High Gain DC-AC High-Frequency Link Inverter with Improved Quasi-Resonant Modulation

This paper presents a high gain pure sine-wave inverter based on the full-bridge DC-AC high-frequency (HF) link cycloconverter topology for telecom or general-purpose applications. The improved quasi-resonant modulation method allows reduction of ringing and turn-off losses of the dc-side switches. This is achieved with minimal energy circulation and requires no multi-mode operation or extra auxiliary clamping circuits. The soft switching can be provided even if relatively large lossless snubber capacitors are connected across the input side transistors. Moreover, two of the switches at the AC side operate at fundamental frequency, while the rest feature zero current turn-off. A 48 VDC to 230 VAC, 1.2 kW sine-wave inverter prototype was developed to verify the proposed concept.