| Summary: | 碩士 === 國立臺灣科技大學 === 電機工程系 === 100 === The subject of this thesis is to eliminate harmonics of the overall input line current in a 24-pulse converter system. The proposed structure applies two identical side-extended transformers with three-phase input voltage source in reverse order, so that four sets of voltage source with 15 degrees phase-shift are generated, and then sent into 6-pulse converters. The 24-pulse converter system is composed of four 6-pulse converters which connected by inter-phase transformers. While the proposed system works as a 24-pulse converter, all harmonics are eliminated except the 24n±1th, the characteristic harmonic. The two first-stage IPTs add the secondary winding to be an active IPT, and the overall input line conditions is improved by injecting compensation current into the secondary winding with a current-controlled inverter. This thesis proposed a compensation strategy to reduce the 24n±1th harmonic, moreover, the strategy also overcomes the total harmonic distortions caused by unbalance impedance of side-extended transformers, and the unbalanced factor of input line currents can be improved, too. A 6 kW prototype is built for test. Both simulation and experimental results demonstrate the validity of the proposed scheme.
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