An analytical method for selecting DC-link-capacitor of a voltage stiff inverter

The scope of this paper is to develop an analytical method for selecting the DC-link-capacitor of a voltage stiff inverter (VSI). The method employs simple small signal AC analysis of a VSI to come up with a simplified equivalent circuit of it. The objective is to select an appropriate DC-link-capacitor to maintain a required amount of DC-line current ripple. Phasor algebra and fast Fourier transforms helped solve the equivalent circuit. The method addresses the proper selection of component parameters, which strongly depend on the operating conditions. The analytical method has been applied to select VSI DC-link-capacitor of an automotive application, for which simulation results have been provided. Some experimental results have also been given to verify the efficacy of the method.