PROJECT TITLE :

An Improved Zero-Current-Switching Single-Phase Transformerless PV H6 Inverter with Switching Loss-Free

ABSTRACT:

An SLF concept for the first six switches H-bridge inverter (H6-I) architecture is presented in this work. The term "SLF" refers to the ability of these switches to work with smooth on/off transitions. A new resonance trajectory is presented in order to achieve the SLF target. With the suggested resonance-trajectory, the losses of resonant tanks may be properly compensated for every switching period. This is a significant improvement over the ZCT-H6I topology presented in earlier work. In order to accomplish this, an implementation circuit based on the H6-I topology is constructed and its detailed operating principle and performance characteristics are investigated. Consequently, all active switches in this new circuit are turned on and off at zero current. The zero-current turn-off property of diodes also alleviates the reverse recovery difficulty of freewheeling diodes. It is theoretically possible to meet the SLF goal. Lastly, the results of a 1 kW prototype at 50 kHz switching frequency are presented to demonstrate the effectiveness of the suggested SLF. Conversion efficiency is above 95% in a wide load range, with an efficiency gain of about 1.5% over the hard-switching H6I architecture. The redesigned circuit.