Harmonic current elimination for single-phase rectifiers based on PR controller with notch filter

Single-phase PWM rectifiers have been widely used in the field of AC electric railway traction drive systems. With the single-phase rectifier powering the DC link, the instantaneous power is fluctuating at twice of the supply frequency, and so is the DC-link voltage. The consequence is that the fluctuating DC link voltage produces low order harmonics of the line current, generating detrimental effects on traction power grid and the other locomotive loads. Aiming to solve this problem, the mechanism of low order harmonic current is first derived in this paper, and the theory of notch filter and proportional-resonant (PR) controller is analyzed in detail. On the basis of theoretical analysis, a control scheme combined notch filter and PR controller is present to suppress the low order harmonics in the line current. Finally, the validity and effectiveness of the proposed scheme are verified in computer simulation.