Variable sampling frequency in iterative learning current Control for Shunt Active Filter in aircraft power systems

This paper investigates the feasibility of an Iterative Leaning current Control (ILC) with variable sampling frequency to realize a 3-phase Shunt Active Filter (SAF) used for harmonic compensation in new generation aircrafts, where a Variable Speed Variable-Frequency (VSVF) power system, typically between 360 and 900Hz, is nowadays used. Due to the high supply frequency, such applications are particularly demanding for both power and control devices, requiring control capabilities even for frequencies up to several kHz. Furthermore variable supply frequency leads to variable frequency harmonics in the aircraft grid that are challenging to track and compensate. An original and effective solution based on an iterative learning control approach, where both the number of samples per period and the sampling frequency are changed, is studied and implemented. Experimental results confirm the validity of the proposed solution.