Resonant current compensator with enhancement of harmonic impedance for LCL-filter based Active rectifiers

Active rectifiers are becoming increasingly popular and viable in high-power applications with requirement of bidirectional power flow. This paper presents a resonant current compensator with enhancement of harmonic impedance for LCL-filter based active rectifiers. Together with a fundamental resonant control, an improved harmonic compensator is realized to enhance harmonic impedance as well as reject current distortion. Based on this method, dc voltage regulation of the rectifier with unity-power-factor operation could be accomplished in the stationary reference frame with no phase-locked-loop used even in distorted line voltages. This is a significant advantage in terms of phase lagging of frame transformation and computing effort of digital signal processing. Controlling considerations of dc voltage based on the so-called nonlinear feedback-linearization are presented. Supporting results from computer simulations as well as laboratory tests validate effectiveness.