Electrical engineeringLesson 1 of 2 in the course Electrical machines

Electric Motors: Construction, Types, History, and Performance

5 flashcards · 5 quiz questions · 5 match pairs · 3 fill-in sentences · English

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Summary

An electric motor converts electrical energy into mechanical energy. This lesson introduces how magnetic forces create motion and how the motor’s main parts work together.

Most electric motors use the interaction between a magnetic field and electric current in a conductor. This interaction produces a Lorentz force. In a motor, the forces on conductors are arranged to create torque, a turning effect on the shaft.

All flashcards

Synchronous motor
An AC motor whose rotor turns at the speed of the stator’s rotating magnetic field under typical steady conditions.
Field system
The part of a motor that establishes its magnetic field.
Back EMF
Voltage induced in a motor’s windings that opposes the supply and generally increases with speed.
Regenerative braking
Operation in which a traction motor acts as a generator to return some motion energy as electrical energy.
Universal motor
A commutated, electrically excited motor designed to operate on either AC or DC.

Quiz questions

  1. What did Michael Faraday demonstrate with electromagnetic rotation in 1821?Answer: A current-carrying wire could rotate around a nearby magnet.
  2. How does a brushless DC motor replace the mechanical commutator?Answer: Electronic switches change winding currents in step with rotor position.
  3. Why does an induction motor’s rotor normally run below the speed of the stator’s rotating field?Answer: Relative motion is needed to induce rotor current and produce torque.
  4. What distinguishes a typical servo system from an open-loop stepper application?Answer: Feedback reports motion so a controller can adjust it toward a target.
  5. Which relation gives rotary mechanical output power from torque and angular speed?Answer: P=TωP=T\omega

Based on the Wikipedia article Electric motor, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.

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