TOPIC

HYSTERESIS MOTOR

GROUP

M.UMER KHAYYAMADIL TAHIRHAMZA IFTIKHAR

CONTENTSDefinitionConstruction of statorConstruction of rotorOperation /Working Torque characteristicsMathematical analysisApplications Advantages and Disadvantages

HYSTERESIS MOTORDefinition:

A Hysteresis Motor is a synchronous motor with a uniform air gap and without DC excitation. It operates both in single and three phase supply. The Torque in a Hysteresis Motor is produced due to hysteresis and eddy current induced in the rotor by the action of the rotating flux of the stator windings.

CONSTRUCTION

Construction of Stator: The stator of the hysteresis motor produces a rotating

magnetic field and is almost similar to the stator of the induction motor. Thus, the stator of the motor is connected either to single supply or to the three phase supply.

Construction of Rotor:The rotor of the hysteresis motor consists of the core of aluminium. The figure below shows the rotor of the hysteresis motor. The rotor of the motor is a smooth cylinder.

 

Operation of a Hysteresis Motor When supply is given applied to the stator, a rotating

magnetic field is produced. This magnetic field magnetizes the rotor ring and induces pole within it. Due to the hysteresis loss in the rotor, the induced rotor flux lags behind the rotating stator flux. The angle δ between the stator magnetic field BS and the rotor magnetic field BR is responsible for the production of the torque.

MATHEMATICAL ANALYSIS  The stator magnetic field produces Eddy

currents in the rotor. The eddy current loss is given by the equation shown below.

Where,ke is a constantf2 is the eddy current frequencyB is the flux density

Continue: Hysteresis power loss in the rotor of the hysteresis motor is

given by

Where,* fr is the frequency in the rotor (Hz) *Bmax is the maximum value of flux density in the air gap (T) *Ph is the heat-power loss due to hysteresis (W) *kh is the hysteresis constant

ADVANTAGESAs rotor has no teeth there are no mechanical

vibrations.Due to the absence of the vibrations the

operation is quiet and noiseless.Possibility of multispeed operation by

employing gear train

DISADVANTAGES/LIMITATIONS

Costlier.Low efficiency.Available in very small sizes.

APPLICATIONSAir conditioners.Due to the noiseless operation it is used in

sound recording instruments , sound producing equipments high quality record players.

REFERENCEBertinov, A. I., and M. A. Ermilov. Gisterezisn

ye elektrodvigateli. Moscow, 1967.Armenskii, E. V., and G. B. Falk. Elektricheski

e mikromashiny. Moscow, 1968V. A. PROKUDIN