Fractional order adaptive feedforward cancellation

In this paper, a fractional order adaptive feedforward cancellation (FO-AFC) scheme is proposed to cancel the periodic disturbance. This FO-AFC offers one more tuning knob the fractional order, for the performance improvement of the periodic disturbance cancellation, according to the interests of the users. The equivalence of fractional order internal model principle (FO-IMP) scheme is derived for FO-AFC. So, the FO-IMP equivalence can be used to analyze the performance of the cancellation for the target periodic disturbance and the suppression for the harmonics and noise. Two FO-AFC cases, fractional order α ∈ (0,1) and α ∈ (1,2), are discussed for the performance analysis, respectively. FO-AFC with additional tuning knob α ∈ (0, 2) has many advantages, and is much more flexible over the integer order adaptive feedforward cancellation (IO-AFC) with only α = 1. Simulation results are presented to validate the performance analysis of FO-AFC comparing with IO-AFC.