An electronic transformer with variable conversion ratio

This paper presents a new switch control strategy for an electronic step-down transformer, providing variable conversion ratio and zero-current switching conditions. To implement the new control technique, a closed-loop nonlinear controller is proposed, based on the sliding mode control theory. The controller provides good transient response, absence of steady-state errors in the output voltage and robust output response with respect to line voltage and load disturbances. The experimental results show the possibilities of using this transformer in a variety of applications.