- Energy efficient motors are motors in which improvements in the design are assimilated so as to increase the efficiency more than the standard motor.
- Design improvements in energy efficient motors mainly target reduction in inherent motor losses.
Each loss is addressed specifically by adopting some measures as follows:
Stator Cu loss:
- Selection of a proper size of the copper conductor so as to reduce its resistance.
- Mostly the copper cross section of winding wires is preferred to increase which decreases resistance and hence I2R losses.
Rotors Cu losses :
- Increasing the section of rotor bars and rings, rotor copper losses can be reduced through weight increase.
- Use of copper conductors in rotor causes less winding resistances comparatively.
- Synchronous speed operation of the motor also reduces I2R loss.
Core losses :
- To reduce hysteresis loss use of low loss grade silicon steel, the modest increase in stator and rotor core length.
- To reduce eddy current use of thinner laminations.
Friction and windage losses:
- Better fan design is adopted.
- Use of improved and proper bearings.
- Improvement in aerodynamic design of rotor and facilitation of airflow.
Stray load losses
- These can be reduced by better electromagnetic design of slots and windings by careful selection of slots and windings by careful selection of :
- All gap length
- Number of slots
- Tooth per slot geometry
- These modification incorporated in to improve efficiency uses more and better material, makes energy efficient motors expensive as compared to standard motors.