Analysis of Class D Series resonant inverter with a switch-controlled capacitor and a body diode

This paper presents an analysis of a Class D series resonant inverter with a switch-controlled capacitor (SCC) and a body diode. A parallel circuit composed of a capacitor and a switch is added to the series resonant circuit in series, to regulate the output power without frequency modulation. Applying the sub optimum Class E switching condition to the auxiliary switch, high power conversion efficiency is maintained. A previous analysis of the Class D series resonant inverter with an SCC was under the assumption of ideal switches. However, the circuit state is changed by the body diode of the auxiliary switch in fact. The calculated results are well agreed with the simulated results with MATLAB/Simulink. And the Class D series resonant inverter with an SCC is able to regulate the output power with satisfying the sub optimum Class E switching condition in the experiment.