In electrical engineering, the problem of converting an actual a.c. voltage into a desired reference a.c. voltage arises in many applications. Such applications may include, for example, power electronics, low-frequency electronics, communications electronics, etc.
The preferred field of application for such methods and circuit arrangements is filtering the voltage of an electric three-phase or a.c. power supply system which is strongly subject to voltage harmonics generated by power electronic equipment and arrangements due to the switching components. Conventional methods of filtering harmonics out of line voltages have involved only methods and arrangements based on passive electronic components. Active methods and circuit arrangements for shaping and filtering a.c. voltage have been used only for filtering harmonics out of line currents.
Since only filters with passive electric components have been used to suppress voltage harmonics, a method of shaping a.c. voltage and a suitable circuit arrangement for this purpose based on active electronic components are to be created so that costs and high losses in passive filters can be reduced.
This principle should theoretically be capable of converting any desired a.c. voltage form to any other a.c. voltage form at a power supply connection point. The field of application of this method and circuit arrangement should thus be expandable to a great extent into areas that are far from being limited to just electric supply systems, power electronic loads or the elimination of harmonics.