and the value measured by the second voltage drop detector V2 is the saturation voltage drop test value of the fifth insulated gate bipolar transistor T5.

[0095] Embodiment five:

[0096] In this embodiment, as shown in Figure 5 A short circuit protection circuit 100 is arranged between the gate and the emitter of the second insulated gate bipolar transistor T2.

[0097] The positive pole of the adjustable current source VCC is connected to the positive pole of the second diode D2, and the negative pole of the adjustable current source VCC is connected to the collector of the second insulated gate bipolar transistor T2.

[0098] The two ends of the first voltage drop detector V1 are connected to the emitter of the second insulated gate bipolar transistor T2 and the anode of the second diode D2 respectively, and the value measured by the first voltage drop detector V1 is the forward conduction voltage drop test value of the second diode D2.

[0099] Specifically, the voltage drop detection process of the second diode D2 in the three-level module is as follows:

[0100] The gate and the emitter of the second insulated gate bipolar transistor T2 are short-circuited for protection, and an adjustable current source VCC is used to give a current flowing from the anode of the second diode D2 and flowing out from the collector terminal of the second insulated gate bipolar transistor T2 to form a loop.

[0101] The voltage drop detection point is the anode of the second diode D2 and the emitter of the second insulated gate bipolar transistor T2, and the value measured by the first voltage drop detector V1 is the forward conduction voltage drop test value of the second diode D2.

[0102] Embodiment Six:

[0103] In this embodiment, as shown in Figure 6 A short-circuit protection circuit 100 is arranged between the gate and the emitter of the fifth insulated gate bipolar transistor T5.

[0104] The anode of the adjustable current source VCC is connected to the emitter of the fifth insulated gate bipolar transistor T5, and the cathode of the adjustable current source VCC is connected to the cathode of the third diode D3.

[0105] The two ends of the second voltage drop detector V2 are connected to the emitter of the fourth insulated gate bipolar transistor T4 and the cathode of the third diode D3 respectively, and the value measured by the second voltage drop detector V2 is the forward conduction voltage drop test value of the third diode D3.

[0106] Specifically, the voltage drop detection process of the third diode D3 in the three-level module is as follows:

[0107] The gate and the emitter of the fifth insulated gate bipolar transistor T5 are short-circuited for protection, and an adjustable current source VCC is used to give a current flowing from the emitter terminal of the fifth insulated gate bipolar transistor T5 and flowing out from the cathode of the third diode D3 to form a loop.

[0108] The voltage drop detection point is the cathode of the third diode D3 and the emitter of the fourth insulated gate bipolar transistor T4, and the value measured by the second voltage drop detector V2 is the forward conduction voltage drop test value of the third diode D3.

[0109] It can be seen from the foregoing embodiments that the collector and the emitter of the single IGBT in the chopper module and the three-level module are respectively connected with the voltage adjustable power supply, the voltage drop detector and the adjustable current source as the voltage application point, the voltage drop detection point and the power input point, and the saturation voltage drop test value of the single-terminal packaged module under the high current condition can be accurately measured by adjusting the current and the voltage for the voltage drop test.

[0110] The above are only the preferred embodiments of the present application, and are not intended to limit the embodiments and the protection scope of the present application. For those skilled in the art, it should be realized that any equivalent replacement and obvious change made according to the content of the present application should be included in the protection scope of the present application.

Claims

1. A chopper module and three-level module voltage drop testing device, characterized in that, Comprise: a voltage adjustable power supply, two ends of which are connected to voltage application points of the chopper module or the three-level module; an adjustable current source, two ends of which are connected to power input points of the chopper module or the three-level module; a voltage drop detector, two ends of which are connected to voltage drop detection points of the chopper module or the three-level module, and the value measured by the voltage drop detector is a saturation voltage drop test value.

2. The pressure drop test device of claim 1, wherein, The chopper module comprises: a first diode, whose positive and negative electrodes are connected to two ends of the voltage drop detector; a first insulated gate bipolar transistor, whose collector is connected to the negative electrode of the first diode, and whose gate and emitter are connected to two ends of the voltage adjustable power supply; the positive electrode of the adjustable current source is connected to the positive electrode of the first diode, and the negative electrode of the adjustable current source is connected to the emitter of the first insulated gate bipolar transistor; the value measured by the voltage drop detector is a forward conduction voltage drop test value of the first diode.

3. The pressure drop test device of claim 2, wherein, Two ends of the voltage adjustable power supply are respectively connected to the gate and emitter of the first insulated gate bipolar transistor; the positive electrode of the adjustable current source is connected to the positive electrode of the first diode, and the negative electrode of the adjustable current source is connected to the emitter of the first insulated gate bipolar transistor; two ends of the voltage drop detector are respectively connected to the collector and emitter of the first insulated gate bipolar transistor, and the value measured by the voltage drop detector is a saturation voltage drop test value of the first insulated gate bipolar transistor.

4. The pressure decay test apparatus of claim 1, wherein, The three-level module comprises: a second insulated gate bipolar transistor, whose emitter is connected to the collector of a third insulated gate bipolar transistor, whose emitter is connected to the collector of a fourth insulated gate bipolar transistor, whose emitter is connected to the collector of a fifth insulated gate bipolar transistor; a second diode, whose negative electrode is connected to the emitter of the second insulated gate bipolar transistor, whose positive electrode is connected to the negative electrode of a third diode, and whose positive electrode is connected to the emitter of the fourth insulated gate bipolar transistor; the voltage adjustable power supply comprises a first voltage adjustable power supply and a second voltage adjustable power supply, two ends of the first voltage adjustable power supply are connected between the gate and emitter of the second insulated gate bipolar transistor, and two ends of the second voltage adjustable power supply are connected between the gate and emitter of the third insulated gate bipolar transistor; the positive electrode of the adjustable current source is connected to the collector of the second insulated gate bipolar transistor, and the negative electrode of the adjustable current source is connected to the emitter of the third insulated gate bipolar transistor; the voltage drop detector comprises a first voltage drop detector and a second voltage drop detector; two ends of the first voltage drop detector are connected between the collector and emitter of the second insulated gate bipolar transistor, and the value measured by the first voltage drop detector is a saturation voltage drop test value of the second insulated gate bipolar transistor; two ends of the second voltage drop detector are connected between the collector and emitter of the third insulated gate bipolar transistor, and the value measured by the second voltage drop detector is a saturation voltage drop test value of the third insulated gate bipolar transistor. The second voltage drop detector is connected between the collector and the emitter of the third insulated gate bipolar transistor, and the value measured by the second voltage drop detector is the saturation voltage drop test value of the third insulated gate bipolar transistor.

5. The pressure drop test device of claim 4, wherein, The two ends of the first voltage adjustable power source are connected between the gate and the emitter of the fourth insulated gate bipolar transistor, and the two ends of the second voltage adjustable power source are connected between the gate and the emitter of the fifth insulated gate bipolar transistor. The positive electrode of the adjustable current source is connected to the collector of the fourth insulated gate bipolar transistor, and the negative electrode of the adjustable current source is connected to the emitter of the fifth insulated gate bipolar transistor. The two ends of the first voltage drop detector are connected between the collector and the emitter of the fourth insulated gate bipolar transistor, and the value measured by the first voltage drop detector is the saturation voltage drop test value of the fourth insulated gate bipolar transistor. The second voltage drop detector is connected between the collector and the emitter of the fifth insulated gate bipolar transistor, and the value measured by the second voltage drop detector is the saturation voltage drop test value of the fifth insulated gate bipolar transistor.

6. The pressure drop test device of claim 4, wherein, The negative electrode of the adjustable current source is connected to the collector of the second insulated gate bipolar transistor. The positive electrode of the adjustable current source is connected to the positive electrode of the second diode, and the negative electrode of the adjustable current source is connected to the collector of the second insulated gate bipolar transistor. The two ends of the first voltage drop detector are respectively connected to the emitter of the second insulated gate bipolar transistor and the positive electrode of the second diode, and the value measured by the first voltage drop detector is the forward conduction voltage drop test value of the second diode.

7. The pressure drop test device of claim 4, wherein, A short circuit protection circuit is arranged between the gate and the emitter of the fifth insulated gate bipolar transistor. The positive electrode of the adjustable current source is connected to the emitter of the fifth insulated gate bipolar transistor, and the negative electrode of the adjustable current source is connected to the negative electrode of the third diode. The two ends of the second voltage drop detector are respectively connected to the emitter of the fourth insulated gate bipolar transistor and the negative electrode of the third diode, and the value measured by the second voltage drop detector is the forward conduction voltage drop test value of the third diode.

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