The Induction Machine Handbook

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The level of prosperity of a community is related to its capability to produce
goods and services. But producing goods and services is strongly related to the
use of energy in an intelligent way.
# ~" i+ U* a% [Motion and temperature (heat) control are paramount in energy usage.
Energy comes into use in a few forms such as thermal, mechanical and
7 H2 G) G' e2 Y+ ]electrical.
& m; X! {$ l& K/ yElectrical energy, measured in kWh, represents more than 30% of all used
energy and it is on the rise. Part of electrical energy is used directly to produce
0 B3 f( L/ u" ~) I; ]( R, Yheat or light (in electrolysis, metallurgical arch furnaces, industrial space
heating, lighting, etc.).
. U3 g& T- \3 m! jThe larger part of electrical energy is converted into mechanical energy in
# T, X% i- u5 S/ H) eelectric motors. Among electric motors, induction motors are most used both for
home appliances and in various industries [1-11].
This is so because they have been traditionally fed directly from the threephase
a.c. electric power grid through electromagnetic power switches with
adequate protection. It is so convenient.
Small power induction motors, in most home appliances, are fed from the
' g  w0 n7 ]- f  Plocal single phase a.c. power grids. Induction motors are rugged and have
" ^! w; ^5 o/ e9 S- j1 l2 n; ymoderate costs, explaining their popularity.
In developed countries today there are more than 3 kW of electric motors
+ X0 _6 [( ^0 G1 W& i# \per person, today and most of it is from induction motors.
# P4 ~6 Z- R' b8 g+ W/ }$ L, @8 QWhile most induction motors are still fed from three-phase or single-phase
power grids, some are supplied through frequency changers (or power
* f: X8 E% R( G# x7 Felectronics converters) to provide variable speed.
In developed countries, 10% of all induction motor power is converted in
variable speed drives applications. The annual growth rate of variable speed
drives has been 9% in the last decade while the electric motor markets showed
an average annual growth rate of 4% in the same time.
Variable speed drives with induction motors are used in transportation,
pumps, compressors, ventilators, machine tools, robotics, hybrid or electric
vehicles, washing machines, etc.
4 Q% h+ T/ u: v9 b! N4 I
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