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

Insulated gate bipolar transistor (IGBT) junction temperature monitoring is crucial for converter's 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 converters require 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 article. The peak values of the bus voltage ringing during switching transient display a linear dependence 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 a converter. The validity of the proposed method is verified by experiments on a double-pulse and three-phase converter. Besides, implementation schemes and calibration approaches for practical applications are discussed. The proposed method has a higher resolution as compared with a traditional ON-state voltage-based IGBT junction temperature monitoring method. Besides, the proposed method reduces the circuit complexity, size, and cost, and it is easy to install. Moreover, the proposed method has a fast response and high resolution, and it does not disturb the normal operation. The proposed method is independent of bond wire degradation of the IGBT module.