Control and Modulation of a Multilevel Active Filtering Solution for Variable-Speed Constant-Frequency More-Electric Aircraft Grids

The increase of power electronic subsystems in more-electrical aircrafts (MEA) brings severe challenges to aircraft power distribution in terms of power quality on board. Active filtering is a viable solution to this problem; however, given the high supply frequency in AC-MEA power networks, effective harmonic compensation using standard converter structures, traditional digital control and reasonable devices switching frequency is a demanding task. A five-level active shunt filter with an enhanced deadbeat current controller is proposed in this paper for a fixed frequency 400 Hz aircraft power grid. The controller shows higher immunity to measurement noise compared with the conventional deadbeat current controller. In order to enhance the system performance when the voltage reference has a high rate of change, a modified pulse width modulation algorithm is proposed. The effective reference tracking of the proposed modulation combined with the employed current control approach is experimentally verified. The proposed controller features a high bandwidth of the current control loop, capable of high frequency harmonic compensation, using a reduced devices switching frequency.