EFFECT OF THE NONLINEARITY OF DEMAGNETIZATION CURVES ON THE TORQUE OFHYBRID STEPPING MOTORS WITH PERMANENT-MAGNETS IN SLOTS

The recent achievements in electronic control as well as the higher pe rformance of advanced permanent magnets have brought about a change in the general strategy for design and development of new types of small electrical machines. A special application of permanent magnets (PM) is represented by hybrid stepping motors (HSM). The latter are a sort of combination of variable reluctance-motors and permanent magnet-moto rs. The influence of various PM inserts into the magnetic circuits of electromechanical converters on field and force distribution has been already investigated by the authors (1996). Promising results for HSM have been reported, especially when rare-earth PMs are used. The main aim of Phl inserting, when they are put into slots of slotted pole sho es with radial N-S polarization, is to focus magnetic field lines in t he corresponding teeth. As a result, the reluctance stepping torque ca n be increased depending on the material used. Now a further step is m ade by extending the analysis from the case of linear to that of non-l inear demagnetization curves of permanent magnets.