|
Permanent Magnet Motors |
Induction Motors |
High Power Density
(lower mass and volume) |
Lower Power Density
(larger mass and volume) |
|
High Efficiency |
Lower efficiency due to magnetizing current |
|
Surface-PM: Magnets are Epoxy glued to rotor; then fixed by carbon fiber sleeve |
No Magnets: Inherently Rugged |
|
Easier to Cool |
Difficulty in cooling Rotor Heat |
|
Surface-PM: Limited Field Weakening |
Excellent Inherent Field Weakening |
|
Internal-PM: Excellent Field Weakening |
|
|
Sensitive to Rotor Heat Loading due to eddy currents at high freq operation
(risk of demagnetization) |
Large Tolerance to over current |
|
Easy to Control |
Complicated Control |