A Simplified Analytical Formulation for Class EF Inverters with Constant AC Voltage or Current Output and Load-Independent Characteristics

This paper presents a systematic analytical approach for designing Class EF inverters that achieve zero-voltage switching (ZVS) over a wide load range with a fixed duty cycle and constant AC output. The method is based on modeling the load’s complex impedance at the switching frequency and deriving explicit design equations, enabling direct and systematic topology synthesis without relying on numerical simulations. An experimental demonstration at 15 MHz and 25 VDC, over loads from 30 Ω to 2700 Ω, confirms the validity and robustness of the approach. The method provides a practical foundation for future designs targeting further reduction of switching losses and electromagnetic interference.