ABSTRACT
Since that high-frequency isolated resonant converters are featured with low switching losses due to wide soft-switching operation range, to minimize the resonant tank current is able to enhance the overall system efficiency and reduce the component stresses as well. In this work, a bidirectional series resonant converter under phase-shifted modulation combined with a modified pulse-width modulation gating scheme is addressed. The modified pulse-width modulation gating scheme is helpful to keep more switches operating in zero-voltage switching at light load. According to the steady-state analysis with fundamental-harmonic approximation approach, a specified control strategy with minimum rms tank current based on three control dimensions is proposed in closed form. The validity of the proposed control strategy is verified through experimental tests. Compared with existing control strategies for minimum current operation, the proposed control strategy demonstrates comparable performance in depressing conduction loss and wider soft-switching range as well so that it is able to achieve high efficiency especially at light load. OPERATION OF A BIDIRECTIONAL SERIES RESONANT CONVERTER WITH MINIMIZED TANK CURRENT AND WIDE ZVS RANGE