Analysis and design of full-bridge Class-DE inverter at fixed duty cycle

This paper presents the following for a full-bridge Class-DE resonant inverter operating at a fixed duty ratio: (a) steady-state analysis using first-harmonic approximation and (b) derivation of closed-form expressions for the currents, voltages, and powers. The conversion from a series-parallel resonant network to a series resonant network is presented. Imposing the zero-voltage and zero-derivative switching conditions, the expression for a shunt capacitance across the MOSFETs in the inverter bridge is derived. The closed-form expressions to calculate the values of the resonant components are presented. A practical design of a Class-DE resonant inverter supplied by a dc input voltage of 230 V, delivering an output power of 920 W, and operating at a switching frequency of 100 kHz is considered and its design methodology is included. Theoretical results are validated by Saber simulations.