Online Bridge-Level Junction Temperature Evaluation of IGBTs via Emitter Parasitic Inductance Voltage Undershoot

Insulated gate bipolar transistor (IGBT) junction temperature evaluation is vital for health assessment. However, most of the existing IGBT junction temperature ( T j ) evaluation approaches require the same number of detecting units and IGBTs. In this article, a thermosensitive electrical parameter based on the turn-OFF induced voltage v eE undershoot between Kelvin and power emitters of lower IGBT for two IGBTs junction temperatures estimation in half-bridge module is proposed, which is independent of bond wires fatigue. The v eE ringing of lower IGBT under designed time sequence has a good linear dependency with T j of upper and lower IGBTs. An improved peak detector circuit is designed to extract the v eE with no disruption to normal operation. Double-pulse test and three-phase converter platforms are built to verify the feasibility of industrial applications. Calibration results show that there is good linearity and high sensitivity between IGBT junction temperature and v eE undershoot under various working conditions. Besides, the approach has high accuracy in junction temperature monitoring validated by infrared. Therefore, this novel bridgelevel T j estimation method has a good commercial prospect.