AC powered motor frequency converter especially for elevators and lifting equipment, has low-pass setter connected between rectifier and intermediate circuit

摘要

A frequency converter has a rectifier (1) for converting the three voltage phases (L1,L2,L3) of an AC network into a DC voltage, and an intermediate circuit (5) forming an energy reservoir for smoothing of the DC voltage, and an inverter (7) for conversion of the DC voltage into three voltage phases (U,V,W) of an AC current. A low-pass setter (4) is connected into circuit between the rectifier (1) and the intermediate circuit (5) and lowers the actual values of the intermediate circuit voltage and holds it constant with time and retains the energy reservoir of the intermediate circuit (5) to a specified energy level, by regulating the current supply over the main current path.