A synchronous boost type energy feedback aging test method for silicon carbide devices

Abstract

The application provides a synchronous Boost type energy feedback aging test method for a silicon carbide device, which comprises the following steps: a test platform is used to cascade a front-stage synchronous Boost bridge arm circuit and a rear-stage synchronous Buck bridge arm circuit; a direct current power supply is input into the front-stage synchronous Boost bridge arm circuit through a diode and connected with an output end of the rear-stage synchronous Buck bridge arm circuit; the direct current power supply is set according to a test working condition; the test platform realizes the circulation of energy in the test platform through two power inductors, so that the power output of the power supply in the test process is reduced; the working modes of the test platform are set as A1, B, A2 and C; the test working condition of the silicon carbide device to be tested is set; the aging of the silicon carbide device under different test working conditions is accelerated; and the aging test result is obtained; and the silicon carbide device is placed in the bridge arm structure circuit, so that the influence of crosstalk on gate oxide reliability under the continuous working condition of the silicon carbide device is fully considered, and the accuracy of the aging test result of the silicon carbide device is improved.

Description

TECHNICAL FIELD

[0001] The present application relates to a synchronous Boost type energy feedback aging test method for a silicon carbide device. BACKGROUND

[0002] SiC material as the third generation of wide band gap semiconductor material, compared with the traditional Si material critical electric field strength is higher, faster saturation electron drift rate, thermal conductivity is larger, the power device or module produced by using SiC material has higher blocking voltage, faster switching speed and better heat dissipation performance, the application of SiC power device can promote the design of modern power converter to the direction of high frequency, high efficiency, high power density.

[0003] However, high-end power electronic converters need to have high reliability due to their diversified application scenarios, among which the reliability of silicon carbide power devices, as one of the most common failure causes, is of great concern. While silicon carbide power devices have greater advantages, they also bring greater challenges to reliability and stability. The defect density of silicon carbide devices (i.e. silicon carbide devices) is very high, and the defect density on the gate oxide and oxide-semiconductor interface is very high, so the long-term reliability problem still exists. On the other hand, there is a trade-off between the reliability of the gate oxide and the on-resistance of the device in the design of the silicon carbide device. To improve the performance of the silicon carbide device, it is essential to accurately evaluate the long-term reliability of the gate oxide.

[0004] The gate oxide layer reliability test of the silicon carbide device can be divided into DC gate bias temperature instability stress test and AC gate bias temperature instability stress test. The DC gate bias temperature instability stress test is to apply static bias stress to the silicon carbide device. The traditional test method is to measure-stress-measure (MSM) in sequence, repeatedly apply bias and temperature stress to the gate, and then read the data. However, the accuracy of this method is largely related to the reading time, so Infineon has improved it by using a pre-treatment pulse for secondary reading, which is not easily affected by reading delay and device condition.

[0005] At the same time, for the evaluation test of the external gate oxide layer reliability of the silicon carbide device, Infineon has developed two test methods, marathon stress test and gate voltage step stress test. The marathon stress test can simultaneously apply stress close to the operating condition to thousands of devices, with high test efficiency, but it needs to be verified in a very complex way, and the selection of gate stress level is also very harsh. The gate voltage step stress test tests by gradually increasing the gate stress bias, which can qualitatively evaluate the reliability of the gate oxide layer of the silicon carbide device, and is relatively accurate and effective, but the test quantity is small.

[0006] DC gate bias temperature instability stress test is tested under the condition of static bias stress, however, in the actual operation of silicon carbide devices, the degree of parameter shift under the condition of specific AC gate bias stress may exceed the typical value after applying standard DC gate stress, for this, it is necessary to evaluate and test the AC gate bias temperature instability (AC BTI) of silicon carbide devices. The test method generally shorts the drain and source of the silicon carbide device to ensure that there is no load current when it is turned on, applies an AC high frequency dynamic voltage stress to the gate for testing, and reads out the data in a certain measurement sequence, under this test, the working condition of the silicon carbide device in the converter is simulated as much as possible, mainly considering the switching frequency, bias upper and lower limit and the influence factors of signal overshoot and undershoot of the gate, and the AC gate bias temperature instability stress test more effectively evaluates the reliability problem of the gate oxide layer of the silicon carbide device in the actual operation.

[0007] The above test methods are all in the isolated state of silicon carbide MOSFET, and the static test method or dynamic test method is used for aging test, and the silicon carbide MOSFET is not placed in the bridge arm type structure circuit, however, in actual application, the silicon carbide MOSFET is often in the bridge arm type structure circuit, so that the crosstalk also has a certain influence on the gate oxide reliability of the silicon carbide MOSFET, at the same time, due to the higher switching speed of the silicon carbide device, the crosstalk problem in the bridge arm type structure topology is more prominent, and the serious crosstalk problem hinders the improvement of switching speed, considering that the gate voltage stress has potential influence on reliability and the risk of bridge arm penetration caused by mis-conduction, the crosstalk problem affects the further improvement of the efficiency, power density and service life of the power electronic converter, limits the further reduction of cost, and even reduces the reliability of the operation of the converter. SUMMARY

[0008] The technical problem to be solved by the present application is to provide a silicon carbide device synchronous Boost type energy feedback aging test method, so that the gate of the silicon carbide device works in continuous switching mode, and at the same time, when the silicon carbide device is accelerated aging test, the working condition is closer to the actual working condition of the silicon carbide device applied in the power electronic converter, and can be freely set. The silicon carbide device aging test method can test multiple silicon carbide devices at a time, improving the test efficiency of the silicon carbide device; the silicon carbide device synchronous Boost type energy feedback aging test method places the silicon carbide device in the bridge arm type structure circuit, fully considers the influence of crosstalk on the gate oxide reliability of the silicon carbide device, and improves the accuracy of the aging test result of the silicon carbide device.

[0009] In a first aspect, the present application provides a silicon carbide device synchronous Boost type energy feedback aging test method, comprising: a test platform, the test platform is a bridge arm type structure circuit with a synchronous type cascade Boost-Buck as a topology, including a front stage synchronous type Boost bridge arm circuit and a rear stage synchronous type Buck bridge arm circuit, cascading the front stage synchronous type Boost bridge arm circuit and the rear stage synchronous type Buck bridge arm circuit;

[0010] A direct current power supply is input to the front stage synchronous type Boost bridge arm circuit through a diode and connected to the output end of the rear stage synchronous type Buck bridge arm circuit; the direct current power supply is set according to a test working condition, and the test platform realizes the circulation of energy in the test platform through the power inductance of the front stage synchronous type Boost bridge arm circuit and the power inductance of the rear stage synchronous type Buck bridge arm circuit;

[0011] By setting the working mode of the test platform and setting the switching frequency, drain-source voltage and drain current of the measured silicon carbide device, the aging of the silicon carbide device under different test working conditions is accelerated, and the aging test result is obtained;

[0012] The working mode of the test platform includes A1 working mode, B working mode, A2 working mode and C working mode in sequence; the A1 working mode is at time t1-t2; the B working mode is at time t3-t4; the A2 working mode is at time t4-t5; and the C working mode is at time t5-t6;

[0013] The A1 working mode is:

[0014] The lower bridge arm silicon carbide device Q1 of the front stage synchronous type Boost bridge arm circuit and the upper bridge arm silicon carbide device Q3 of the rear stage synchronous type Buck bridge arm circuit are turned on, the current of the front stage synchronous type Boost bridge arm circuit flows through the power inductance L1 and the lower bridge arm silicon carbide device Q1 in sequence, the current of the rear stage synchronous type Buck bridge arm circuit flows through the upper bridge arm silicon carbide device Q3 and the power inductance L2 in sequence, the capacitor C1 and the capacitor C2 are discharged, and the power inductances L1 and L2 are charged;

[0015] The B working mode is:

[0016] The lower bridge arm silicon carbide device Q1 of the front synchronous Boost bridge arm circuit keeps conducting, and the upper bridge arm silicon carbide device Q3 of the rear synchronous Buck bridge arm circuit is turned off, the lower bridge arm silicon carbide device Q4 thereof is turned on to conduct current, the current direction in the front synchronous Boost bridge arm circuit does not change, and the current in the rear synchronous Buck bridge arm circuit flows through the lower bridge arm silicon carbide device Q4 and the power inductor L2 in turn, at this time, the capacitor C2 keeps the current state unchanged, neither charging nor discharging, the energy is provided by the power inductor L2, the power inductor L2 is discharged, the energy of the front synchronous Boost bridge arm circuit is provided by the capacitor C1, and the power inductor L1 is charged;

[0017] The A2 working mode is:

[0018] The lower bridge arm silicon carbide device Q1 of the front synchronous Boost bridge arm circuit and the upper bridge arm silicon carbide device Q3 in the upper bridge arm of the rear synchronous Buck bridge arm circuit are turned on, the current of the front synchronous Boost bridge arm circuit flows through the power inductor L1 and the lower bridge arm silicon carbide device Q1 in turn, the current of the rear synchronous Buck bridge arm circuit flows through the upper bridge arm silicon carbide device Q3 and the power inductor L2 in turn, the capacitor C1 and the capacitor C2 are discharged, and the power inductors L1 and L2 are charged;

[0019] The C working mode is:

[0020] The state of the front synchronous Boost bridge arm circuit enters the freewheeling state, which is conducted by the upper bridge arm silicon carbide device Q2 of the front synchronous Boost bridge arm circuit, the current of the front synchronous Boost bridge arm circuit flows through the power inductor L1 and the upper bridge arm silicon carbide device Q2 in turn, the energy is provided by the power inductor L1, and the power inductor L1 is in a discharging state; the upper bridge arm silicon carbide device Q3 of the rear synchronous Buck bridge arm circuit is turned on, the energy is provided by the capacitor C2, and the power inductor L2 is in a charging state.

[0021] Further, the test platform comprises a direct current power supply and a diode BD;

[0022] The front synchronous Boost bridge arm circuit comprises a capacitor C1, a power inductor L1, a lower bridge arm silicon carbide device Q1, a first driving unit, an upper bridge arm silicon carbide device Q2 and a second driving unit;

[0023] The rear synchronous Buck bridge arm circuit comprises a capacitor C2, a power inductor L2, an upper bridge arm silicon carbide device Q3, a third driving unit, a lower bridge arm silicon carbide device Q4 and a fourth driving unit;

[0024] The positive pole of the direct current power supply is connected to one end of the capacitor C1, one end of the power inductor L1 and one end of the power inductor L2 through the diode BD; the negative pole of the direct current power supply is connected to the other end of the capacitor C1, the source of the lower bridge arm silicon carbide device Q1, one end of the capacitor C2 and the source of the lower bridge arm silicon carbide device Q4; the other end of the power inductor L1 is connected to the source of the upper bridge arm silicon carbide device Q2 and the drain of the lower bridge arm silicon carbide device Q1, the drain of the upper bridge arm silicon carbide device Q2 is connected to the other end of the capacitor C2 and the drain of the upper bridge arm silicon carbide device Q3, and the other end of the power inductor L2 is connected to the source of the upper bridge arm silicon carbide device Q3 and the drain of the lower bridge arm silicon carbide device Q4; the first driving unit is used to drive the lower bridge arm silicon carbide device Q1, the second driving unit is used to drive the upper bridge arm silicon carbide device Q2, the third driving unit is used to drive the upper bridge arm silicon carbide device Q3, and the fourth driving unit is used to drive the lower bridge arm silicon carbide device Q4.

[0025] Further, by setting the working mode of the test platform and setting the switching frequency, drain-source voltage and drain current of the measured silicon carbide device, the aging of the silicon carbide device under different test conditions is accelerated, and the aging test result is further specific: the duty cycle of the synchronous Buck bridge arm circuit in the later stage is determined and fixed, and then according to the input voltage of the direct current power supply, the voltage level of the test condition is determined, and the duty cycle of the silicon carbide device in the synchronous Boost bridge arm circuit in the former stage is adjusted to achieve the target of the preset test condition;

[0026] First, the duty cycle D2 of the synchronous Buck bridge arm circuit in the later stage is determined, and according to the relationship between the test condition voltage and the duty cycle of the synchronous Buck bridge arm circuit in the later stage, the input voltage of the direct current power supply is determined, as formula (5):

[0027]

[0028] In formula (5), V in is the input voltage of the direct current power supply, V2 is the output voltage of the synchronous Boost bridge arm circuit in the former stage, according to the volt-second characteristic of the power inductors L1 and L2 of the synchronous Boost bridge arm circuit in the former stage and the synchronous Buck bridge arm circuit in the later stage in each switching period, the duty cycle of the lower bridge arm silicon carbide device Q1 is obtained as formula (6);

[0029]

[0030] In formula (6), D1 is the duty cycle of the lower bridge arm silicon carbide device Q1 in the synchronous Boost bridge arm circuit in the former stage, D2 is the duty cycle of the upper bridge arm silicon carbide device Q3 in the synchronous Buck bridge arm circuit in the later stage, I DThe drain current of the four silicon carbide devices;

[0031] Simplifying and solving formula (6), wherein The phase difference between the driving waveform of the front-stage synchronous Boost bridge arm circuit and the driving waveform of the rear-stage synchronous Buck bridge arm circuit in each switching cycle; the duty cycle of the front-stage synchronous Boost bridge arm circuit is calculated as formula (7):

[0032]

[0033] According to the relationship between the phase difference between the driving waveform of the front-stage synchronous Boost bridge arm circuit and the driving waveform of the rear-stage synchronous Buck bridge arm circuit and the duty cycle of the lower bridge arm silicon carbide device Q1, as formula (8):

[0034]

[0035] Further, the equation of the phase difference between the driving waveform of the front-stage synchronous Boost bridge arm circuit and the driving waveform of the rear-stage synchronous Buck bridge arm circuit is obtained as formula (9):

[0036]

[0037] As can be seen from formula (7), when the duty cycle of the upper bridge arm silicon carbide device Q3 of the rear-stage synchronous Buck bridge arm circuit is determined, the voltage level of the test working condition is determined, and the duty cycle of the lower bridge arm silicon carbide device Q1 of the front-stage synchronous Boost bridge arm circuit is related to the test current and the input voltage. By setting the target of the input test working condition, the duty cycle of the front-stage synchronous Boost bridge arm circuit is determined, and the continuous switching test of the silicon carbide device under the set test working condition is carried out, and the aging test result is obtained.

[0038] The one or more technical solutions provided in the embodiments of the present application have at least the following technical effects or advantages:

[0039] 1. The silicon carbide device crosstalk problem has certain research significance: the silicon carbide device synchronous Boost energy feedback aging test method has a bridge arm structure, and in the process of normal operation of the test platform, the silicon carbide device will not only be biased by a certain frequency of gate voltage, including positive bias and negative bias, but also be affected by crosstalk stress caused by high switching speed. Therefore, the synchronous Boost energy feedback aging test platform can not only be used to evaluate the long-term reliability of the silicon carbide device, but also can be placed in the bridge arm structure circuit, considering the influence of crosstalk on the gate oxide reliability of the silicon carbide device, and improving the accuracy of the aging test result of the silicon carbide device.

[0040] 2. Energy feedback: The silicon carbide device synchronous Boost type energy feedback aging test method can realize the function of energy feedback. Through the simulation waveform, it can be seen that the power supply only provides excitation energy when the test platform starts, and thereafter in the normal operation of the test platform, the energy is no longer provided by the power supply, but the energy is circulated in the test platform through the power inductance. This function can effectively reduce the energy consumption of the test platform and greatly reduce the test cost of the silicon carbide device.

[0041] 3. Accelerate the aging degree of silicon carbide device: The silicon carbide device synchronous Boost type energy feedback aging test method can realize the accelerated aging test of the silicon carbide device, test the long-term reliability of the gate oxide layer, and the running condition of the silicon carbide device synchronous Boost type energy feedback aging test method is more in line with the actual working condition of the silicon carbide device applied in the power electronic converter, and the test data is also more close to the actual situation, which has strong credibility.

[0042] 4. Continuous switching test condition: The silicon carbide device synchronous Boost type energy feedback aging test method can test the silicon carbide device under continuous switching test condition, apply a certain frequency of gate voltage stress to the tested silicon carbide device, accelerate the aging degree of the silicon carbide device, and can effectively evaluate the long-term reliability of the silicon carbide device under dynamic stress. Compared with the test method of applying static stress, it is more close to the actual application of the silicon carbide device, and the test result is also more close to the actual situation.

[0043] 5. Free setting condition: The silicon carbide device synchronous Boost type energy feedback aging test method can be set according to the required test condition, and the condition is not unique. It can simulate the actual application condition of the silicon carbide device to the greatest extent, so that the test result is more reliable and accurate, and the gate alternating current bias temperature instability (AC BTI) of the silicon carbide device can be effectively evaluated.

[0044] 6. Multiple silicon carbide devices are tested at the same time: The silicon carbide device synchronous Boost type energy feedback aging test method can be seen from the simulation waveform that the working condition of the four silicon carbide devices is almost the same, so the high temperature gate bias (HTGB) test can be performed on the four silicon carbide devices at the same time, and the long-term reliability of the silicon carbide device can be evaluated at the same time, which effectively improves the test efficiency and speeds up the test progress of the silicon carbide device.

[0045] 7. The power voltage level is low, safe and reliable: the silicon carbide device synchronous Boost type energy feedback aging test method can achieve the test purpose of setting the silicon carbide device under the condition that the input power voltage is lower than the test working voltage, the test platform is connected with low power voltage, the safety requirement of insulation is relatively loose, and the silicon carbide MOSFET aging test is easy to realize.

[0046] The above description is only a summary of the technical scheme of the present application, in order to more clearly understand the technical means of the present application, and to implement the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described below. BRIEF DESCRIPTION OF DRAWINGS

[0047] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0048] Figure 1 The test platform circuit schematic diagram of the silicon carbide device synchronous Boost type energy feedback aging test method of the present application;

[0049] Figure 2 The working waveform diagram of the working mode of the silicon carbide device synchronous Boost type energy feedback aging test method of the present application;

[0050] Figures 3a to 3d The working mode principle diagram of the present application;

[0051] Figure 4 The working mode time relationship diagram of the present application;

[0052] Figure 5 The driving waveform diagram of each silicon carbide device during the first test of the present application;

[0053] Figure 6 The voltage waveform diagram of the capacitor in the rear synchronous type Buck bridge arm circuit during the first test of the present application;

[0054] Figure 7 The drain-source voltage and drain current waveform diagram of the silicon carbide device in the front synchronous type Boost bridge arm circuit during the first test of the present application;

[0055] Figure 8 The drain-source voltage and drain current waveform diagram of the silicon carbide device in the rear synchronous type Buck bridge arm circuit during the first test of the present application;

[0056] Figure 9 The power current waveform diagram during the first test of the present application;

[0057] Figure 10The driving waveform diagram of each silicon carbide device for the second test of the present application;

[0058] Figure 11 The current waveform diagram of the power inductor for the second test of the present application;

[0059] Figure 12 The drain-source voltage and drain current waveform diagram of the silicon carbide device of the front-stage synchronous type Boost bridge arm circuit for the second test of the present application;

[0060] Figure 13 The drain-source voltage and drain current waveform diagram of the silicon carbide device of the rear-stage synchronous type Buck bridge arm circuit for the second test of the present application;

[0061] Figure 14 The driving waveform diagram of each silicon carbide device for the third test of the present application;

[0062] Figure 15 The current waveform diagram of the power inductor for the third test of the present application;

[0063] Figure 16 The drain-source voltage and drain current waveform diagram of the silicon carbide device of the front-stage synchronous type Boost bridge arm circuit for the third test of the present application;

[0064] Figure 17 The drain-source voltage and drain current waveform diagram of the silicon carbide device of the rear-stage synchronous type Buck bridge arm circuit for the third test of the present application;

[0065] Figure 18 The driving waveform diagram of each silicon carbide device for the fourth test of the present application;

[0066] Figure 19 The current waveform diagram of the power inductor for the fourth test of the present application;

[0067] Figure 20 The drain-source voltage and drain current waveform diagram of the silicon carbide device of the front-stage synchronous type Boost bridge arm circuit for the fourth test of the present application;

[0068] Figure 21 The drain-source voltage and drain current waveform diagram of the silicon carbide device of the rear-stage synchronous type Buck bridge arm circuit for the fourth test of the present application. DETAILED DESCRIPTION

[0069] The technical solution in the embodiment of the present application has the following general idea:

[0070] 1. The topology of the synchronous Boost energy feedback aging test platform of the application is a bridge arm type structure circuit of a synchronous cascaded Boost-Buck topology, the front stage is a synchronous Boost bridge arm topology, and the rear stage is a synchronous Buck bridge arm topology, which are cascaded to form the synchronous Boost energy feedback aging test platform of the application, can realize the circulation of energy in the test platform, reduce the power output of the power supply in the test process, and place the silicon carbide device in the bridge arm type structure circuit, which can apply dynamic voltage stress to SiC MOSFET in continuous switching mode.

[0071] 2. The synchronous Boost energy feedback aging test platform of the application has a mixed Boost working mode and Buck working mode, and has four working modes in actual operation.

[0072] 3. The topology of the synchronous Boost energy feedback aging test platform of the application can realize the test of four SiC MOSFET, and in the operation of the test platform, the working conditions of each SiC MOSFET are the same, so that the acceleration aging test of four SiC MOSFET can be carried out at the same time under the same set working condition, the long-term reliability of the SiC MOSFET is tested, and the test efficiency is greatly improved. At the same time, since the synchronous Boost energy feedback aging test platform of the application adopts all SiC MOSFET, and due to the topology characteristics, there may be crosstalk problem at high switching speed, and the synchronous Boost energy feedback aging test platform of the application is beneficial to evaluate the influence of the crosstalk problem of SiC MOSFET in the operation of the converter on the long-term reliability.

[0073] 4. The front stage of the synchronous Boost energy feedback aging test platform of the application is converted by Boost, the input voltage of the direct current power supply is boosted to the working condition required voltage, and the driving signal of SiC MOSFET is reasonably designed by the prior art, so that the current flowing through SiC MOSFET reaches the working condition required current, so as to effectively evaluate the gate alternating current bias temperature instability (AC BTI) of SiC MOSFET in actual application.

[0074] As shown in Figure 1 The test platform in the application adopts a synchronous cascaded Boost-Buck topology, which includes a front-stage synchronous Boost bridge arm circuit and a rear-stage synchronous Buck bridge arm circuit, and the front-stage synchronous Boost bridge arm circuit and the rear-stage synchronous Buck bridge arm circuit are cascaded.

[0075] The test platform includes a direct current power supply and a diode BD.

[0076] The front-stage synchronous Boost bridge arm circuit comprises a capacitor C1, a power inductor L1, a lower bridge arm silicon carbide device Q1, a first driving unit, an upper bridge arm silicon carbide device Q2 and a second driving unit;

[0077] The rear-stage synchronous Buck bridge arm circuit comprises a capacitor C2, a power inductor L2, an upper bridge arm silicon carbide device Q3, a third driving unit, a lower bridge arm silicon carbide device Q4 and a fourth driving unit;

[0078] The positive pole of the direct current power supply is connected to one end of the capacitor C1, one end of the power inductor L1 and one end of the power inductor L2 through a diode BD; the negative pole of the direct current power supply is connected to the other end of the capacitor C1, the source of the lower bridge arm silicon carbide device Q1, one end of the capacitor C2 and the source of the lower bridge arm silicon carbide device Q4; the other end of the power inductor L1 is connected to the source of the upper bridge arm silicon carbide device Q2 and the drain of the lower bridge arm silicon carbide device Q1, the drain of the upper bridge arm silicon carbide device Q2 is connected to the other end of the capacitor C2 and the drain of the upper bridge arm silicon carbide device Q3, the other end of the power inductor L2 is connected to the source of the upper bridge arm silicon carbide device Q3 and the drain of the lower bridge arm silicon carbide device Q4; the first driving unit is used for driving the lower bridge arm silicon carbide device Q1, the second driving unit is used for driving the upper bridge arm silicon carbide device Q2, the third driving unit is used for driving the upper bridge arm silicon carbide device Q3, and the fourth driving unit is used for driving the lower bridge arm silicon carbide device Q4. Wherein, the resistances R Q1 , R Q2 , R Q3 , R Q4 are the on-resistances of the lower bridge arm silicon carbide device Q1, the upper bridge arm silicon carbide device Q2, the upper bridge arm silicon carbide device Q3 and the lower bridge arm silicon carbide device Q4 respectively, and the resistance R L1 is the impedance of the power inductor L1; and the resistances R L2The self impedance of the power inductor L2 is the first drive unit connected with a drive signal and RC circuit and the lower bridge arm silicon carbide device Q1, which is used to drive the switch of the lower bridge arm silicon carbide device Q1; the second drive unit connected with a drive signal and RC circuit and the upper bridge arm silicon carbide device Q2, which is used to drive the switch of the upper bridge arm silicon carbide device Q2; the third drive unit connected with a drive signal and RC circuit and the upper bridge arm silicon carbide device Q3, which is used to drive the switch of the upper bridge arm silicon carbide device Q3; the fourth drive unit connected with a drive signal and RC circuit and the lower bridge arm silicon carbide device Q4, which is used to drive the switch of the lower bridge arm silicon carbide device Q4; the first drive unit, the second drive unit, the third drive unit and the fourth drive unit are set by using the prior art, including a drive signal, a drive resistor and a control capacitor; the drive resistor is set according to the drive signal, and the capacitor is used to adjust the switching speed; and the drive signal is sent by the existing drive circuit.

[0079] The test platform places the silicon carbide MOSFET in the bridge arm structure circuit, so that the influence of crosstalk on the gate oxide reliability of the silicon carbide MOSFET under continuous working conditions is fully considered, and the accuracy of the aging test result of the silicon carbide device is improved.

[0080] The test platform can realize the aging test of the silicon carbide device under continuous switching test, can effectively evaluate the long-term reliability of the silicon carbide device when dynamic stress is applied to the device, and compared with the test method of applying static stress, is closer to the actual application of the silicon carbide device.

[0081] The test platform not only considers the influence of a certain frequency gate voltage bias of the silicon carbide device on the aging degree of the silicon carbide device during normal operation of the converter, but also places the silicon carbide device in the bridge arm type structure circuit, so that the influence of crosstalk on the gate oxide reliability of the silicon carbide device is fully considered when the silicon carbide device works at a high switching speed, and the aging test result of the silicon carbide device is further closer to the actual application of the silicon carbide device, and the test result is more accurate.

[0082] The direct current power supply (V in ) is input to the front-stage synchronous Boost topology through a diode, and is connected to the output end of the rear-stage synchronous Buck topology, so as to prevent damage of the power supply; the input voltage is set according to the test working condition (the test working condition is the switching frequency, the drain-source voltage and the drain current of the silicon carbide device); the test platform realizes the flow of energy in the test platform through the power inductor of the synchronous Boost and the power inductor of the synchronous Buck; the working mode of the test platform considers the impedance of each silicon carbide device and the inductive impedance, and has four working modes: A1 working mode, B working mode, A2 working mode and C working mode; the working principle will be analyzed in detail below and verification will be given.

[0083] 1. Working principle

[0084] like Figure 2 As shown, the operating modes of the synchronous Boost-type energy feedback aging test method for silicon carbide devices of the present invention are, in sequence, A1, B, A2, and C. This method combines Boost and Buck operating modes to achieve energy circulation within the test platform. Its operating waveform is shown below. Figure 2 As shown

[0085] (1) The A1 working mode (t1-t2) does not include time t2.

[0086] like Figure 3a As shown, this is the first operating mode of the test platform—A1 operating mode. The lower arm silicon carbide device Q1 of the front-stage synchronous Boost and the lower arm silicon carbide device Q3 of the rear-stage synchronous Buck are turned on. The current of the front-stage topology flows sequentially through the power inductor L1 and silicon carbide device Q1, while the current of the rear-stage topology flows sequentially through silicon carbide device Q3 and power inductor L2. The capacitors C1 and C2 of the synchronous Boost and synchronous Buck are both discharging, providing energy, while the power inductors L1 and L2 are both charging. During this stage, the voltage across silicon carbide devices Q1 and Q3 is slightly low due to the on-resistance, while the voltage across silicon carbide devices Q2 and Q4 is approximately equal to the output voltage of the front-stage synchronous Boost. The state equation of the test platform during this stage is shown in equation (1).

[0087]

[0088] In equation (1), R Q1 R is the on-resistance of the lower bridge arm silicon carbide device Q1. Q3 R is the on-resistance of the upper bridge arm silicon carbide device Q3. L1 R is the impedance of the power inductor L1. L2 The impedance of power inductor L2 is V. in V1 is the input voltage, V2 is the output voltage of the preceding synchronous Boost bridge arm circuit, and I is the input voltage. L1 I is the steady-state current of the power inductor L1. L2 Let L be the steady-state current of the power inductor L2.

[0089] (2) Working mode B (t2-t3) does not include time t3.

[0090] like Figure 3bAs shown, it is the second working mode of the test platform, B working mode, in which the lower bridge arm SiC device Q1 of the bridge arm in the front-stage synchronous Boost bridge arm circuit remains in the on state, and the lower bridge arm SiC device Q3 of the bridge arm in the rear-stage synchronous Buck bridge arm circuit is off, and the lower bridge arm SiC device Q4 is on to conduct current freewheeling, the current flow direction in the front-stage synchronous Boost bridge arm circuit remains unchanged, and the current in the rear-stage synchronous Buck bridge arm circuit flows through the SiC device Q4 and the power inductor L2 in turn, at this time, the capacitor of the rear-stage synchronous Buck bridge arm circuit remains in the current state without charging or discharging, and the energy is provided by the power inductor L2, and the power inductor L2 is discharged, however, the energy of the front-stage synchronous Boost bridge arm circuit is still provided by the front-stage capacitor, and the power inductor L1 is charged. In this stage, the drain-source voltage of the lower bridge arm SiC devices Q1 and Q4 of the bridge arm of the front-stage synchronous Boost bridge arm circuit and the bridge arm of the rear-stage synchronous Buck bridge arm circuit is approximately zero, and the lower bridge arm SiC devices Q2 and Q3 of each are approximately the output voltage of the front-stage synchronous Boost bridge arm circuit, and the state equation of the test platform in this mode is shown in equation (2).

[0091]

[0092] In equation (2), R Q1 is the on-resistance of the lower bridge arm SiC device Q1, R Q4 is the on-resistance of the lower bridge arm SiC device Q4, R L1 is the impedance of the power inductor L1, R L2 is the impedance of the power inductor L2, V in is the input voltage of the DC power supply, V2 is the output voltage of the front-stage synchronous Boost bridge arm circuit, I L1 is the steady-state current of the power inductor L1, I L2 is the steady-state current of the power inductor L2.

[0093] (3) A working mode (t3-t4) does not include t4 time

[0094] This working mode reverts to the A working mode, in which the lower bridge arm SiC device Q1 in the bridge arm of the front-stage synchronous Boost bridge arm circuit and the upper bridge arm SiC device Q3 in the bridge arm of the rear-stage synchronous Buck bridge arm circuit are simultaneously turned on, at this time, the energy of the rear-stage synchronous Buck bridge arm circuit is no longer provided by the power inductor L2, but by the capacitor C2 of the rear-stage synchronous Buck bridge arm circuit, and the power inductor L2 is charged, and the state equation of the test platform is shown in equation (3).

[0095]

[0096] In equation (3), RQ1 R on is the on-resistance of the lower bridge arm silicon carbide device Q1 Q3 R on is the on-resistance of the upper bridge arm silicon carbide device Q3 L1 R L1 is the impedance of the power inductor L1 L2 R L2 is the impedance of the power inductor L2 in V in is the input voltage of the DC power supply, V out is the output voltage of the pre-stage synchronous Boost bridge arm circuit, I in is the input current of the DC power supply L1 I L1 is the steady-state current of the power inductor L1 L2 I L2 is the steady-state current of the power inductor L2

[0097] (4) C mode of operation (t4-t5)

[0098] Figure 3d As shown in the figure, the last mode of operation of the test platform is the C mode, in which the state of the pre-stage synchronous Boost bridge arm circuit enters the freewheeling state, which is freewelled by the lower bridge arm silicon carbide device Q2 in the bridge arm of the pre-stage synchronous Boost bridge arm circuit, the current of the pre-stage synchronous Boost bridge arm circuit flows through the power inductor L1 and the silicon carbide device Q2 in turn, and the energy is provided by the power inductor L1, which is in the discharging state; the lower bridge arm silicon carbide device Q3 in the bridge arm of the post-stage synchronous Buck bridge arm circuit is turned on, and the energy is provided by the capacitor C2 of the post-stage synchronous Buck bridge arm circuit, and the power inductor L2 is in the charging state. In this stage, the lower bridge arm silicon carbide devices Q2 and Q3 in the bridge arm of the pre-stage synchronous Boost bridge arm circuit and the bridge arm of the post-stage synchronous Buck bridge arm circuit have a voltage of approximately zero due to being in the on state, and the voltages across the lower bridge arm silicon carbide devices Q1 and Q4 of the respective bridge arms are approximately the output voltage of the pre-stage synchronous Boost bridge arm circuit, and the state equation of the test platform in this stage is shown in equation (4).

[0099]

[0100] R on is the on-resistance of the lower bridge arm silicon carbide device Q1 Q2 R on is the on-resistance of the upper bridge arm silicon carbide device Q2 Q3 R on is the on-resistance of the upper bridge arm silicon carbide device Q3 L1 R L1 is the impedance of the power inductor L1 L2 R L2 is the impedance of the power inductor L2 in V in is the input voltage, V out is the output voltage of the pre-stage synchronous Boost bridge arm circuit, I in is the input current L1 I L1 is the steady-state current of the power inductor L1 L2 I L2 is the steady-state current of the power inductor L2

[0101] 2. Test condition setting parameter design

[0102] (1) Test working condition expected target

[0103] The synchronous Boost type energy feedback aging test platform can set the switching frequency, drain-source voltage and drain current of the measured silicon carbide device, and can accelerate the aging of the silicon carbide device under different working conditions, so as to adapt to the working conditions of the silicon carbide device in the actual operation of the converter, and make the test result more close to the actual working condition.

[0104] (2) Test working condition parameter design

[0105] The synchronous Boost type energy feedback aging test platform needs to determine the duty cycle of the synchronous Buck bridge arm circuit in the rear stage, and is fixed and unchanged, and then the voltage level of the test working condition can be determined according to the input voltage of the direct current power supply, and the duty cycle of the silicon carbide device in the synchronous Boost bridge arm circuit in the front stage is adjusted to realize the preset working condition target. The parameter design for setting the working condition will be described in detail below.

[0106] Firstly, the duty cycle D2 of the synchronous Buck bridge arm circuit in the rear stage needs to be determined, and the input voltage is determined according to the relationship between the test working condition voltage and the duty cycle of the synchronous Buck bridge arm circuit in the rear stage, as shown in formula (5).

[0107]

[0108] According to the volt-second characteristic of the power inductors L1 and L2 of the synchronous Boost bridge arm circuit in the front stage and the synchronous Buck bridge arm circuit in the rear stage in each switching cycle, as shown in formula (6), the duty cycle of the silicon carbide device Q1 in the lower bridge arm can be obtained.

[0109]

[0110] In formula (6), D1 is the duty cycle of the silicon carbide device Q1 in the lower bridge arm of the synchronous Boost type in the front stage, D2 is the duty cycle of the silicon carbide device Q3 in the upper bridge arm of the synchronous Buck type in the rear stage, I D is the drain current of the four silicon carbide devices.

[0111] As Figure 4 shown, it is the working mode time relationship, and formula (6) is simplified and solved. Wherein, dA is the time of each A working mode in each switching cycle, is the phase difference between the driving waveform of the synchronous Boost bridge arm circuit in the front stage and the driving waveform of the synchronous Buck bridge arm circuit in the rear stage in each switching cycle, and the equation of the duty cycle of the synchronous Boost bridge arm circuit in the front stage can be obtained. The duty cycle of the synchronous Boost bridge arm circuit in the front stage can be calculated by solving the equation, as shown in formula (7).

[0112]

[0113]

[0114] And according to the phase difference of the driving waveform of the front-stage synchronous Boost bridge arm circuit and the driving waveform of the rear-stage synchronous Buck bridge arm circuit and the duty cycle of the lower bridge arm silicon carbide device Q1, as shown in equation (8), the phase difference of the driving waveform in the front-stage synchronous Boost bridge arm circuit and the driving waveform in the rear-stage synchronous Buck bridge arm circuit can be further obtained, as shown in equation (9).

[0115]

[0116] As shown in equation (7), when the duty cycle of the rear-stage synchronous Buck bridge arm circuit is determined, the voltage level of the test working condition can be determined, and the duty cycle of the front-stage synchronous Boost bridge arm circuit is related to the test current and the input voltage of the direct current power supply, so the target can be set by the input working condition, thereby determining the duty cycle of the front-stage synchronous Boost bridge arm circuit, and then the continuous switching test of the silicon carbide device under the specific working condition is carried out; the required voltage or current can be tested by connecting the corresponding voltage test probe, current test probe or other test equipment, so as to obtain the aging test result.

[0117] 3.Simulation verification

[0118] (1) Test working condition setting

[0119] The principle of the synchronous Boost energy feedback aging test platform of the application is simulated by using Plecs simulation software, the input voltage of the direct current power supply is 400V, and the specific topology parameters are shown in Table 1.

[0120] Table 1 Simulation topology parameters

[0121]

[0122] The test working condition is set according to the actual situation, and the test working condition set in the simulation of the application is shown in Table 2.

[0123] Table 2 Test working condition parameters

[0124]

[0125] According to the above test working condition, the duty cycle of the front-stage synchronous Boost bridge arm circuit and the phase difference of the driving waveforms of the power devices of the front-stage synchronous Boost bridge arm circuit and the rear-stage synchronous Buck bridge arm circuit can be set, and the calculation results are shown in Table 3.

[0126] Table 3 Calculation parameters

[0127]

[0128]

[0129] (2)Simulation results

[0130] For the simulation of the silicon carbide device aging test method described in the application, four different test conditions are simulated, and the test conditions of four silicon carbide devices in different test conditions are concerned.

[0131] (a) First test

[0132] The test condition is set as drain-source voltage 800V, drain current 20A, and switching frequency 100kHz. The gate drive waveform of each silicon carbide device is as shown in Figure 5 It can be seen that the synchronous Boost type energy feedback aging test platform described in the application works in A1, B, A2 and C modes, and V gs represents the driving voltage.

[0133] As shown in Figure 6 , the current waveforms of power inductance L1 and power inductance L2 are stable at 20A.

[0134] Figure 7 The SiC MOSFET drain-source voltage and drain current waveforms of the front-stage synchronous Boost bridge arm circuit are Figure 8 The SiC MOSFET drain-source voltage and drain current waveforms of the rear-stage synchronous Buck bridge arm circuit are From the waveforms, it can be seen that in the synchronous Boost type energy feedback aging test platform described in the application, the test conditions of each SiC MOSFET are almost the same, and its drain-source voltage and drain current meet the preset condition setting value of 800V and 20A.

[0135] As shown in Figure 9 , the power supply current is 0, and after the power supply gives a transient excitation when the test platform is started, the energy circulates in the test platform and is no longer supplied to the test platform by the power supply, which realizes the function of energy feedback.

[0136] (b) Second test

[0137] As shown in Figure 10 , in the second test, the test condition is set as drain-source voltage 800V, drain current 30A, and switching frequency 100kHz. The gate drive waveform of each silicon carbide device is

[0138] As can be seen from the driving waveform, when driven according to the calculated duty cycle of the preceding synchronous Boost bridge arm circuit, its operating mode is A1, B, A2, or C, which conforms to the working principle of the synchronous Boost energy feedback aging test platform described in this invention. Figure 11 The waveform of the current in the power inductor is 30A, which is consistent with the test conditions.

[0139] like Figure 12 The test results for silicon carbide devices in the front-end synchronous Boost bridge arm circuit are shown below, while the test results for silicon carbide devices in the rear-end synchronous Buck bridge arm circuit are shown below. Figure 13 As shown, each silicon carbide device is under the set test conditions—800V, 30A, and 100kHz, so accelerated aging tests can be performed on each silicon carbide device simultaneously under these test conditions.

[0140] (c) Third Test

[0141] The test settings for the third test were: drain-source voltage 800V, drain current 40A, and switching frequency 100kHz. The gate drive waveform for each silicon carbide device was as follows: Figure 14 As shown in the diagram, the test platform operates normally according to modes A1, B, A2, and C, with the duty cycle matching the theoretically calculated value, as observed through the drive waveform.

[0142] like Figure 15 As shown, the current waveform of the power inductor is 40A under test conditions, which is consistent with the theoretical calculation value.

[0143] like Figure 16 The figure shows the drain voltage and drain current of the silicon carbide device in the front-end synchronous Boost bridge arm circuit, and the drain voltage and drain current of the silicon carbide device in the rear-end synchronous Buck bridge arm circuit, as shown below. Figure 17 As shown, it can be seen that under the set test conditions, the drain voltage is 800V, the drain current is 40A, and the switching frequency is 100kHz.

[0144] (d) Fourth test

[0145] In the fourth test, the test conditions were set as follows: drain-source voltage 800V, drain current 50A, switching frequency 100kHz. The drive waveforms for each silicon carbide device are as follows: Figure 18 As shown, the test platform runs normally according to modes A1, B, A2, and C, which is consistent with the theoretical analysis above.

[0146] like Figure 18 As shown, the phase relationship and duty cycle conform to the theoretical calculation values, and the current of the power inductor also conforms to the calculated value of 50A. The current waveform of the power inductor is as follows.Figure 19 As shown.

[0147] like Figure 20 As shown, the drain voltage and drain current of the silicon carbide device in the preceding synchronous Boost bridge arm circuit are as follows: Figure 21 As shown, the drain voltage and drain current of the silicon carbide devices in the synchronous Buck bridge arm circuit of the subsequent stage are displayed. Each silicon carbide device is under the same test conditions, and the test conditions meet the set test conditions. Therefore, the silicon carbide device aging test method described in this invention can be used to conduct accelerated aging tests on the silicon carbide devices.

[0148] In the simulation circuit described above, it can be seen that the silicon carbide MOSFET is placed in the bridge arm structure circuit. In the synchronous Boost type energy feedback aging test method for silicon carbide devices described in this invention, not only is the long-term reliability of silicon carbide devices under dynamic continuous switching operation considered, but also the influence of crosstalk on the gate oxide reliability of silicon carbide devices is fully considered. As a result, the test results of the silicon carbide aging test method described in this invention are closer to the actual application of silicon carbide devices, and the accuracy of the aging test results is improved.

[0149] While specific embodiments of the present invention have been described above, those skilled in the art should understand that the specific embodiments described are merely illustrative and not intended to limit the scope of the present invention. Equivalent modifications and variations made by those skilled in the art in accordance with the spirit of the present invention should be covered within the scope of protection of the claims of the present invention.

Claims

1. A method for synchronous boost type energy feedback burn-in test of silicon carbide devices, characterized in that: The application relates to a silicon carbide device synchronous Boost type energy feedback aging test method. The test platform is a bridge arm type structure circuit with a synchronous type cascade Boost-Buck as a topology, and comprises a front-stage synchronous type Boost bridge arm circuit and a rear-stage synchronous type Buck bridge arm circuit; the front-stage synchronous type Boost bridge arm circuit and the rear-stage synchronous type Buck bridge arm circuit are cascaded; a direct current power supply is connected to the front-stage synchronous type Boost bridge arm circuit through a diode and is connected to an output end of the rear-stage synchronous type Buck bridge arm circuit; the direct current power supply is set according to a test working condition; the test platform realizes the circulation of energy in the test platform through a power inductor of the front-stage synchronous type Boost bridge arm circuit and a power inductor of the rear-stage synchronous type Buck bridge arm circuit; the working mode of the test platform is set, the switching frequency, the drain-source voltage and the drain current of the measured silicon carbide device are set, the aging of the silicon carbide device is accelerated under different test working conditions, and the aging test result is obtained; the A1 working mode is that the direct current power supply is connected to the front-stage synchronous type Boost bridge arm circuit through the diode, the rear-stage synchronous type Buck bridge arm circuit is connected to the output end of the front-stage synchronous type Boost bridge arm circuit, the direct current power supply is set according to the test working condition, the test platform realizes the circulation of energy in the test platform through the power inductor of the front-stage synchronous type Boost bridge arm circuit and the power inductor of the rear-stage synchronous type Buck bridge arm circuit, the working mode of the test platform is set, the switching frequency, the drain-source voltage and the drain current of the measured silicon carbide device are set, the aging of the silicon carbide device is accelerated under different test working conditions, and the aging test result is obtained; the B working mode is that the direct current power supply is connected to the front-stage synchronous type Boost bridge arm circuit through the diode, the rear-stage synchronous type Buck bridge arm circuit is connected to the output end of the front-stage synchronous type Boost bridge arm circuit, the direct current power supply is set according to the test working condition, the test platform realizes the circulation of energy in the test platform through the power inductor of the front-stage synchronous type Boost bridge arm circuit and the power inductor of the rear-stage synchronous type Buck bridge arm circuit, the working mode of the test platform is set, the switching frequency, the drain-source voltage and the drain current of the measured silicon carbide device are set, the aging of the silicon carbide device is accelerated under different test working conditions, and the aging test result is obtained; the A2 working mode is that the direct current power supply is connected to the front-stage synchronous type Boost bridge arm circuit through the diode, the rear-stage synchronous type Buck bridge arm circuit is connected to the output end of the front-stage synchronous type Boost bridge arm circuit, the direct current power supply is set according to the test working condition, the test platform realizes the circulation of energy in the test platform through the power inductor of the front-stage synchronous type Boost bridge arm circuit and the power inductor of the rear-stage synchronous type Buck bridge arm circuit, the working mode of the test platform is set, the switching frequency, the drain-source voltage and the drain current of the measured silicon carbide device are set, the aging of the silicon carbide device is accelerated under different test working conditions, and the aging test result is obtained; the C working mode is that the direct current power supply is connected to the front-stage synchronous type Boost bridge arm circuit through the diode, the rear-stage synchronous type Buck bridge arm circuit is connected to the output end of the front-stage synchronous type Boost bridge arm circuit, the direct current power supply is set according to the test working condition, the test platform realizes the circulation of energy in the test platform through the power inductor of the front-stage synchronous type Boost bridge arm circuit and the power inductor of the rear-stage synchronous type Buck bridge arm circuit, the working mode of the test platform is set, the switching frequency, the drain-source voltage and the drain current of the measured silicon carbide device are set, the aging of the silicon carbide device is accelerated under different test working conditions, and the aging test result is obtained. ​ ​ The working modes of the test platform in sequence include an A1 working mode, a B working mode, an A2 working mode and a C working mode; the A1 working mode is at time t 1- t 2; the B working mode is at time t 3- t 4; the A2 working mode is at time t 4- t 5; and the C working mode is at time t 5- t 6. ​ SiC devices of lower bridge arm of front-stage synchronous boost bridge arm circuit Q SiC devices of upper bridge arm of 1 and rear-stage synchronous buck bridge arm circuit Q 3 is turned on, current of front-stage synchronous boost bridge arm circuit flows through power inductor in turn L 1 and SiC device of lower bridge arm Q 1, current of rear-stage synchronous buck bridge arm circuit flows through SiC device of upper bridge arm in turn Q 3 and power inductor L 2, capacitor C 1 and capacitor C 2 are discharged, power inductor L 1 and L 2 are charged; ​ SiC device of the lower bridge leg of the front synchronous Boost bridge leg circuit Q 1 remains on, while the SiC device of the upper bridge leg of the back synchronous Buck bridge leg circuit Q 3 turns off, the SiC device of the lower bridge leg Q 4 turns on, freewheels the current, the current in the front synchronous Boost bridge leg circuit keeps flowing, while the current in the back synchronous Buck bridge leg circuit flows through the SiC device of the lower bridge leg in turn Q 4 and the power inductor L 2, at this time the capacitor C 2 keeps the current state unchanged, neither charges nor discharges, the energy is provided by the power inductor L 2, the power inductor L 2 discharges, the energy of the front synchronous Boost bridge leg circuit is provided by the capacitor C 1 provides, the power inductor L 1 charges; ​ SiC devices in the lower bridge arm of a front-stage synchronous Boost bridge arm circuit Q SiC devices in the upper bridge arm of a back-stage synchronous Buck bridge arm circuit Q 3 is turned on, the current of the front-stage synchronous Boost bridge arm circuit flows through the power inductor in turn L 1 and the SiC device in the lower bridge arm Q 1, the current of the back-stage synchronous Buck bridge arm circuit flows through the SiC device in the upper bridge arm in turn Q 3 and the power inductor L 2, the capacitor C 1 and the capacitor C 2 are discharged in turn, the power inductor L 1 and L 2 are charged in turn; ​ The state of the front synchronous Boost bridge arm circuit enters the freewheeling state, which is caused by the silicon carbide device of the upper bridge arm of the front synchronous Boost bridge arm circuit Q 2. The current of the front synchronous Boost bridge arm circuit flows through the power inductor L 1 and the silicon carbide device of the upper bridge arm in turn Q 2. The energy is provided by the power inductor L 1. The power inductor L 1 is in the discharging state; the silicon carbide device of the upper bridge arm of the rear synchronous Buck bridge arm circuit Q 3 is turned on, and the energy is provided by the capacitor C 2. The power inductor L 2 is in the charging state; ​ The front-stage synchronization type Boost bridge arm circuit comprises a capacitor C 1, power inductor L 1, lower bridge arm silicon carbide device Q 1, first driving unit, upper bridge arm silicon carbide device Q 2 and second driving unit; The post-stage synchronous Buck bridge arm circuit includes a capacitor C 2, power inductor L 2, upper bridge arm silicon carbide device Q 3, third driving unit, lower bridge arm silicon carbide device Q 4, and fourth driving unit The positive pole of the direct current power source is connected to one end of the capacitor C 1, the power inductor L 1, and the power inductor L 2; the negative pole of the direct current power source is connected to the other end of the capacitor C 1, the lower bridge arm silicon carbide device Q 1, the capacitor C 2, and the lower bridge arm silicon carbide device Q 4; the power inductor L 1 is connected to the upper bridge arm silicon carbide device Q 2, and the lower bridge arm silicon carbide device Q 1, the upper bridge arm silicon carbide device Q 2 is connected to the capacitor C 2, and the upper bridge arm silicon carbide device Q 3; the power inductor L 2 is connected to the upper bridge arm silicon carbide device Q 3, and the lower bridge arm silicon carbide device Q 4; the first driving unit is used for driving the lower bridge arm silicon carbide device Q 1; the second driving unit is used for driving the upper bridge arm silicon carbide device Q 2; the third driving unit is used for driving the upper bridge arm silicon carbide device Q 3; the fourth driving unit is used for driving the lower bridge arm silicon carbide device Q 4. ​ ​ First, the duty cycle of the post-stage synchronous Buck bridge arm circuit is determined D 2, and the input voltage of the DC power supply is determined according to the relationship between the test working condition voltage and the duty cycle of the post-stage synchronous Buck bridge arm circuit, as shown in equation (5): （5） In formula (5), V in is the input voltage of the DC power supply, V 2is the output voltage of the front-stage synchronous Boost bridge arm circuit, and the power inductors L1and L2of the front-stage synchronous Boost bridge arm circuit and the rear-stage synchronous Buck bridge arm circuit are determined according to the power of the front-stage synchronous Boost bridge arm circuit and the rear-stage synchronous Buck bridge arm circuit in each switching cycle L 1and L 2are determined according to the voltage-second characteristic of the front-stage synchronous Boost bridge arm circuit and the rear-stage synchronous Buck bridge arm circuit, and the duty cycle of the lower bridge arm silicon carbide device of the front-stage synchronous Boost bridge arm circuit is obtained according to formula (6) Q 1; （6） In formula (6) D 1 is a silicon carbide device in a lower bridge arm of a pre-stage synchronous type Boost bridge arm circuit Q 1 is a duty cycle of D 2 is a silicon carbide device in an upper bridge arm of a post-stage synchronous type Buck bridge arm circuit Q 3 is a duty cycle of I D is a drain current of the four silicon carbide devices Simplifying and solving formula (6), where is the phase difference between the driving waveform of the front-stage synchronous Boost bridge arm circuit and the driving waveform of the rear-stage synchronous Buck bridge arm circuit in each switching cycle. ​ （7） And according to the phase difference between the driving waveform of the front-stage synchronous type Boost bridge arm circuit and the driving waveform of the rear-stage synchronous type Buck bridge arm circuit and the lower bridge arm silicon carbide device Q 1, as formula (8): (8) Further, the equation of the phase difference between the driving waveform of the front-stage synchronous Boost bridge arm circuit and the driving waveform of the rear-stage synchronous Buck bridge arm circuit is obtained, as shown in equation (9): (9) As can be seen from equation (7), when the upper arm silicon carbide device of the subsequent synchronous Buck bridge arm circuit... Q When the duty cycle of 3 is determined, the voltage level of the test condition is determined, and the silicon carbide device of the lower bridge arm of the preceding synchronous Boost bridge arm circuit is determined. Q The duty cycle of 1 is related to the test current and input voltage. By inputting the target of the test condition, the duty cycle of the front-end synchronous Boost bridge arm circuit is determined, and then the silicon carbide device is subjected to continuous switching test under the set test condition to obtain the aging test results.

Images