A stabilized single phase electronic autotransformer

Abstract

A stabilized single-phase electronic step-down autotransformer with improved switching characteristics is presented in this paper. It employs bi-directional switches in a four step PWM switching strategy for commutating inductive load currents. A low cost microcontroller is employed simplifying the control circuitry, giving robustness and reliability. A 600 VA-220 V/110 V prototype operating at 18 kHz has been built, and experimental results are presented validating the AC controller operation.