A PSFB-Based Integrated PEV Onboard Charger With Extended ZVS Range and Zero Duty Cycle Loss

A conventional phase-shift full-bridge (PSFB) converter suffers from easy failure of zero-voltage switching (ZVS) in the lagging leg under light load conditions. This poses a significant challenge to the optimal design of PSFB-based plug-in electric vehicle (PEV) onboard chargers. In this paper, a self-reconfigured integrated onboard charger architecture is proposed for PEVs to cope with this design challenge. In this architecture, the PSFB converter is adopted as the main topology to charge the high-voltage battery pack, while the half-bridge LLC resonant converter is employed to charge the low-voltage auxiliary battery. Under light-charging mode, the half-bridge LLC converter is reconfigured to be paralleled with the PSFB topology to guarantee the ZVS of the lagging leg MOSFETs. Moreover, a capacitor-diode-diode snubber is added to resolve the duty cycle loss issue of the PSFB converter and to reduce the circulating current. Practical design considerations are presented for both the PSFB and the half-bridge LLC converters. Frequency modulation and the phase-shift modulation provide two degrees of freedom to regulate the output voltage/current of both converters. The proposed charger architecture maintains low cost and high efficiency in this specific application. A 390 V input, 420 V/2.4 A, 14 V/21 A outputs, 1.3 kW rated converter prototype is designed, analyzed, and tested to verify the proof of concept.