Current Ripple Reduction Method in a Three-Phase Diode Rectifier With an Instantaneous Reactive Power Compensator

This article discussesthe control method for an ac/dc rectifier system consisting of a three-phase diode rectifier, a buck converter, and an instantaneous reactive power compensator (IRPC). The IRPC makes the grid current sinusoidal by controlling only the instantaneous reactive power. Thus, it is possible to reduce the size of the dc capacitors and ac inductors. This article analyzes the overlap in the rectifier, derives the suitable gain in the damping control, and proposes a modified control method for the IRPC to reduce the current ripple. A 4.5-kW laboratory setup was assembled and examined to verify the theory developed in this article. As a result, the modified control method effectively suppresses the spike current around the overlap duration and damps the overshoot/ringing caused by the resonance. The proposed ac/dc rectifier exhibits an improved power conversion efficiency of 98.2%.