Size – Efficiency Multi-Objective Design of DC-Link Capacitor in Two-Stage Single-Phase Converters

In a single-phase grid-connected two-stage converter with power factor correction, the design of the DC-link capacitor possesses a fundamental trade-off between the capacitor size and efficiency. Larger energy storage capacitors reduce the double-line frequency ripple to ensure a stable voltage for the DC-DC stage improving its soft-switched performance and efficiency. However, this advantage comes at the expense of a larger capacitor size. This work aims to find the optimal value of the capacitor value that balances the above two performance matrices. Specifically, a multi-objective design optimization is followed to identify Pareto solutions for a 3.3 kW, 48 V electric vehicle charger interfaced with the single-phase grid.