SiC diode high-frequency power circulation circuit and control method

Abstract

The embodiment of the invention relates to the technical field of power testing, and discloses a SiC diode high-frequency power circulation circuit and a control method. The SiC diode high-frequency power circulation circuit comprises a capacitor, an inductor, a first switch tube, a second SiC diode, a third SiC diode and a fourth switch tube. The emitter of the first switch tube is connected with the cathode of the third SiC diode, and the collector of the first switch tube is connected in parallel with the cathode of the second SiC diode and the cathode of the capacitor; the collector of the fourth switch tube is connected with the anode of the second SiC diode, and the emitter of the fourth switch tube is connected with the anode of the third SiC diode; the inductor is connected in series between the first switch tube and the fourth switch tube. According to the SiC diode high-frequency power circulation circuit and the control method provided by the embodiment of the invention, the aging condition of the to-be-tested device in the actual working condition can be effectively simulated.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of power testing technology, and in particular to a SiC diode high-frequency power circulation circuit and a control method. Background Art

[0002] Power cycling test is a method used to test the power consumption, efficiency and stability of a device, system or circuit under different load conditions. In actual applications, the junction temperature fluctuations in the device are simulated through load current heating and switching operations, thereby accelerating the aging of the device and exposing the weak points of the packaging material in advance to evaluate its impact on the device life under different working conditions. In actual applications, the power module needs to operate stably for a long time, so its reliability and stability are crucial to the overall operation of the system. To ensure the stability of the power module, a reactive aging test is usually performed, which can effectively detect potential faults and predict the life of the device.

[0003] At present, traditional power cycle aging tests usually adopt a constant current control strategy and mainly test single devices. However, this method cannot effectively simulate the complex working conditions in the actual system loop, resulting in certain differences between the test results and the performance in actual applications. Especially when simulating the aging of devices under high-frequency conditions, traditional methods are not effective and cannot accurately reflect the working status and potential failures of devices in real systems. Therefore, how to effectively simulate the aging of the device under test in actual working conditions is an important issue. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a SiC diode high-frequency power circulation circuit and control method, which can effectively simulate the aging of the device under test in actual working conditions.

[0005] To solve the above technical problems, an embodiment of the present application provides a SiC diode high-frequency power circulation circuit, which includes a capacitor, an inductor, a first switch tube, a second SiC diode, a third SiC diode, and a fourth switch tube; wherein the emitter of the first switch tube is connected to the cathode of the third SiC diode, and the collector of the first switch tube is connected in parallel with the cathode of the second SiC diode and the negative electrode of the capacitor; the collector of the fourth switch tube is connected to the anode of the second SiC diode, and the emitter of the fourth switch tube is connected to the anode of the third SiC diode; and the inductor is connected in series between the first switch tube and the fourth switch tube.

[0006] The SiC diode high-frequency power cycle circuit provided in the embodiment of the present application adopts a SiC diode high-frequency power cycle circuit composed of a capacitor, an inductor, a first switch tube, a second SiC diode, a third SiC diode, and a fourth switch tube to address the problem that the traditional power cycle aging test cannot effectively simulate the working conditions in the actual system loop. By simulating the power cycle of the normal switch of the SiC diode in the circuit, the circuit can perform repeated power cycles under given conditions. Thereby, the aging of the device in actual working conditions can be effectively simulated.

[0007] In some embodiments, the first switch tube is connected in parallel with a first diode, the collector of the first switch tube is connected to the cathode of the first diode, and the emitter of the first switch tube is connected to the anode of the first diode; the fourth switch tube is connected in parallel with a fourth diode, the collector of the fourth switch tube is connected to the cathode of the fourth diode, and the emitter of the fourth switch tube is connected to the anode of the fourth diode.

[0008] In some implementations, the first switch tube and the first diode are provided by a first IGBT device, and the fourth switch tube and the fourth diode are provided by a second IGBT device.

[0009] In some embodiments, the current carrying capacity of the first switch tube and the fourth switch tube is greater than or equal to 1.5 times that of the third SiC diode and the second SiC diode.

[0010] In some implementations, the first switch tube and the fourth switch tube receive a constant pulse current and are set to a half-bridge working state.

[0011] Correspondingly, an embodiment of the present application also provides a control method for a SiC diode high-frequency power circulation circuit. The control method adopts the above-mentioned SiC diode high-frequency power circulation circuit, and the control method includes: setting the circulation circuit to enter a half-bridge working state; passing a constant pulse current to cyclically control the on and off of the first switch tube and the fourth switch tube to make the third SiC diode and the second SiC diode circulate and continue current; monitoring the temperature of the third SiC diode and the second SiC diode; judging whether the preset condition for ending the cycle is met, and if the preset condition for ending the cycle is met, then ending the cycle; if the preset condition for ending the cycle is not met, then continuing to work.

[0012] In some embodiments, the preset condition for ending the cycle refers to a temperature threshold of the third SiC diode and the second SiC diode, a current threshold through the third SiC diode and the second SiC diode, or a cycle period.

[0013] In some embodiments, the on and off of the first switch tube and the fourth switch tube are cyclically controlled, including: in a first time period, turning on the first switch tube and the fourth switch tube at the same time; in a second time period, turning on one of the first switch tube or the fourth switch tube and turning off the other; in a third time period, turning off the first switch tube and the fourth switch tube at the same time; in a fourth time period, reversing the switching states of the first switch tube and the fourth switch tube in the second time period.

[0014] In some embodiments, in a first time period, the first switch tube and the fourth switch tube are turned on at the same time, so that the inductor stores energy; in a second time period, the first switch tube is turned on and the fourth switch tube is turned off, the current of the inductor is continued through the second SiC diode and the first switch tube, and the second SiC diode is heated; in a third time period, the first switch tube and the fourth switch tube are turned off at the same time, the current of the inductor is continued through the third SiC diode and the second SiC diode in turn, the second SiC diode is heated and the third SiC diode is heated at the same time; in a fourth time period, the first switch tube is turned off and the fourth switch tube is turned on, the current of the inductor is continued through the third SiC diode and the fourth switch tube, and the third SiC diode is heated.

[0015] In some implementations, the pulse width period of the first switch tube and the fourth switch tube is 20us, the capacitance is 1000V2uF, the inductance is 400uH, the operating frequency of the cyclic circuit is 50KHz, and the time interval of each time period is 20us. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0017] Figure 1 is a schematic diagram of a SiC diode high-frequency power circulation circuit provided by some embodiments of the present application;

[0018] Figure 2 It is a schematic diagram of the working mode of the SiC diode high-frequency power circulation circuit provided by some embodiments of the present application;

[0019] Figure 3 This is a flow chart of a control method of a SiC diode high-frequency power circulation circuit provided in some embodiments of the present application. DETAILED DESCRIPTION

[0020] To make the purpose, technical scheme and advantages of the embodiments of the present application clearer, each embodiment of the present application will be described in detail below in conjunction with the accompanying drawings. However, it will be appreciated by those skilled in the art that in each embodiment of the present application, many technical details are proposed in order to enable the reader to better understand the present application. However, even without these technical details and various changes and modifications based on the following embodiments, the technical scheme claimed in the present application can also be implemented. The division of the following embodiments is for the convenience of description, and the specific implementation of the present application should not constitute any limitation, and the various embodiments can be combined with each other and referenced to each other without contradiction.

[0021] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by technicians in the technical field to which this application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit this application; the terms "including" and "having" in the specification and claims of this application and the above-mentioned figure descriptions and any variations thereof are intended to cover non-exclusive inclusions.

[0022] In the description of the embodiments of the present application, the technical terms "first", "second", etc. are only used to distinguish different objects, and cannot be understood as indicating or implying relative importance or implicitly indicating the number, specific order or primary and secondary relationship of the indicated technical features. In the description of the embodiments of the present application, the meaning of "multiple" is more than two, unless otherwise clearly and specifically defined.

[0023] In the description of the embodiments of the present application, the term "and / or" is only a description of 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. In addition, the character " / " in this article generally indicates that the associated objects before and after are in an "or" relationship.

[0024] In the description of the embodiments of the present application, unless otherwise clearly specified and limited, technical terms such as "installed", "connected", "connected" and the like should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, and it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0025] The traditional aging test method, which uses a single device and controls constant current, does have the advantages of simple operation and strong pertinence. However, in actual applications, devices usually work in complex system loops, which may include a variety of different electronic components and complex current and voltage changes. The traditional aging test method only tests a single device and cannot consider the complex factors in these actual system loops. Therefore, the test results may be different from the performance of the device in actual applications.

[0026] To this end, some embodiments of the present application provide a SiC diode high-frequency power cycle circuit. In view of the problem that traditional power cycle aging tests cannot effectively simulate the working conditions in the actual system loop, a SiC diode high-frequency power cycle circuit composed of a capacitor, an inductor, a first switch tube, a second SiC diode, a third SiC diode, and a fourth switch tube is used. By simulating the power cycle of the normal switch of the SiC diode in the circuit, the circuit can perform repeated power cycles under given conditions. Thereby, the aging of the device under test in actual working conditions can be effectively simulated.

[0027] Combine the following Figures 1 to 3 , illustrating a SiC diode high frequency power circulation circuit provided in some embodiments of the present application.

[0028] like Figure 1 As shown, the device provided by some embodiments of the present application includes a capacitor C, an inductor L, a first switch tube Q1, a second SiC diode D2, a third SiC diode D3, and a fourth switch tube Q4; wherein, the emitter of the first switch tube Q1 is connected to the cathode of the third SiC diode D3, and the collector of the first switch tube Q1 is connected in parallel with the cathode of the second SiC diode and the negative electrode of the capacitor C; the collector of the fourth switch tube Q4 is connected to the anode of the second SiC diode, and the emitter of the fourth switch tube Q4 is connected to the anode of the third SiC diode D3; and the inductor L is connected in series between the first switch tube Q1 and the fourth switch tube Q4.

[0029] Capacitor C is used to store energy. When the switch tube is turned off, capacitor C can release energy and continue to provide power to the circuit to ensure stable operation of the circuit. Inductor L is connected in series between the first switch tube Q1 and the fourth switch tube Q4. Inductor L is an energy storage element that can store energy in its magnetic field. In the process of switching on and off the switch tube, inductor L will store and release energy to help maintain the current continuity in the circuit.

[0030] The first switch tube Q1 and the fourth switch tube Q4 are connected through the inductor L to form the main path of the current. The emitter and collector of the first switch tube Q1 are connected to the cathode of the third SiC diode D3 and the cathode of the second SiC diode D2 respectively. The fourth switch tube Q4 is connected to the anode of the second SiC diode D2 through its collector and to the anode of the third SiC diode D3 through the emitter, allowing the current to circulate between the inductor L, the SiC diode and the switch tube. The first switch tube Q1 and the fourth switch tube Q4 are used as control tubes or accompanying test tubes to control the switching state of the circuit. By controlling their conduction and shutdown, the storage and release of electrical energy can be achieved, thereby driving other components in the circuit to work.

[0031] The third SiC diode D3 and the second SiC diode D2 are the devices to be tested and are used to evaluate the performance and aging characteristics of SiC diodes under high-frequency power cycling conditions. SiC diodes have very small reverse recovery inertia, which makes them more advantageous in high-frequency rectification or high-frequency switching applications. In addition, SiC materials also exhibit the superior performance of low impedance and low thermal resistance. Figure 1 As shown, the cathode of the third SiC diode D3 is connected to the emitter of the first switch tube Q1, and the anode is connected to the capacitor CC and the fourth switch tube Q4. When the first switch tube Q1 is turned on, the current passes through the second SiC diode D2 to test its aging and performance under actual working conditions. The anode of the second SiC diode D2 is connected to the collector of the fourth switch tube Q4, and the cathode is connected to the inductor L. When the fourth switch tube Q4 is turned on, the current passes through the third SiC diode D3, and a similar test is performed. By controlling the working state of the first and fourth switch tubes Q4, the circuit can simulate different power cycle conditions, evaluate the performance of SiC diodes under high-frequency operation and different power cycle conditions, and understand their aging and reliability in long-term use.

[0032] Some embodiments of the present application provide a SiC diode high-frequency power circulation circuit, which connects two SiC diodes and two switch tubes, and simulates the power of SiC diodes in different states. Through the coordination of inductance L and capacitance C, as well as the control of the drive circuit and the drive signal, the switching states of the first switch tube Q1 and the fourth switch tube Q4 are flexibly adjusted, thereby realizing the power circulation of the aging circuit. This can effectively simulate the aging of the device under test in actual working conditions.

[0033] In some embodiments, the first switch tube Q1 is connected in parallel with a first diode D1, the collector of the first switch tube Q1 is connected to the cathode of the first diode D1, and the emitter of the first switch tube Q1 is connected to the anode of the first diode D1; the fourth switch tube Q4 is connected in parallel with a fourth diode D4, the collector of the fourth switch tube Q4 is connected to the cathode of the fourth diode D4, and the emitter of the fourth switch tube Q4 is connected to the anode of the fourth diode D4.

[0034] Each switch tube can be connected in parallel with a diode, so that when the switch tube is turned off, the diode can provide a reverse voltage protection path for the circuit. This helps to protect other components in the circuit from possible overvoltage, thereby effectively protecting the circuit and significantly enhancing the stability and safety of the overall circuit.

[0035] In some embodiments, the first switch tube Q1 and the first diode D1 are provided by a first IGBT device, and the fourth switch tube Q4 and the fourth diode D4 are provided by a second IGBT device.

[0036] Integrating the switch tube and the diode into the same IGBT device can improve the circuit integration and performance, reduce costs and reduce design complexity.

[0037] In some embodiments, the current carrying capacity of the first switch tube Q1 and the fourth switch tube Q4 is greater than or equal to 1.5 times that of the third SiC diode D3 and the second SiC diode D2.

[0038] During the aging test, the test conditions for SiC power devices and ordinary power devices are different. Since ordinary devices have higher thermal resistance, the temperature will be higher than that of SiC devices under the same heat dissipation conditions. Therefore, when used together under high-frequency conditions, the flow capacity and heat absorption capacity of the control tube need to be higher than that of the SiC diode, which needs to be about 1.5 times that of the SiC diode. When setting parameters, the adaptability of the control tube will be comprehensively considered.

[0039] The first switch tube Q1 and the fourth switch tube Q4 are used as the accompanying test tubes in the test, and their current carrying capacity is designed to be greater than or equal to 1.5 times that of the third SiC diode D3 and the second SiC diode D2. This design is to ensure that the accompanying test tube has higher reliability in the power cycle test, can operate under higher current conditions, reduce the risk of interrupting the test due to accompanying test tube failure, and thus improve the stability and accuracy of the entire test. By improving the current carrying capacity of the accompanying test tube, the accuracy of the performance and life evaluation of the device during the test process can be effectively guaranteed.

[0040] In some embodiments, the first switch tube Q1 and the fourth switch tube Q4 receive a constant pulse current and are set to a half-bridge working state.

[0041] The first switch tube Q1 and the fourth switch tube Q4 are configured to receive constant pulse current and are set to half-bridge working state. With this configuration, the switch tube can achieve efficient current switching during the power cycle and ensure a stable working state. The application of constant pulse current helps to simulate the current changes in actual working conditions, so as to more accurately evaluate the working characteristics and life of the third SiC diode D3 and the second SiC diode D2 to be tested in the actual use environment. The setting of the half-bridge working state also further improves the efficiency and reliability of the test circuit.

[0042] Accordingly, an embodiment of the present application further provides a control method for a SiC diode high-frequency power circulation circuit, and the control method adopts the above-mentioned SiC diode high-frequency power circulation circuit. Figure 3 As shown, the control method includes:

[0043] S1: Set the circulation circuit to enter the half-bridge working state;

[0044] S2: a constant pulse current is passed to cyclically control the on and off of the first switch tube Q1 and the fourth switch tube Q4, so as to make the third SiC diode D3 and the second SiC diode D2 cyclically freewheel;

[0045] S3: monitoring the temperatures of the third SiC diode D3 and the second SiC diode D2;

[0046] S4: Determine whether the preset condition for ending the cycle is met. If the preset condition for ending the cycle is met, the cycle is ended. If the preset condition for ending the cycle is not met, the operation continues.

[0047] In some embodiments, the preset condition for ending the cycle refers to a temperature threshold of the third SiC diode D3 and the second SiC diode D2 , a current threshold through the third SiC diode D3 and the second SiC diode D2 , or a cycle period.

[0048] SiC diodes generate heat when working. If the temperature is too high, it may cause its performance to degrade or even be damaged. Therefore, by setting the temperature threshold, the temperature condition of the SiC diode can be monitored in real time to effectively prevent it from being damaged by overheating. At the same time, excessive current will also pose a threat to SiC diodes. To this end, setting the current threshold can ensure that the SiC diode operates stably within a safe current range and avoid damage caused by overcurrent. By observing the performance of SiC diodes when approaching or reaching these thresholds, its reliability and stability under extreme conditions can be evaluated, which is of vital importance for determining the life and performance of SiC diodes in practical applications.

[0049] In addition, by setting a shorter cycle period, the bonding ability of the bond wire can be tested. In a shorter cycle, the temperature change and mechanical stress experienced by the bond wire are more limited, which helps to evaluate its bonding strength and stability separately. By setting a longer cycle period, the reliability of the bond wire and the solder layer can be tested. During long power cycling, the bond wire and the solder layer will experience more temperature changes and mechanical stress, which more realistically simulates its working environment in actual applications. Such tests help to discover potential problems, such as loosening of the bond wire, fatigue of the solder layer, etc., so as to make improvements and optimizations in advance.

[0050] In some embodiments, the on and off of the first switch tube Q1 and the fourth switch tube Q4 are cyclically controlled, including: in a first time period, turning on the first switch tube Q1 and the fourth switch tube Q4 at the same time; in a second time period, turning on one of the first switch tube Q1 or the fourth switch tube Q4 and turning off the other; in a third time period, turning off the first switch tube Q1 and the fourth switch tube Q4 at the same time; in a fourth time period, reversing the switching states of the first switch tube Q1 and the fourth switch tube Q4 in the second time period.

[0051] In some embodiments, in a first time period, the first switch tube Q1 and the fourth switch tube Q4 are turned on at the same time, so that the inductor L stores energy; in a second time period, the first switch tube Q1 is turned on, the fourth switch tube Q4 is turned off, the current of the inductor L continues to flow through the second SiC diode D2 and the first switch tube Q1, and the second SiC diode D2 generates heat; in a third time period, the first switch tube Q1 and the fourth switch tube Q4 are turned off at the same time, the current of the inductor L continues to flow through the third SiC diode D3 and the second SiC diode D2 in turn, the second SiC diode D2 generates heat and the third SiC diode D3 generates heat at the same time; in a fourth time period, the first switch tube Q1 is turned off, the fourth switch tube Q4 is turned on, the current of the inductor L continues to flow through the third SiC diode D3 and the fourth switch tube Q4, and the third SiC diode D3 generates heat.

[0052] In some embodiments, the pulse width period of the first switch tube Q1 and the fourth switch tube Q4 is 20us, the capacitor C is 1000V2uF, the inductor L is 400uH, the operating frequency of the cyclic circuit is 50KHz, and the time interval of each time period is 20us.

[0053] Specifically, the second and third SiC diodes D3 of 1200V 40A are used as test tubes, and the first and second switch tubes of 1200V 75AIGBT are used as accompanying test tubes. The circuit is connected according to the connection method of the photovoltaic inverter Boost boost circuit. The test frequency is set to 50KHz, the switching cycle is 20us, the capacitor C is 1000V 2uF, and the inductor L is 400uH. The ripple current is selected as 20% of the constant current, that is, 40A*20%=8A, to ensure that the second and third SiC diodes D3 are heated evenly during the continuous current.

[0054] Turn on the test equipment, set the cycle circuit to enter the half-bridge working state, and perform a high-frequency power cycle aging test on the circuit. During the test, monitor the temperature and other related parameters of the second and third SiC diodes D3 in real time. According to the preset end cycle conditions (such as the number of cycles, time, temperature, etc.), determine whether the test is over. If the end conditions are met, stop the test; if not, continue the test.

[0055] During the test, if Figure 2 As shown, during the period t0-t1, the first switch tube Q1 and the fourth switch tube Q4 are turned on at the same time, the inductor L stores energy, and the inductor current iL rises. During the period t1-t2, the fourth switch tube Q4 is turned off, the first switch tube Q1 is turned on, and the inductor current iL continues to flow through the second SiC diode D2 and the first switch tube Q1, and the second SiC diode D2 is working in a heating state. During the period t3-t4, the fourth switch tube Q4 is turned on, the first switch tube Q1 is turned off, and the inductor current iL continues to flow through the fourth switch tube Q4 and the third SiC diode D3, and the third SiC diode D3 is working in a heating state. After the moment t4, the first switch tube Q1 and the fourth switch tube Q4 are turned on again at the same time. The moment t4 marks the completion of a cycle of the power circulation circuit, and the circuit begins to perform a cyclic power cycle under given conditions.

[0056] Those skilled in the art will appreciate that the above-mentioned embodiments are specific examples for implementing the present application, and in actual applications, various changes may be made thereto in form and detail without departing from the spirit and scope of the present application.

Claims

1. A SiC diode high frequency power circulation circuit, characterized in that: include: A capacitor, an inductor, a first switch tube, a second SiC diode, a third SiC diode, and a fourth switch tube; wherein the emitter of the first switch tube is connected to the cathode of the third SiC diode, the collector of the first switch tube is connected in parallel with the cathode of the second SiC diode and the negative electrode of the capacitor; the collector of the fourth switch tube is connected to the anode of the second SiC diode, and the emitter of the fourth switch tube is connected to the anode of the third SiC diode; the inductor is connected in series between the first switch tube and the fourth switch tube.

2. A SiC diode high frequency power circulation circuit according to claim 1, characterized in that: The first switch tube is connected in parallel with a first diode, the collector of the first switch tube is connected to the cathode of the first diode, and the emitter of the first switch tube is connected to the anode of the first diode; the fourth switch tube is connected in parallel with a fourth diode, the collector of the fourth switch tube is connected to the cathode of the fourth diode, and the emitter of the fourth switch tube is connected to the anode of the fourth diode.

3. A SiC diode high frequency power circulation circuit according to claim 2, characterized in that: The first switch tube and the first diode are provided by a first IGBT device, and the fourth switch tube and the fourth diode are provided by a second IGBT device.

4. A SiC diode high frequency power circulation circuit according to claim 3, characterized in that: The current carrying capacity of the first switch tube and the fourth switch tube is greater than or equal to 1.5 times that of the third SiC diode and the second SiC diode.

5. A SiC diode high frequency power circulation circuit according to claim 4, characterized in that: The first switch tube and the fourth switch tube receive a constant pulse current and are set to a half-bridge working state.

6. A control method for a SiC diode high frequency power circulation circuit, characterized in that: Using a SiC diode high-frequency power circulation circuit as claimed in any one of claims 1 to 5, the control method comprises: Setting the circulation circuit to enter a half-bridge working state; A constant pulse current is passed to cyclically control the on and off of the first switch tube and the fourth switch tube, so as to make the third SiC diode and the second SiC diode cyclically freewheel; monitoring the temperatures of the third SiC diode and the second SiC diode; Determine whether the preset condition for ending the cycle is met. If the preset condition for ending the cycle is met, end the cycle; if the preset condition for ending the cycle is not met, continue working.

7. A control method for a SiC diode high frequency power circulation circuit according to claim 6, characterized in that: The preset condition for ending the cycle refers to a temperature threshold of the third SiC diode and the second SiC diode, a current threshold or a cycle period passing through the third SiC diode and the second SiC diode.

8. The control method of a SiC diode high frequency power circulation circuit according to claim 7, characterized in that: The cyclic control of turning on and off the first switch tube and the fourth switch tube includes: In a first time period, the first switch tube and the fourth switch tube are turned on simultaneously; In a second time period, one of the first switch tube or the fourth switch tube is turned on, and the other is turned off; In a third time period, the first switch tube and the fourth switch tube are turned off simultaneously; In a fourth time period, the switching states of the first switch tube and the fourth switch tube in the second time period are reversed.

9. The control method of a SiC diode high frequency power circulation circuit according to claim 8, characterized in that: In the first time period, the first switch tube and the fourth switch tube are turned on simultaneously, so that the inductor stores energy; In the second time period, the first switch tube is turned on, the fourth switch tube is turned off, the current of the inductor is freewheeling through the second SiC diode and the first switch tube, and the second SiC diode generates heat; In the third time period, the first switch tube and the fourth switch tube are turned off at the same time, the current of the inductor is freewheeling through the third SiC diode and the second SiC diode in sequence, and the second SiC diode is heated and the third SiC diode is heated at the same time; In the fourth time period, the first switch tube is turned off, the fourth switch tube is turned on, the current of the inductor is freewheeling through the third SiC diode and the fourth switch tube, and the third SiC diode generates heat.

10. The control method of a SiC diode high frequency power circulation circuit according to claim 9, characterized in that: The pulse width period of the first switch tube and the fourth switch tube is 20us, the capacitor is 1000V 2uF, the inductor is 400uH, the operating frequency of the cyclic circuit is 50KHz, and the time interval of each time period is 20us.

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