Control and performance of a zero-current-switched three-phase inverter equipped with resonant circuits on the AC-side

This paper presents a zero-current-switched voltage-fed inverter equipped with resonant circuits on the AC side. The current flowing through a switching device, i.e., an IGBT is a sum of the load current and the resonant current. If the amplitude of the resonant current is larger than that of the load current, the current in a switching device becomes zero at an instant in each resonant cycle. This allows the switching device to be turned on or off at the zero current. The zero-current-switching makes a significant contribution to reduction of switching losses and electromagnetic noises. In this paper, the principle of zero-current-switching operation, and a novel control scheme are described from a theoretical and practical point of view. Experimental results obtained from a laboratory system of 5 kVA verify the practicability. Moreover, the efficiency and losses of the proposed soft-switched inverter are compared with those of a hard-switched inverter.