Integrated series active filter with reduced capacitance requirements for variable frequency aerospace systems

This article considers the design and development of an integrated series active filter with a front-end consisting of a standard 6-pulse bridge rectifier to satisfy power supply harmonic standards for aerospace actuation and other dynamic and passive loads. Unlike previously reported fixed frequency solutions for enhancing power quality (typically based around 18- to 24-pulse TRUs for this application sector), the proposed converter reported here can be applied to non-ideal, non-stiff, frequency wild (380-800 Hz) supplies. Specifically, the proposed converter is shown to satisfy key harmonic limits over the full 380-800 Hz range of supply frequency variation, be robust to significant distortion in the input supply voltage waveform and have reduced capacitance requirements. Experimental results on a 2.5 kW converter are used to demonstrate the underlying harmonic attenuation provided by the prototype system, coupled with control robustness to significant input voltage distortion. The realisation of such power converter solutions that can accommodate variable frequency input supplies provides the opportunity to eliminate the complex hydraulic gearbox stages normally employed within aircraft generators to regulate electrical supply frequency when subject to engine speed variations.