An Accurate Loss Model of Single-Stage Single-Phase Isolated PFC Converter for Bidirectional Plug-in EV Charger

In recent years, the power handling capability of EV chargers has been growing to reduce the charging time. In order to enhance the design and efficiency of EV chargers, an in-depth investigation of the losses caused in plug-in EV chargers is needed. This article presents an accurate loss model of a novel single-stage single-phase isolated PFC converter for a bidirectional EV charging application. The EV charger includes a current-fed full-bridge converter with bidirectional switches on the grid side with a swinging boost inductor that is affiliated with a full-bridge converter at the dc-side coupled via a high-frequency transformer. The AC-side current can be controlled to obtain power factor correction with low current total harmonic distortion (THD). The AC-side switches are naturally commutated and attained zero current switching (ZCS) without any external passive components. Additionally, zero current turn-ON is accomplished for DC-side switches to realize a high-efficiency EV charger. This is achieved with a modified control strategy and novel modulation method are adopted for achieving soft-switching operation and bidirectional power flow. To ensure that the proposed EV charger is feasible, experimental results with loss analysis of a 1.5 kVA unit are presented showing that the operation, analysis, and design are perfectly accorded.