An Efficient Parallel Resonant DC-Link Inverter Without Circulation Current Loss

To eliminate the circulation current loss in resonant dc-link inverters, an efficient parallel resonant dc-link inverter without circulation current loss is proposed in this paper. When the commutation of the auxiliary circuit ends, there is no constant current circulating freely through auxiliary circuit or main circuit. Besides, when the bus voltage is zero, it is not necessary to set the threshold value of the resonant elements according to the load current, which reduces the control difficulty and improves the reliability of the inverter. At the same time, the peak current of the resonant inductor is suppressed, which reflects that the current stress of the switches is reduced. Thus, the loss caused by the auxiliary circuit is further reduced. In this paper, all switches of the proposed parallel resonant dc-link inverter realize soft switching, main switches realize zero-voltage-switching (ZVS) turn-on and ZVS turn-off, and auxiliary switches realize zero-current-switching (ZCS) turn-on and ZCS turn-off. Finally, the effectiveness of the proposed topology and the modulation strategy is verified by an experimental prototype.