METHOD OF SUPPRESSING CIRCULATING CURRENT OF PARALLEL MULTIPLE INVERTER AND PARALLEL MULTIPLE INVERTER

摘要

PURPOSE:To suppress a circulating current which flows between unit inverters through parallel reactors by a method wherein the polarity of the circulating current immediately before a period when a output voltage is zero is detected and a switching mode which reduces the circulating current is selected. CONSTITUTION:The circulating current of a parallel multiple inverter 1 is produced by voltages which are applied to parallel reactors 8U-8W during a period of a switching mode wherein the output voltage of the inverter 1 is zero. Two types, for instance, of the switching modes wherein the output voltage is zero exist and different voltages are applied to the parallel reactors 8U-8W by the two types of the switching modes. Therefore, if the circulating current in the switching mode immediately before the period when the output voltage is zero is detected and a switching mode wherein a voltage having a polarity opposite to the polarity of the circulating current is applied is selected, voltages which reduce the circulating current are applied to the parallel reactor 8U-8W.