High-Efficiency Zero-Voltage Switching Single-Stage Switching Amplifier With Half-Bridge Active Clamping Circuit

A zero-voltage switching (ZVS) single-stage switching amplifier (SSA) is proposed in this paper. The proposed SSA is composed of a bipolar phase shift modulation (BPSM) high-frequency link single-stage inverter and a half-bridge active clamp (HBAC) circuit. HBAC circuit is developed to clamp the voltages across cycloconverter switches and to recycle the energy in filter inductor and leakage inductance. ZVS of cycloconverter switches can be realized with the help of active clamp circuit. By utilization of magnetizing current, wide range ZVS of primary-side switches can be achieved. By delaying the turn on time of clamp switches to primary-side switches, full range ZVS of active clamp switches can be realized. High efficiency of the proposed HBAC-SSA is achieved with single-stage power conversion, recycling of inductive energy, and wide range ZVS. Benefiting with BPSM and voltage clamp across cycloconverter switches, low distortion of output voltage is also obtained. A 120 W prototype with 93.6% peak efficiency and 0.07% total harmonics distortion has been built to verify the analysis results of the proposed HBAC-SSA.