Temperature duty cycle characteristics of parallel IGBTs

IGBT parallel connections are an effective way to increase the capacity of power electronic converters. The junction temperature balance between IGBTs is one of the key factors in the safe and stable operation of parallel IGBTs system. Therefore, it is very important to study the influence of junction temperature on the power loss of parallel IGBTs system to improve their stability. However, existing research mainly focuses on the loss of a single IGBT or the optimal operating frequency range of parallel IGBTs. It does not involve research on the optimal operating duty cycle range (ODCR) of parallel IGBTs. When IGBT devices work in the positive temperature coefficient range, the on-state loss difference caused by the junction temperature difference and the switching loss difference have different temperature characteristics. Therefore, the concept of the inflection point duty cycle (IPDC) is proposed to evaluate the trend of the junction temperature mismatch between parallel IGBTs. In this paper, an inflection point duty cycle model (IPDCM) is established to analyze the influence of circuit design parameters, IGBT device parameters, and junction temperature differences on the ODCR of parallel IGBTs. Experimental results show that the IPDCM can provide a feasible reference for the reliability, circuit design parameters, and device selection of parallel power devices.