Test system capable of increasing static parameter test speed

Abstract

This invention relates to a test system that improves the testing speed of static parameters. It includes a pulse constant current source, a bias voltage source unit, a voltage measurement unit, and a switching matrix. The switching matrix selects the pulse constant current source, bias voltage source unit, and voltage measurement unit to be adapted and connected to the device under test (DUT) unit for testing a bridge arm circuit or a DUT. The pulse constant current source provides excitation current to the bridge arm circuit or DUT under test; the bias voltage source unit provides a driving bias voltage to drive the corresponding power switching device to a conducting or turning-off state; the voltage measurement unit measures the voltage of the DUT under test to determine the static parameters of the DUT unit using the measured test voltage. This invention effectively improves the testing speed of static parameters of semiconductor devices and extends the service life of the switching matrix.

Description

Technical Field

[0001] This utility model relates to a testing system, and more particularly to a testing system that can improve the testing speed of static parameters. Background Technology

[0002] The static characteristics of power semiconductor devices are crucial and are mandatory tests conducted during manufacturing. Taking IGBT (Insulated Gate Bipolar Transistor) devices as an example (this also applies to MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor), diode, BJT (Bipolar Junction Transistor), SCR (Silicon Controlled Rectifier), IGCT (Integrated Gate-Commutated Thyristor), and HEMT (High Electron Mobility Transistor) power devices), their static parameters include V... GE(th) V (BR)CES I CES V CEsat V F I GES etc., among which, V GE(th) V is the gate-emitter threshold voltage of the IGBT device. (BR)CES I is the collector-emitter blocking voltage of the IGBT device. CES V is the collector-emitter leakage current of the IGBT device. CEsat V is the on-state voltage drop of the IGBT device. F For the forward voltage drop of the freewheeling diode connected to the IGBT device, I GES This refers to the gate-emitter leakage current of the IGBT device.

[0003] In the mass production of power semiconductor devices, static characteristics are tested on the production line using static testing machines. Testing efficiency is a critical performance characteristic of these machines, directly determining production efficiency and cost. Among the several static characteristic tests for power semiconductor devices, the on-state voltage drop Von is... CEsat and the forward voltage drop V of the freewheeling diode F These are two relatively time-consuming test items, specifically: Because the static testing machine internally uses mechanical switches (which switch the circuit on and off through mechanical action; relays are a type of mechanical switch) to switch different test circuits to perform various test items. The on-state voltage drop V... CEsat and the forward voltage drop V of the freewheeling diodeF Both test items require the use of high current (several amperes to tens of thousands of amperes) to excite the power semiconductor device. The test circuit necessitates a high-voltage, high-current mechanical switch (capable of withstanding high voltage when open and high current when closed). These high-voltage, high-current mechanical switches have large moving parts and significant mass, and their operating time is relatively long, resulting in a high on-state voltage drop V0. CEsat and the forward voltage drop V of the freewheeling diode F Two test items often become the efficiency bottleneck of static testing.

[0004] According to testing standards, different static test items require different circuits. That is, before performing a test, the device under test (DUT) must be connected to the corresponding test circuit, usually using mechanical switches to switch the test circuit. The time spent testing each static parameter generally includes two parts: switching time and test time.

[0005] To improve the testing efficiency of static testing machines, the traditional approach is to continuously shorten circuit switching time and testing time, especially the on-state voltage drop V. CEsat and the forward voltage drop V of the freewheeling diode F The circuit switching time during static number testing is essentially a compression of the operating time of high-voltage, high-current mechanical switches. However, the physical characteristics of high-voltage, high-current switches are that the distance between the moving and stationary contacts is relatively large (to ensure sufficient voltage withstand capability) and the moving contact has a relatively large mass (to ensure sufficient current carrying capacity). The larger distance between the moving and stationary contacts means that the displacement of the switch action is larger (requiring more operating time), and the larger mass of the moving contact means that the acceleration of the moving contact during switch action is smaller (requiring more operating time).

[0006] Currently, to reduce the operating time of high-voltage, high-current mechanical switches, the only option is to increase the driving force of the moving contact. However, excessive driving force can lead to violent collisions between the moving and stationary contacts when the mechanical switch operates, generating significant noise and reducing the lifespan of the mechanical switch (the collisions cause wear, deformation, or even breakage of the moving and stationary contacts). Therefore, simply increasing the driving force of the moving contact is not an effective way to improve the efficiency of static parameter testing. How to effectively improve the testing efficiency of static parameters of power semiconductor devices remains a pressing technical challenge. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of the existing technology and provide a test system that can improve the testing speed of static parameters, effectively improve the testing speed of static parameters of semiconductor devices, and extend the working life of the switch matrix.

[0008] According to the technical solution provided by this utility model, a test system that can improve the testing speed of static parameters is provided. The test system includes a pulse constant current source, a bias voltage source unit, a voltage measurement unit, and a switching matrix. The pulse constant current source, bias voltage source unit, and voltage measurement unit are all connected to the device under test unit via a switch matrix. The device under test unit includes at least one bridge arm circuit, and the bridge arm circuit includes two adapted components under test. Each component under test includes a power switching device and a freewheeling diode for freewheeling when the power switching device is turned off. A switch matrix is ​​used to select and connect a pulse constant current source, a bias voltage source unit, and a voltage measurement unit to the device under test (DUT) unit for testing the bridge arm circuit or a component under test. A pulsed constant current source is used to provide excitation current to the bridge arm circuit or component under test. The bias voltage source unit provides a drive bias voltage to drive the corresponding power switching device to the on state; A voltage measurement unit is used to measure the voltage of the device under test (DUT) in order to determine the static parameters of the DUT using the measured test voltage.

[0009] For any power switching device, a first auxiliary connection terminal and a first main connection terminal are provided at the first connection end of the power switching device, and the first main connection terminal and the first auxiliary connection terminal are electrically connected to the first connection end. A second auxiliary connection terminal and a second main connection terminal are provided at the second connection end of the semiconductor device, and both the second main connection terminal and the second auxiliary connection terminal are electrically connected to the second connection end. For a component under test, the cathode of the freewheeling diode is electrically connected to the first connection terminal of the power switching device, and the anode of the freewheeling diode is electrically connected to the second connection terminal of the power switching device. Within the bridge arm circuit, one component under test forms the upper bridge arm unit, and another test component forms the lower bridge arm unit. The second main connection terminal in the upper bridge arm unit is electrically connected to the first main connection terminal in the lower bridge arm unit. When testing a component under test, the component under test is adapted to a pulse constant current source through a first main connection terminal and a second main connection terminal, and the excitation current flows into the component under test through the first main connection terminal or the second main connection terminal.

[0010] The switching matrix includes constant current source switching units adapted and connected to a pulse constant current source, wherein, The constant current source switching unit includes a constant current excitation first branch and a constant current excitation second branch, and the constant current excitation first branch and constant current excitation second branch are adapted and connected to a pulse constant current source. The constant current excitation first branch includes several constant current excitation first branch switches; The constant current excitation second branch includes several constant current excitation second branch switches; The number of constant current excitation first branch switches and the number of constant current excitation second branch switches shall not be less than the number of power switching devices in the device under test unit; When testing a bridge arm circuit or a component under test, a corresponding constant current excitation first branch switch in the constant current excitation first branch is configured to be closed, and a corresponding constant current excitation second branch switch in the constant current excitation second branch is configured to be closed, so that the pulse constant current source can be adapted to connect with the bridge arm circuit or component under test. For any component under test, the direction of the excitation current applied to the power switching device is opposite to the direction of the excitation current applied to the freewheeling diode.

[0011] The pulsed constant current source includes a current source and a current direction switching circuit adapted and connected to the current source, wherein, The current direction switching circuit includes a first direction switching branch connected in parallel with the current source and a second direction switching branch. The first branch of the direction switching includes NMOS transistor Q1 and NMOS transistor Q3. The drain terminal of NMOS transistor Q1 is connected to the positive terminal of the current source, and the source terminal of NMOS transistor Q1 is connected to the drain terminal of NMOS transistor Q3 and the constant current excitation first branch. The second branch of the direction switching includes NMOS transistors Q2 and Q4. The drain terminal of NMOS transistor Q2 is connected to the positive terminal of the current source, and the source terminal of NMOS transistor Q2 is connected to the drain terminal of NMOS transistor Q4 and the constant current excitation second branch. The source terminals of NMOS transistors Q3 and Q4 are both connected to the negative terminal of the current source. When NMOS transistors Q1 and Q4 are simultaneously turned on, and NMOS transistors Q2 and Q3 are simultaneously turned off, the pulse current source provides the excitation current in the first current direction. When NMOS transistors Q2 and Q3 are simultaneously turned on, and NMOS transistors Q1 and Q4 are simultaneously turned off, the pulse current source provides the excitation current in the second current direction.

[0012] For any constant current excitation first branch switch, the first terminal of the constant current excitation first branch switch is connected to the source terminal of NMOS transistor Q1 and the drain terminal of NMOS transistor Q3, and the second terminal of the constant current excitation first branch switch is electrically connected to the first connection main terminal of a corresponding power switching device. For any constant current excitation second branch switch, the first terminal of the constant current excitation second branch switch is connected to the source terminal of NMOS transistor Q2 and the drain terminal of NMOS transistor Q4, and the second terminal of the constant current excitation second branch switch is electrically connected to the second connection main terminal of a corresponding power switching device.

[0013] The pulsed constant current source also includes a commutation drive circuit, wherein... The commutation drive circuit includes at least four commutation drive modules, with each of the NMOS transistors Q1, Q2, Q3, and Q4 being adapted and connected to a commutation drive module. For any commutation drive module, it includes an optocoupler isolator, a drive amplifier, a signal conditioning circuit, and a drive connection circuit connected in sequence, wherein, The driving connection circuit includes a driving connection for a first NMOS transistor and a driving connection for a second NMOS transistor. The gate terminals of both the driving connection for the first NMOS transistor and the driving connection for the second NMOS transistor are connected to the signal processing circuit. The drain terminal of the first NMOS transistor is connected to the isolation voltage output by the isolation power supply, and the source terminal of the first NMOS transistor is connected to the drain terminal of the second NMOS transistor and the gate terminal of an NMOS transistor in the current direction switching circuit. The source terminal of the second NMOS transistor is connected to the source terminal of the NMOS transistor connected in the current direction switching circuit.

[0014] The bias voltage source unit includes two bias voltage sources, and the switch matrix includes two sets of bias voltage switch units. The bias voltage sources and bias voltage switch units are connected in a one-to-one correspondence. For any bias voltage switching unit, the bias voltage switching unit includes a first bias voltage branch and a second bias voltage branch, wherein, The first bias voltage branch includes several first bias voltage branch switches; The second bias voltage branch includes several second bias voltage branch switches; The number of switches for the first branch of the bias voltage and the number of switches for the second branch of the bias voltage shall not be less than the number of bridge arm circuits in the unit of the device under test. For a power switching device, the control terminal of the power switching device is connected to the positive terminal of the corresponding bias voltage source through a first bias voltage branch switch, and the second auxiliary connection terminal of the power switching device is connected to the negative terminal of the corresponding bias voltage source through a second bias voltage branch switch.

[0015] The voltage measurement unit includes two sets of voltage measurement components, wherein, Each voltage measurement component corresponds to a component under test, so as to measure the voltage between the first main connection terminal and the second auxiliary connection terminal, the voltage between the first auxiliary connection terminal and the second auxiliary connection terminal, and the voltage between the second main connection terminal and the second auxiliary connection terminal using the voltage measurement component.

[0016] Each voltage measurement assembly includes three voltmeters, and the switch matrix includes voltmeter switch units corresponding to each voltage measurement assembly. The voltmeter switching unit includes voltmeter lines that are respectively connected to three voltmeters; For any voltmeter circuit, the voltmeter circuit includes a first branch of the voltmeter and a second branch of the voltmeter. The voltmeter is adapted to a power switching device through the first branch of the voltmeter and the second branch of the voltmeter to perform voltage measurement.

[0017] Both the constant current excitation first branch switch and the constant current excitation second branch switch are high-voltage, high-current mechanical switches.

[0018] The advantages of this invention are: by using a switch matrix to select the pulse constant current source, bias voltage source unit, and voltage measurement unit to be adapted and connected to the device under test (DUT) unit, the bridge arm circuit or a single DUT can be tested, and multiple V values ​​can be measured in parallel in a single test. CEsat Parameters and V F Parameters, and in a single test, V can be achieved. CEsat Parameters and V F The testing of parameters improves testing efficiency, which helps to extend the service life and mean time between failures of the testing equipment, reduces the lifespan consumption of switches in the switch matrix, and lowers the maintenance cost of the equipment. Attached Figure Description

[0019] Figure 1 This is a circuit schematic diagram of an embodiment of the present invention for static parameter testing of the device unit under test.

[0020] Figure 2 This utility model provides a V-type power switching device for the upper bridge arm unit. CEsat A schematic diagram of an example of parameter testing.

[0021] Figure 3 This utility model provides a V-type adjustment for the freewheeling diode in the upper bridge arm unit. F A schematic diagram of an example of parameter testing.

[0022] Figure 4 This utility model allows for simultaneous V-switching of two power switching devices in the bridge arm circuit. CEsat A schematic diagram of an example of parameter testing.

[0023] Figure 5This utility model applies V to the bridge arm circuit sequentially during the same test process. CEsat Parameters and V F A schematic diagram of an example of parameter testing.

[0024] Figure 6 This is a circuit diagram of one embodiment of the pulse constant current source of this utility model. Detailed Implementation

[0025] The present invention will be further described below with reference to the specific accompanying drawings and embodiments.

[0026] To effectively improve the testing speed of static parameters of semiconductor devices and extend the service life of switching matrices, this invention provides a testing system for improving the testing speed of static parameters. Specifically, the testing system includes a pulse constant current source, a bias voltage source unit, a voltage measurement unit, and a switching matrix. The pulse constant current source, bias voltage source unit, and voltage measurement unit are all connected to the device under test unit via a switch matrix. The device under test unit includes at least one bridge arm circuit, and the bridge arm circuit includes two adapted components under test. Each component under test includes a power switching device and a freewheeling diode for freewheeling when the power switching device is turned off. A switch matrix is ​​used to select and connect a pulse constant current source, a bias voltage source unit, and a voltage measurement unit to the device under test (DUT) unit for testing the bridge arm circuit or a component under test. A pulsed constant current source is used to provide excitation current to the bridge arm circuit or component under test. The bias voltage source unit provides a drive bias voltage to drive the corresponding power switching device to be in the on or off state. A voltage measurement unit is used to measure the voltage of the device under test (DUT) in order to determine the static parameters of the DUT using the measured test voltage.

[0027] It should be noted that the static parameter test performed by this utility model's test system is the same as the static parameter test for power semiconductors mentioned above. The details of the static parameters can be found in the above description. During static parameter testing, a device under test (DUT) unit should be provided. This DUT unit is the test object of this utility model's test system. Specifically, the DUT unit should include at least one bridge arm circuit. The number of bridge arm circuits can be selected as needed. Each bridge arm circuit should include two components under test; that is, two components under test connected together can form a bridge arm circuit. Examples of forming bridge arm circuits will be provided below.

[0028] In practical implementation, the two components under test (DUTs) preferably adopt the same form. Each DUT should include a power switching device and a freewheeling diode. The power switching device can be of the power semiconductor device types mentioned above, such as IGBT devices, MOSFET devices, etc. For each DUT, when the power switching device is in the off state, freewheeling current can be provided through the freewheeling diode. The method and purpose of using the freewheeling diode for freewheeling current are consistent with existing technologies. It is understood that during static parameter testing, the main focus is on determining the corresponding static parameters of the power switching device and freewheeling diode within the DUT.

[0029] To meet the requirements of static testing, the testing system of this utility model should include a pulse constant current source, a bias voltage source unit, a voltage measurement unit, and a switch matrix. The pulse constant current source, bias voltage source unit, and voltage measurement unit are all connected to the device under test (DUT) unit via the switch matrix. The connection state between the pulse constant current source, bias voltage source unit, voltage measurement unit, and DUT unit can be adjusted via the switch matrix. By adjusting the connection state with the DUT unit, static parameter testing under different testing requirements can be achieved, thus enabling rapid static parameter testing. Therefore, the specific method of adjusting the connection state should meet the requirements of static parameter testing under different testing conditions. The specific details of adjusting the connection state will be explained later.

[0030] During static parameter testing, static parameter testing can be performed on the entire bridge arm circuit or on a component under test within the bridge arm circuit. In this case, the bridge arm circuit or a component under test within the bridge arm circuit becomes the test object. The test object can be selected as needed. Specifically, a pulse constant current source can provide the excitation current required for static parameter testing, that is, the pulse constant current source can provide the excitation current for the bridge arm circuit or the component under test in static testing.

[0031] It should be understood that when performing static parameter tests on power switching devices, the power switching devices should be configured to operate in the corresponding state. For example, the static parameter test of the power switching device is V. CEsat When configuring parameters, the power switching device should be in the ON state, and the static parameter test for the power switching device is V. (BR)CES Parameters and I CES For the parameters, the power switching devices should be configured to be in the off state. Specifically, the bias voltage source unit can provide a drive bias voltage to drive the corresponding power switching devices to the on or off state. The drive state of the power switching devices is related to the requirements of static parameter testing, such as V-parameter testing of the bridge arm circuit. CEsat During parameter testing, the bias voltage source unit should drive both power switching devices within the same bridge arm circuit to be in the ON state. For example, when testing a component under test (V...CEsat During parameter testing, only the power switching device in the static parameter test can be driven to the on state. The driving state of the power switching device by the driving bias voltage can be related to the type of power switching device. The situation of using the driving bias voltage to drive the power switching device to the on or off state is consistent with the existing technology, and will not be elaborated here.

[0032] In the following description, V is defined as the static parameter test performed on the power switching device. CEsat Taking parameter testing as an example, the method and process of static parameter testing of this utility model will be illustrated. That is, in the following description, static parameter testing specifically refers to V CEsat For parameter testing details, please refer to this section.

[0033] In practice, when performing static parameter tests on power switching devices, the corresponding power switching devices should first be configured to be in the on state. Then, a pulse constant current source applies the excitation current. When the excitation current flows through the bridge arm circuit or the component under test in the on state, a voltage drop will occur. At this time, the voltage measurement unit can be used to measure the voltage of the component under test, so as to determine the static parameters of the device under test unit using the measured test voltage. The method of determining static parameters using test voltage will be illustrated below.

[0034] It should be noted that during static parameter testing, since the conditions for freewheeling operation are not met, the corresponding power switching device should be configured to be in the off state when performing static parameter testing on the freewheeling diode. When an excitation current is applied, the excitation current can flow through the freewheeling diode to perform static parameter testing. The method for testing the static parameters of the freewheeling diode can be consistent with existing technologies, such as... Figure 1 When performing static parameter testing on the freewheeling diode DUT-U, the excitation current should flow from the anode to the cathode of the freewheeling diode DUT-U, or, as... Figure 4 In this system, static parameter tests can be performed simultaneously on both the freewheeling diode DUT-U and the freewheeling diode DUT-L within the bridge arm circuit.

[0035] It should be understood that when performing static parameter testing on a freewheeling diode, the VF parameter of the freewheeling diode is mainly determined. Furthermore, when performing static parameter testing on a freewheeling diode, the direction of the excitation current flowing through the freewheeling diode is opposite to the direction of the excitation current flowing through the power switching device.

[0036] In one embodiment of the present invention, for any power switching device, a first auxiliary connection terminal and a first main connection terminal are provided at the first connection end of the power switching device, and the first main connection terminal and the first auxiliary connection terminal are electrically connected to the first connection end. A second auxiliary connection terminal and a second main connection terminal are provided at the second connection end of the semiconductor device, and both the second main connection terminal and the second auxiliary connection terminal are electrically connected to the second connection end. For a component under test, the cathode of the freewheeling diode is electrically connected to the first connection terminal of the power switching device, and the anode of the freewheeling diode is electrically connected to the second connection terminal of the power switching device. Within the bridge arm circuit, one component under test forms the upper bridge arm unit, and another test component forms the lower bridge arm unit. The second main connection terminal in the upper bridge arm unit is electrically connected to the first main connection terminal in the lower bridge arm unit. When testing a component under test, the component under test is adapted to a pulse constant current source through a first main connection terminal and a second main connection terminal, and the excitation current flows into the component under test through the first main connection terminal or the second main connection terminal.

[0037] It should be noted that the power switching device refers to the power semiconductor device mentioned above (excluding diode devices). The power switching device is a three-terminal device, with the three terminals being the first connection terminal, the second connection terminal, and the control terminal. The type of the three terminals is related to the type of power switching device. For example, when the power switching device is an IGBT-type device, the control terminal is the gate terminal of the IGBT-type device, the first connection terminal is the collector terminal of the IGBT-type device, and the second connection terminal is the emitter terminal of the IGBT-type device. When the power switching device is a MOSFET-type device, the control terminal is the gate terminal of the MOSFET-type device, the first connection terminal is the drain terminal of the MOSFET-type device, and the second connection terminal is the source terminal of the MOSFET-type device. When the power switching device is of other types, the control terminal, the first connection terminal, and the second connection terminal can be determined according to the type of power switching device. Examples will not be provided here.

[0038] It should be noted that the component under test in this invention, including the power switching device and the freewheeling diode, can be a power module formed by co-packaging. For the packaged power module, a first auxiliary connection terminal and a first main connection terminal are generally provided at the first connection end of the power switching device. The first main connection terminal is usually used for connecting high-current circuits and is relatively large in size, while the first auxiliary connection terminal is usually used for connecting small-signal circuits and is relatively small in size. In the following description, the main terminal and auxiliary terminal have the same meaning and can be referred to here. Similarly, a second auxiliary connection terminal and a second main connection terminal are provided at the second connection end of the power switching device.

[0039] Figures 1-4 The figure illustrates one embodiment of the test system of this invention for testing the device under test. The figure shows a case where the power switching device is an IGBT device. Figures 1-4 In this circuit, G1 and G2 are two power switching devices, and DUT-U and DUT-L are two freewheeling diodes. Power switching device G1 and freewheeling diode DUT-U can form a component under test (DUT), and power switching device G2 and freewheeling diode DUT-L can form another DUT. The two DUTs are connected in a bridge arm circuit, i.e. Figures 1-4 The diagram illustrates one embodiment where the device under test (DUT) unit includes one bridge arm circuit. When the DUT unit includes two bridge arm circuits, the two bridge arm circuits are independent of each other and are connected to the pulse constant current source, bias voltage source unit, and voltage measurement unit mentioned above through a switch matrix. The difference is that the form of the switch matrix will be different, which will be explained in detail below.

[0040] Figures 1-4 In the diagram, P1 is the first main connection terminal of power switch device G1, C1 is the first auxiliary connection terminal of power switch device G1, E1 is the second auxiliary connection terminal of power switch device G1, U represents the configuration formed by interconnecting the second main connection terminal of power switch device G1 with the first main connection terminal of power switch device G2, C2 is the first auxiliary connection terminal of power switch device G2, E2 is the second auxiliary connection terminal of power switch device G2, and N1 is the second main connection terminal of power switch device G2. Therefore, it can be determined according to... Figures 1-4 The form of the bridge arm circuit is obtained. It should be noted that... Figures 1-4 The diagram only shows the correspondence between the main terminals and the auxiliary terminals. The relationship between the main terminals and the auxiliary terminals can be found in the above description.

[0041] As can be seen from the above description of the types of power switching devices, when testing a component under test (DUT), the power switching device within the DUT is connected to a pulse constant current source via a first main connection terminal and a second main connection terminal. The excitation current flows into the DUT through either the first or second main connection terminal. Similarly, the excitation current for static parameter testing of a bridge arm circuit can be obtained.

[0042] In one embodiment of this utility model, the switch matrix includes a constant current source switch unit adapted and connected to a pulse constant current source, wherein... The constant current source switching unit includes a constant current excitation first branch and a constant current excitation second branch, and the constant current excitation first branch and constant current excitation second branch are adapted and connected to a pulse constant current source. The constant current excitation first branch includes several constant current excitation first branch switches; The constant current excitation second branch includes several constant current excitation second branch switches; The number of constant current excitation first branch switches and the number of constant current excitation second branch switches shall not be less than the number of power switching devices in the device under test unit; When testing a bridge arm circuit or a component under test, a corresponding constant current excitation first branch switch in the constant current excitation first branch is configured to be closed, and a corresponding constant current excitation second branch switch in the constant current excitation second branch is configured to be closed, so that the pulse constant current source can be adapted to connect with the bridge arm circuit or component under test. For any component under test, the direction of the excitation current applied to the power switching device is opposite to the direction of the excitation current applied to the freewheeling diode.

[0043] As explained above, the test objects for static parameter testing can be different. When the test objects are different, the pulse constant current source should be able to apply excitation current to the corresponding test object. In specific implementation, when the test objects are different, the application of excitation current can be adjusted by the constant current source switching unit within the switching matrix. To control the application of excitation current, the constant current source switching unit should include a first constant current excitation branch and a second constant current excitation branch. The first constant current excitation branch includes several constant current excitation first branch switches, and the second constant current excitation branch includes several constant current excitation second branch switches. Generally, the number of constant current excitation first branch switches and the number of constant current excitation second branch switches should not be less than the number of power switching devices in the device under test unit. Figures 1-4 When the device under test unit includes two power switching devices, the number of constant current excitation first branch switches and the number of constant current excitation second branch switches shall not be less than 2. Other cases can be referred to here for explanation, and will not be listed one by one.

[0044] Figures 1-4 In the middle, switch K 1a Switch K 1b For the two constant current excitation first branch switches in the constant current excitation first branch, switch K 1c Switch K 1d The two constant current excitation second switches within the second constant current excitation branch should be understood to include corresponding connection lines within both the first and second constant current excitation branches to ensure compatibility with pulse constant current sources. It should be noted that due to the large excitation current, both the first and second constant current excitation branch switches are high-voltage, high-current mechanical switches.

[0045] Figures 1-4 In the middle, switch K 1a The first end, switch K 1b The first terminal is connected to a pulse constant current source, switch K 1a The second terminal is connected to the first main connection terminal of the power switching device G1, and the switch K 1b The second terminal is connected to the first main connection terminal of the power switching device G2, and the switch K 1c The first end, switch K 1dThe first terminal is connected to a pulse constant current source, switch K 1c The second terminal is connected to the second main connection terminal of the power switching device G1, and the switch K 1d The second terminal is connected to the second main connection terminal of the power switching device G2.

[0046] Figure 2 The diagram illustrates an embodiment of static parameter testing for power switching device G1, in which power switching device G1 is in the ON state, and switch K should be configured. 1a and switch K 1c When in the closed state, the pulse constant current source applies excitation current to the power switching device G1, and the direction of the excitation current is from the first connection terminal of the power switching device G1 to the second connection terminal of the power switching device G1.

[0047] Figure 3 The image shows an embodiment of static parameter testing for the freewheeling diode DUT-U, in which switch K is still configured. 1a and switch K 1c The device is in a closed state, but the direction of the excitation current flows from the second connection terminal of the power switching device G1 to the first connection terminal of the power switching device G1. The difference is that at this time, the power switching device G1 should be in a closed state, and the excitation current flows through the freewheeling diode DUT-U.

[0048] Figure 4 The diagram illustrates an embodiment for static parameter testing of the bridge arm circuit. In this case, both power switching devices G1 and G2 are in the ON state, and switch K should be configured. 1a and switch K 1d When in a closed state, during static parameter testing, the excitation current flows in from the first connection terminal of power switching device G1, and flows back to the pulse constant current source through the second connection terminal of power switching device G1 - the first connection terminal of power switching device G2 - the second connection terminal of power switching device G2, thus forming a closed loop.

[0049] When static parameter testing of the freewheeling diodes DUT-U and DUT-L in the bridge arm circuit is required, the above can be referred to. Figure 4 , Figure 3 The corresponding explanations mentioned above will not be repeated here. Furthermore, when simultaneous static parameter testing of both bridge arm circuits is required, please refer to the relevant documentation. Figure 4 The configuration of the switch matrix should be based on the specific conditions required to achieve static parameter testing of both bridge arm circuits.

[0050] In one embodiment of this utility model, the pulse constant current source includes a current source and a current direction switching circuit adapted and connected to the current source, wherein... The current direction switching circuit includes a first direction switching branch connected in parallel with the current source and a second direction switching branch. The first branch of the direction switching includes NMOS transistor Q1 and NMOS transistor Q3. The drain terminal of NMOS transistor Q1 is connected to the positive terminal of the current source, and the source terminal of NMOS transistor Q1 is connected to the drain terminal of NMOS transistor Q3 and the constant current excitation first branch. The second branch of the direction switching includes NMOS transistors Q2 and Q4. The drain terminal of NMOS transistor Q2 is connected to the positive terminal of the current source, and the source terminal of NMOS transistor Q2 is connected to the drain terminal of NMOS transistor Q4 and the constant current excitation second branch. The source terminals of NMOS transistors Q3 and Q4 are both connected to the negative terminal of the current source. When NMOS transistors Q1 and Q4 are simultaneously turned on, and NMOS transistors Q2 and Q3 are simultaneously turned off, the pulse current source provides the excitation current in the first current direction. When NMOS transistors Q2 and Q3 are simultaneously turned on, and NMOS transistors Q1 and Q4 are simultaneously turned off, the pulse current source provides the excitation current in the second current direction.

[0051] Figures 1-4 and Figure 6 The figure illustrates one embodiment of a pulsed constant current source. As shown in the figure, the pulsed constant current source may include a current source and a current direction switching circuit. The current source can adopt a commonly used form. Figures 1-4 as well as Figure 6 In this circuit, I1 is a current source, which can provide excitation current. Therefore, the current source can be designed to provide the required excitation current, and current commutation can be achieved through a current direction switching circuit. Figure 2 and Figure 3 Two different current directions are used to meet the requirements of static parameter testing. In specific implementation, the excitation current with different current directions can be output by configuring the corresponding conduction states of NMOS transistors Q1, Q2, Q3, and Q4.

[0052] When the pulse constant current source adopts the above form, then: for any constant current excitation first branch switch, the first terminal of the constant current excitation first branch switch is connected to the source terminal of NMOS transistor Q1 and the drain terminal of NMOS transistor Q3, and the second terminal of the constant current excitation first branch switch is electrically connected to the first connection main terminal of a corresponding power switching device. For any constant current excitation second branch switch, the first terminal of the constant current excitation second branch switch is connected to the source terminal of NMOS transistor Q2 and the drain terminal of NMOS transistor Q4, and the second terminal of the constant current excitation second branch switch is electrically connected to the second connection main terminal of a corresponding power switching device.

[0053] Figures 1-4 In the middle, switch K 1a The first end, switch K 1b The first terminal is connected to the source terminal of NMOS transistor Q1 and the drain terminal of NMOS transistor Q3, and switch K... 1c The first end, switch K 1d The first terminal is connected to the source terminal of NMOS transistor Q2 and the drain terminal of NMOS transistor Q3.

[0054] In one embodiment of this utility model, the pulse constant current source further includes a commutation drive circuit, wherein... The commutation drive circuit includes at least four commutation drive modules, with each of the NMOS transistors Q1, Q2, Q3, and Q4 being adapted and connected to a commutation drive module. For any commutation drive module, it includes an optocoupler isolator, a drive amplifier, a signal conditioning circuit, and a drive connection circuit connected in sequence, wherein, The driving connection circuit includes a driving connection for a first NMOS transistor and a driving connection for a second NMOS transistor. The gate terminals of both the driving connection for the first NMOS transistor and the driving connection for the second NMOS transistor are connected to the signal processing circuit. The drain terminal of the first NMOS transistor is connected to the isolation voltage output by the isolation power supply, and the source terminal of the first NMOS transistor is connected to the drain terminal of the second NMOS transistor and the gate terminal of an NMOS transistor in the current direction switching circuit. The source terminal of the second NMOS transistor is connected to the source terminal of the NMOS transistor connected in the current direction switching circuit.

[0055] As explained above, the current output from the current source can be reversed using a current direction switching circuit. When the current direction switching circuit adopts the above form, a commutation drive circuit is needed to drive and control the corresponding conduction states of NMOS transistors Q1 to Q4 within the current direction switching circuit. Figure 6 The figure shows an embodiment of a commutation drive circuit. The commutation drive circuit includes four commutation drive modules, each of which corresponds to NMOS transistors Q1 to Q4. That is, one commutation drive module can drive one corresponding NMOS transistor. Figure 6 In the diagram, the structure within each dashed box represents a commutation drive module.

[0056] Depend on Figure 6 It can be seen that each commutation drive module may include an optocoupler isolator, a drive amplifier, a signal conditioning circuit, and a drive connection circuit connected in sequence, so as to... Figure 6 The following explanation uses the commutation drive module corresponding to NMOS transistor Q4 as an example. Figure 6 In this circuit, OG4 is an optocoupler isolator, OA4 is a driver amplifier, and OD4 is a signal conditioning circuit. The driver connection circuit includes NMOS transistors M40 and M41. In this case, NMOS transistor M40 forms a driver connection for the first NMOS transistor, and NMOS transistor M41 forms a driver connection for the second NMOS transistor. The optocoupler OG4 can isolate the input signal, and the driver amplifier OA4 can amplify the output signal of the optocoupler OG4. The signal conditioning circuit OD4 is used to condition the signal output by the driver amplifier OA4, such as by filtering. The form of the signal conditioning circuit OD4 can be selected as needed.

[0057] Depend on Figure 6 It can be seen that each commutation drive module can be powered by a DC-DC isolated power supply, which can output a 15V supply voltage. Figure 6 The power supply in this system is a DC-DC isolated power supply. In practice, the drive states of all commutation drive modules are configured by the Forward, Backward, and GND signals. Specifically, when the Forward signal is high relative to the GND signal and the Backward signal is low relative to the GND signal, NMOS transistors Q1 and Q3 are turned on, and the pulse constant current source outputs the excitation current in the first current direction. Conversely, when the Forward signal is low relative to the GND signal and the Backward signal is high relative to the GND signal, NMOS transistors Q2 and Q4 are turned on, and the pulse constant current source outputs the excitation current in the second current direction.

[0058] Of course, other forms of commutation drive circuits can also be used. The driving form of the commutation drive circuit can be selected as needed, based on the requirement of being able to drive the ground current direction switching circuit for commutation. Examples will not be given here.

[0059] In one embodiment of this utility model, the bias voltage source unit includes two bias voltage sources, and the switch matrix includes two sets of bias voltage switch units, with the bias voltage sources and bias voltage switch units connected in a one-to-one correspondence. For any bias voltage switching unit, the bias voltage switching unit includes a first bias voltage branch and a second bias voltage branch, wherein, The first bias voltage branch includes several first bias voltage branch switches; The second bias voltage branch includes several second bias voltage branch switches; The number of switches for the first branch of the bias voltage and the number of switches for the second branch of the bias voltage shall not be less than the number of bridge arm circuits in the unit of the device under test. For a power switching device, the control terminal of the power switching device is connected to the positive terminal of the corresponding bias voltage source through a first bias voltage branch switch, and the second auxiliary connection terminal of the power switching device is connected to the negative terminal of the corresponding bias voltage source through a second bias voltage branch switch.

[0060] Figures 1-4 The figure illustrates an embodiment of a bias voltage source unit comprising two bias voltage sources. In the figure, VS1 and VS2 are two voltage sources. Voltage source VS1 provides a drive bias voltage to power switching device G1, and voltage source VS2 provides a drive bias voltage to power switching device G2. It should be noted that the drive bias voltage provided by voltage source VS1 is mainly able to drive power switching device G1 to turn on or off. Similarly, the drive bias voltage provided by voltage source VS2 should be able to drive power switching device G2 to turn on or off. Therefore, the form adopted by voltage source VS1 and voltage source VS2 and the output voltage should be based on being able to drive the power switching device to turn on or off.

[0061] Similar to the pulse constant current source described above, each bias voltage source should be connected and cooperated with a corresponding bias voltage switching unit so that the bias voltage source can be configured to apply a bias voltage using the bias voltage switching unit. The bias voltage switching unit includes a first bias voltage branch and a second bias voltage branch. The first bias voltage branch includes a plurality of first bias voltage branch switches, and the second bias voltage branch includes a plurality of second bias voltage branch switches. Specifically, the number of first bias voltage branch switches and the number of second bias voltage branch switches are not less than the number of bridge arm circuits in the device under test unit. For example, if the device under test unit includes one bridge arm circuit, then the number of first bias voltage branch switches in each bias voltage switching unit should be 1. If it includes two bridge arm units, then the number of first bias voltage branch switches in each bias voltage switching unit should be 2.

[0062] like Figures 1-4 In the middle, K 2a K is the first branch switch for bias voltage. 2b For the second branch switch of the bias voltage, switch K 2a Switch K 2b Corresponding to voltage source VS1, switch K 2a The first terminal is connected to the positive terminal of voltage source VS1, and switch K... 2aThe second terminal is connected to the control terminal of the power switching device G1, and the second auxiliary terminal of the power switching device G1 is connected to the switch K. 2b It is connected to the negative terminal of voltage source VS1, therefore, when switch K... 2a Switch K 2b When both are closed, voltage source VS1 can drive power switching device G1 to turn on or off. Similarly, K 2c K is the first branch switch for bias voltage. 2d For the second branch switch of the bias voltage, switch K 2c Switch K 2d Corresponding to voltage source VS2, voltage source VS2 is controlled by switch K. 2c Switch K 2d For the connection and cooperation with power switch device G2, and the driving of power switch device G2 to turn on or off, please refer to the above description of the cooperation between power switch device G1 and voltage source VS1, which will not be repeated here.

[0063] When there are multiple bridge arm circuits, voltage source VS1 or voltage source VS2 can be used to drive the power switching devices in different bridge arm circuits to turn on or off. At this time, it is necessary to set the bias voltage switching unit in the switching matrix to meet the required driving and turning purpose. Examples will not be given here.

[0064] In one embodiment of this utility model, the voltage measurement unit includes two sets of voltage measurement components, wherein... Each voltage measurement component corresponds to a component under test, so as to measure the voltage between the first main connection terminal and the second main connection terminal, the voltage between the first auxiliary connection terminal and the second main connection terminal, and the voltage between the second auxiliary connection terminal and the second main connection terminal using the voltage measurement component.

[0065] As can be seen from the above description, the static parameters of power switching devices can be determined by voltage measurement during testing. Therefore, for a bridge arm circuit, the voltage measurement unit should include two sets of voltage measurement components. One set of voltage measurement components can be used to perform the required voltage measurement on a device under test.

[0066] In one embodiment of this invention, each voltage measurement component includes three voltmeters, and the switch matrix includes voltmeter switch units corresponding to each voltage measurement component. The voltmeter switching unit includes voltmeter lines that are respectively connected to three voltmeters; For any voltmeter circuit, the voltmeter circuit includes a first branch of the voltmeter and a second branch of the voltmeter. The voltmeter is adapted to a power switching device through the first branch of the voltmeter and the second branch of the voltmeter to perform voltage measurement.

[0067] Figures 1-4The figure illustrates an embodiment with two sets of voltage measurement components, each set including three voltmeters. In the figure, voltmeters Vl1 to Vl3 belong to the same voltage measurement component, and voltmeters Vl4 to Vl6 belong to the same voltage measurement component. It should be noted that... Figures 1-4 In the diagram, components that are not in operation are represented in grayscale, while components that are in operation are represented by normal lines, such as... Figure 2 In the diagram, the circuits corresponding to voltmeters Vl4 to Vl6 are grayed out, indicating that they are in a non-operating state. For the others, please refer to the explanation here.

[0068] Figure 2 In the circuit, for voltmeter Vl1, the first branch of the voltmeter includes switch K. 3a and switch K 3b One end of the voltmeter Vl1 is connected to switch K 3a The other end of the voltmeter Vl1 is connected to the first main terminal of the power switching device G1, and is connected to the switch K. 3b Connected to the second main terminal of power switching device G1, voltmeter Vl1 can measure the voltage between the first and second main terminals of power switching device G1. For details on the connection of voltmeters Vl2 to Vl6 to the power switching device via voltmeter circuitry, please refer to [reference needed]. Figures 2-4 And this explanation.

[0069] Figure 2 In this circuit, voltmeters Vl1 to Vl3 can measure the voltage corresponding to the power switching device G1. Specifically, after voltage measurement, the voltage drop between the first main connection terminal, the first auxiliary connection terminal, and the second auxiliary connection terminal of the power switching device G1 in the on state and the second main connection terminal can be measured (denoted as VU1, VU2, and VU3). At this time, we have: V CEsat(UCm-UEm)= VU1, V CEsat(UCa-UEa) =VU2-VU3, V CEsat(UCm-UEa) =VU1-VU3, V CEsat(UCa-UEm) =VU2, where, In the above characters, U represents the upper half of the bridge arm circuit, such as... Figure 1 In the diagram, power switching device G1 is the upper half of the bridge arm located in the bridge arm circuit, DUT-U represents the freewheeling diode corresponding to the power switching device, and L represents the lower half of the bridge arm in the bridge arm circuit. The case of L can be referred to the explanation of U here, and will not be described in detail again. C represents the collector of the power switch device, E represents the emitter of the power switch device, m represents the main terminal of the power switch device, and a represents the auxiliary terminal of the power switch device. Therefore, UCm represents the voltage measurement position of the main terminal of the collector of power switch device G1, UEm represents the voltage measurement position of the main terminal of the emitter of power switch device G1, and UEa represents the voltage measurement position of the auxiliary terminal of the emitter of power switch device. Other cases can be referred to here for explanation, and will not be explained one by one. It can be seen that through a single test, the voltage V of various combinations of main and auxiliary terminals can be obtained simultaneously. CEsat For other voltage measurements and determination of static parameters, please refer to the instructions here.

[0070] It should be noted that, except for the constant current excitation first branch switch and the constant current excitation second branch switch, which are both high voltage and high current mechanical switches, all other switches in the switch matrix are high voltage and low current mechanical switches.

[0071] As can be seen from the above description, the testing system of this utility model can test V CEsat Parameters and V F The corresponding tests for the parameters are merged into a single test. Figure 5 V is shown in CEsat Parameters and V F A timing diagram for parameter merging testing, the specific process of which is as follows: At time t0: Set the bias voltage for the power switching device to turn on the power switching device under test.

[0072] At time t1: Turn on NMOS transistors Q1 and Q3. Figure 5 A high level indicates that NMOS transistors Q1 and Q3 are turned on, while NMOS transistors Q2 and Q4 are turned off. Figure 5 A low level indicates that NMOS transistors Q2 and Q4 are off.

[0073] During the t2~t3 period: At time t2, the current source begins to output current, which gradually increases over time, reaching the target current value at time t3 and remaining constant; this is the excitation current. During this period, the voltage V of the power switching device under test... CE There will be transient voltage waveform response, but this voltage change process can be ignored.

[0074] During the t3~t4 period: the excitation current of the power switching device under test is constant, and the voltage response quickly enters a steady state. The voltage waveform is collected, and the average value of the waveform in the steady segment is the voltage V of the power switching device. CEsat parameter.

[0075] At time t4: Turn on NMOS transistors Q2 and Q4, and turn off NMOS transistors Q1 and Q3. At this time, the excitation current undergoes a current reversal, switching from the forward direction (flowing in from the collector, out from the emitter, and through the power switching device) to the reverse direction (flowing in from the emitter, out from the collector, and through the freewheeling diode).

[0076] At time t5: Turn off the power switching device under test to ensure that all excitation current flows into the freewheeling diode.

[0077] During the t5~t6 period: the excitation current of the freewheeling diode under test is constant, and the voltage response quickly enters a steady state. The voltage waveform is collected, and the average value of the waveform in the steady segment is taken. The absolute value is the voltage V of the freewheeling diode. F parameter.

[0078] During the time interval t6~t7: The current source begins to reduce its output current, which gradually decreases over time, reaching zero at time t7. During this time interval, the voltage V of the power switching device within the component under test... CE There will be transient voltage waveform response, but this voltage change process can be ignored.

[0079] At time t8: Turn off NMOS transistors Q2 and Q4, and the test ends.

[0080] It should be noted that when performing static parameter tests on the test object in other cases, the configuration of the pulse constant current source and the bias voltage source in conjunction with the test object, as well as the method of voltage measurement, can all be referred to here, and will not be repeated here.

[0081] Furthermore, the aforementioned test system only demonstrates the V testing of power switching devices. CEsat Parameter testing, and V testing of the freewheeling diode. F For example, when other static parameter tests are required, corresponding test elements can be added to the test system according to the test requirements of the corresponding static parameters, and the corresponding tests can be carried out according to the test requirements. The specific methods and processes for testing other static parameters will not be illustrated here.

Claims

1. A test system capable of improving the speed of static parameter testing, characterized in that, The test system includes a pulse constant current source, a bias voltage source unit, a voltage measurement unit, and a switch matrix, wherein... The pulse constant current source, bias voltage source unit, and voltage measurement unit are all connected to the device under test unit via a switch matrix. The device under test unit includes at least one bridge arm circuit, and the bridge arm circuit includes two adapted components under test. Each component under test includes a power switching device and a freewheeling diode for freewheeling when the power switching device is turned off. A switch matrix is ​​used to select and connect a pulse constant current source, a bias voltage source unit, and a voltage measurement unit to the device under test (DUT) unit for testing the bridge arm circuit or a component under test. A pulsed constant current source is used to provide excitation current to the bridge arm circuit or component under test. The bias voltage source unit provides a drive bias voltage to drive the corresponding power switching device to be in the on or off state. A voltage measurement unit is used to measure the voltage of the device under test (DUT) in order to determine the static parameters of the DUT using the measured test voltage.

2. The testing system according to claim 1, which can improve the testing speed of static parameters, is characterized in that: For any power switching device, a first auxiliary connection terminal and a first main connection terminal are provided at the first connection end of the power switching device, and both the first main connection terminal and the first auxiliary connection terminal are electrically connected to the first connection end. A second auxiliary connection terminal and a second main connection terminal are provided at the second connection end of the semiconductor device, and both the second main connection terminal and the second auxiliary connection terminal are electrically connected to the second connection end. For a component under test, the cathode of the freewheeling diode is electrically connected to the first connection terminal of the power switching device, and the anode of the freewheeling diode is electrically connected to the second connection terminal of the power switching device. Within the bridge arm circuit, one component under test forms the upper bridge arm unit, and another test component forms the lower bridge arm unit. The second main connection terminal in the upper bridge arm unit is electrically connected to the first main connection terminal in the lower bridge arm unit. When testing a component under test, the component under test is adapted to a pulse constant current source through a first main connection terminal and a second main connection terminal, and the excitation current flows into the component under test through the first main connection terminal or the second main connection terminal.

3. The test system of claim 2, wherein: The switching matrix includes constant current source switching units adapted and connected to a pulse constant current source, wherein, The constant current source switching unit includes a constant current excitation first branch and a constant current excitation second branch, and the constant current excitation first branch and constant current excitation second branch are adapted and connected to a pulse constant current source. The constant current excitation first branch includes several constant current excitation first branch switches; The constant current excitation second branch includes several constant current excitation second branch switches; The number of constant current excitation first branch switches and the number of constant current excitation second branch switches shall not be less than the number of power switching devices in the device under test unit; When testing a bridge arm circuit or a component under test, a corresponding constant current excitation first branch switch in the constant current excitation first branch is configured to be closed, and a corresponding constant current excitation second branch switch in the constant current excitation second branch is configured to be closed, so that the pulse constant current source can be adapted to connect with the bridge arm circuit or component under test. For any component under test, the direction of the excitation current applied to the power switching device is opposite to the direction of the excitation current applied to the freewheeling diode.

4. The test system of claim 3, wherein: The pulsed constant current source includes a current source and a current direction switching circuit adapted and connected to the current source, wherein, The current direction switching circuit includes a first direction switching branch connected in parallel with the current source and a second direction switching branch. The first branch of the direction switching includes NMOS transistor Q1 and NMOS transistor Q3. The drain terminal of NMOS transistor Q1 is connected to the positive terminal of the current source, and the source terminal of NMOS transistor Q1 is connected to the drain terminal of NMOS transistor Q3 and the constant current excitation first branch. The second branch of the direction switching includes NMOS transistors Q2 and Q4. The drain terminal of NMOS transistor Q2 is connected to the positive terminal of the current source, and the source terminal of NMOS transistor Q2 is connected to the drain terminal of NMOS transistor Q4 and the constant current excitation second branch. The source terminals of NMOS transistors Q3 and Q4 are both connected to the negative terminal of the current source. When NMOS transistors Q1 and Q4 are simultaneously turned on, and NMOS transistors Q2 and Q3 are simultaneously turned off, the pulse current source provides the excitation current in the first current direction. When NMOS transistors Q2 and Q3 are simultaneously turned on, and NMOS transistors Q1 and Q4 are simultaneously turned off, the pulse current source provides the excitation current in the second current direction.

5. The test system of claim 4, wherein: For any constant current excitation first branch switch, the first terminal of the constant current excitation first branch switch is connected to the source terminal of NMOS transistor Q1 and the drain terminal of NMOS transistor Q3, and the second terminal of the constant current excitation first branch switch is electrically connected to the first connection main terminal of a corresponding power switching device. For any constant current excitation second branch switch, the first terminal of the constant current excitation second branch switch is connected to the source terminal of NMOS transistor Q2 and the drain terminal of NMOS transistor Q4, and the second terminal of the constant current excitation second branch switch is electrically connected to the second connection main terminal of a corresponding power switching device.

6. The testing system according to claim 4, which can improve the testing speed of static parameters, is characterized in that: The pulsed constant current source also includes a commutation drive circuit, wherein... The commutation drive circuit includes at least four commutation drive modules, with each of the NMOS transistors Q1, Q2, Q3, and Q4 being adapted and connected to a commutation drive module. For any commutation drive module, it includes an optocoupler isolator, a drive amplifier, a signal conditioning circuit, and a drive connection circuit connected in sequence, wherein, The driving connection circuit includes a driving connection for a first NMOS transistor and a driving connection for a second NMOS transistor. The gate terminals of both the driving connection for the first NMOS transistor and the driving connection for the second NMOS transistor are connected to the signal processing circuit. The drain terminal of the first NMOS transistor is connected to the isolation voltage output by the isolation power supply, and the source terminal of the first NMOS transistor is connected to the drain terminal of the second NMOS transistor and the gate terminal of an NMOS transistor in the current direction switching circuit. The source terminal of the second NMOS transistor is connected to the source terminal of the NMOS transistor connected in the current direction switching circuit.

7. The testing system according to any one of claims 2 to 6, characterized in that: The bias voltage source unit includes two bias voltage sources, and the switch matrix includes two sets of bias voltage switch units. The bias voltage sources and bias voltage switch units are connected in a one-to-one correspondence. For any bias voltage switching unit, the bias voltage switching unit includes a first bias voltage branch and a second bias voltage branch, wherein, The first bias voltage branch includes several first bias voltage branch switches; The second bias voltage branch includes several second bias voltage branch switches; The number of switches for the first branch of the bias voltage and the number of switches for the second branch of the bias voltage shall not be less than the number of bridge arm circuits in the unit of the device under test. For a power switching device, the control terminal of the power switching device is connected to the positive terminal of the corresponding bias voltage source through a first bias voltage branch switch, and the second auxiliary connection terminal of the power switching device is connected to the negative terminal of the corresponding bias voltage source through a second bias voltage branch switch.

8. The testing system according to any one of claims 2 to 6, characterized in that: The voltage measurement unit includes two sets of voltage measurement components, wherein, Each voltage measurement component corresponds to a component under test, so as to measure the voltage between the first main connection terminal and the second main connection terminal, the voltage between the first auxiliary connection terminal and the second main connection terminal, and the voltage between the second auxiliary connection terminal and the second main connection terminal using the voltage measurement component.

9. The testing system according to claim 8, which can improve the testing speed of static parameters, is characterized in that: Each voltage measurement assembly includes three voltmeters, and the switch matrix includes voltmeter switch units corresponding to each voltage measurement assembly. The voltmeter switching unit includes voltmeter lines that are respectively connected to three voltmeters; For any voltmeter circuit, the voltmeter circuit includes a first branch of the voltmeter and a second branch of the voltmeter. The voltmeter is adapted to a power switching device through the first branch of the voltmeter and the second branch of the voltmeter to perform voltage measurement.

10. The testing system according to claim 3, which can improve the testing speed of static parameters, is characterized in that: Both the constant current excitation first branch switch and the constant current excitation second branch switch are high-voltage, high-current mechanical switches.

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