Chaotic motors - Laroche, C. and Labbe, R. and Petrelis, F. and Fauve, S.
AMERICAN JOURNAL OF PHYSICS 80, 113-121 (2012)
Abstract : We show that electric motors and dynamos can be used to illustrate most
elementary instabilities or bifurcations discussed in courses on
nonlinear oscillators and dynamical systems. These examples are easier
to understand and display a richer behavior than the ones commonly used
from mechanics, electronics, hydrodynamics, lasers, chemical reactions,
and population dynamics. In particular, an electric motor driven by a
dynamo can display stationary, Hopf, and codimension-two bifurcations by
tuning the driving speed of the dynamo and the electric current in the
stator of the electric motor. When the dynamo is driven at constant
torque instead of constant rotation rate, chaotic reversals of the
generated current and of the angular rotation of the motor are observed.
Simple deterministic models are presented which capture the observed
dynamical regimes. (C) 2012 American Association of Physics Teachers.