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Chapter 3: Electromechanical-Energy-Conversion

Principles

This lecture note is based on the textbook # 1. Electric Machinery - A.E. Fitzgerald, Charles Kingsley, Jr., Stephen D. Umans- 6th edition- Mc Graw Hill series in Electrical Engineering. Power and Energy

  • The electromechanical-energy-conversion process takes place through the medium of the electric or magnetic field of the conversion device of which the structures depend on their respective functions.
  • Transducers: microphone, pickup, sensor, loudspeaker
  • Force producing devices: solenoid, relay, electromagnet
  • Continuous energy conversion equipment: motor, generator

This chapter is devoted to the principles of electromechanical energy conversion and the analysis of the devices accomplishing this function. Emphasis is placed on the analysis of systems that use magnetic fields as the conversion medium.

  • The concepts and techniques can be applied to a wide range of engineering situations involving electromechanical energy conversion.
  • Based on the energy method, we are to develop expressions for forces and torques in magnetic-field-based electromechanical systems.

§3.1 Forces and Torques in Magnetic Field Systems

  • The Lorentz Force Law gives the force F on a particle of charge q in the presence of electric and magnetic fields.

F = q ( E + v × B ) size 12{F=q \( E+v times B \) } {} (3.1)

F : newtons, q : coulombs, E : volts/meter, B : telsas, v : meters/second

  • In a pure electric-field system,

F  qE (3.2)

  • In pure magnetic-field systems,

F = q ( v × B ) size 12{F=q \( v times B \) } {} (3.3)

Figure 3.1 Right-hand rule for F=( q x v) B .

  • For situations where large numbers of charged particles are in motion,

F v = ρ ( E + v × B ) size 12{F rSub { size 8{v} } =ρ \( E+v times B \) } {} (3.4)

J = ρv size 12{J=ρv} {} (3.5)

F v = J × B size 12{F rSub { size 8{v} } =J times B} {} (3.6)

 (charge density): coulombs/ m 3 size 12{m rSup { size 8{3} } } {} , F (force density): newtons/ m 3 size 12{m rSup { size 8{3} } } {} ,

J = ρv size 12{J=ρv} {} (current density): amperes/ m 2 size 12{m rSup { size 8{2} } } {} .

  • Most electromechanical-energy-conversion devices contain magnetic material.
  • Forces act directly on the magnetic material of these devices which are constructed of rigid, nondeforming structures.
  • The performance of these devices is typically determined by the net force, or torque, acting on the moving component. It is rarely necessary to calculate the details of the internal force distribution.
  • Just as a compass needle tries to align with the earth’s magnetic field, the two sets of fields associated with the rotor and the stator of rotating machinery attempt to align, and torque is associated with their displacement from alignment.
    • In a motor, the stator magnetic field rotates ahead of that of the rotor, pulling on it and performing work.
    • For a generator, the rotor does the work on the stator.
      • The Energy Method
  • Based on the principle of conservation of energy: energy is neither created nor destroyed; it is merely changed in form.
  • Fig. 3.2(a): a magnetic-field-based electromechanical-energy-conversion device.
    • A lossless magnetic-energy-storage system with two terminals
    • The electric terminal has two terminal variables: e (voltage), i (current).
    • The mechanical terminal has two terminal variables: f fld size 12{f rSub { size 8{ ital "fld"} } } {} (force), x (position)
    • The loss mechanism is separated from the energy-storage mechanism.

Questions & Answers

where we get a research paper on Nano chemistry....?
Maira Reply
what are the products of Nano chemistry?
Maira Reply
There are lots of products of nano chemistry... Like nano coatings.....carbon fiber.. And lots of others..
learn
Even nanotechnology is pretty much all about chemistry... Its the chemistry on quantum or atomic level
learn
Google
da
no nanotechnology is also a part of physics and maths it requires angle formulas and some pressure regarding concepts
Bhagvanji
Preparation and Applications of Nanomaterial for Drug Delivery
Hafiz Reply
revolt
da
Application of nanotechnology in medicine
what is variations in raman spectra for nanomaterials
Jyoti Reply
I only see partial conversation and what's the question here!
Crow Reply
what about nanotechnology for water purification
RAW Reply
please someone correct me if I'm wrong but I think one can use nanoparticles, specially silver nanoparticles for water treatment.
Damian
yes that's correct
Professor
I think
Professor
Nasa has use it in the 60's, copper as water purification in the moon travel.
Alexandre
nanocopper obvius
Alexandre
what is the stm
Brian Reply
is there industrial application of fullrenes. What is the method to prepare fullrene on large scale.?
Rafiq
industrial application...? mmm I think on the medical side as drug carrier, but you should go deeper on your research, I may be wrong
Damian
How we are making nano material?
LITNING Reply
what is a peer
LITNING Reply
What is meant by 'nano scale'?
LITNING Reply
What is STMs full form?
LITNING
scanning tunneling microscope
Sahil
how nano science is used for hydrophobicity
Santosh
Do u think that Graphene and Fullrene fiber can be used to make Air Plane body structure the lightest and strongest. Rafiq
Rafiq
what is differents between GO and RGO?
Mahi
what is simplest way to understand the applications of nano robots used to detect the cancer affected cell of human body.? How this robot is carried to required site of body cell.? what will be the carrier material and how can be detected that correct delivery of drug is done Rafiq
Rafiq
if virus is killing to make ARTIFICIAL DNA OF GRAPHENE FOR KILLED THE VIRUS .THIS IS OUR ASSUMPTION
Anam
analytical skills graphene is prepared to kill any type viruses .
Anam
Any one who tell me about Preparation and application of Nanomaterial for drug Delivery
Hafiz
what is Nano technology ?
Bob Reply
write examples of Nano molecule?
Bob
The nanotechnology is as new science, to scale nanometric
brayan
nanotechnology is the study, desing, synthesis, manipulation and application of materials and functional systems through control of matter at nanoscale
Damian
Is there any normative that regulates the use of silver nanoparticles?
Damian Reply
what king of growth are you checking .?
Renato
What fields keep nano created devices from performing or assimulating ? Magnetic fields ? Are do they assimilate ?
Stoney Reply
why we need to study biomolecules, molecular biology in nanotechnology?
Adin Reply
?
Kyle
yes I'm doing my masters in nanotechnology, we are being studying all these domains as well..
Adin
why?
Adin
what school?
Kyle
biomolecules are e building blocks of every organics and inorganic materials.
Joe
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Source:  OpenStax, Intergrated library system management. OpenStax CNX. Jul 29, 2009 Download for free at http://cnx.org/content/col10801/1.1
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