Closed loop input current control of a hybrid 12-pulse rectifier

This paper presents a novel closed loop current control strategy for a hybrid 12-pulse rectifier that uses a two-switch boost stage for output voltage regulation. Unlike previous attempts to mitigate input current distortion, e.g. by injecting voltages on the rectifier output side in open loop control mode, this new closed loop current control scheme directly controls the input current space vector and/or impresses sinusoidal input currents. In this paper, the control strategy is explained and the modulation functions for each pi/3-wide mains voltage sector are derived. The hardware implementation is described, and experimental results demonstrate that the control strategy ensures a high quality input current for ideal or distorted mains.