Parallel operation of active and passive filters for variable speed cycloconverter drive systems

The authors prepared a digital simulation program consisting of a passive filter, active filter, cycloconverter, and power supply system, and they studied a variety of combinations of passive and active filters in terms of harmonic compensation, parallel resonance suppression, and series resonance suppression. It is shown that the harmonic compensation equipment with a combined use of active and passive filters can effectively compensate a variable-frequency harmonic current generated by the cycloconverter over a wide operation range and can suppress the parallel and series resonance phenomena. The authors analyze the characteristics of three types of arrangement of the active and passive filters. The total harmonic current compensation and total current feedback compensation show good characteristics in terms of harmonic compensation and resonance suppression