Factors affecting the operation of a phase-controlled cycloconvertor

The paper discusses the operation of a phase-controlled cycloconvertor such as may be used for a.c.-drive applications. The output-voltage functions obtained using different combinations of control and modulating signals are deduced. An assessment is made of the factors affecting the magnitude of circulating current which can flow in this type of convertor, while as an alternative approach the logical conditions necessary for operation without circulating current are formulated. It is concluded that, although circulating current can be limited by building appropriate reactance into a convertor, the magnitudes involved imply that its prevention by logical control is to be preferred.