Investigation on serial and parallel operations of insulated gate biploar transistor

Insulated gate biploar transistors(IGBTs) operating in series and parallel, which endure high voltage and heavy load currents, bring the problems of static and dynamic voltage and current balancing, which can be minimized by using passive balancing methods. This paper analyzes the main factors causing unbalance in theory and describes the passive snubber circuit used to equalize the voltage sharing and current balancing for serial and parallel IGBTs in both switching transients and steady state. The passive snubber circuit for voltage sharing consists of an RCD snubber and a balancing resistor. The current balancing technique consists of derating the parallel devices and impedance balancing by using a current balancing transformer. The snubber circuit was optimized by modeling the behavior