An induction motor converts alternating-current electrical energy into mechanical motion using electromagnetic induction. This lesson introduces its defining features, historical development, and main physical parts.
An induction motor, also called an asynchronous motor, is an AC motor in which current in the rotor is induced by the magnetic field produced by the stator. The induced rotor current creates magnetic forces and torque, so the rotor does not need a direct electrical connection.
All flashcards
Induction motor
An AC motor in which the stator’s magnetic field induces rotor current that produces torque.
Squirrel-cage rotor
A rotor whose conductive bars are joined at their ends to form closed current paths.
Variable-frequency drive (VFD)
A drive that varies the voltage and frequency supplied to an induction motor to control its speed.
Scalar control
VFD control that adjusts voltage magnitude and frequency without directly coordinating control with rotor position.
Steinmetz equivalent circuit
A steady-state electrical model that represents a balanced induction motor with equivalent circuit elements.
Quiz questions
What is the synchronous speed of a four-pole induction motor supplied at 50 Hz?Answer: 1500 rpm
Why does an induction motor produce no induction torque when its rotor reaches synchronous speed?Answer: There is no relative motion between the rotating field and rotor conductors.
How does a shaded-pole motor create a modest starting torque?Answer: An induced current in a copper turn delays the magnetic field in part of a stator pole.
How can the rotation direction of a three-phase induction motor be reversed?Answer: Interchange any two of the three phase connections.
How is induction-motor efficiency defined?Answer: Mechanical output power divided by electrical input power.
Based on the Wikipedia article Induction motor, licensed CC BY-SA 4.0. Adapted into a summary, flashcards and quizzes.