A series-resonant single-phase ac chopper

Abstract

A series-resonant single-phase series-resonant ac chopper is presented. The presented single-phase ac chopper is configured by a series-resonant conversion without cycloconversion and auxiliary switches. The presented single-phase ac chopper is a series resonator with four main switches to configure adaptively the resonant voltage robes. The synthesized sinusoidal waveform (SSW) before output filter is synthesized by a series of sinusoidal amplitude quasi-sinusoidal pulses (QSPs) following the input voltage amplitude. Because the synthesized SSW very closes sinusoidal waveform, the presented single-phase ac chopper can use a simple LC filter to filter the undesired harmonics and get the sinusoidal voltage with low total harmonic distortion (THD). The presented single-phase ac chopper is operated by constant frequency pulse width modulation with control technique. Waveform syntheses for the output sinusoidal voltage are clearly analysed and derived. A typical design example of a 600W series-resonant single-phase ac chopper is examined to assess the system performance. The power efficiency is over 91% when the output power is at maximum output rated power. The total harmonic distortion (THD) when the output power is at maximum output rated power is within 5%.