Sizing of DC-Link Capacitor Considering Voltage and Current Ripple Requirements for a 3-Phase Voltage Source Inverter

An analytical approach to size DC link capacitor for an automotive inverter is presented in this paper considering the DC-link ripple voltage and capacitor ripple current. The analytical method derived in this paper show the variation of DC link voltage ripple with the change of power factor and modulation index. This analysis can be applied to determine maximum possible ripple voltage for a given capacitor or the minimum capacitance needed to keep the voltage ripple under a limit. Then current ripple analysis is used for the final selection of the capacitor taking account of the thermal consideration. The research presents a sequential process to select DC-link capacitor accounting for system level requirements. The analysis is verified by simulation and experimental results where the effect of components' parasitic on the voltage and current ripple is presented.