Phase-Shift Soft-Switching Power Amplifier with Lower EMI Noise

This work presents detailed analysis for a phase-shift soft switching inverter. The optimum soft switching operation algorithm is proposed based on the maximum soft switching operation range and also the smallest device current stress. Meanwhile, the soft switching control algorithm is proposed to guarantee the zero-voltage-switching (ZVS) within each switching period. A compact coupled circulating inductor based on the spiral structure is utilized to provide circulating current for the soft switching. Other design considerations such as the minimum circulating current for ZVS operation, dead time selection are also included. Finally, a 600V, 300A prototype is demonstrated to show the feasibility of reducing the EMI noise through soft-switching technique.