A Combined System of a Series Active Filter and a Double-Series Diode Rectifier with a DC Smoothing Capacitor.

This paper proposes a new rectifing system consisting of a series active filter and a double-series three-phase twelve-pulse diode rectifier. The supply current in the proposed system has a sinusoidal wave shape because the series active filter suppresses the current harmonics produced by the diode rectifier. Since almost no 5th- and 7th-harmonics are produced by the double-series twelve-pulse diode rectifier, the required peak rating of the series active filter is only 7% of the diode rectifier.In this paper, the control scheme and operating characteristics of the series active filter are theoretically and experimentally discussed. A novel conception that connection of a parallel capacitor to each diode of the rectifier makes a great contribution to reducing the required rating of the series active filter is also presented and verified by some experimental results.