A BRUSHLESS SYSTEM FOR POSITION CONTROL

The problems related to the use of a Brushless motor in a position control are analysed. The motor is a P.M. Synchronous motor, for which a magnetically isotropic or anisotropic structure may occur, according to the magnets arrangement in the rotor. The attention is firstly devoted to the drive system prerogatives, which must be suitable for a positioning system. These prerogatives are strictly similar to the ones obtainable with the use of a brush type D.C. motor. Then, the working characteristics particularly related to the use of a machine having anisotropic structure are analysed, with special care to the torque ripple due to the armature reaction effects, and some methods for reducing or eliminating this drawback are discussed. Finally, experimental results are given, wich allow to confirm the validity and the interest for the analysed drive system.