A new procedure to detect rotor position during startup in medium voltage synchronous motor drives with incremental encoder

There are several application fields where high power synchronous motor drives are requested to supply high torques at standstill. To this end, the information on the rotor absolute angular position is needed from the first instant of operations. A new procedure to detect the rotor position of synchronous motors without absolute encoder is presented. In particular, an automatic procedure and a simplified low speed back electro motive force compensation, which increase the reliability of a high performance synchronous motor drive, are proposed.