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.
Motion and temperature (heat) control are paramount in energy usage.
Energy comes into use in a few forms such as thermal, mechanical and
electrical.
The level of prosperity of a community is related to its capability to produce; u1 F: D6 ^! R8 Q* I' G2 t
goods and services. But producing goods and services is strongly related to the; |. z/ _, Z; E$ B/ j" A/ L
use of energy in an intelligent way.' _" p4 ^0 o* @/ } l3 F
Motion and temperature (heat) control are paramount in energy usage. % J9 b6 }4 h' ?, EEnergy comes into use in a few forms such as thermal, mechanical and0 U% b. g0 W! g7 y }; y! d
electrical.9 p/ X1 ~& K8 H$ k" e! `
Electrical energy, measured in kWh, represents more than 30% of all used " @1 M( q* p$ x3 x3 Cenergy and it is on the rise. Part of electrical energy is used directly to produce 4 A3 V0 I3 O( ^1 jheat or light (in electrolysis, metallurgical arch furnaces, industrial space / s7 }( ~; C- S" B- u+ uheating, lighting, etc.).) f5 J0 |& q1 t* ?
The larger part of electrical energy is converted into mechanical energy in% d% l7 {% X8 t. q K: O% p* d
electric motors. Among electric motors, induction motors are most used both for6 H/ B) j" U1 M
home appliances and in various industries [1-11]. 8 w5 Q n. Z. O5 F9 |$ qThis is so because they have been traditionally fed directly from the threephase - W' L! a4 X0 Na.c. electric power grid through electromagnetic power switches with + U- N2 V/ E5 ]* cadequate protection. It is so convenient. ! y) I. f; K! H4 i; u8 G9 SSmall power induction motors, in most home appliances, are fed from the$ t4 j4 J) J7 O3 K; t4 a
local single phase a.c. power grids. Induction motors are rugged and have2 {9 N# a4 @6 Z' I
moderate costs, explaining their popularity.+ f$ [) k! _% c" R) L z7 ^% G
In developed countries today there are more than 3 kW of electric motors1 G: T3 G T1 B6 h
per person, today and most of it is from induction motors. w, G: X( Y# l- H; f( e
While most induction motors are still fed from three-phase or single-phase 6 F i. E8 a( {" `2 s) Z* m9 b' Vpower grids, some are supplied through frequency changers (or power5 Z0 N6 d7 d7 i8 C% ^8 r
electronics converters) to provide variable speed. 2 R$ x4 w6 o. a! J1 g3 l. MIn developed countries, 10% of all induction motor power is converted in) s1 F0 M$ j: [: x1 I: Z6 y
variable speed drives applications. The annual growth rate of variable speed 5 A' q Y3 K/ hdrives has been 9% in the last decade while the electric motor markets showed. s+ j0 k+ v* g) L1 @+ Z) ^
an average annual growth rate of 4% in the same time. 8 M' }9 o3 z1 z+ {Variable speed drives with induction motors are used in transportation,: f( x& s: [# n" E! p" u; t' X
pumps, compressors, ventilators, machine tools, robotics, hybrid or electric2 h8 R7 I; X5 Y6 F5 s: K( H! q5 t& I
vehicles, washing machines, etc.2 E; Q7 `$ \) p7 f$ t% O
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斑主,给我加点分阿,叩谢!