A single-phase active power filter for high-order harmonic current compensation is presented in this paper. In modern railway
locomotives, multi-paralleled PWM converters provide unity power factor operation with low THD, but their high-order harmonics
current may provoke interference problems to the railway tack signal and public telecommunication lines. A hybrid digital filter is
proposed to extract the harmonics reference currents compensated in active filters. A prediction algorithm to compensate the delay
problem that appears in the deadbeat current control is also proposed to produce a predicted harmonics reference current. The
effectiveness of the proposed algorithms are verified through simulations and experiments.