Abstract: A series resonant DC-to-AC inverter. This inverter comprises a series-resonant circuit including a resonant capacitor and a resonant inductor, a diode parallel with the series resonant circuit, a switch device controlling the conduction condition between the series resonant circuit and a DC voltage, a cycloconverter and an output filter. The switch device is controlled by a pulse-width-modulated signal. During three operation stages of charging, resonance and discharging, an unipolar composite sinusoidal signal is formed at the resonant capacitor. The cycloconverter transforms the unipolar composite sinusoidal signal into a bipolar composite sinusoidal signal and then the output filter filters out its high-frequency components to generate an AC voltage.