In-Situ Calibration Method of Online Junction Temperature Estimation in IGBTs for Electric Vehicle Drives

Junction temperature is the most important factor to induce the insulated gate bipolar transistor module failure and conduct operational management. In-situ calibrated method and junction temperature calculation model are proposed to timely indicate the junction temperature for the electric vehicle drive system. It aims to solve that the conventional calibration methods need to be calibrated in the temperature chamber and the model cannot meet variable current conditions, which ignores the effects of the stray parameters of electrode connection on the on-state voltage. A mathematical junction temperature estimation model based on the relationship between saturation voltage drop and different currents is established, whose accuracy depends on the prior narrow range junction temperature calibration. A control strategy for the in-situ calibration is proposed to generate an instantaneous large current by creating a zero-torque condition and using integrated negative temperature coefficient thermistors, current sensor, and on-state voltage measured circuit when the new-energy vehicle is in an idle state. Experimental results prove that the proposed in-situ calibration method can be realized totally inside the electric vehicle, which can serve the full-service lifetime of the electric vehicle with high precision.