Hysteresis Motor

Hysteresis Motor

Construction Continuously revolving magnetic field is required Stator  

Split phase hysteresis motor Shaded pole hysteresis motor

Rotor  

No winding Smooth cylinder of hard magnetic materials with very large hysteresis loop (chrome ,cobalt steel)

-high resistivity to reduce eddy current loss

Construction..

Operation B lags inducing magnetizing force H. δ – hysteresis angle 



Depends on the nature of material and hysteresis loop - not on rotor speed constant from standstill to Ns.

Th α stator mmf * rotor mmf * sin δ Rotor to accelerate Th>TL At Slip s, 

 

Ph = sPh0

;Ph=Hyst. loss

Th= (Ph/s)*(1/ωs) =Ph0/ ωs Th- independent of slip and speed

Advantages Constant torque 

it can synchronize any load inertia coupled to its shaft which it can accelerate

Smooth rotor  

quite operation No magnetic and mechanical vibration

Limitations the output is about one-quarter that of an induction motor of the same dimension Low Efficiency Low Power factor low torque and available in very small sizes

Applications Constant speed applications 

Electric clock (gear train used)

Air conditioner Sound recording and sound producing instruments  

Tape recorders Record players