A High-Frequency Inverter Cycloconverter Cascade

A conversion technique using high-frequency inverters and cycloconverters is presented. The technique has application to battery charger and inverter applications. The high operating frequencies and reversible nature of the converters can result in significant cost, weight, and size reductions. The technique is applied to produce high-efficiency converters for photovoltaic systems. Results for a 6-kVA 110-Vdc/240-Vac single-phase converter are presented. The converter consists of two phase square wave inverters supplying a four-pulse cycloconverter stage. A peak conversion efficiency of 95 percent is achieved with a total output distortion below 3 percent. Standing losses are extremely low, being approximately 1 percent of the converter rating. The converters are reversible by nature and operation as an ac-dc intertie is possible.