A Single-Stage Series-Resonant Transformer-Isolated AC-AC Converter

A single-stage series-resonant transformerisolated AC-AC converter is proposed in this paper. The proposed AC-AC converter has the functions of step up/down voltage dependence on the instantaneous duty-cycle and electrical isolated. The proposed AC-AC converter adopts the series-resonant method to generate the resonant voltage pulse trains. Then, they is synthesized the synthesized sinusoidal waveform (SSW) before output filter. The SSW very closes sinusoidal waveform and its undesired harmonics is low. Thus, The SSW can remove the undesired harmonics by a simple LC filter to get the sinusoidal voltage waveform with low total harmonic distortion (THD). The proposed ACAC converter adopts the constant frequency pulse width modulation (PWM) technique. It can easily implement and it is simple. A design example of a 600W proposed AC-AC converter is examined to assess the system performance. Under rated output power, the power efficiency is over 91.5% and the total harmonic distortion (THD) is within 5%.