Design of a novel AC regulator

A design in which an AC-to-AC electronic transformer is connected in series with the AC mains to provide a regulated AC output voltage is described. The approach reduces the required voltage and power ratings of the circuit components in the electronic transformer and indirectly increases the conversion efficiency. Since the transformer is designed to accept AC mains directly as the input, no rectifier or mains frequency filtering circuit is required. This, together with the high switching frequency, allows the design of small-size and high-efficiency AC regulators for practical use. An experimental 50 W regulator has been designed to give a typical efficiency of 96%.>