Digital modelling for performance prediction of hysteresis motors

The performance prediction of the hysteresis motor depends largely on the success of optimized representation of the actual B-H loop of its rotor hysteresis material. Digital simulation of the typical hysteresis materials like 175 cobalt steel, 36% cobalt steel and Oerstit-70 alloys having coercivity lying between 4 and 20 kA/m and remanent flux density lying between 0.8 and 1.3 T are carried out. The simulation is based on the modified Frölich’s approach. Reasonably close agreement is found between the simulated and those supplied by the power magnet manufacturing company. -- On the basis of parallelogram approximations analytical models of the circumferential-flux hysteresis motor have been given. The motor field equations are then solved, to predict the terminal quantities, using the digital B-H loop modelling. The air-gap power of the hysteresis motor is studied as a function of coercive force, remanent flux density, saturated relative permeability and unsaturated relative permeability of the hysteresis material. A series of tests were carried out using 17% cobalt steel hysteresis rotor. The reasonably close agreement between the terminal quantities predicted form the digital simulation and those measured experimentally validates the usefulness of digital simulation of the hysteresis motor