DIGITALLY-CONTROLLED CYCLOCONVERTER

摘要

A digitally-controlled cycloconverter converts a multiple-phase power signal of variable frequency into a single-phase or multiple-phase signal of a lower selected frequency. The cosinusoidal algorithm is utilized to determine the firing delay times, with the analog reference wave used in that algorithm being created from a digitized hardware table. The cosinusoidal algorithm is further simplified by defining the relationship between the analog reference wave and the cosinusoidal timing waves in terms of a two-part piecewise linear relationship which is incorporated into a digital algorithm. The digital algorithm is implemented on a system employing a high-power microprocessor having hardware multiplication and division capability, allowing the algorithm to be used with supply voltages having frequencies about those previously used for cycloconversion. The control logic involved with the firing of a series of thyristors is simplified by utilizing pulse transformers.