Analysis and Performance of a Three-Phase Ring Inverter

An analysis of a three-phase ring inverter for purely resistive loads is presented. The initial voltages on all of the six condensers have been taken into account. The instantaneous output voltages and the harmonic content of the output have been obtained. The analysis can be easily extended to circuits with more than six stages, to circuits using a ballast inductance in series with the dc source, and for inductive loads. Experimental results are presented for comparison with the predicted results. In addition, a modified form of circuit, which was found quite adequate for operation on the highly inductive load presented by an induction motor on no load, is presented.