Frequency Domain Based Repetitive Control of Three Phase Boost PWM Rectifier under Distorted Supply Voltage Conditions

This paper presents a digital plug-in frequency domain based repetitive control scheme 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 plugin repetitive controller is designed to achieve line side currents with low THD for the three phase PWM boost rectifier. The repetitive control learning algorithm is designed in frequency domain instead of commonly used time domain and provides the flexibility of choosing different learning gains and phase delay compensations individually for each harmonic component. The experimental test results obtained from a 1.6 kVA laboratory based PWM rectifier confirm that the THD of the line side current can be reduced from 21.09% to 4.12% with the insertion of the plug-in frequency domain based repetitive controller.