Positive polarity square wave power supply circuit, test device of device to be tested and power supply method

Abstract

The invention provides a positive polarity square wave power supply circuit, a test device of a to-be-tested device and a power supply method.The positive polarity square wave power supply circuit comprises a square wave generation unit, and the square wave generation unit comprises a plurality of cascaded half-bridge structures; each half-bridge structure comprises a high-voltage direct-current power supply, an energy storage module, a first switch module located on the first bridge wall and a second switch module located on the second bridge wall, and the high-voltage direct-current power supply and the energy storage module are connected in parallel. The power supply circuit is simple in structure and good in expandability, all the stages are mutually independent, waveform parameters of output square waves can be flexibly adjusted, the power supply circuit is suitable for being used as a positive polarity square wave power supply circuit for high-voltage SiC packaging insulation assessment, and the problem that a high-voltage positive polarity square wave power supply for high-voltage SiC packaging insulation assessment is lacked in the prior art is solved. Therefore, the problem that the partial discharge inside the high-voltage silicon carbide device exposed under the positive polarity square wave voltage cannot be fully evaluated is solved.

Description

Technical Field

[0001] The present application relates to the field of high-voltage SiC package insulation assessment, and more specifically, to a positive polarity square wave power supply circuit, a test device for a device under test, and a method for powering the device under test using any one of the positive polarity square wave power supply circuits. Background Art

[0002] Silicon carbide (SiC), as the third-generation wide bandgap semiconductor device, is considered to be the core device for the future development of power grids due to its excellent properties such as high voltage, high frequency, high temperature resistance, fast switching speed and low loss.

[0003] However, due to the lack of high-voltage positive-polarity square-wave power supplies for high-voltage SiC package insulation testing, there is currently almost no research on partial discharge under high-slew rate, high-amplitude square wave conditions in actual high-voltage silicon carbide devices, and the research is still limited to testing samples of internal components of the device.

[0004] The generated square wave signal is relatively simple and cannot meet the multi-signal requirements of semiconductor devices, making the test cumbersome and complicated. Summary of the invention

[0005] The main purpose of the present application is to provide a positive polarity square wave power supply circuit, a test device for a device under test, and a method for powering the device under test using any one of the positive polarity square wave power supply circuits, so as to at least solve the problem that there is a lack of high-voltage positive polarity square wave power supply for high-voltage SiC packaging insulation assessment in the prior art, resulting in the inability to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to a positive polarity square wave voltage.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present application, a positive polarity square wave power supply circuit is provided, including: a square wave generating unit, used to generate a positive polarity square wave signal, the square wave generating unit includes a plurality of cascaded half-bridge structures, each of the half-bridge structures includes a high-voltage DC power supply, an energy storage module, a first switch module located on a first bridge wall, and a second switch module on a second bridge wall, the high-voltage DC power supply and the energy storage module are connected in parallel, the first end of the first switch module is electrically connected to the positive electrode of the high-voltage DC power supply, and the second end of the second switch module is electrically connected to the negative electrode of the high-voltage DC power supply.

[0007] Optionally, the first end of the first switch module is electrically connected to the positive electrode of the high-voltage DC power supply, and the control end of the first switch module is used to input a first control signal; the first end of the second switch module is electrically connected to the second end of the first switch module, the control end of the second switch module is used to input a second control signal, and the second end of the second switch module is electrically connected to the negative electrode of the high-voltage DC power supply, wherein the first switch module and the second switch module are connected in a half-bridge manner.

[0008] Optionally, each of the switch modules includes a MOS device.

[0009] Optionally, the energy storage module includes at least one energy storage capacitor.

[0010] Optionally, the power supply circuit further includes: a current limiting unit connected in series with the square wave generating unit.

[0011] Optionally, the current limiting unit includes at least one current limiting resistor.

[0012] Optionally, when the current limiting unit includes multiple current limiting resistors, all the current limiting resistors are connected in series.

[0013] According to another aspect of the present application, a testing device for a device under test is provided, comprising: any one of the positive polarity square wave power supply circuits, the positive polarity square wave power supply circuit being used to power the device under test when the device under test is undergoing a package insulation test; and a test circuit being used to be electrically connected to the device under test and to perform a package insulation test on the device under test.

[0014] According to another aspect of the present application, a method for powering a device under test using any one of the positive polarity square wave power supply circuits is provided, the method comprising: controlling each switching device in a half-bridge structure in a square wave generating unit to be turned on or off according to a preset period to provide the positive polarity square wave power supply to the device under test; wherein the switching devices on the first bridge wall of the half-bridge structure and the switching devices on the second bridge wall are not turned on at the same time, the first bridge wall is the main branch of the half-bridge structure, and the second bridge wall is the leakage branch of the half-bridge structure.

[0015] Optionally, controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset cycle includes: controlling the switch device of the first bridge wall in the square wave generating unit to be turned on, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide a high level to the device under test; after providing the high level to the device under test, controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off; controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned on, so as to provide a low level to the device under test; after providing the low level to the device under test, controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide the positive polarity square wave power supply to the device under test.

[0016] Optionally, the half-bridge structure includes a first switch module and a second switch module, which controls the switch device of the first bridge wall in the square wave generating unit to be turned on, and controls the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide a high level for the device under test, including: controlling all the switch devices in the first switch module to be turned on, and controlling the switch devices in the second switch module to be turned off, so as to provide a high level for the device under test.

[0017] Optionally, the half-bridge structure includes a first switch module and a second switch module, and controls the switch devices of the first bridge wall in the square wave generating unit to be cut off, and controls the switch devices of the second bridge wall in the square wave generating unit to be cut off, including: controlling all the switch devices in the first switch module to be cut off, and controlling all the switch devices in the second switch module to be cut off.

[0018] Optionally, the half-bridge structure includes a first switch module and a second switch module, and controls the switch device of the first bridge wall in the square wave generating unit to be cut off, and controls the switch device of the second bridge wall in the square wave generating unit to be turned on, so as to provide a low level to the device under test, including: controlling all the switch devices in the first switch module to be cut off, and controlling all the switch devices in the second switch module to be turned on, so as to provide a low level to the device under test.

[0019] Optionally, the half-bridge structure includes a first switch module and a second switch module, which controls the switch device of the first bridge wall in the square wave generating unit to be cut off, and controls the switch device of the second bridge wall in the square wave generating unit to be cut off, so as to provide the positive polarity square wave power supply to the device under test, including: controlling all the switch devices in the first switch module to be cut off, and controlling all the switch devices in the second switch module to be cut off, so as to provide the positive polarity square wave power supply to the device under test.

[0020] Optionally, the square wave generating unit includes n cascaded half-bridge structures, and the high level provided by the square wave generating unit to the device under test is , where V DUT is the voltage value of the high level, i is the number of stages of the half-bridge structure, n is the number of all the half-bridge structures, V DCi is the voltage value of the high-voltage DC power supply in the i-th stage half-bridge structure, and the low level provided by the square wave generating unit to the device under test is 0.

[0021] Applying the technical solution of the present application, the above-mentioned polarity square wave power supply circuit includes a square wave generating unit, the square wave generating unit is used to generate a positive polarity square wave signal, the square wave generating unit includes a plurality of cascaded half-bridge structures, each half-bridge structure includes a high-voltage DC power supply, an energy storage module, a first switch module located on the first bridge wall, and a second switch module on the second bridge wall, the high-voltage DC power supply and the energy storage module are connected in parallel, the first end of the first switch module is electrically connected to the positive pole of the high-voltage DC power supply, and the second end of the second switch module is electrically connected to the negative pole of the high-voltage DC power supply. The power supply circuit has a simple structure, good scalability, each level is independent of each other, and the output square wave waveform parameters can be flexibly adjusted. It is suitable as a positive polarity square wave power supply circuit for high-voltage SiC package insulation assessment, which solves the problem that there is a lack of high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment in the prior art, resulting in the inability to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to the positive polarity square wave voltage. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] The drawings constituting part of the present application are used to provide a further understanding of the present application. The exemplary embodiments and descriptions of the present application are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0023] Figure 1 A parameterized schematic diagram of a positive polarity square wave voltage waveform provided in an embodiment of the present application is shown;

[0024] Figure 2 A schematic diagram showing the effect of partial discharge testing based on existing test standards is shown;

[0025] Figure 3 A schematic structural diagram of a positive polarity square wave power supply circuit provided in an embodiment of the present application is shown;

[0026] Figure 4 A schematic structural diagram of another positive polarity square wave power supply circuit provided in an embodiment of the present application is shown;

[0027] Figure 5 A schematic structural diagram of another positive polarity square wave power supply circuit provided in an embodiment of the present application is shown;

[0028] Figure 6 A logic schematic diagram of a method for using any one of the positive polarity square wave power supply circuits to power a device under test is shown according to an embodiment of the present application;

[0029] Figure 7 A schematic diagram of a simulation waveform of a positive polarity square wave provided in an embodiment of the present application is shown;

[0030] Figure 8 A schematic structural diagram of a device under test test apparatus provided in an embodiment of the present application is shown;

[0031] Fig. 9 A control signal transmission logic schematic diagram provided in an embodiment of the present application is shown;

[0032] Fig.10 A schematic diagram of key pins of a 4 V to 800 V isolated power module provided in an embodiment of the present application is shown;

[0033] Fig.11 A waveform diagram of an output voltage applied to two ends of a device under test and an output current flowing through the device under test provided in an embodiment of the present application is shown;

[0034] Fig.12 A schematic diagram showing voltage output characteristics of different sample capacitance values ​​provided in an embodiment of the present application is shown;

[0035] Fig.13 A schematic diagram of an output voltage waveform when different levels of square wave generating units are put into use according to an embodiment of the present application is shown;

[0036] Fig.14 A schematic diagram of an output voltage waveform when a driving signal with different duty cycles is set according to an embodiment of the present application is shown;

[0037] Fig.15 A schematic diagram of an output voltage waveform when a driving signal with different frequencies is set according to an embodiment of the present application is shown;

[0038] Fig.16 A schematic diagram of an output voltage waveform when a driving signal provided in an embodiment of the present application is set with different delay times is shown.

[0039] The above drawings include the following reference numerals:

[0040] 01. Positive polarity square wave power supply circuit; 02. Test circuit; 10. Square wave generating unit; 11. Half-bridge structure; 111. Energy storage module; 112. First switch module; 113. Second switch module; 20. Device under test; 30. Current limiting unit. DETAILED DESCRIPTION

[0041] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0042] In order to enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of this application.

[0043] It should be noted that the terms "first", "second", etc. in the specification and claims of the present application and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequential order. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present application described here. In addition, the terms "including" and "having" and any of their variations are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device comprising a series of steps or units is not necessarily limited to those steps or units clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0044] As introduced in the background technology, the voltage level of high-voltage silicon carbide devices can reach up to 27 kV, and the high voltage amplitude increases the electric field stress inside the module. While high-voltage silicon carbide devices are subjected to higher temperatures, during repeated on and off processes, the drain-source level of the device is subjected to high voltage in the off state, while the device is almost not subjected to pressure in the on state. Therefore, its internal chip and package insulation structure are subjected to positive polarity square wave voltage, which has the characteristics of high amplitude, high slew rate and high repetition frequency. Under the positive polarity square wave voltage, the weak links of insulation are also more prone to discharge. Figure 1The positive polarity square wave voltage waveform is parameterized, and its indicators include voltage amplitude, rise time, fall time, pulse width, and pulse period. For the positive polarity square wave voltage, the pulse period is the inverse of the frequency, and the ratio of the pulse width to the pulse period is the duty cycle.

[0045] Currently, the current standard for evaluating the insulation performance of IGBT power devices specifies the partial discharge measurement requirements of IGBT power devices under 50 Hz (or 60 Hz) AC voltage. Referring to the current standard, the partial discharge test procedure is as follows: Figure 2 shown. Figure 2 The horizontal axis represents time, and the vertical axis represents the effective value of the applied 50 Hz test voltage, where U m It is the maximum blocking voltage of the power device. In the test, the gate, collector and emitter of the IGBT power device need to be short-circuited, and an AC voltage is applied between the short-circuited part and the metal base plate. The effective value of the AC voltage rises to 1.5U in 10 s. m / , then hold for 60 s (e.g. Figure 2 Medium 1 At t 1 During this period, partial discharge may occur. After that, the effective value of the AC voltage drops to 1.1U within 10 s. m / , then hold for 30 seconds (such as Figure 2 Medium 2 As shown), at t 2 The partial discharge level of the device under test is measured in the last 5 s of the period, and the maximum discharge standards for components and sub-components that pass the test are 10 pC and 50 pC, respectively.

[0046] There are three main defects in the current standard for the assessment of high-voltage silicon carbide devices: First, the standard uses an AC voltage with a relatively low du / dt (rather than a bipolar square wave voltage with a relatively higher du / dt) for partial discharge assessment, and the partial discharge phenomenon of high-voltage silicon carbide devices under AC conditions is different from that under bipolar square wave conditions; second, the AC condition itself is different from the positive polarity square wave voltage condition actually borne by the chip and packaging insulation structure inside the high-voltage silicon carbide device, and relevant literature also points out that the positive polarity repetitive square wave voltage condition is more likely to cause partial discharge; third, the standard only tests the insulation performance between the bottom plate and other insulating parts, and does not evaluate the insulation performance of the insulation structure composed of the chip and packaging material. In summary, the assessment content of this standard is not rigorous and comprehensive when applied to high-voltage silicon carbide devices. In addition, the current standard can no longer fully evaluate the partial discharge problem inside high-voltage silicon carbide devices exposed to positive polarity square wave voltage, and calls for the inclusion of square wave voltage assessment in the reliability assessment of silicon carbide devices.

[0047] However, due to the lack of high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment, there is currently almost no research on partial discharge under high-slew rate and high-amplitude square wave conditions in actual high-voltage silicon carbide devices. Testing is still limited to samples of internal components of the device. Therefore, there is a lack of guidelines for partial discharge suppression of DBC under square wave conditions and high slew rate (>50kV / μs).

[0048] In order to solve the problem that the prior art lacks a high-voltage positive polarity square wave power supply for high-voltage SiC packaging insulation assessment, resulting in the inability to fully evaluate the local discharge inside a high-voltage silicon carbide device exposed to a positive polarity square wave voltage, the embodiments of the present application provide a positive polarity square wave power supply circuit, a method for powering a device under test using any one of the above-mentioned positive polarity square wave power supply circuits, and a test device for the device under test.

[0049] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0050] Figure 3 The structure diagram of a positive polarity square wave power supply circuit is shown. The positive polarity square wave power supply circuit is used to provide a test power supply for the package insulation test of the device under test. Figure 3 and Figure 4 As shown, the power supply circuit includes: a square wave generating unit 10, which is used to generate a positive polarity square wave signal. The square wave generating unit 10 includes a plurality of cascaded half-bridge structures 11, each of which includes a high voltage DC power supply V DCn , an energy storage module 111, a first switch module 112 located on the first bridge wall, and a second switch module 113 located on the second bridge wall, the high voltage DC power supply V DCn The energy storage module 111 is connected in parallel with the first end of the first switch module 112 and the high voltage DC power supply V DCn The second end of the second switch module 113 is electrically connected to the positive electrode of the high voltage DC power supply V DCn The negative electrode is electrically connected to the

[0051] Among them, Figure 4 As shown, the square wave generating unit is used to provide a positive polarity square wave power supply to the device under test 20. In this way, a square wave generating unit with a lower voltage level can be used to realize the square wave output function by cascading.

[0052] The above-mentioned polarity square wave power supply circuit of the present application includes a square wave generating unit, the square wave generating unit includes a plurality of cascaded half-bridge structures, each half-bridge structure includes at least two switch modules, and the square wave generating unit is used to generate a positive polarity square wave signal. The power supply circuit has a simple structure, good scalability, each level is independent of each other, and the output square wave waveform parameters can be flexibly adjusted. It is suitable as a positive polarity square wave power supply circuit for high-voltage SiC package insulation assessment, which solves the problem that there is a lack of high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment in the prior art, resulting in the inability to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to the positive polarity square wave voltage.

[0053] In some instances, such as Figure 4 As shown, the square wave generating unit further includes: a high voltage DC power supply V DCn ; Energy storage module 111, the first end of the energy storage module 111 and the high voltage DC power supply V DCn The second end of the energy storage module 111 is electrically connected to the positive electrode of the high voltage DC power supply V DCn The negative electrode is electrically connected to the

[0054] Specifically, the high voltage DC power supply V DCn Where n is the total number of half-bridge structures, and the high-voltage DC power supply of the first half-bridge structure is V DC1 , the high voltage DC power supply of the second half-bridge structure is V DC2 , the high voltage DC power supply of the i-th half-bridge structure is V DCi . High voltage DC power supply V DCi It is used to supply energy to the busbar of the half-bridge structure. The output voltage of each square wave generating unit is supplied by the high voltage DC power supply V DCi and energy storage unit clamping, there is no risk of unit overvoltage due to a single square wave.

[0055] In some instances, such as Figure 4 and Figure 5 As shown, the energy storage module 111 includes N series-connected energy storage capacitors C n , wherein the energy storage module 111 includes only one energy storage capacitor C n In the case of n The first end is connected to the high voltage DC power supply V DCn The positive electrode of the energy storage capacitor C n The second end is connected to the high voltage DC power supply V DCn The negative electrode is electrically connected to the

[0056] In some examples, the energy storage module includes at least one energy storage capacitor.

[0057] In some examples, the energy storage module may include multiple energy storage capacitors. A certain number of energy storage capacitors can increase the stability of the circuit. For example, if two energy storage capacitors are set up, when one of them is damaged, the other one can function to ensure the stability of the circuit.

[0058] Among them, the high voltage DC power supply V DCn n in and the energy storage capacitor C n The n in the figure represents the total number of half-bridge structures. The energy storage capacitor of the first half-bridge structure is C 1 , the energy storage capacitor of the second half-bridge structure is C 2 , the energy storage capacitor of the i-th half-bridge structure is C i .

[0059] Among them, the energy storage capacitor C i To improve voltage stability, the output voltage of each square wave generating unit is supplied by a high voltage DC power supply V DCi and energy storage capacitor C i Clamped, there is no risk of unit overvoltage from a single square wave.

[0060] In some instances, such as Figure 4 As shown, the switch module includes a first switch module 112 and a second switch module 113, wherein a first end of the first switch module 112 is connected to the high voltage DC power supply V DCn The positive electrode of the first switch module 112 is electrically connected, the control end of the first switch module 112 is used to input a first control signal, and the first switch module 112 is located on the first bridge wall of the half-bridge structure 11; the first end of the second switch module 113 is electrically connected to the second end of the first switch module 112, the control end of the second switch module 113 is used to input a second control signal, and the second end of the second switch module 113 is electrically connected to the high-voltage DC power supply V DCn The first switch module 112 and the second switch module 113 are electrically connected in a half-bridge manner, and the second switch module 113 is located on the second bridge wall of the half-bridge structure 11.

[0061] In some instances, such as Figure 4 and Figure 5 As shown, the first switch module 112 comprises: a main branch MOS device S n-1 , the main branch MOS device S n-1 The first end is connected to the high voltage DC power supply V DCn The positive electrode of the main branch MOS device S n-1 The control terminal of the main branch MOS device S is used to input the first control signal. n-1 The second end of is electrically connected to the first end of the second switch module 113.

[0062] Among them, the main branch MOS device S n-1 The n in the figure represents the total number of half-bridge structures, 1 represents the main branch, and the main branch MOS device of the first half-bridge structure is S 1-1 The high voltage DC power supply of the second half-bridge structure is S 2-1 , the high voltage DC power supply of the i-th half-bridge structure is S i-1 .

[0063] In some embodiments, each of the switch modules includes a MOS device.

[0064] In some examples, there may be multiple main branch MOS devices, and multiple main branch MOS devices can increase the stability of the circuit. In the event that one of the main branch MOS devices is damaged, the other main branch MOS devices can continue to function. In addition, setting multiple main branch MOS devices can increase the accuracy of control and prevent square wave power supply output failure caused by one of the main branch MOS devices being misconnected.

[0065] Among them, the main branch SiC MOSFET switch S i-1 Used to provide the high level of the square wave.

[0066] In some instances, such as Figure 4 and Figure 5 As shown, the second switch module 113 includes: a leakage branch MOS device S n-2 , the above leakage branch MOS device S n-2 The first end of the MOS device S is electrically connected to the second end of the first switch module 112. n-2 The control end of the MOS device S is used to input the second control signal. n-2 The second end is connected to the high voltage DC power supply V DCn The negative electrode is electrically connected to the

[0067] Among them, the leakage branch MOS device S n-2 The n in the figure represents the total number of half-bridge structures, 2 represents the leakage branch, and the main branch MOS device of the first half-bridge structure is S 1-2 The high voltage DC power supply of the second half-bridge structure is S 2-2 , the high voltage DC power supply of the i-th half-bridge structure is S i-2 .

[0068] Among them, the leakage branch SiC MOSFET switch S i-2 Used to provide the low level of a square wave.

[0069] In some instances, such as Figure 4As shown, the power supply circuit further includes: a current limiting unit 30 connected in series with the square wave generating unit 10. The current limiting unit 30 is electrically connected to the device under test 20 and the square wave generating unit 10 respectively, and the current limiting unit 30 is used to limit the current in the loop to be less than or equal to the maximum current threshold.

[0070] In some examples, the current limiting unit includes at least one current limiting resistor.

[0071] Among them, Figure 4 and Figure 5 As shown, the current limiting unit 30 includes: a current limiting resistor R s , the above current limiting resistor R s The first end of the current limiting resistor R s The second end of is electrically connected to the first end of the device under test 20, and the second end of the device under test 20 is grounded and electrically connected to the second end of the square wave generating unit.

[0072] Specifically, the power supply circuit can achieve flexible output of different voltage levels through appropriate circuit design and switch control; by adopting modular design, the design schemes of square wave generating units of different levels are completely consistent, which simplifies the complexity of circuit design and increases reliability.

[0073] In some examples, when the current limiting unit includes a plurality of current limiting resistors, all the current limiting resistors are connected in series, which can increase the resistance value of the current limiting resistors.

[0074] The embodiment of the present application also provides a method for using any of the above-mentioned positive polarity square wave power supply circuits to power a device under test, such as Figure 6 As shown, the method includes:

[0075] Step S101, controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset period to provide the above-mentioned positive polarity square wave power supply to the above-mentioned device under test; wherein the above-mentioned switch devices on the first bridge wall of the above-mentioned half-bridge structure and the above-mentioned switch devices on the second bridge wall are not turned on at the same time, the above-mentioned first bridge wall is the main branch of the half-bridge structure, and the above-mentioned second bridge wall is the leakage branch of the half-bridge structure.

[0076] The power supply method of the present application includes: controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset cycle to provide a positive polarity square wave power supply to the device under test; wherein the switch device on the first bridge wall of the half-bridge structure and the switch device on the second bridge wall are not turned on at the same time, the first bridge wall is the main branch of the half-bridge structure, and the second bridge wall is the leakage branch of the half-bridge structure. The power supply method can achieve flexible output of different voltage levels through appropriate circuit design and switch control, solving the problem of the lack of high-voltage positive polarity square wave power supply for high-voltage SiC packaging insulation assessment in the prior art, resulting in the inability to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to the positive polarity square wave voltage.

[0077] In some examples, controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset cycle includes: controlling the switch device of the first bridge wall in the square wave generating unit to be turned on, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide a high level to the device under test; after providing the high level to the device under test, controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off; controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned on, so as to provide a low level to the device under test; after providing the low level to the device under test, controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide the positive polarity square wave power supply to the device under test.

[0078] The first bridge wall is the main branch, and the second bridge wall is the leakage branch. Through appropriate circuit design and switch control, flexible output with different voltage levels can be achieved.

[0079] In some instances, such as Figure 4 As shown, the half-bridge structure 11 includes a first switch module 112 and a second switch module 113, which controls the switch devices of the first bridge wall in the square wave generating unit to be turned on, and controls the switch devices of the second bridge wall in the square wave generating unit to be turned off, so as to provide a high level for the device under test 20, including: controlling all the switch devices in the first switch module 112 to be turned on, and controlling the switch devices in the second switch module 113 to be turned off, so as to provide a high level for the device under test 20.

[0080] The first switch module and the second switch module include at least one switch device, and when all the switch devices in the first switch module are turned on and all the switch devices in the leakage branch are turned off, a high level of a square wave is provided for the device under test.

[0081] In some instances, such as Figure 4 As shown, the half-bridge structure 11 includes a first switch module 112 and a second switch module 113, and controls the switching devices of the first bridge wall in the square wave generating unit to be cut off, and controls the switching devices of the second bridge wall in the square wave generating unit to be cut off, including: controlling all the switching devices in the first switch module 112 to be cut off, and controlling all the switching devices in the second switch module 113 to be cut off.

[0082] Wherein, all the switch devices in the first switch module and all the switch devices in the second switch module are turned off synchronously to switch the high level of the square wave to the low level.

[0083] In some instances, such as Figure 4 As shown, the half-bridge structure 11 includes a first switch module 112 and a second switch module 113, which controls the switch device of the first bridge wall in the square wave generating unit to be cut off, and controls the switch device of the second bridge wall in the square wave generating unit to be turned on, so as to provide a low level to the device under test 20, including: controlling all the switch devices in the first switch module 112 to be cut off, and controlling all the switch devices in the second switch module 113 to be turned on, so as to provide a low level to the device under test 20.

[0084] The first switch module and the second switch module include at least one switch device, and when all the switch devices in the first switch module are turned off and all the switch devices in the leakage branch are turned on, a low level of a square wave is provided for the device under test.

[0085] In some instances, such as Figure 4 As shown, the half-bridge structure 11 includes a first switch module 112 and a second switch module 113, which controls the switch devices of the first bridge wall in the square wave generating unit to be cut off, and controls the switch devices of the second bridge wall in the square wave generating unit to be cut off, so as to provide the positive polarity square wave power supply to the device under test 20, including: controlling all the switch devices in the first switch module 112 to be cut off, and controlling all the switch devices in the second switch module 113 to be cut off, so as to provide the positive polarity square wave power supply to the device under test 20.

[0086] Wherein, all the above-mentioned switch devices in the first switch module and all the above-mentioned switch devices in the second switch module are turned off synchronously to switch the low level of the square wave to the high level.

[0087] In some instances, such as Figure 3 and Figure 4As shown, the square wave generating unit 10 includes n cascaded half-bridge structures 11. The high level provided by the square wave generating unit 10 to the device under test 20 is , where V DUT is the voltage value of the high level, i is the number of stages of the half-bridge structure 11, n is the number of all the half-bridge structures, V DCi is the voltage value of the high-voltage DC power supply in the i-th stage half-bridge structure 11, and the low level provided by the square wave generating unit 10 to the device under test 20 is 0.

[0088] Among them, flexible output with different voltage levels can be achieved through appropriate circuit design and switch control.

[0089] In some instances, such as Figure 5 As shown in the figure, the working process of the positive polarity square wave power supply circuit used for high-voltage SiC package insulation assessment can be divided into the following four working stages:

[0090] Assume that the capacitor C i Pre-charging is completed and the main branch SiC MOSFET switch S i-1 and leakage branch SiC MOSFET switch S i-2 All are in off state.

[0091] In the first stage, the main branch SiC MOSFET switch S is turned on synchronously i-1 , leakage branch SiC MOSFET switch S i-2 Keep it off, and the voltage across the DUT is ;

[0092] In the second stage, the main branch SiC MOSFET switch S is turned off synchronously. i-1 , leakage branch SiC MOSFET switch S i-2 Keep it off;

[0093] In the third stage, the SiC MOSFET switch S in the leakage branch is turned on synchronously. i-2 , main branch SiC MOSFET switch S i-1 Keep it off, and the voltage across the DUT is ;

[0094] In the fourth stage, the leakage branch SiC MOSFET switch S is synchronously turned off. i-2 , main branch SiC MOSFET switch S i-1 Keep it off.

[0095] In some instances, Figure 7 This is a schematic diagram of a simulation waveform of a positive polarity square wave. The simulation waveform output by the positive polarity square wave power supply circuit is as follows: Figure 7 shown.

[0096] The present application also provides a device for testing a device under test. Figure 8 As shown, it includes: any one of the above-mentioned positive polarity square wave power supply circuits 01, the above-mentioned positive polarity square wave power supply circuit 01 is used to power the above-mentioned device under test 20 when the device under test 20 is subjected to a package insulation test; a test circuit 02, which is used to be electrically connected to the above-mentioned device under test 20 and is used to perform a package insulation test on the above-mentioned device under test 20.

[0097] The test device of the device under test of the present application comprises: any one of positive polarity square wave power supply circuits, the positive polarity square wave power supply circuit is used to power the device under test when the device under test is subjected to a package insulation test; a test circuit, which is used to be electrically connected to the device under test and is used to perform a package insulation test on the device under test. The test device can achieve flexible outputs of different voltage levels through appropriate circuit design and switch control, solving the problem of the lack of high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment in the prior art, which makes it impossible to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to a positive polarity square wave voltage.

[0098] In order to realize the precise control function of the square wave power supply, and considering the number of IO ports and hardware performance requirements for the construction of a visual control system, this embodiment uses a field programmable gate array (FPGA) to generate control signals. Through program writing, multiple different digital signals can be output to meet the control requirements of the square wave power supply.

[0099] In order to achieve complete isolation between the FPGA control system and the high voltage output part, and out of consideration for building a square wave power supply with a higher voltage level, this embodiment adopts the following Fig. 9 The control signal transmission logic is shown in FIG. Fig. 9 As shown, the electrical signal output by the FPGA is converted into an optical signal via a fiber optic transmitter, and then converted back into an electrical signal via a fiber optic transmission line, which is used for driving control of the high / low side SiC MOSFET in the square wave generating unit and output voltage control.

[0100] The 24 V to 800 V isolated power module selected in the above embodiment is as follows: Fig.10 As shown in the figure. The module has a 0~5 V TTL voltage regulation interface to adjust the output voltage in proportion. The acquisition of 0~5 V modulation voltage is realized through a digital-to-analog conversion chip (PWM to Analog Converter, PAC), which can linearly convert the 0%~100% duty cycle PWM input signal into a 0~5 V analog voltage output signal.

[0101] Since the half-bridge driver selected in the above embodiment has realized the anti-shoot-through function of the upper and lower bridge arms through the dead time programming resistor outside the driver, it is only necessary to write a simple counter program and write it into the FPGA, without considering the setting of the dead time, to realize the flexible control of frequency and duty cycle. No further details will be given here.

[0102] The cascaded nanosecond rise time high voltage positive polarity square wave power supply in the above embodiment is a PD experiment for high voltage silicon carbide devices and their equivalent samples. High voltage silicon carbide devices and their equivalent samples are high resistance and capacitance as loads. LTspice simulation software is used to build a 5-level square wave power supply circuit, and the feasibility of the topology is verified by simulation.

[0103] In the simulation circuit diagram, the main branch switch S i-1 , discharge branch switch S i-2 The SPICE model uses SiC MOSFET discrete devices; the high-voltage DC power supply V DCi The voltage is set to 1 kV; the energy storage capacitor C i The capacitance is set to 0.5 μF; the driving circuit is replaced by an ideal PWM signal source, the rise / fall time of the ideal PWM signal source is set to 15 ns, the high / low level is set to -5 / 20 V respectively, and the dead time is set to 1 μs; the current limiting resistor is set to 100 Ω; the DUT is equivalent to a resistor in parallel with a capacitor, in which the resistance value is set to 100 MΩ and the capacitance value is set to 20~400 pF; the square wave repetition frequency f sw Set to 100 kHz, that is, the square wave period T sw is 10 μs; if the duty cycle D is set to 50%, then theoretically the high level duration of the square wave is D×T sw is 5 μs.

[0104] In normal working mode, the output voltage applied to both ends of the DUT and the output current flowing through the DUT are shown in the following figure: Fig.11 shown.

[0105] Depend on Fig.12 It can be seen that in the square wave period T sw When the duty cycle D is set to 10 μs and 50%, the theoretical high level duration of the square wave is D×T sw The tailing phase is caused by the high resistance-capacitance load characteristic of the DUT. i-1 After closing, the remaining charge on the DUT has almost no discharge path, resulting in a high voltage across the DUT. i-2After the switch is turned on, the remaining charge on the DUT is discharged through the leakage branch switch S i-2 The voltage across the DUT is forced to “0” only after it is discharged to the ground.

[0106] When setting different sample capacitance values, the output characteristics of the square wave power supply are as follows: Fig.12 As shown, Fig.12 A is the output voltage curve when V=20pF, B is the output voltage curve when V=50pF, C is the output voltage curve when V=100pF, D is the output voltage curve when V=200pF, and E is the output voltage curve when V=400pF. Fig.12 It can be seen that the output voltage rise / fall time of the square wave power supply increases as the capacitance of the sample increases.

[0107] Fig.13 , Fig.14 , Fig.15 , Fig.16 The output voltage waveforms are shown when different numbers of square wave generating units are used, when different duty cycles or different frequencies of driving signals are set, and when different delay times of driving signals are set.

[0108] For the convenience of observation, the dead time is reset to 50 ns in the simulation of this embodiment to avoid the high level duration D×T of the square wave. sw Deviation from the observed value.

[0109] like Fig.13 As shown, a is a curve diagram of the output voltage when there is a first-level square wave generating subunit, b is a curve diagram of the output voltage when there are two-level square wave generating subunits, c is a curve diagram of the output voltage when there are three-level square wave generating subunits, d is a curve diagram of the output voltage when there are four-level square wave generating subunits, and e is a curve diagram of the output voltage when there are five-level square wave generating subunits.

[0110] Depend on Fig.13 It can be seen that when different levels of square wave generating units are put into use, the amplitude of the output voltage is equal to the high-voltage DC power supply V in the square wave generating unit put into use. DCi The sum of the amplitudes of verifies the flexible and adjustable output voltage function of the square wave power supply proposed in the above embodiment.

[0111] like Fig.14 As shown, a1 is the waveform of the output voltage when the duty cycle of the driving signal is 0.1, a2 is the waveform of the output voltage when the duty cycle of the driving signal is 0.3, a3 is the waveform of the output voltage when the duty cycle of the driving signal is 0.5, a4 is the waveform of the output voltage when the duty cycle of the driving signal is 0.7, and a5 is the waveform of the output voltage when the duty cycle of the driving signal is 0.9.

[0112] Depend on Fig.14 It can be seen that setting the square wave period Tsw The duty cycle of the driving signal is 10 μs, and different pulse widths of square waves can be obtained by setting different duty cycles, which verifies the flexible and adjustable duty cycle function of the square wave power supply proposed in the above embodiment.

[0113] like Fig.15 As shown, by setting the duty cycle D to 0.5 and setting different repetition frequencies for the driving signal, square waves with different repetition frequencies can be obtained, which verifies the flexible and adjustable repetition frequency function of the square wave power supply proposed in the above embodiment.

[0114] Depend on Fig.16 It can be seen that according to different waveform requirements, different driving delays are set for the driving signal, and a square wave similar to a step wave can be obtained, which verifies the flexible and adjustable function of the square wave power waveform shape proposed in the above embodiment.

[0115] From the above description, it can be seen that the above embodiments of the present application achieve the following technical effects:

[0116] 1) The above-mentioned polarity square wave power supply circuit of the present application includes a square wave generating unit, which includes a plurality of cascaded half-bridge structures, each half-bridge structure includes at least two switch modules, and the square wave generating unit is used to generate a positive polarity square wave signal. The power supply circuit has a simple structure, good scalability, and each level is independent of each other. The output square wave waveform parameters can be flexibly adjusted. It is suitable as a positive polarity square wave power supply circuit for high-voltage SiC package insulation assessment, which solves the problem that there is a lack of high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment in the prior art, resulting in the inability to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to the positive polarity square wave voltage.

[0117] 2) The test device of the device under test of the present application comprises: any one of positive polarity square wave power supply circuits, which is used to power the device under test when the device under test is subjected to a package insulation test; and a test circuit, which is used to be electrically connected to the device under test and is used to perform a package insulation test on the device under test. The test device can achieve flexible outputs of different voltage levels through appropriate circuit design and switch control, solving the problem of the lack of high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment in the prior art, which makes it impossible to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to a positive polarity square wave voltage.

[0118] 3) The power supply method of the present application includes: controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset cycle to provide a positive polarity square wave power supply to the device under test; wherein, the switch devices on the first bridge wall of the half-bridge structure and the switch devices on the second bridge wall are not turned on at the same time, the first bridge wall is the main branch of the half-bridge structure, and the second bridge wall is the leakage branch of the half-bridge structure. The power supply method can achieve flexible output of different voltage levels through appropriate circuit design and switch control, solving the problem that the prior art lacks a high-voltage positive polarity square wave power supply for high-voltage SiC package insulation assessment, resulting in the inability to fully evaluate the partial discharge inside the high-voltage silicon carbide device exposed to a positive polarity square wave voltage.

[0119] The above description is only the preferred embodiment of the present application and is not intended to limit the present application. For those skilled in the art, the present application may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A positive polarity square wave power supply circuit, characterized in that: include: A square wave generating unit is used to generate a positive polarity square wave signal, the square wave generating unit includes a plurality of cascaded half-bridge structures, each of the half-bridge structures includes a high-voltage DC power supply, an energy storage module, a first switch module located on a first bridge wall, and a second switch module on a second bridge wall, the high-voltage DC power supply and the energy storage module are connected in parallel, a first end of the first switch module is electrically connected to a positive electrode of the high-voltage DC power supply, and a second end of the second switch module is electrically connected to a negative electrode of the high-voltage DC power supply.

2. The positive polarity square wave power supply circuit according to claim 1, characterized in that: in, The first end of the first switch module is electrically connected to the positive electrode of the high-voltage DC power supply, and the control end of the first switch module is used to input a first control signal; The first end of the second switch module is electrically connected to the second end of the first switch module, the control end of the second switch module is used to input a second control signal, and the second end of the second switch module is electrically connected to the negative electrode of the high-voltage DC power supply, wherein the first switch module and the second switch module are connected in a half-bridge manner.

3. The positive polarity square wave power supply circuit according to claim 1, characterized in that: Each of the switch modules includes a MOS device.

4. The positive polarity square wave power supply circuit according to claim 1, characterized in that: The energy storage module includes at least one energy storage capacitor.

5. The positive polarity square wave power supply circuit according to claim 1, characterized in that: The power supply circuit further includes: a current limiting unit connected in series with the square wave generating unit.

6. The positive polarity square wave power supply circuit according to claim 5, characterized in that: The current limiting unit includes at least one current limiting resistor.

7. The positive polarity square wave power supply circuit according to claim 6, characterized in that: In the case that the current limiting unit includes a plurality of current limiting resistors, all the current limiting resistors are connected in series.

8. A device for testing a device under test, characterized in that: include: The positive polarity square wave power supply circuit according to any one of claims 1 to 7, wherein the positive polarity square wave power supply circuit is used to supply power to the device under test when the device under test is subjected to a package insulation test; The test circuit is used to be electrically connected to the device under test and to perform a package insulation test on the device under test.

9. A method for supplying power to a device under test using the positive polarity square wave power supply circuit as claimed in any one of claims 1 to 7, characterized in that: The method includes: Controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset period, so as to provide the positive polarity square wave power supply to the device under test; The switch device on the first bridge wall of the half-bridge structure and the switch device on the second bridge wall are not turned on at the same time, the first bridge wall is the main branch of the half-bridge structure, and the second bridge wall is the leakage branch of the half-bridge structure.

10. The method according to claim 9, characterized in that Controlling each switch device in the half-bridge structure in the square wave generating unit to be turned on or off according to a preset period includes: Controlling the switch device of the first bridge wall in the square wave generating unit to be turned on, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide a high level to the device under test; After providing a high level to the device under test, controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned off; Controlling the switch device of the first bridge wall in the square wave generating unit to be turned off, and controlling the switch device of the second bridge wall in the square wave generating unit to be turned on, so as to provide a low level to the device under test; After providing a low level to the device under test, the switch device of the first bridge wall in the square wave generating unit is controlled to be turned off, and the switch device of the second bridge wall in the square wave generating unit is controlled to be turned off, so as to provide the positive polarity square wave power supply to the device under test.

11. The method according to claim 10, characterized in that The half-bridge structure includes a first switch module and a second switch module, which controls the switch device of the first bridge wall in the square wave generating unit to be turned on, and controls the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide a high level to the device under test, including: All the switch devices in the first switch module are controlled to be turned on, and the switch devices in the second switch module are controlled to be turned off, so as to provide a high level to the device under test.

12. The method according to claim 10, characterized in that The half-bridge structure includes a first switch module and a second switch module, and controls the switch device of the first bridge wall in the square wave generating unit to be turned off, and controls the switch device of the second bridge wall in the square wave generating unit to be turned off, including: All the switch devices in the first switch module are controlled to be turned off, and all the switch devices in the second switch module are controlled to be turned off.

13. The method according to claim 10, characterized in that The half-bridge structure includes a first switch module and a second switch module, which controls the switch device of the first bridge wall in the square wave generating unit to be turned off, and controls the switch device of the second bridge wall in the square wave generating unit to be turned on, so as to provide a low level to the device under test, including: All the switch devices in the first switch module are controlled to be turned off, and all the switch devices in the second switch module are controlled to be turned on, so as to provide a low level to the device under test.

14. The method according to claim 10, characterized in that The half-bridge structure includes a first switch module and a second switch module, controls the switch device of the first bridge wall in the square wave generating unit to be turned off, and controls the switch device of the second bridge wall in the square wave generating unit to be turned off, so as to provide the positive polarity square wave power supply to the device under test, including: All the switch devices in the first switch module are controlled to be turned off, and all the switch devices in the second switch module are controlled to be turned off, so as to provide the positive polarity square wave power supply to the device under test.

15. The method according to claim 10, characterized in that The square wave generating unit includes n cascaded half-bridge structures, and the high level provided by the square wave generating unit to the device under test is , where V DUT is the voltage value of the high level, i is the number of stages of the half-bridge structure, n is the number of all the half-bridge structures, V DCi is the voltage value of the high-voltage DC power supply in the i-th stage half-bridge structure, and the low level provided by the square wave generating unit to the device under test is 0.

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