Performance analysis of series asymmetrical half-bridge converter with voltage-auto-balance

In this paper, an isolated series asymmetrical half-bridge converter (SA-HBC) is proposed. The SA-HBC circuit consists of two series half-bridge cells, sharing one leakage inductance and one transformer. Two advantages make SA-HBC suitable for the high input voltage applications: (a) the voltage stress of each switch is reduced to half of the input voltage; (b) the voltages across the input capacitors are automatically balanced by the inherent switched capacitor technique, without additional circuits or control methods. Moreover, zero-voltage-switching (ZVS) condition is achieved for all switches. The operational principles, circuit performance including output voltage, ZVS condition and voltage-auto-balance scheme of SA-HBC are analyzed in detail. And all these analyses are confirmed by the experimental results from a prototype with 500–600V input and 48V/20A output.