Single-phase active power filter for multiple nonlinear loads and method therefor

摘要

An active filter and method for stabilizing a single-phase ac line to which multiple nonlinear loads are connected, comprises two pairs of switches connected in two switching loops across a capacitor. One loop is connected to one leg of the line through an inductor and the other loop is connected to the other leg of the line directly. Voltage from the capacitor is followed and averaged to produce a scaling factor which is multiplied by a value corresponding to the actual ac line voltage. The resulting trajectory for the line current is compared to the actual line current and used to switch the pair of switches in the first loop to shape of the line current. A zero-crossing detector connected to receive the ac line voltage determines the polarity of the shaped current.