Control of a multi-level active shunt power filter for More Electric Aircraft

The proposed increase of power electronic subsystems for More Electrical Aircraft (MEA) brings severe challenges to aircraft power distribution. Current aircraft power systems work at a fundamental frequency of 400 Hz while proposed AC MEA power networks for next generation aircrafts will have a fundamental frequency which varies most probably between 360 and 900 Hz. An active shunt filter (ASF) is recognized as an effective device for reducing harmonic pollution. However for the AC aircraft power system, harmonics for a 400 Hz fundamental (an in the future up to 900 Hz) should be controlled. A five-level active shunt filter with a high-bandwidth current controller combined together with an enhanced pulse-width modulation algorithm is proposed. The effective reference tracking of the proposed modulation combined with the employed current control approach is experimentally verified for frequencies of up to 2.8 kHz (corresponding to the 7^th harmonic component when a fundamental frequency of 400 Hz is employed) with a device switching frequency of just up to 5 kHz. The proposed active filtering system therefore is suitable for more electric aircraft applications on current aircraft and can evolve to a viable solution also for the next generation aircrafts with a higher and variable supply frequency.