An Online Junction Temperature Estimation Method of IGBTs Based on the Improved On-state Voltage Measuring Circuit

On-state voltage (v
_CE-ON
) is a useful thermal-sensitive electronic parameter (TSEP) for Insulated gate bipolar transistors (IGBTs). In this article, an online junction temperature estimation method of IGBTs based on improved v
_CE-ON
measuring circuit (OVMC) is proposed. By using high resistance resistor, low-voltage auxiliary components, proposed measuring circuit has high accuracy, wide voltage and ambient temperature adaptation range. What’s more, in order to overcome the steady error of the measured v
_CE-ON
in inductive load for junction temperature monitoring and improving the anti-interference ability of monitoring method, the changing rate of v
_CE-ON
on collector current (
iC
) is used as TSEP in inductive load. Firstly, the changing rate of v
_CE-ON
on iC is analyzed in detail. Then the structure and principle of the proposed circuit are studied, design guidance and error analysis are given. Finally, double pulse test and power cycling test have verified the effectiveness of proposed monitoring method. Compared with traditional online junction temperature monitoring method based on v
_CE-ON
, the proposed circuit can achieve higher reliability, wider voltage adaptation range and accuracy, and the proposed monitoring method presents stronger anti- interference ability, which is more suitable to use in high voltage conditions.