An A.C. supply converter.

摘要

An A.C. supply converter of the type described in co-pending British Patent Application No. 80.06636 in which the control of the bidirectional switches connecting each conductor of a polyphase input supply to each conductor of an output supply is effected by a microcomputer, the operation of the program of which is synchronized by interrupt with the input supply. The microcomputer calculates for each output phase 2 values representing pulse widths out of a repeating sequence of 3 (for three phase input and output supplies) and pulse generators produce 3 abutting width modulated pulses in a constant period much shorter than the periods of the supplies. The interrupt operates a software phase locked loop, The pulse generators include an interlock circuit ensuring that the width modulated pulses do not overlap and an overload detector responsive to the turn-on times of the switches. A default logic circuit responsive to hardware or software failure makes the width modulated pulses of equal duration.