Design of Bus Bar Structure in Power Converter Circuit to Obtain Optimized Switching Waveform

Abstract

In a power converter circuit, it is well known that the bus bar structure affects both surge voltage and switching loss. However, the bus bar structure may be one of the causes for the oscillation waveform to induce electromagnetic interference (EMI) issues. This study proposes a design procedure of an optimized bus bar structure. Since the parasitic parameters of the bus bar geometory, such as inductance, capacitance, and resistance, are complicated in the megahertz frequency range, the parasitic parameters that have frequency characteristics are analyzed by the finite element method. The surge voltage and oscillation voltage under a turn-off operation are evaluated by using the bus bar modeled as S-parameters. It demonstrated that the optimal bus bar structure can reduce the surge voltage and oscillation. In accordance with the method to design an optimal bus bar, bus bar prototypes are designed, and the experimental results rated at 400V, 30A are presented to verify the analysis and simulation.