Minimizing DC-Link Capacitor RMS Current in Power Conversion Units Through Synchronous Operation

Abstract

DC-Link filtering capacitors occupy a significant volume in DC-DC-AC power conversion unit (PCU) for electric vehicle (EV) applications, where manufacturing costs and power density are related metrics and are important. Typically, the DCLink capacitor is sized electrically based on the desired voltage ripple and rms current capacity, with the latter being the ultimate deciding factor in the capacitor overall physical volume. This paper proposes a synchronous modulation strategy that matches the current of an interleaved DC-DC converter in discontinuous conduction mode (DCM) with that of the inverter-drawn current to significantly reduce the RMS current ripple in the DC-link capacitor, and thus enabling a volumetric reduction when considering system design and increasing capacitor lifetime.Simulation and experimental results are presented to validate the claims of this work.