Analysis and control of a single phase AC chopper in series connection with an auto-transformer

In this paper, a novel topology of single phase AC chopper is presented. The AC chopper has the structure of a combined conventional AC chopper in series connection with an auto-transformer. Detailed design of the AC chopper and the associated filter are described in the paper. A combined feedforward and PI feedback control is applied to stabilize the output voltage at the desired level when it is subject to unexpected input voltage and load variations. The proposed ac chopper has advantages in accurate voltage regulation, less harmonic distortion, fast responses and low cost.