Electrical Drives with Active Rectifiers Connected to Distorted Utility Grid

The paper presents analysis of active rectifier application in electrical drives in order to improve energy efficiency. Recuperation of braking energy in drives with vertical transport of load, as well as during the speed reduction within high inertia drives present the most decisive factors for active rectifiers application. The power factor to the grid is approximately equal to unit, but can be adjusted differently if necessary to dynamically compensate for the reactive power of other consumers connected to the same bus as drive with active rectifier. This is only possible if there is an adequate reserve in the power of the inverter. One of the major issues concerning the active rectifier is its operation under distorted grid voltages, due to harmonics or unbalances, which inflict large low-order harmonics in the output voltage and input currents. Although listed advantages make an active rectifier the best choice for high performance electrical drives, the mitigation of low order harmonics in grid currents under different kinds of distortions and unbalances is still a problem analyzed in research community, as well as in the paper.