Exploiting a Multi-Port Transformer for Minimal DC-Link Capacitance for an Automotive Onboard Charger

In contrast to common 3-phase topologies, DC-link capacitance can be reduced by combining input power after the DC-link using a multi-port transformer and suitable control. Initial results of this approach demonstrate stable 12 kW output power using only 5 μF DC-link capacitance per phase, promising higher power density and reliability. Furthermore, a novel control scheme is proposed that allows high frequency reactive power flow through the multi-port transformer to be manipulated via gate-signal phase angles, in order to achieve maximum efficiency and minimum DC-link voltage ripple for any load condition.