Input Reactive Power and Characteristic Harmonic Currents of Cycloconverter Using Non-Symmetrical Triggering Method

Abstract

In general, the cycloconverter is adopted as VVVF power source to drive large scale motors and linear motors. However, it is necessary to improve its input power factor because the input power factor is low. This paper describes a method to reduce the input reactive power by using a non-symmetrical gate triggering control for the cycloconverter.
In this method, some converters which are connected in series are separated into two groups. One group generates maximum voltage, and the other controls output voltage. For both circulating current and non-circulating current type cycloconverters, the input current waveforms are analyzed in this control method, and the relationship between the maximum voltage of converter and the reduction effect on input reactive power is made clear. Further, the characteristic harmonic components in input current are investigated. They are confirmed by digital simulation and the examination using a large scale cycloconverter at Miyazaki Maglev Test Track.