A Hybrid Harmonic Reduction Multi-Pulse Rectifier with a DC-Side Auxiliary Circuit

A new hybrid DC-side harmonic reduction technique is proposed to further enhance the harmonic suppression capability of a 12-pulse rectifier. In this paper, a conventional 12-pulse rectifier is connected in series with an auxiliary single-phase full-bridge rectifier (ASR). By designing the turns ratio of the interphase reactor (IPR), the rectifier operates in a 24-pulse. Based on this, an additional passive harmonic reduction circuit is added to the output bridge arms of the two groups of three-phase rectifiers, which works synergistically with the ASR. The harmonic reduction circuit adjusts the bridge arms' output current, compensates the bridge arm currents, and modulates them into approximately ideal triangular waves, so that reconstruction of the input current waveform. As a result, the THD of the 24-pulse rectifier is reduced from the theoretical value of 7.56
^%
to 0.98%. The proposed method features a simple circuit structure, with conduction losses less than 5% of the rectifier's output power, and demonstrates significant harmonic suppression effects. Finally, MATLAB/Simulink testing is used to confirm the efficacy of the hybrid harmonic reduction strategy.