Harmonic Reduction in Synchronous Chopper-Converter Combinations

The synchronous chopper-converter combination has previously been shown to be suitable for moderate to high power ac/dc converter applications. Operation at unity displacement factor, however, was seen to be accompanied by a significant increase in the harmonic compensation requirements. Techniques for reducing the input harmonic current levels in the synchronous chopper-converter combination are investigated. Operating the synchronous chopper at higher frequencies allows selective harmonic elimination but results in restricted output voltage control. The use of a multiphase synchronous chopper yields greatly improved input characteristics but requires additional power components. A compromise solution involves a single-phase chopper operated at different frequencies over its operating range.