A DC planar bus bar of high-frequency power converter with enhanced current distribution

Abstract

In recent times, high frequency power converters have become popular in electric vehicle applications due to advantages in terms of accomplished compact size for the given power density. But design of high frequency power converters is challenging as switching at high frequencies generate electromagnetic noise which interferes with neighbouring circuits through inductive or capacitive coupling. So, it is necessary to have an optimum stray impedance current loop of DC busbar, switches, AC conducting paths, etc. Among all components, DC busbar carries all the three-phase currents at approximately thrice the switching frequency. Thus, stray inductance of the busbar would affect the free flow of current due to opposing potentials developed across the busbar and lead to uneven distribution of charge. This causes conducted or radiated electromagnetic noise depending upon the operating frequency. In this paper, planar DC busbar for 20kVA DC-AC converter is accessed and a new configuration with a ground busbar sandwiched between positive and negative busbars is proposed to reduce the effect of stray inductance by introducing virtual parallel capacitances across the busbars. This would ensure uniform distribution of the charge (current) density. The proposed busbar configuration is modelled and simulated in ANSYS Q3D and MATLAB Simulink and it is observed that effective inductance is reduced with an increase in the charge density and uniform current distribution which eventually reduces noise and makes the converter electromagnetically compatible.