文档介绍：Massachusetts Institute of Technology
Department of Electrical Engineering puter Science
Electric Machinery
Class Notes 8: Analytic Design Evaluation of Induction Machines February 11, 2004
c 2003 James L. Kirtley Jr.
1 Introduction
Induction machines are perhaps the most widely used of all electric motors. They are generally
simple to build and rugged, offer reasonable asynchronous performance: a manageable torque-speed
curve, stable operation under load, and generally satisfactory efficiency. Because they are so widely
used, they are worth understanding.
In addition to their current economic importance, induction motors and generators may find
application in some new applications with designs that are not similar to motors currently in
commerce. An example is very high speed motors for pressors, perhaps with squirrel cage
rotors, perhaps with solid iron (or perhaps with both).
Because it is possible that future, high performance induction machines will be required to
have characteristics different from those of existing machines, it is necessary to understand them
from first principles, and that is the objective of this document. It starts with a circuit theoretic
view of the induction machine. This analysis is strictly appropriate only for wound-rotor machines,
but leads to an understanding of plex machines. This model will be used to explain the
basic operation of induction machines. Then we will derive a model for squirrel-cage machines.
Finally, we will show how models for solid rotor and mixed solid rotor/squirrel cage machines can
be constructed.
The view that we will take in this document is relentlessly classical. All of the elements that
we will use are calculated from first principles, and we do not resort to numerical analysis or
empirical methods unless we have no choice. While this may seem to be seriously limiting, it serves
our basic objective here, which is to achieve an understanding of how these machines work. It is