Analysis of a zero voltage switching DC/DC converter without output inductor

This study presents the analysis, design and implementation of a DC/DC converter with two series-connected half-bridge converters without output inductor. In the high-voltage side, two half-bridge converters with the asymmetric pulse-width modulation (PWM) are adopted to achieve zero voltage switching (ZVS) for all switching devices. The voltage stress of power switch is clamped at one-half of input DC voltage. Thus, active switches with low-voltage stress can be used at high input voltage application. At low-voltage side, the secondary sides of two half-bridge converters are connected in parallel to share load current. As two half-bridge converters are operated with interleaved PWM, the ripple current at output capacitor is reduced. On the basis of the resonant behaviour by the output capacitance of metal-oxide-semiconductor field-effect transistors (MOSFETs) and the resonant inductance, active switches can be turned on at ZVS during the transition interval. For each half-bridge converter, two transformers are connected in series at the primary and secondary sides. Each transformer can be operated as an inductor or a transformer. Therefore no output inductor is needed in each half-bridge converter. Finally, experiments based on a 960-W laboratory prototype are provided to demonstrate the performance of proposed converter.