A soft commutation constant high frequency link DC/AC converter operating with sinusoidal output voltage

The purpose of this paper is to introduce and analyze a high frequency link DC-AC converter for small power UPS applications, with the following properties: operation at constant frequency, soft commutation, isolation by a high frequency transformer, bi-directional power flow capability, absorption of the parasitic elements in the commutation process, simple control circuitry, no need to detect the semiconductor conduction state, and low harmonic distortion at the output voltage. These properties are achieved with a system composed of a high frequency ZVS inverter and a high frequency ZCS cycloconverter interconnected to each other by a high frequency transformer. The output voltage is regulated by a phase-shift between the two converters. In addition to the analysis results, experimental results taken from a laboratory prototype rated at 500 W are also presented in this paper