Innovative (New Teaching Technique) Computer Simulation Of Rotating Magnetic Fields In Three Phase Induction Motors Using Matlab Animation.

Rotating magnetic fields in three-phase electrical machines has been one of the hardest topics to convey to our students in the area of energy conversion, because these fields are transformed into phasors that rotate in space around the stator of the electrical machine. Also, the mathematical proof of such rotation can be done quite elegantly, but the mathematics of it and the assumptions made tend to cloud the clarity of the concept. Classic textbooks approach this concept in a mathematical way and usually is left to the students to imagine the space phasor rotation. This is no longer the case, now we can simulate it and SEE IT in our desktop computers using Matlab. Polyphase Analysis Three phase induction machines are the work-horse of industry and these machines have what is called the “rotating magnetic field”. We consider a sequence a-b-c and a symmetric distribution of the phases by 120 electrical degrees each in space and around the air gap. The basic three-phase machine will have three coils, a coil per phase, that have the following terminals: a a b b’ c c’ These coils are excited by a time dependent sinusoidal alternating current producing a sinusoidal magnetomotive force (mmf) wave at the center of the magnetic axis of a particular phase. Therefore the three-space sinusoidal mmf waves are displaced 120 electrical degrees in space. Notice that the coils are placed physically in the stator of the machine. P ge 688.1 Proceedings of the 2001 American Society for Engineering Education Annual Conference & Exposition Copyright 2001, American Society for Engineering Education a’