Method for monitoring degradation mechanism of switch device in power conversion circuit

A method for monitoring a degradation mechanism of a switch device in a power conversion circuit, comprising:

• S1, disposing a sensor on a loop where a source and a drain of the switch device are located;
• S2, obtaining a reference current change rate of a drain-source current of the switch device;
• S3, collecting, by the sensor, a real-time current change rate of the drain-source current during the switch device is in an on-state;
• S4, comparing the real-time current change rate of the drain-source current with the reference current change rate of the drain-source current;
• and
• S5, determining the degradation mechanism of internal defects of the switch device according to a change trend of the real-time current change rate, judging that degradation is caused by an increase of an oxide layer defect density of the switch device when the real-time current change rate is decreased, judging that degradation is caused by an increase of an interface defect density when the real-time current change rate is increased;
• wherein the determining the degradation mechanism of internal defects of the switch device according to a change trend of the real-time current change rate, specifically comprises the following steps:
• A1, in response to the real-time current change rate being decreased, judging that degradation is internal defect degradation of the switch device caused by the increase of the oxide layer defect density;
• whereas, in response to the real-time current change rate being increased, performing the following step A2;
• A2, comparing a real-time on-state resistance with a reference on-state resistance, in a linear region;
• and testing the interface defect density of the switch device through low-frequency noise;
• A3, in response to the real-time on-state resistance being less than the reference on-state resistance and the interface defect density being increased, judging that degradation is internal defect degradation of the switch device caused by the increase of the interface defect density;
• in response to the real-time on-state resistance being greater than the reference on-state resistance and the interface defect density being with no change, judging that degradation of the switch device is packaging degradation;
• in response to the real-time on-state resistance being greater than the reference on-state resistance and the interface defect density being increased, judging that both packaging degradation, and internal defect degradation of the switch device caused by the increase of the interface defect density occurred on the switch device.