Design of Bus Bar Structures in Power Converter Circuit Considering Both Parasitic Inductance and AC Resistance

In power converter circuits, it is well known that a bus-bar structure affects both surge voltage and switching loss. The stray inductance and capacitance depending on bus-bar structure also can be one of the causes such as the oscillation waveform that induces EMI issues. This paper proposes a design procedure of an optimized bus bar structure taking AC resistance into consideration. Those parameters that have frequency characteristics can be analyzed by finite element method, and it is shown that the AC resistance of the bus bar has an ability to suppress the oscillation. The validation of simulation results are shown by comparing the simulation and experimental results using a buck chopper circuit with input voltage of 300 V and output current of 30 A. The surge voltage and oscillation current are evaluated by using the bus bar modeled as S-parameters. In addition, the gate resistor is inserted to suppress them so that this paper includes among the surge voltage, oscillation and the switching loss. It is shown that the optimal parameters of busbar structure and gate resistor can reduce the surge voltage and oscillation current.