A Rapid DC Component Elimination Strategy for Alternative Current in Frequency Converter

The principle achievement of this contribution is to develop and to describe a rapid DC component elimination strategy for AC currents in the frequency converter, simply by selecting transient period. To avoid DC component on the line current, it’s known that the transition of active and/or reactive power should not be rapid. If the transition time is relatively long compared to the fundamental period, the current may be considered as symmetrical and the DC component can be neglected. In comparison to the usually slow transient that characterizes a DC component free current transient; in this paper much faster transient also without DC component is achieved, simply by choosing a well-defined transition period. The present method is verified for a simple linear circuit. It can also be used, for example, with a three or more level inverter including, but not limited to, a Neutral Point Clamped. Simulation and verification results for different operating points and transitions between them highlight the capabilities of the proposed control strategy. These include the ability to operate with unity power factor and better current quality without continuous component.