Improving Efficiency in Series Resonant Constant Current Converter

Conventional constant current converters which have been employed in many transmission systems have good constant current characteristics but do not have high efficiency. A series resonant converter also has constant current characteristics and it´s switching loss is small. However, the on-period loss in this converter is larger thah that for the conventional one. This paper describes a technique for decreasing on-period loss and improving the efficiency of the series resonant constant current converter. The maximum duty ratio is designed to reduce the rms current. The drive condition of the transistor is designed to minimize transistor loss, and the Litz wire is adopted as the winding method to decrease transformer and inductor losses. As a result, efficiency has been improved to 92%.