A Utility-Interfaced Phase-Modulated High-Frequency Isolated Dual LCL DC/AC Converter

This paper presents a phase-modulated high-frequency isolated dc/ac converter as the grid interface in a distributed generation system. The converter includes two full-bridge HF LCL-type resonant inverters working at fixed duty cycle. The power control is realized by means of the phase-shift between the two bridges. Using the LCL-type resonant tank, zero-voltage-switching is achieved for all switches for the whole power range. With the phase-shift modulated sinusoidally, a full-wave rectified output current synchronized with the utility line is obtained, which is unfolded and fed to the single-phase utility line. The analysis is verified with computer simulation results. Experimental data based on a 500-W prototype circuit is included for validation purpose.