A Novel Converter-Level IGBT Junction Temperature Estimation Method Based on the Bus Voltage Ringing

IGBT junction temperature monitoring is crucial for converter healthy management and condition monitoring. However, most conventional IGBT junction temperature estimation methods are device-level, which means that monitoring junction temperatures of all IGBTs in converter requires the same number of monitoring units as IGBTs, which is of high complexity and cost. A converter-level IGBT junction temperature estimation method based on the DC bus voltage ringing is proposed in this paper. The peak values of bus voltage ringing during switching transient display a linear dependency on the junction temperatures of the corresponding switching IGBTs. Hence, the bus voltage ringing can be used for estimating the junction temperatures of the IGBTs in converter. The validity of the proposed method is verified by experiments on double-pulse and three-phase converter. Besides, implementation schemes and calibration approach for practical application are discussed. The method proposed has a higher resolution compared with traditional on-state voltage-based IGBT junction temperature monitoring method. Besides, the method proposed reduces the circuit complexity, size, cost, and it is easy to install. Moreover, the method proposed has a fast response, high resolution, and does not disturb the normal operation. The method proposed is independent of bond wire degradation of the IGBT module.