Design of DC-side wiring structure for high-speed switching operation using SiC power devices

In power electronics circuits, the stray inductance of a bus bar between a DC capacitor and power devices may affect an overvoltage and influence the switching losses under high-speed switching operation. Therefore, it is necessary to design the wiring structure by considering the stray inductance of the bus bar. An inductance map is proposed to clarify the relationship between wiring structure and stray inductance of a DC-side bus bar. The inductance map is drawn using a partial inductance calculation method. In addition, the design procedure of the wiring structure with consideration the stray inductance of the bus bar is shown using the inductance map. This paper makes four types of DC-side bus bars for a buck chopper circuit, and the over voltages under the turn-off switching are discussed by the experiments. The experimental results rated at 500 V, and 70 A for a buck chopper circuit using SiC-MOSFET and SiC-SBD confirm the validity of the design procedure.