An Improved Parameter Design Method of Active Clamping Circuit for Voltage Balancing of Series-Connected IGBTs

Connecting multiple insulated gate bipolar transistors (IGBTs) in series is the most direct and effective way to meet the voltage rating requirements of high power and high voltage converters, but there is severe voltage imbalance during the switching process of series-connected IGBTs. The active clamping circuit has been widely used for its simple structure and high reliability for voltage balancing of series-connected IGBTs. Based on the existing research, this paper presents an improved parameter design scheme for the active clamping circuit. Through theoretical analysis and experiments, it's verified that the active clamping circuit using the proposed parameter design method can achieve static voltage balancing without additional power-side static voltage balancing resistance, and the influence of clamping circuit parameters on voltage balancing effect and IGBTs switching loss is also discussed. The work of this paper provides suggestions for the design and selection of appropriate active clamping circuit parameters in practical applications.