Current distortion reduction in six-pulse parallel-connected ac/dc rectifiers

This paper presents an innovative method for reducing current distortion on the ac side of six-pulse parallel-connected ac/dc rectifiers. The principle of the method is to modify the current waveforms on the do side of the rectifier by using two self-commutated switches (insulated-gate bipolar transistors). It is demonstrated that accurate shaping of currents on the do side achieves low distortion levels in currents I-A, I-B, and I-C on the ac side. The effectiveness of the method is confirmed by laboratory recordings, which are related to steady-state and transient studies.