An isolated fully soft-switching single-stage three-level power amplifier (SS3L) based on dual auxiliary networks (DAN) is proposed in this Letter. Compared with the conventional class-D power amplifier, the proposed DAN-SS3L achieves high level of integration without bulky dc link capacitor, and high-efficiency by single-stage conversion and zero voltage switching for all the switches under different operating conditions from light load to full load, which is suitable for highvoltage audio distribution systems. By adopting active auxiliary network, the energy stored in the leakage inductor can be recycled, which eliminates the pulse width modulation voltage spikes. The passive auxiliary network provides enough reactive current for primary-side switches, extending soft-switching range. In addition, commutation overlap strategy is employed to enable natural commutation of bidirectional switches. Experimental results of a 200 W prototype are presented to verify the analysis results.

No abstract