Closed-loop control on DC link voltage ripple of plug-in hybrid electric vehicle charger with sinusoidal charging

The bulk intermediate DC link capacitor is one of the major power density barrier for high frequency on-board battery charger for plug-in hybrid electric vehicle (PHEV). This capacitance is determined by the ripple power at two times the line frequency and cannot be reduced like other passive components by increasing the switching frequency. This limitation can be circumvented by allowing the ripple current at two times line frequency to flow directly to the battery, effectively reducing the DC link capacitor. However, the non-idealities such as converter loss can cause ripple power imbalance. In this paper, the impact of converter loss on the ripple power balance is analyzed, based on which a feedforward and a feedback control on the DC offset on the battery current are proposed, further reducing the DC link capacitance. Experimental results verify the effectiveness of the proposed solutions.