A Passive Lossless and Nonshoot-Through Soft-Switching High Power Density Inverter

Soft switching technique is the main method to increase the inverter switching frequency and thus improve the power density, which is one of the current research hotspots. Inverter soft switching needs to operate in four quadrants, wide range, time-varying load current conditions, the realization of the more complex. At this stage, soft-switching inverters are mainly based on bridge circuits, and the intertwined soft-switching and shoot-through deadtime problems in bridge circuits is one of the difficulties in limiting the improvement of inverter switching frequency and power density. To solve this problem, a passive lossless and non-shoot-through soft-switching inverter is designed in this paper, which fundamentally eliminates the constrains of shoot-through to soft-switching of inverter. The four-quadrant operating mode is given, in which the high-frequency chopper bridge operates at unidirectional voltage and current conditions, thus achieving full-load range soft switching using passive coupled inductors. Increased switching frequency and the size of the filtering components is significantly reduced. The paper analyses the specific operating modes, soft switching conditions, losses, parameters and control methods. A 1kW prototype is established, and the results of experiment verify the correctness of theoretical analysis. The prototype achieves the power density of 5.8kW/L and the peak efficiency of 97.1% at 400kHz.