A new three-phase harmonic-free rectification scheme based on zero-sequence current injection

This paper proposes a new three-phase harmonic-free rectification scheme based on a zero-sequence injection technique. The proposed scheme incorporates two half-bridge inverters and two single-phase transformers to actively and individually shape the positive and negative DC rail currents of the rectifier. The shaped zero-sequence harmonic currents are then circulated through the AC side of the rectifier via a zigzag transformer, resulting in pure sinusoidal input currents in the three-phase diode rectifier. A design example along with component ratings calculation is detailed. Experimental results on a 1.5 kVA prototype are provided to validate the proposed technique.