Which motor type uses permanent magnets on the rotor?

Which motor type uses permanent magnets on the rotor?

• A. Induction motor
• B. Synchronous motor
• C. Permanent magnet motor
• D. Universal motor

Answer: (C)

When the rotor carries permanent magnets, the rotor’s magnetic field is fixed and does not require windings or current to create flux. The stator produces a rotating magnetic field, and the interaction between that rotating field and the fixed magnets on the rotor generates torque. Because the rotor field is fixed, the motor tends to run at synchronous speed with respect to the supply frequency (little to no slip under steady load), which is a hallmark of this type of motor. This is why the best choice is the motor that explicitly uses permanent magnets on the rotor. Induction motors rely on currents induced in rotor conductors, not fixed magnets. Universal motors have wound rotors, not permanent magnets. Synchronous motors can be wound-rotor or permanent-magnet rotor, but the term that directly matches “permanent magnets on the rotor” is the permanent-magnet motor.

When the rotor carries permanent magnets, the rotor’s magnetic field is fixed and does not require windings or current to create flux. The stator produces a rotating magnetic field, and the interaction between that rotating field and the fixed magnets on the rotor generates torque. Because the rotor field is fixed, the motor tends to run at synchronous speed with respect to the supply frequency (little to no slip under steady load), which is a hallmark of this type of motor.

This is why the best choice is the motor that explicitly uses permanent magnets on the rotor. Induction motors rely on currents induced in rotor conductors, not fixed magnets. Universal motors have wound rotors, not permanent magnets. Synchronous motors can be wound-rotor or permanent-magnet rotor, but the term that directly matches “permanent magnets on the rotor” is the permanent-magnet motor.