AC Electronic Transformer

Abstract

PROBLEM TO BE SOLVED: To reduce the size of an AC transformer by providing a polarity inversion circuit on an input line and inverting the winding current at high speed so that the flux has no chance of growing significantly thereby reducing the volume of a magnetic body. SOLUTION: A high frequency circuit comprises a polarity switching high frequency switch 2 and a high speed reswitching switch 4 provided, respectively, at the input and output so that the switch elements are bi-directional. When the switch element is driven in synchronism with the input side, polarity is reinverted to reproduce the original low frequency component. Consequently, the voltage is converted while sustaining the waveform accurately and bidirectivity of current flow is sustained automatically without requiring any control and the size of a power converter can be reduced as required depending on the switching frequency.