A PWM current source inverter with DC link notching circuit

Switching losses in current source inverters (CSIs) can be substantially reduced by means of an energy recovery circuit, a resonant DC link, or a DC bus commutation circuit. This paper proposes a CSI with an auxiliary circuit connected across the DC link inductor, whose purpose is to place zero current notches in the DC bus current at appropriate instants. It thus allows switches in the main power circuit to commutate under zero-current switching conditions. Since the auxiliary circuit consists of a few components, it provides a simple and cost effective way of reducing switching losses. The paper explains the operation of the proposed power converter, including the problems that may arise and their solution. The feasibility of the power converter is shown with results obtained from an experimental prototype