Iterative learning control with variable sampling frequency for current control of grid-connected converters in aircraft power systems

This paper investigates the feasibility of an iterative learning control (ILC) with variable sampling frequency for current control of power converters in frequency-wild power systems. The proposed solution is explained and demonstrated for the case of a shunt active filter in new-generation aircraft, where a variable-speed variable-frequency power system, typically between 360 and 900 Hz, is nowadays used. Due to the high supply frequency, such application is particularly demanding for both power and control devices, requiring control capabilities even for frequencies up to several kilohertz. 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 ILC 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 strategy. © 1972-2012 IEEE.