Design of a 6.6 kW charger based on an SRT converter applying a parallel structure of IGBT and Si-MOSFET

In this study, we propose a design method for a 6.6 kW charger using a hybrid switching technique that operates an insulated-gate bipolar transistor (IGBT) and metal–oxide–semiconductor field-effect transistor (MOSFET) in parallel for the high frequency of IGBT. The proposed circuit is based on a secondary resonant tank (SRT) converter with a resonant tank placed on the secondary side. In the SRT converter, the lower switches can be configured using only IGBTs, because the switching loss is small; however, configuring the upper switches only with IGBTs is difficult owing to the high turn-off current. This disadvantage can be overcome by operating the IGBTs and MOSFETs in parallel. IGBTs and MOSFETs are responsible for the conduction loss and switching loss, respectively. The feasibility of the proposed circuit was verified through the design and experimental results of a prototype with input and output voltages of 600–750 and 450–900 V, respectively.