In view of such defects of traditional model predictive control（ MPC） as high sampling rate and uncertain switching frequency

a kind of model predictive current control with fixed switching frequency（FSF-MPCC） strategy in three-phase four-leg active power filter is proposed. In this method

the operation time of each voltage vector is calculated by way of locating the position of grid voltage vector at αβγ coordinate system and in accordance with the influence of the voltage vector in the section on the current variation rate as well as with minimum current error as objective so to keep the system operate in fixed frequency with combination of space vector modulation principle. The current distortion rate of the method after compensation

compared to traditional MPCC

is smaller

compensation accuracy is higher and the dynamic performance is superior. The effectiveness of the method is verified by both simulation and experiment.