Microprocessor control of triac cycloconvertor

On account of drive-system requirements, convertor performance and cost, it is becoming more and more desirable to replace the relatively complex control circuits of solid-state cycloconvertors by microprocessor-based controllers. A dedicated-microprocessor controller for triac cycloconvertors, making use of the MC6809 family of components, is described, which relies on software for timing and delay-angle computation as well as for convertor selection and blanking control. Provision for smooth transition in changing the output frequency and amplitude is included as an added feature. Descriptions of the hardware and software designs of the controller are given and experimental results are presented to illustrate the performance achieved.