  In this work we use classical electromagnetism to analyse a three-phase
induction motor. We first cast the motor as a boundary value problem involving
two phenomenological time-constants. These are derived from the widely used
equivalent circuit model of the induction motor. We then use an iterative
procedure to evaluate these constants and obtain the motor performance
equations. Our results depend only on the geometrical parameters of the motor
and can be used to derive precise expressions for the excitation frequency and
applied voltage needed to extract maximum performance from a given motor at any
rotation speed.
