Charging and discharging device

Abstract

The embodiment of the invention relates to a charging and discharging device, and relates to the technical field of circuits. The charging and discharging device comprises a power interface circuit, a first inductor, a first switch, a second switch, a third switch, a fourth switch, a first test end and a second test end. The first end of the first switch, the first end of the second switch and the first end of the first inductor are all coupled with the first test end. The first end of the third switch, the first end of the fourth switch and the second end of the first inductor are all coupled with the second test end. The second end of the first switch and the second end of the third switch are both coupled with the first end of the power interface circuit, and the second end of the second switch and the second end of the fourth switch are both coupled with the second end of the power interface circuit. The first test end and the second test end are used for being coupled with a power device. The power interface circuit is used for inputting or outputting current. In this way, the problem that the frequency of surge testing is low can be solved.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of circuit technology, and in particular to a charging and discharging device. Background Art

[0002] Silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs) are increasingly being used in high-voltage, high-current scenarios, so the long-term reliability of SiC MOSFETs is very important, among which surge reliability is a particularly important reliability indicator. SiC MOSFETs need to undergo surge testing before leaving the factory to eliminate devices that fail early. Traditional surge testing can output square wave current to test SiC MOSFETs, but when surge testing is repeated, the frequency of surge testing is low. Summary of the invention

[0003] The embodiment of the present application provides a charging and discharging device, which solves the problem in the prior art that the frequency of surge testing is low when surge testing is repeated.

[0004] In order to achieve the above purpose, the embodiment of the present application adopts the following technical solution:

[0005] In a first aspect, a charge and discharge device is provided, and the charge and discharge device includes a power interface circuit, a first inductor, a first switch, a second switch, a third switch, a fourth switch, a first test terminal, and a second test terminal. The first end of the first switch, the first end of the second switch, and the first end of the first inductor are all coupled to the first test terminal. The first end of the third switch, the first end of the fourth switch, and the second end of the first inductor are all coupled to the second test terminal. The second end of the first switch and the second end of the third switch are both coupled to the first end of the power interface circuit, and the second end of the second switch and the second end of the fourth switch are both coupled to the second end of the power interface circuit. The first test terminal and the second test terminal are used to couple with a power device. The power interface circuit is used to input or output current.

[0006] In the above technical solution, the power interface circuit can not only input current when the first inductor needs to be charged, so that the first inductor is charged through the power interface circuit, but also output residual current after the first inductor provides square wave current, so that the first inductor outputs the residual current through the power interface current, avoiding the problem that all residual currents need to wait for energy-consuming devices (such as resistors) to be consumed, thereby avoiding the problem that the energy-consuming devices consume too much residual current and cause serious heating of the circuit and need to wait for the circuit to dissipate heat, and reducing the waiting time between multiple tests. Therefore, on the one hand, the charging and discharging device can increase the test frequency and improve the system reliability of long-term repeated testing. On the other hand, the charging and discharging device can reach a test frequency of microseconds, which can meet the needs of multi-time scale surge testing. On the other hand, the test cost of the charging and discharging device is low, which can meet the needs of batch testing.

[0007] In a possible implementation of the first aspect, the first inductor is used to: when the first switch and the fourth switch are turned on and the second switch and the third switch are turned off, the first inductor is charged through the power interface circuit to store a first amount of electricity. When the first switch, the second switch, the third switch and the fourth switch are turned off, a square wave current is output to the power device through the first test terminal and the second test terminal based on the stored first amount of electricity. When the second switch and the third switch are turned on and the first switch and the fourth switch are turned off, a return current is output through the power interface circuit. The return current is the residual current in the first inductor after the square wave current is output. In the above possible implementation, when the first switch and the fourth switch are turned on and the second switch and the third switch are turned off, the first inductor forms a loop with the power interface circuit, and the first inductor can be charged through the power interface circuit. When the first switch, the second switch, the third switch and the fourth switch are turned off, the first inductor forms a loop with the power device, and the first inductor can be used to output a square wave current to the power device. When the second switch and the third switch are turned on and the first switch and the fourth switch are turned off, the first inductor forms a loop with the power interface circuit, and the first inductor can output a return current to the power interface circuit, and release the residual current through the power interface circuit to consume the residual current of the first inductor. In this way, the heating of the resistor can be greatly reduced, and the power loss of the fourth surge test circuit can be reduced. Furthermore, power circulation and energy recovery can be achieved.

[0008] In a possible implementation of the first aspect, the charge and discharge circuit further includes a first power supply, and the first power supply is used for power supply or energy storage. The first end of the first power supply is coupled to the first end of the power interface circuit, and the second end of the first power supply is coupled to the second end of the power interface circuit. In the above possible implementations, by providing a first power supply with an energy storage function, the first power supply interface circuit can provide the first power and recover energy, thereby reducing power loss. In addition, the first power supply is used for power supply or energy storage, and the device with energy storage function and power supply function is set to the same device, so that the circuit setting is simpler.

[0009] In a possible implementation of the first aspect, the power interface circuit further includes a power switch, a return switch, a power supply end, and a return end. The charging and discharging device further includes a second power supply and an energy storage circuit, the second power supply is used for power supply, and the energy storage circuit is used for energy storage. The power supply end of the power interface circuit is coupled to the first end of the second power supply. The return end of the power interface circuit is coupled to the first end of the energy storage circuit. The second end of the second power supply and the second end of the energy storage circuit are both coupled to the second end of the power interface circuit. The power supply end of the power interface circuit is coupled to the first end of the power switch, the return end of the power interface circuit is coupled to the first end of the return switch, and the second end of the power switch and the second end of the return switch are both coupled to the first end of the power interface circuit. In the above possible implementation, by setting a second power supply for power supply, the first amount of electricity can be provided through the power interface circuit, and by setting an energy storage circuit for energy storage, energy can be recovered through the power interface circuit to reduce power loss. And, the devices with energy storage function and power supply function are set as different devices, the second power supply can be a power supply with energy storage function, or a common power supply, the energy storage circuit can also include a simple energy storage element, and the types of the second power supply and the energy storage circuit are not limited.

[0010] In a possible implementation of the first aspect, the charging and discharging device further includes a first relay switch, a second relay switch, a first freewheeling loop switch, a second freewheeling loop switch, a capacitor, a resistor, and a second inductor. The first end of the first relay switch, the first end of the second relay switch, and the first end of the first switch are all coupled to the first end of the second switch. The second end of the first relay switch is coupled to the first end of the first inductor. The second end of the second relay switch is coupled to the first end of the capacitor. The second end of the first inductor, the second end of the capacitor, the first end of the first freewheeling loop switch, the first end of the second inductor, and the first end of the third switch are all coupled to the first end of the fourth switch. The second end of the second inductor is coupled to the first end of the resistor. The second end of the resistor is coupled to the first end of the second freewheeling loop switch. The second end of the first freewheeling loop switch and the second end of the second freewheeling loop switch are both coupled to the second test end. In the above possible implementation, the charging and discharging device can output a square wave current through the first inductor; and can output a sinusoidal half-wave current through an oscillation circuit composed of a capacitor, a second inductor, and a resistor. In this way, the charging and discharging device can output both square wave current and half-sine wave current, and comprehensive surge tests with different surge waveforms can be performed in the same device.

[0011] In a possible implementation of the first aspect, the charge and discharge device further includes a first relay switch, a second relay switch, a first freewheeling loop switch, a second freewheeling loop switch, a capacitor and a resistor. The first end of the first relay switch, the first end of the second relay switch and the first end of the first switch are all coupled to the first end of the second switch. The second end of the first relay switch and the first end of the resistor are all coupled to the first end of the first inductor. The second end of the second relay switch is coupled to the first end of the capacitor. The second end of the first inductor, the second end of the capacitor, the first end of the first freewheeling loop switch and the first end of the third switch are all coupled to the first end of the fourth switch. The second end of the resistor is coupled to the first end of the second freewheeling loop switch. The second end of the first freewheeling loop switch and the second end of the second freewheeling loop switch are both coupled to the second test end. In the above possible implementation, the charge and discharge device can output a square wave current through the first inductor; and can output a sinusoidal half-wave current through an oscillation circuit formed by the capacitor, the first inductor and the resistor. In this way, the charge and discharge device can output both a square wave current and a sinusoidal half-wave current, and a comprehensive surge test of different surge waveforms can be performed in the same device. Furthermore, the first inductor is reused to output a half-sine wave current or a square wave current, thereby saving hardware cost.

[0012] In a possible implementation of the first aspect, the first inductor is used to: when the first switch, the fourth switch and the first relay switch are turned on, the second switch, the third switch are turned off, and the second relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, charge through the power interface circuit to store a first amount of electricity. When the first relay switch and the first freewheeling loop switch are turned on, and the first switch, the second switch, the third switch, the fourth switch, the second relay switch and the second freewheeling loop switch are turned off, output a square wave current to the power device through the first test terminal and the second test terminal based on the stored first amount of electricity. When the second switch, the third switch and the first relay switch are turned on, and the first switch, the fourth switch, the second relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, output a return current through the first end of the power interface circuit and the second end of the power interface circuit. The return current is the residual current in the first inductor after the square wave current is output. In the above possible implementations, when the first switch, the fourth switch and the first relay switch are turned on, and the second switch, the third switch are turned off, and the second relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, the first inductor forms a loop with the power interface circuit, and the first inductor can be charged through the power interface circuit. When the first relay switch and the first freewheeling loop switch are turned on, and the first switch, the second switch, the third switch, the fourth switch, the second relay switch and the second freewheeling loop switch are turned off, the first inductor forms a loop with the power device, and the first inductor can be used to output a square wave current to the power device. When the second switch, the third switch and the first relay switch are turned on, and the first switch, the fourth switch, the second relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, the first inductor forms a loop with the power interface circuit, and the first inductor can output a return current through the power interface circuit. By controlling each switch to be turned on or off, a basis is provided for the charging and discharging device to output a square wave current through the first inductor.

[0013] In a possible implementation of the first aspect, the capacitor is used to: when the second switch, the third switch, and the second relay switch are turned on, and the first switch, the fourth switch, the first relay switch, the first freewheeling loop switch, and the second freewheeling loop switch are turned off, the capacitor is charged through the power interface circuit to store the second amount of electricity. When the first switch, the second switch, the third switch, the fourth switch, the first relay switch, and the first freewheeling loop switch are turned off, and the second relay switch and the second freewheeling loop switch are turned on, a sinusoidal half-wave current is output to the power device through the first test terminal and the second test terminal based on the stored second amount of electricity. In the above possible implementation, when the second switch, the third switch, and the second relay switch are turned on, and the first switch, the fourth switch, the first relay switch, the first freewheeling loop switch, and the second freewheeling loop switch are turned off, the capacitor forms a loop with the power interface circuit, and the capacitor can be charged through the power interface circuit. When the first switch, the second switch, the third switch, the fourth switch, the first relay switch, and the first freewheeling loop switch are turned off, and the second relay switch and the second freewheeling loop switch are turned on, the capacitor forms an oscillation loop with the resistor, the first inductor, or the second inductor, and the capacitor can be used to output a sinusoidal half-wave current to the power device. By controlling each switch to be turned on or off, a basis is provided for the charging and discharging device to output a half-sine wave current through the capacitor.

[0014] In a possible implementation of the first aspect, there are multiple power devices, and the first test terminal and the second test terminal are used to couple multiple power devices connected in series. In the above possible implementation, multiple power devices are connected in series to the charging and discharging device to achieve multi-station testing, and the test current between each station is consistent.

[0015] In a possible implementation of the first aspect, the device further includes a control circuit, which is coupled to at least one of the first switch, the second switch, the third switch, and the fourth switch. In the above possible implementation, the first switch, the second switch, the third switch, and the fourth switch can be flexibly controlled by the control circuit to be turned on or off, so that the test can be automatically performed, making the test operation simpler. The charge and discharge device can study the comprehensive performance of the DUT under complex surge waveforms, multiple time scales, complex surge current stresses, complex surge test frequencies, etc. The test frequency can reach microseconds, and the minimum pulse width of the surge current is not limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 A schematic diagram of the structure of a surge test device provided in an embodiment of the present application;

[0017] Figure 2 A schematic diagram of the structure of a first surge test circuit provided in an embodiment of the present application;

[0018] Figure 3A schematic diagram of the structure of a second surge test circuit provided in an embodiment of the present application;

[0019] Figure 4 A schematic diagram of the structure of a third surge test circuit provided in an embodiment of the present application;

[0020] Figure 5 A schematic diagram of a fourth surge test circuit provided in an embodiment of the present application Figure 1 ;

[0021] Figure 6 A schematic diagram of a fourth surge test circuit provided in an embodiment of the present application Figure 2 ;

[0022] Figure 7 A schematic diagram of a fourth surge test circuit provided in an embodiment of the present application Figure 3 ;

[0023] Figure 8 A schematic diagram of a fourth surge test circuit provided in an embodiment of the present application Figure 4 ;

[0024] Fig. 9 A schematic diagram of a fourth surge test circuit provided in an embodiment of the present application Figure 5 ;

[0025] Fig.10 A schematic diagram of a fourth surge test circuit provided in an embodiment of the present application Figure 6 ;

[0026] Fig.11 A waveform diagram of a square wave surge test provided in an embodiment of the present application;

[0027] Fig.12 A waveform diagram of a comprehensive waveform surge test provided in an embodiment of the present application. DETAILED DESCRIPTION

[0028] In the embodiment of the present application, "at least one" refers to one or more, and "multiple" refers to two or more. "And / or" describes the association relationship of the associated objects, indicating that there may be three relationships. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone, where A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single items or plural items. For example, at least one of a, b, or c can represent: a, b, c, ab, ac, bc, or abc, where a, b, c can be single or multiple. In addition, the embodiment of the present application uses words such as "first" and "second" to distinguish between the same items or similar items with basically the same functions and effects. For example, the first threshold and the second threshold are only to distinguish different thresholds, and do not limit their order. Those skilled in the art can understand that words such as "first" and "second" do not limit the quantity and execution order.

[0029] In the embodiments of the present application, the words "exemplary" or "for example" are used to indicate examples, illustrations or descriptions. Any embodiment or design described as "exemplary" or "for example" in the embodiments of the present application should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of words such as "exemplary" or "for example" is intended to present related concepts in a specific way.

[0030] In the embodiments of the present application, the terms "first", "second", etc. are only used for convenience of description and cannot be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. In addition, the step numbers are only used to distinguish different steps, and are not used to define the order or importance between the steps.

[0031] In the embodiments of the present application, the term "coupling" should be understood in a broad sense. For example, "coupling" can be direct coupling or indirect coupling through an intermediate medium.

[0032] Before introducing the specific contents of the embodiments of the present application, the technical terms involved in the embodiments of the present application are first explained.

[0033] Surge current refers to the peak current that flows into a device when the power is turned on or when the device is disturbed by an external spike pulse. Usually, the surge current is much larger than the steady-state input current, so the surge current may cause the device to burn out or cause the PN junction of the transistor device to break down, and other device failure risks.

[0034] Surge testing (ST) refers to testing the transient surge current or voltage of a device to evaluate the device's tolerance by simulating the overcurrent or overvoltage conditions that may occur under real usage conditions. During the productization process, surge testing can verify whether the device can withstand surge current and some characteristic changes under surge current, and eliminate early failure devices with surface effect defects.

[0035] Silicon carbide (SiC) materials have the characteristics of high critical breakdown electric field, high thermal conductivity, high electron saturation drift velocity, and large bandgap width. SiC power devices can achieve the requirements of higher power, smaller size, and working under more severe conditions. Among them, SiC metal-oxide-semiconductor field-effect transistor (MOSFET) devices are used in ultra-high voltage AC and DC transmission, electric vehicles and other fields. These fields need to withstand high voltage and large current (such as surge current), so the long-term reliability of SiC MOSFET devices is very important. In order to save costs, some application scenarios replace the anti-parallel diode in the device with a body diode. When the device is subjected to the stress of surge current, the surge current is mainly borne by the body diode inside the device. Under the stress of the surge circuit, the body diode of SiC MOSFET may experience bipolar degradation, and its influencing factors may include the number of basal plane dislocations (BPD), current density, temperature, and excitation time. To ensure the reliability of the device, a series of reliability tests are used to evaluate and screen the device before it leaves the factory. Among them, surge testing is very important. At present, the reason why the device fails after surge testing is still unclear, which may be related to temperature, pulse width, gate voltage and other reasons. For SiC MOSFET, comprehensive surge test (CST) reliability research with different time scales (microseconds, milliseconds, seconds) and different surge current waveforms (half-sine wave, square wave) is of great significance to improving the surge resistance of SiC MOSFET.

[0036] Next, the application scenarios of the embodiments of the present application are introduced. The charging and discharging device in the embodiments of the present application can be applied to a surge test device, and the surge test device can be used to provide surge current for the device. Figure 1 The surge test device 100 is used to couple a device under test (DUT) and provide a surge current to the DUT. The surge current may be a square wave current or a half-sine wave current.

[0037] In some possible implementations, Figure 1The surge test device 100 shown may be a first surge test circuit for providing a half-sine wave surge current. Figure 2 As shown, the first surge test circuit 100A includes a first voltage source V1A, a first capacitor C1A, a first transistor Q1A, a first resistor R1A, a second transistor Q2A, a second resistor R2A, and a first inductor L2A. Among them, the first voltage source V1A, the first transistor Q1A and the first resistor R1A are connected in series. The second transistor Q2A, the second resistor R2A and the first inductor L2A are used to be connected in series with the DUT. The branch where the first voltage source V1A, the first transistor Q1A, and the first resistor R1A are located, and the branch where the first capacitor C1A is located, and the branch where the second transistor Q2A, the second resistor R2A, the first inductor L2A, and the DUT are located are connected in parallel. By controlling each switch to be turned on or off, the first surge test circuit 100A can be controlled to be in different working states.

[0038] For example, in the first working state of the first surge test circuit 100A, the first transistor Q1A is turned on, the second transistor Q2A is turned off, and the turned-on circuit is as follows: Figure 2 As shown by the dotted line ① in the figure. At this time, the first voltage source V1A charges the first capacitor C1A through the first resistor R1A. When the voltage of the first capacitor C1A reaches the voltage of the first voltage source V1A, the first capacitor C1A is fully charged, and the circuit can be switched to the second working state to discharge the first capacitor C1A to the DUT. In the second working state of the first surge test circuit 100A, the second transistor Q2A is turned on, and the first transistor Q1A is turned off. The turned-on circuit is as shown in FIG. Figure 2 As shown by the dotted line ② in FIG. At this time, the oscillation circuit composed of the first capacitor C1A, the second resistor R2A, and the first inductor L2A is used to output a sinusoidal half-wave surge current to the DUT, and the second resistor R2A is the energy dissipation resistor of the circuit. When the second transistor Q2A is turned off, a sinusoidal half-wave surge current test is completed.

[0039] Exemplarily, by repeating the above two working states, the sinusoidal half-wave surge current test can be repeated. However, the first surge test circuit 100A has the following problems: First, the second resistor R2A generates severe heat, and the circuit loses severe power. It takes a long time to wait for the resistor to dissipate heat during repeated testing, which limits the test frequency, and there is a risk of system reliability for long-term repeated testing. Second, it only supports test frequencies at the millisecond level, and it is difficult to support test frequencies at the microsecond level, so it is difficult to perform surge tests on multiple time scales. Third, it only supports sinusoidal half-wave surge current tests, and does not support square wave surge current tests, so comprehensive surge tests with different surge current waveforms cannot be performed in the same circuit.

[0040] In some possible implementations, Figure 1The surge test device 100 shown may be a second surge test circuit for providing a square wave surge current. Figure 3 As shown, the second surge test circuit 100B includes a second voltage source V1B, a second capacitor C1B, a third transistor Q1B, a fourth transistor Q2B, and a third resistor R2B. The second voltage source V1B and the third transistor Q1B are connected in series. The fourth transistor Q2B and the third resistor R2B are used to be connected in series with the DUT. The branch where the second voltage source V1B and the third transistor Q1B are located, the branch where the second capacitor C1B is located, and the branch where the fourth transistor Q2B, the third resistor R2B, and the DUT are located are connected in parallel. By controlling each switch to be turned on or off, the second surge test circuit 100B can be controlled to be in different working states.

[0041] For example, in the first working state of the second surge test circuit 100B, the third transistor Q1B is turned on, and the fourth transistor Q2B is turned off. Figure 3 At this time, the second voltage source V1B charges the second capacitor C1B. When the voltage of the second capacitor C1B reaches the voltage of the second voltage source V1B, the second capacitor C1B is fully charged, and the circuit can be switched to the second working state to discharge the second capacitor C1B to the DUT.

[0042] For example, in the second working state of the second surge test circuit 100B, the fourth transistor Q2B is turned on, and the third transistor Q1B is turned off. Figure 3 As shown by the dotted line ④ in FIG. At this time, the loop formed by the second capacitor C1B and the third resistor R2B is used to output a square wave surge current to the DUT, and the third resistor R2B is an energy dissipation resistor of the loop. When the fourth transistor Q2B is turned off, a square wave surge current test is completed.

[0043] Exemplarily, by repeating the above two working states, the square wave surge current test can be repeated. However, the second surge test circuit 100B has the following problems: First, the third resistor R2B generates severe heat, and the circuit loses severe power. It takes a long time to wait for the resistor to dissipate heat during repeated testing, which limits the test frequency, and there is a risk of system reliability for long-term repeated testing. Second, it only supports test frequencies at the millisecond level, and it is difficult to support test frequencies at the microsecond level, so it is difficult to perform surge tests on multiple time scales. Third, it only supports square wave surge current tests, and does not support sinusoidal half-wave surge current tests, so it is not possible to perform comprehensive surge tests with different surge current waveforms in the same circuit.

[0044] In some possible implementations, Figure 1 The surge test device 100 shown may be a third surge test circuit for providing a half-sine wave and a square wave surge current. Figure 4As shown, the third surge test circuit 100C includes a programmable current source 110C, an auxiliary circuit 120C and a host computer ( Figure 4 ). Among them, the host computer is used to set the number of tests, frequency and amplitude according to the surge current waveform (such as half-sine wave or square wave, etc.) to be tested, and control the programmable current source 110C to output the surge current to the DUT through the auxiliary circuit 120C to achieve repeated surge current testing. The third surge test circuit 100C can support a test frequency at the microsecond level, but there are the following problems: First, the programmable current source 110C is expensive, the test cost is high, and it is difficult to meet the needs of batch testing. Second, the minimum pulse width of the surge current that the programmable current source 110C can provide is limited.

[0045] Analysis of the above problems shows that the square wave circuit (circuit for outputting square wave current) usually consumes residual current through energy-consuming devices (such as resistors). Generally, the square wave circuit can include a capacitor-resistance square wave circuit or an inductance square wave circuit. The capacitor-resistance square wave circuit includes a circuit of capacitor and resistor, wherein the capacitor is used to output square wave current through the resistor. The inductance square wave circuit includes an inductor, wherein the inductor is used to output square wave current. Since both capacitors and inductors are reactive power devices, after the square wave current is output to the DUT, the residual current needs to be consumed by the resistor, so the inductance square wave circuit usually also needs to be connected in series with the inductor. As a result, two problems will arise. The first problem is that in the process of the square wave circuit outputting the square wave current, the square wave current will pass through the resistor to make the resistor heat up, which will cause partial heating. The second problem is that after the square wave circuit outputs the square wave current, all the residual current will pass through the resistor to make the resistor continue to heat up, which will cause another part of the heating.

[0046] In some possible implementations, to improve the above problems, Figure 1 The surge test device 100 shown may be a charge-discharge device provided in an embodiment of the present application. The charge-discharge device may be Figure 5 The fourth surge test circuit 100D in the embodiment of the present invention can output a square wave current through the first inductor L1D, thereby performing a square wave surge current test. The first inductor L1D can include a plurality of inductors connected in series or in parallel.

[0047] Exemplarily, the fourth surge test circuit 100D may include a power interface circuit 110D, a first inductor L1D, a first switch Q1D, a second switch Q2D, a third switch Q3D, a fourth switch Q4D, a first test terminal, and a second test terminal. The first terminal of the first switch Q1D, the first terminal of the second switch Q2D, and the first terminal of the first inductor L1D are all coupled to the first test terminal. The first terminal of the third switch Q3D, the first terminal of the fourth switch Q4D, and the second terminal of the first inductor L1D are all coupled to the second test terminal. The second terminal of the first switch Q1D and the second terminal of the third switch Q3D are both coupled to the first terminal of the power interface circuit 110D. The second terminal of the second switch Q2D and the second terminal of the fourth switch Q4D are both coupled to the second terminal of the power interface circuit 110D. The first test terminal and the second test terminal are used to couple with a power device. The power interface circuit 110D is used to input or output current.

[0048] Exemplarily, the first switch Q1D, the second switch Q2D, the third switch Q3D, and the fourth switch Q4D may be an H-bridge circuit structure, the branch where the first switch Q1D and the second switch Q2D are located is one arm of the H-bridge, the branch where the third switch Q3D and the fourth switch Q4D are located is the other arm of the H-bridge, and the branch where the first inductor L1D is located is arranged between the two arms. Exemplarily, the power interface circuit 110D may be DC coupled to a DC voltage source having an energy storage function.

[0049] Exemplarily, the first inductor L1D is used to charge through the power interface circuit 110D. After charging is completed, the first inductor L1D is used to output a square wave current to the DUT through the first test terminal and the second test terminal, thereby performing a square wave surge current test on the DUT. After the output of the square wave current is completed, there is still residual current in the first inductor L1D. If the residual current is consumed by energy-consuming devices (such as resistors), the circuit will heat up. When the surge test is repeated, a certain waiting time is required between the two surge tests to allow the energy-consuming devices to completely dissipate heat, which will make the frequency of the surge test lower. In addition, circuit heating may reduce the reliability of the system for long-term repeated testing. In the present application, Figure 5In the illustrated embodiment, the power interface circuit 110D can not only input current when the first inductor L1D needs to be charged, so that the first inductor L1D is charged through the power interface circuit 110D, but also output current after the first inductor L1D provides square wave current, so that the first inductor L1D outputs the residual current through the power interface current, avoiding the problem that all residual current needs to wait for energy-consuming devices to consume, thereby avoiding the problem that the energy-consuming devices consume too much residual current and cause serious circuit heating and need to wait for the circuit to dissipate heat, and reducing the waiting time between multiple tests. Therefore, on the one hand, the fourth surge test circuit 100D can increase the test frequency and improve the system reliability of long-term repeated tests. On the other hand, the fourth surge test circuit 100D can reach a test frequency of microseconds, which can meet the needs of multi-time scale surge testing. On the other hand, the test cost of the fourth surge test circuit 100D is low, which can meet the needs of batch testing.

[0050] In some possible implementations, such as Figure 5 As shown, the number of DUTs can be multiple, and the first test terminal and the second test terminal are used to couple multiple DUTs in series. Exemplarily, the DUT can be a power device. For example, the DUT can include: at least one of a diode, a triode, a field effect transistor, a thyristor, an insulated gate bipolar transistor (IGBT) and other transistors. Exemplarily, the material of the DUT can be SiC material, or silicon material, or other materials, and the embodiment of the present application does not limit this. In an embodiment of the present application, multiple transistors to be tested are connected in series to the fourth surge test circuit 100D, so that multi-station testing can be achieved, and the test current between each station is consistent.

[0051] In some possible implementations, by controlling the on or off of the first switch Q1D, the second switch Q2D, the third switch Q3D, and the fourth switch Q4D, the current flow direction of the fourth surge test circuit 100D can be controlled, thereby controlling the charging or discharging of the first inductor L1D.

[0052] For example, in combination with the first inductor L1D and the on / off states of the first switch Q1D, the second switch Q2D, the third switch Q3D, and the fourth switch Q4D, Figure 5 The working states of the fourth surge test circuit 100D shown in the figure at different time periods when performing a square wave surge current test are introduced.

[0053] Please refer to Figure 6In (a), in the first time period, the first switch Q1D and the fourth switch Q4D are turned on, and the second switch Q2D and the third switch Q3D are turned off, and the conductive loop is shown as the dotted line ⑤. According to the circuit, it can be seen that the first inductor L1D is charged from the DC voltage source DC through the power interface circuit 110D to store the first electric quantity. The length of the first time period can be determined according to the expected surge current peak Im and the inductance of the first inductor L1D. When the current of the first inductor L1D is charged to Im, the first time period ends.

[0054] Please refer to Figure 6 In (b), in the second period after the first period, the first switch Q1D, the second switch Q2D, the third switch Q3D and the fourth switch Q4D are turned off, and the conductive loop is shown as the dotted line ⑥. According to the circuit, it can be seen that the first inductor L1D outputs a square wave current to the DUT through the first test terminal and the second test terminal based on the stored first electric quantity. The current of the first inductor L1D does not change suddenly, and the current is a square wave current with a current peak value of Im. The length of the second period can be determined according to the expected duration of the surge current.

[0055] Please refer to Figure 6 In (c), in the third period after the second period, the second switch Q2D and the third switch Q3D are turned on, and the first switch Q1D and the fourth switch Q4D are turned off, and the conductive loop is shown as the dotted line ⑦. According to the circuit, it can be seen that the first inductor L1D outputs a return current to the DC voltage source DC through the power interface circuit 110D. The return current is the residual current in the first inductor L1D after the square wave current is output. The current of the first inductor L1D does not change suddenly, and the return current output to the DC voltage source is still Im.

[0056] Exemplarily, the square wave surge current test can be repeated by repeating the above three time periods. In an embodiment of the present application, the first inductor L1D can be charged through the power interface circuit 110D, and output a square wave current to the DUT after charging. After the square wave current is output, the first inductor L1D can output a return current to the power interface circuit 110D, and release the residual current through the power interface circuit 110D to consume the residual current of the first inductor L1D. No energy-consuming device may be set in the fourth surge test circuit 100D to consume the residual current, and only a small part of the resistors that may exist inside the DUT will generate heat. In this way, the heating of the resistors can be greatly reduced, and the power loss of the fourth surge test circuit 100D can be reduced. Furthermore, power circulation and energy recovery can be achieved.

[0057] In some possible implementations, the fourth surge test circuit 100D may include an energy-consuming device, such as a first resistor, in addition to the first inductor L1D. Exemplarily, the first end of the first switch Q1D and the first end of the second switch Q2D are coupled to the first end of the first resistor, and the second end of the first resistor is coupled to the first end of the first inductor L1D. That is, the first resistor is connected in series with the first inductor L1D. In the embodiment of the present application, in the third period, the first inductor L1D outputs a residual current to the power interface circuit 110D. When the residual current passes through the first resistor, part of the residual current will be consumed by the first resistor, and the remaining part of the residual current is output to the power supply circuit 130D for storage. In the embodiment of the present application, it is impossible to avoid the first resistor from heating up in the process of outputting the square wave current, but after the square wave current is output, only part of the residual current is consumed by the first resistor, which can reduce part of the heating compared to the whole residual current being consumed by the first resistor. In addition, part of the residual current is output to the power supply circuit 130D for storage, which can recover part of the energy and reduce the power consumption of the fourth surge test circuit 100D.

[0058] In some other possible implementations, the fourth surge test circuit 100D may include a first capacitor and a second resistor. The test principle and effect thereof may refer to the above embodiments, and the present application will not elaborate on them herein.

[0059] In some possible implementations, the fourth surge test circuit 100D further includes a control circuit, which can be used to control the on or off of the above-mentioned multiple switches. Exemplarily, the control circuit is coupled to the first switch Q1D, the second switch Q2D, the third switch Q3D, and the fourth switch Q4D. The control circuit can be a chip with a control function, for example, the control circuit is a microcontroller unit (MCU). When the control circuit is a chip with a control function, the control circuit can control the on or off of the above-mentioned multiple switches according to a software code set by it or according to an internal hardware circuit. In an embodiment of the present application, the above-mentioned multiple switches can be flexibly controlled to be on or off by the control circuit, and the test can be automatically performed, making the test operation simpler. In addition, the test frequency can reach the microsecond level.

[0060] For example, the control circuit can control the on-time duration and on-time interval of the above-mentioned multiple switches, combined with the inductance, to control various parameters of the test, such as the number of tests, test frequency or current amplitude of the square wave surge test. For example, Figure 6 (d) shows the Figure 6 When the circuits in (a), (b) and (c) are subjected to square wave surge current tests, the waveforms of the voltage applied to each switch and the corresponding square wave current waveforms on the DUT are shown. Figure 6In (d), the relationship between the level applied to the switch and the conduction of the switch is: when a high level is applied to each switch, the corresponding switch is turned on, and when a low level is applied to each switch, the corresponding switch is turned off. Optionally, the relationship between the level applied to the switch and the conduction of the switch can also be: when a low level is applied to each switch, the corresponding switch is turned on, and when a high level is applied to each switch, the corresponding switch is turned off.

[0061] Exemplarily, if the fourth surge test circuit 100D does not include a control circuit, the fourth surge test circuit 100D may be applied to an electronic device carrying a control circuit, and reuse the control circuit of the electronic device.

[0062] In some possible implementations, the fourth surge test circuit 100D further includes a first power supply, which is used for supplying power or storing energy. The power interface circuit 110D can input current from the first power supply, or output current to the first power supply.

[0063] Exemplarily, the first power source may refer to Figure 5 and Figure 6 The DC voltage source DC is shown. The first end of the first power supply is coupled to the first end of the power interface circuit 110D, and the second end of the first power supply is coupled to the second end of the power interface circuit 110D. The first power supply is used to: provide a first amount of electricity to the power interface circuit 110D in the above-mentioned first time period. And, in the above-mentioned third time period, receive the return current output by the power interface circuit 110D, and store the return current. Among them, the first power supply can be a power supply with an energy storage function, such as a battery. In an embodiment of the present application, by setting a first power supply with an energy storage function, the first amount of electricity can be provided by the power interface circuit 110D, and energy can be recovered, thereby reducing power loss. And, the first power supply is used for power supply or energy storage, and the device with energy storage function and power supply function is set to the same device, and the circuit setting is simpler.

[0064] In some possible implementations, the fourth surge test circuit 100D further includes a second power supply and an energy storage circuit, wherein the second power supply is used for supplying power and the energy storage circuit is used for storing energy. The power interface circuit 110D can input current from the second power supply or output current to the energy storage circuit.

[0065] For example, the second power supply can refer to Figure 7The voltage source V1 and capacitor C1D are shown. The power interface circuit 110D also includes a power switch K1D, a return switch K2D, a power supply end and a return end. The power supply end of the power interface circuit 110D is coupled to the first end of the second power supply. The return end of the power interface circuit 110D is coupled to the first end of the energy storage circuit. The second end of the second power supply and the second end of the energy storage circuit are both coupled to the second end of the power interface circuit 110D. The power supply end of the power interface circuit 110D is coupled to the first end of the power switch K1D, the return end of the power interface circuit 110D is coupled to the first end of the return switch K2D, and the second end of the power switch K1D and the second end of the return switch K2D are both coupled to the first end of the power interface circuit 110D. The second power supply is used to: provide the first amount of electricity to the power interface circuit 110D in the above-mentioned first period. The energy storage circuit is used to: receive the return current output by the power interface circuit 110D in the above-mentioned third period, and store the return current. Among them, the second power supply can be a power supply with energy storage function, such as a battery. The energy storage circuit may include energy storage devices, such as energy storage capacitor C1D (capacitor for energy storage), etc. In the embodiment of the present application, by setting a second power supply for power supply, the first amount of electricity can be provided through the power interface circuit 110D, and by setting an energy storage circuit for energy storage, energy can be recovered through the power interface circuit 110D to reduce power loss. In addition, the devices with energy storage function and power supply function are set as different devices, the second power supply can be a power supply with energy storage function, or it can be an ordinary power supply, the energy storage circuit can also include a simple energy storage element, and the types of the second power supply and the energy storage circuit are not limited.

[0066] In some possible implementations, the fourth surge test circuit 100D can output not only a square wave current but also a half-sine wave current, so as to perform a half-sine wave surge current test on the DUT.

[0067] For example, Figure 8As shown, the fourth surge test circuit 100D also includes a first relay switch K3D, a second relay switch K4D, a first freewheeling loop switch Q5D, a second freewheeling loop switch Q6D, a second capacitor C2D, a third resistor R1D and a second inductor L2D. The first end of the first relay switch K3D, the first end of the second relay switch K4D and the first end of the first switch Q1D are all coupled to the first end of the second switch Q2D. The second end of the first relay switch K3D is coupled to the first end of the first inductor L1D. The second end of the second relay switch K4D is coupled to the first end of the second capacitor C2D. The second end of the first inductor L1D, the second end of the second capacitor C2D, the first end of the first freewheeling loop switch Q5D, the first end of the second inductor L2D and the first end of the third switch Q3D are all coupled to the first end of the fourth switch Q4D. The second end of the second inductor L2D is coupled to the first end of the third resistor R1D. The second end of the third resistor R1D is coupled to the first end of the second freewheeling loop switch Q6D. The second end of the first freewheeling loop switch Q5D and the second end of the second freewheeling loop switch Q6D are coupled to the second test end. The second capacitor C2D may include a plurality of capacitors connected in series or in parallel, and the third resistor R1D may include a plurality of resistors connected in series or in parallel. The oscillation circuit formed by the second capacitor C2D, the second inductor L2D, and the third resistor R1D is used to output a half-sine wave current. Exemplarily, the fourth surge test circuit 100D may also include other devices, which are not limited in the embodiment of the present application.

[0068] In the embodiments of the present application, Figure 8 The fourth surge test circuit 100D shown also includes a first relay switch K3D, a second relay switch K4D, a first freewheeling loop switch Q5D, a second freewheeling loop switch Q6D, a second capacitor C2D, a third resistor R1D, and a second inductor L2D. A square wave current can be output through the first inductor L1D; a sinusoidal half-wave current can be output through the oscillation loop formed by the second capacitor C2D, the second inductor L2D, and the third resistor R1D. In this way, both square wave current and sinusoidal half-wave current can be output, and a comprehensive surge test with different surge waveforms can be performed in the same circuit.

[0069] In some possible implementations, by controlling the on or off of the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the first relay switch K3D, the second relay switch K4D, the first freewheeling loop switch Q5D, and the second freewheeling loop switch Q6D, the current flow direction of the fourth surge test circuit 100D can be controlled, thereby controlling the charging or discharging of the devices in the fourth surge test circuit 100D.

[0070] For example, Figure 8 When the fourth surge test circuit 100D shown performs a square wave surge current test, the working states in different time periods are introduced. In the first time period, the first switch Q1D, the fourth switch Q4D and the first relay switch K3D are turned on, the second switch Q2D, the third switch Q3D are turned off, the second relay switch K4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off. The first inductor L1D is used to charge through the power interface circuit 110D to store the first amount of electricity. In the second time period after the first time period, the first relay switch K3D and the first freewheeling loop switch Q5D are turned on, and the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the second relay switch K4D and the second freewheeling loop switch Q6D are turned off. The first inductor L1D is used to output a square wave current to the power device through the first test terminal and the second test terminal based on the stored first amount of electricity. In a third period after the second period, the second switch Q2D, the third switch Q3D and the first relay switch K3D are turned on, and the first switch Q1D, the fourth switch Q4D, the second relay switch K4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off. The first inductor L1D is used to output the return current through the first end of the power interface circuit 110D and the second end of the power interface circuit 110D. Figure 8 The effect of the fourth surge test circuit 100D shown in FIG. 1 on the square wave surge current test can be referred to as Figure 5 The effects of the fourth surge test circuit 100D are not described in detail in this application.

[0071] For example, Figure 8When the fourth surge test circuit 100D shown performs a sinusoidal half-wave surge current test, the working states in different time periods are introduced. In the fourth time period, the second switch Q2D, the third switch Q3D and the second relay switch K4D are turned on, and the first switch Q1D, the fourth switch Q4D, the first relay switch K3D, the first freewheeling circuit switch Q5D and the second freewheeling circuit switch Q6D are turned off; or, the first switch Q1D, the fourth switch Q4D and the second relay switch K4D are turned on, and the second switch Q2D, the third switch Q3D, the first relay switch K3D, the first freewheeling circuit switch Q5D and the second freewheeling circuit switch Q6D are turned off. The first capacitor is used to charge through the power interface circuit 110D to store the second amount of electricity. In the fifth time period after the fourth time period, the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the first relay switch K3D and the first freewheeling circuit switch Q5D are turned off, and the second relay switch K4D and the second freewheeling circuit switch Q6D are turned on. At this time, the DUT is connected to the first test terminal and the second test terminal, and the capacitor is used to output a half-sine wave current to the power device through the first test terminal and the second test terminal based on the second stored electricity. In the fifth time period, the charging and discharging device will exhaust the stored second electricity, and there will be no residual current. Exemplarily, the fourth time period and the fifth time period can be before the first time period or after the third time period.

[0072] The fourth surge test circuit 100D outputs a square wave current through the first inductor L1D to provide a basis.

[0073] When the second switch Q2D, the third switch Q3D, and the second relay switch K4D are turned on, and the first switch Q1D, the fourth switch Q4D, the first relay switch K3D, the first freewheeling loop switch Q5D, and the second freewheeling loop switch Q6D are turned off, the second capacitor C2D forms a loop with the power interface circuit 110D, and the second capacitor C2D can be charged through the power interface circuit 110D. When the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the first relay switch K3D, the first freewheeling loop switch Q5D, the second relay switch K4D, and the second freewheeling loop switch Q6D are turned on, the second capacitor C2D forms an oscillation loop with the third resistor R1D and the second inductor L2D, and the second capacitor C2D can be used to output a sinusoidal half-wave current to the power device. By controlling each switch to be turned on or off, the second switch Q2D and the third switch Q3D are reused to Figure 8 or Fig. 9 The fourth surge test circuit 100D shown provides a basis for outputting a half-sine wave current through a second capacitor C2D.

[0074] In some possible implementations, Figure 8 The fourth surge test circuit 100D shown can set the first inductor L1D and the second inductor L2D to be the same inductor, thereby reusing the inductors.

[0075] For example, Fig. 9 As shown, the first end of the first relay switch K3D, the first end of the second relay switch K4D, and the first end of the first switch Q1D are all coupled to the first end of the second switch Q2D. The second end of the first relay switch K3D and the first end of the third resistor R1D are all coupled to the first end of the first inductor L1D. The second end of the second relay switch K4D is coupled to the first end of the second capacitor C2D. The second end of the first inductor L1D, the second end of the second capacitor C2D, the first end of the first freewheeling loop switch Q5D, and the first end of the third switch Q3D are all coupled to the first end of the fourth switch Q4D. The second end of the third resistor R1D is coupled to the first end of the second freewheeling loop switch Q6D. The second end of the first freewheeling loop switch Q5D and the second end of the second freewheeling loop switch Q6D are both coupled to the second test end.

[0076] In the embodiments of the present application, Fig. 9 The fourth surge test circuit 100D shown also includes a first relay switch K3D, a second relay switch K4D, a first freewheeling loop switch Q5D, a second freewheeling loop switch Q6D, a second capacitor C2D, and a third resistor R1D. A square wave current can be output through the first inductor L1D; a sinusoidal half-wave current can be output through the oscillation circuit formed by the second capacitor C2D, the first inductor L1D, and the third resistor R1D. In this way, the charging and discharging device can output both square wave current and sinusoidal half-wave current, and a comprehensive surge test of different surge waveforms can be performed in the same circuit. In addition, the first inductor L1D is reused to output a sinusoidal half-wave current or a square wave current, which can save hardware costs.

[0077] In some possible implementations, by controlling the on or off of the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the first relay switch K3D, the second relay switch K4D, the first freewheeling loop switch Q5D, and the second freewheeling loop switch Q6D, the current flow direction of the fourth surge test circuit 100D can be controlled, thereby controlling the charging or discharging of the devices in the fourth surge test circuit 100D.

[0078] For example, Fig. 9When the fourth surge test circuit 100D shown performs a square wave surge current test, the working states in different time periods are introduced. In the first time period, the first relay switch K3D, the first switch Q1D and the fourth switch Q4D are turned on, and the second relay switch K4D, the second switch Q2D, the third switch Q3D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off. The first charging current flows through the circuit: the DC voltage source DC, the first end of the power interface circuit 110D, the first switch Q1D, the first relay switch K3D, the first inductor L1D, the fourth switch Q4D, the second end of the power interface circuit 110D, and the DC voltage source DC. At this time, the DC voltage source DC outputs the first electric quantity, and the first inductor L1D is used to charge through the power interface circuit 110D to store the first electric quantity. In the second period, the first relay switch K3D and the first freewheeling loop switch Q5D are turned on, and the second relay switch K4D, the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D and the second freewheeling loop switch Q6D are turned off. The DUT is connected to the first test terminal and the second test terminal, and the circuit in which the square wave current is turned on is: the first inductor L1D, the first freewheeling loop switch Q5D, the DUT, the first relay switch K3D, and the first inductor L1D. At this time, the first inductor L1D is used to output a square wave current to the power device through the first test terminal and the second test terminal based on the first stored electric quantity. In the third period, the first relay switch K3D, the second switch Q2D and the third switch Q3D are turned on, and the second relay switch K4D, the first switch Q1D, the fourth switch Q4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off. The loop of the return current is: the first inductor L1D, the third switch Q3D, the first end of the power interface circuit 110D, the DC voltage source DC, the second end of the power interface circuit 110D, the second switch Q2D, the first relay switch K3D, and the first inductor L1D. At this time, the first inductor L1D is used to output the return current through the first end of the power interface circuit 110D and the second end of the power interface circuit 110D, and the DC voltage source DC is charged by the return current. Exemplarily, the above three time periods are repeated to repeat the square wave surge current test.

[0079] For example, Fig. 9 The fourth surge test circuit 100D shown in the figure is used to introduce the working status at different time periods when performing a half-sine wave surge current test. Fig.10In (a), in the fourth time period, the second relay switch K4D, the second switch Q2D and the third switch Q3D are turned on, and the first relay switch K3D, the first switch Q1D, the fourth switch Q4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off, and the turned-on loop is shown as the dotted line ⑧. According to the circuit, it can be seen that the second capacitor C2D is used to charge through the power interface circuit 110D to store the second amount of electricity. The length of the fourth time period can be determined according to the expected surge current peak, the capacity of the second capacitor C2D and the inductance of the first inductor L1D. When the voltage of the second capacitor C2D is charged to the expected voltage, the fourth time period ends. Please refer to Fig.10 (b) in the fifth time period, the second relay switch K4D and the second freewheeling loop switch Q6D are turned on, and the first relay switch K3D, the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D and the first freewheeling loop switch Q5D are turned off. The turned-on loop is shown as the dotted line ⑨. According to its circuit, it can be seen that the current will show a characteristic similar to a half-sine wave due to the resonance of the first inductor L1D and the second capacitor C2D (LC), and the initial current of the first inductor L1D is 0, and the current waveform will show a characteristic similar to a half-sine wave. The second capacitor C2D is used to output a half-sine wave current to the power device through the first test terminal and the second test terminal based on the second stored electric quantity. The length of the fifth time period is determined according to the time when the current is exhausted in the DUT. Exemplarily, the above two time periods are repeated to repeat the half-sine wave surge current test.

[0080] In the embodiment of the present application, when the first switch Q1D, the fourth switch Q4D and the first relay switch K3D are turned on, the second switch Q2D, the third switch Q3D are turned off, the second relay switch K4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off, the first inductor L1D forms a loop with the power interface circuit 110D, and the first inductor L1D can be charged through the power interface circuit 110D. When the first relay switch K3D and the first freewheeling loop switch Q5D are turned on, and the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the second relay switch K4D and the second freewheeling loop switch Q6D are turned off, the first inductor L1D forms a loop with the power device, and the first inductor L1D can be used to output a square wave current to the power device. When the second switch Q2D, the third switch Q3D and the first relay switch K3D are turned on, and the first switch Q1D, the fourth switch Q4D, the second relay switch K4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D are turned off, the first inductor L1D forms a loop with the power interface circuit 110D, and the first inductor L1D can output a return current through the power interface circuit 110D. By controlling each switch to be turned on or off, Figure 8 or Fig. 9The fourth surge test circuit 100D shown provides a basis for outputting a square wave current through the first inductor L1D.

[0081] When the second switch Q2D, the third switch Q3D, and the second relay switch K4D are turned on, and the first switch Q1D, the fourth switch Q4D, the first relay switch K3D, the first freewheeling loop switch Q5D, and the second freewheeling loop switch Q6D are turned off, the second capacitor C2D forms a loop with the power interface circuit 110D, and the second capacitor C2D can be charged through the power interface circuit 110D. When the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the first relay switch K3D, and the first freewheeling loop switch Q5D are turned off, and the second relay switch K4D and the second freewheeling loop switch Q6D are turned on, the second capacitor C2D forms an oscillation loop with the third resistor R1D and the first inductor L1D, and the second capacitor C2D can be used to output a sinusoidal half-wave current to the power device. By controlling each switch to be turned on or off, Figure 8 or Fig. 9 The fourth surge test circuit 100D shown provides a basis for outputting a half-sine wave current through a second capacitor C2D.

[0082] In some possible implementations, the control circuit may also be coupled to the first relay switch K3D, the second relay switch K4D, the first freewheeling circuit switch Q5D, and the second freewheeling circuit switch Q6D. The control circuit may be used to control these switches to be turned on or off, thereby controlling at least one of the following parameters: the number of tests, the test frequency, or the current amplitude of the surge test. For example, Fig.10 (c) shows that according to Fig.10 When the circuits in (a) and (b) are subjected to a sinusoidal half-wave surge current test, the waveform diagram of the voltage applied to each switch and the waveform diagram of the corresponding sinusoidal half-wave current on the DUT are shown. Fig.11 Shown according to Fig. 9 When the circuit is tested with square wave surge current, the waveform of the voltage applied to each switch and the waveform of the corresponding square wave current on the DUT are shown. Fig.10 (c) and Fig.11 In the embodiment, the relationship between the level applied to the switch and the conduction of the switch is: when a high level (such as 1) is applied to each switch, the corresponding switch is turned on, and when a low level (such as 0) is applied to each switch, the corresponding switch is turned off. Optionally, the relationship between the level applied to the switch and the conduction of the switch can also be: when a low level is applied to each switch, the corresponding switch is turned on, and when a high level is applied to each switch, the corresponding switch is turned off.

[0083] For example, Fig.12 The current waveform of the combined surge test of square wave and half sine wave is shown. Figure 8 or Fig. 9 The fourth surge test circuit 100D shown can provide square wave current and half-sine wave current at intervals, the duration of each test can be different, the test frequency of each test can be different, and the peak current provided each time can be different. In the embodiment of the present application, the fourth surge test circuit 100D can study the comprehensive performance of the DUT under complex surge waveforms, multiple time scales, complex surge current stress, complex surge test frequencies, etc. The test frequency can reach microseconds, and the minimum pulse width of the surge current is not limited.

[0084] In some possible implementations, Figure 5 , Figure 8 and Fig. 9 The circuit shown can be used for surge testing, and can also be used for other experiments, such as high temperature operating life testing (HTOL), which is not limited in the embodiments of the present application.

[0085] Exemplarily, the first switch Q1D, the second switch Q2D, the third switch Q3D, the fourth switch Q4D, the first freewheeling loop switch Q5D and the second freewheeling loop switch Q6D may be MOS tubes, IGBTs, thyristors or other switch devices.

[0086] In some possible implementations, the charge-discharge device may be the fourth surge test circuit 100D, or may be a surge test device including a housing and the fourth surge test circuit 100D, wherein the fourth surge test circuit 100D is disposed in the housing.

[0087] Finally, it should be noted that the above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application should be based on the protection scope of the claims.

Claims

1. A charging and discharging device, It is characterized in that The charging and discharging device includes a power interface circuit, a first inductor, a first switch, a second switch, a third switch, a fourth switch, a first test terminal and a second test terminal; The first end of the first switch, the first end of the second switch, and the first end of the first inductor are all coupled to the first test end; the first end of the third switch, the first end of the fourth switch, and the second end of the first inductor are all coupled to the second test end; the second end of the first switch and the second end of the third switch are both coupled to the first end of the power interface circuit, and the second end of the second switch and the second end of the fourth switch are both coupled to the second end of the power interface circuit; The first test terminal and the second test terminal are used to couple with a power device; and the power interface circuit is used to input or output current.

2. The device according to claim 1, It is characterized in that The first inductor is used for: When the first switch and the fourth switch are turned on and the second switch and the third switch are turned off, charging through the power interface circuit to store a first amount of electricity; When the first switch, the second switch, the third switch and the fourth switch are turned off, outputting a square wave current to the power device through the first test terminal and the second test terminal based on the first stored electric quantity; When the second switch and the third switch are turned on and the first switch and the fourth switch are turned off, a return current is output through the power interface circuit; The return current is a residual current in the first inductor after the square wave current is output.

3. The device according to claim 1 or 2, It is characterized in that The charging and discharging circuit further includes a first power supply, which is used for supplying power or storing energy; A first terminal of the first power supply is coupled to a first terminal of the power interface circuit, and a second terminal of the first power supply is coupled to a second terminal of the power interface circuit.

4. The device according to claim 1 or 2, It is characterized in that The power interface circuit further includes a power switch, a return switch, a power supply terminal and a return terminal; the charging and discharging device further includes a second power supply and an energy storage circuit, the second power supply is used for power supply, and the energy storage circuit is used for energy storage; The power supply end of the power interface circuit is coupled to the first end of the second power supply; the return end of the power interface circuit is coupled to the first end of the energy storage circuit; the second end of the second power supply and the second end of the energy storage circuit are both coupled to the second end of the power interface circuit; The power supply end of the power interface circuit is coupled to the first end of the power switch, the return end of the power interface circuit is coupled to the first end of the return switch, and the second end of the power switch and the second end of the return switch are both coupled to the first end of the power interface circuit.

5. The device according to any one of claims 1 to 4, It is characterized in that The charging and discharging device further includes a first relay switch, a second relay switch, a first freewheeling loop switch, a second freewheeling loop switch, a capacitor, a resistor and a second inductor; The first end of the first relay switch, the first end of the second relay switch and the first end of the first switch are all coupled to the first end of the second switch; the second end of the first relay switch is coupled to the first end of the first inductor; the second end of the second relay switch is coupled to the first end of the capacitor; the second end of the first inductor, the second end of the capacitor, the first end of the first freewheeling loop switch, the first end of the second inductor and the first end of the third switch are all coupled to the first end of the fourth switch; the second end of the second inductor is coupled to the first end of the resistor; the second end of the resistor is coupled to the first end of the second freewheeling loop switch; the second end of the first freewheeling loop switch and the second end of the second freewheeling loop switch are both coupled to the second test end.

6. The device according to any one of claims 1 to 4, It is characterized in that The charging and discharging device also includes a first relay switch, a second relay switch, a first freewheeling loop switch, a second freewheeling loop switch, a capacitor and a resistor; the first end of the first relay switch, the first end of the second relay switch and the first end of the first switch are all coupled to the first end of the second switch; the second end of the first relay switch and the first end of the resistor are both coupled to the first end of the first inductor; the second end of the second relay switch is coupled to the first end of the capacitor; the second end of the first inductor, the second end of the capacitor, the first end of the first freewheeling loop switch and the first end of the third switch are all coupled to the first end of the fourth switch; the second end of the resistor is coupled to the first end of the second freewheeling loop switch; the second end of the first freewheeling loop switch and the second end of the second freewheeling loop switch are both coupled to the second test end.

7. The device according to claim 5 or 6, It is characterized in that The first inductor is used for: When the first switch, the fourth switch and the first relay switch are turned on, the second switch, the third switch are turned off, the second relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, charging through the power interface circuit to store a first amount of electricity; When the first relay switch and the first freewheeling loop switch are turned on, and the first switch, the second switch, the third switch, the fourth switch, the second relay switch, and the second freewheeling loop switch are turned off, outputting a square wave current to the power device through the first test terminal and the second test terminal based on the first stored electric quantity; When the second switch, the third switch and the first relay switch are turned on, and the first switch, the fourth switch, the second relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, a return current is output through the power interface circuit; the return current is the residual current in the first inductor after the square wave current is output.

8. The device according to any one of claims 5 to 7, It is characterized in that The capacitors are used for: When the second switch, the third switch and the second relay switch are turned on, and the first switch, the fourth switch, the first relay switch, the first freewheeling loop switch and the second freewheeling loop switch are turned off, charging through the power interface circuit to store a second amount of electricity; When the first switch, the second switch, the third switch, the fourth switch, the first relay switch and the first freewheeling loop switch are turned off, and the second relay switch and the second freewheeling loop switch are turned on, a sinusoidal half-wave current is output to the power device through the first test terminal and the second test terminal based on the stored second electric quantity.

9. The device according to any one of claims 1 to 8, It is characterized in that There are multiple power devices, and the first test end and the second test end are used to couple multiple power devices connected in series.

10. The device according to any one of claims 1 to 9, It is characterized in that The apparatus also includes a control circuit coupled to at least one of the first switch, the second switch, the third switch, and the fourth switch.

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