Harmonic Reduction for 12-Pulse Rectifiers Using a Single-Switch Controllable Step-Tripling Inter-phase Reactor

To effectively suppress the input current harmonics of the 12-pulse rectifier, a novel multi-pulse rectifier with singleswitch controllable step-tripling inter-phase reactor (SSCST-IPR) at DC-side is proposed. The proposed SSCST-IPR consists of a single active switch, three auxiliary diodes, and an inter-phase reactor with a secondary winding. The coordinated modulation of the single active switch and the three auxiliary diodes modifies the rectifier bridge's output current into a three-level waveform. Based on the relationship between the AC and DC side currents, the number of input current steps increases from 12 to 36, and the total harmonic distortion (THD) is reduced from 11.8% to 2.3%. Since the proposed SSCST-IPR requires only one active switching device and its capacity is only 3.63% of the output power, the proposed scheme is characterized by a simple structure, small auxiliary circuit capacity, and low cost. An experimental prototype with an output power of 3.1 kW was constructed to verify the correctness and effectiveness of the theoretical analysis.