Design and implementation of a multilevel active power filter for more electric aircraft variable frequency systems

This paper presents the design, simulation and implementation of a Multilevel Aeronautical Active Power Filter (AAPF) for a Variable Speed Variable Frequency (VSVF) advanced aircraft electric power system. AAPF are most commonly used to mitigate current harmonics, improve the source power factor and to mitigate the effects of unbalanced loads. The Aircraft Electrical Power System (AEPS) is very different than the residential and industrial power systems, in this systems, the frequency may vary between 360 Hz and 900 Hz, and the load dynamics is often modified. For aircraft purposes an enhanced filtering technique is required. The proposed AAPF topology is composed by an Asymmetrical Multilevel Inverter (AMI), controlled by the Conservative Power Theory (CPT) and synchronized by a Kalman Filter Phase-Locked Loop (KF-PLL). Finally, a single phase AAPF prototype was developed and hardware responses were taken, reflecting proper system operation and accurateness to the simulations.