A Junction Temperature Measurement Method for Power MOSFETs Through Body Diode With Compensation Ideality Factor

Power metal–oxide–semiconductor field-effect transistors (MOSFETs) have been widely used in various power conditioning circuits due to their advantages. The junction temperature significantly impacts the reliability, performance, and lifetime of these MOSFETs. Therefore, accurate monitoring the junction temperature of power MOSFETs is essential to ensure the safe operation of power circuit systems. In application scenarios such as half-bridge converters, full-bridge converters, and motor drive circuits, MOSFETs operate in a state where the body diodes are in freewheeling mode. The body diode forward voltage is superior to other temperature-sensitive electrical parameters (TSEPs) in linearity, sensitivity, integration, and aging effect. Therefore, the body diode forward voltage is a reliable TSEP for the junction temperature measurement of power MOSFETs. This article proposes a junction temperature measurement method for power MOSFETs through processing body diode forward voltage with compensation ideality factor. This method only needs to collect the body diode forward voltage under two different forward currents, the junction temperature is then obtained from the forward voltage. The method adopts a way that compensates the intercept difference of $V_{F}$ –T curves at 0 K to eliminate the influence of the body diode ideality factor and improve the precision of junction temperature measurement. The effect of aging on forward voltage is also considered for junction temperature measurement. The effectiveness of the method has been verified by both theoretical simulations and experiments.