Development of the high-performance synchronous permanent magnet planar motor and its key technologies

The synchronous permanent magnet planar motors (SPMPM) have many advantages such as direct driving, high force density, low heat consumption, high accuracy, and has broad application prospects in modern precision, ultra precision machining equipments, especially in the extreme-UV lithography equipment. According to the structures of magnet and coil array, the SPMPM have been divided into four categories, e. g. combined planar motors, semi-combined planar motors, winding stacked planar motors and symmetric planar motors. Characteristics of each category were described. The development of the key technology of SPMPM was summa- rized. In accordance with the current problems, some possible development trends of the SPMPM are discussed at the last.