Dual frame control scheme with a plug-in frequency domain based repetitive controller for three phase PWM boost rectifier under distorted and unbalanced supply voltages

Abstract

This paper presents a dual frame control scheme with a digital plug-in frequency domain based repetitive controller (FDRC) for minimizing the even order harmonics at the output dc link voltage and odd order harmonics in the line currents under the distorted and unbalanced supply voltage conditions. The proposed current controller consists of a conventional PI controller and a frequency domain based plug-in repetitive controller. Based on the mathematical model of the three-phase PWM boost rectifier under the generalized supply voltage conditions, the control task is divided into: (a) dc-link voltage harmonics control and (b) line side current harmonics control. The algorithm of the reference current calculation is based on voltage harmonics control to make sure that the dc link voltage is maintained constant and the supply side power factor is kept close to unity. The plug-in repetitive controller is designed to achieve line side currents with low THD for the three phase PWM boost rectifier. The experimental test results obtained from a 1.6 kVA laboratory based PWM rectifier confirm that the ripple at the dc link voltage can be reduced from 2.5% with the single frame controller to 1.0% with a dual rotating frame controller. Further, with the insertion of the proposed plug-in FDRC controller, the ripple at the dc link is reduced to 0.5%. Also, the THD of the line side current is improved from 29.03% to 5.93% by using the proposed control scheme.