A half-bridge inverter based current balancer with the reduced DC capacitors in single-phase three-wire distribution feeders

This paper proposes a half-bridge inverter based current balancer in single-phase three-wire distribution systems with the reduced dc capacitors. The proposed current balancer can use a 6-in-1 IGBT module. Two legs perform a half-bridge inverter based current balancer, which compensates the reactive and unbalanced active components on the source-side. The third-leg performs a power de-coupler with a dc-capacitor voltage balancer. This power de-coupler sinks the power fluctuation, which flows into the dc capacitors, caused by the unbalanced conditions of two half-bridge inverters. Thus the capacity of the dc capacitors of the half-bridge inverter based current balancer can be dramatically reduced as compared to those of the previously proposed current balancer. The basic principle of the proposed half-bridge inverter based current balancer with the reduced dc capacitors is discussed in detail, and then confirmed by digital computer simulation using PSIM software. A prototype experimental model is constructed and tested. Experimental results demonstrate that the balanced source currents are obtained on the secondary-side of the pole-mounted distribution transformer, reducing the capacity of the dc capacitors of the half-bridge inverter based current balancer.