ELECTROMECHANICAL ENERGYElectric Motors and Generators

Electromechanical Devices converts electrical energy into mechanical energy or vice versa via the process of electromechanical energy conversion.

Electromechanical Energy ConversionReversible (energy transfer between electrical and mechanical systems)Electric or Magnetic Fields are used as medium

Energy can neither be created nor destroyed: it can only be transformed from one state to another.

1821 Michael Faraday demonstration of electromagnetic rotation.1822 Peter Barlow Barlow's wheel spinning wheel using electromagnetism.1825-1826 William Sturgeon invents the electromagnet.Brief History of Electric Motors and Generators

1831-1832 Michael Faraday Faradays Disk - potential difference is generated between the ends of an electrical conductor that moves perpendicular to a magnetic field.1832 Andr-Marie Ampre and Hippolyte Pixii used a permanent magnet to create the first dynamo based on Faradays principles.

1832 William Ritchie electromagnetic generator with four rotor coils, a commutator and brushes.1833 Heinrich Friedrich Emil Lenz found the "law of reciprocity of the magneto-electric and electromagnetic phenomena", i.e. the reversibility of electric generator and motor.

1834 Moritz Hermann Jacobi first real electric motors using electromagnets.1835 Thomas Davenport and Orange Smalley experimented with solenoids to create their first rotary machine.1835 Sibrandus Stratingh and Christopher Becker built a small electrically driven three-wheeled vehicle of about 3 kg in weight.

1866 Werner von Siemens perfects the dynamo eliminating the use of permanent magnets. Henry Wilde first commercially successful generator.1867 Znobe-Thophile Gramme better generator with higher voltages than previous attempts. 1872 Werner von Siemens reemerged and invented the modern type of dynamo, drum armature type of machine.

Operation PrinciplesWhenever the number of magnetic flux linking with a coil changes, an e.m.f. gets induced in that coil. The magnitude of the induced e.m.f. is directly proportional to the rate of change of flux linkages i.e., flux X # of turns.The induced e.m.f. sets up a current in such a direction so as to oppose the cause producing it. (Statically induced e.m.f.)If there is relative motion due to physical movement of conductor or magnetic field between a conductor and the flux, e.m.f. gets induced in the conductor. (Dynamically induced e.m.f.)Laws of Electromagnetism

If the conductor is moving with a velocity v (m/s) at an angle measured with plane of the flux then the induced e.m.f. in the conductor is given by: e = B/vsin()If a current carrying conductor is placed in the lines of the magnetic field then it experiences a force.The magnitude of the forced experienced by such a current carrying conductor is given by F = ILB.Laws of Electromagnetism

Energy Flow

Energy Flow

Types of Electromechanical Energy Conversion DevicesGenerally used for measurement and controlLinear input-output conditionsHandle relatively small signalsVibrating motion

Transducers

Mechanical force or torque basedMostly for linear motion drivesHandle larger energy signals compared to transducersForce-Producing Devices

Rotational motionCan handle very large signals compared to the previous onesGenerators and MotorsContinuous Energy-Conversion Devices

Other Applications

Advantages and DisadvantagesLeakage fluxesHysteresis lossesEddy-current lossesFriction (brushes, air, bearings, etc.)Winding lossesAccuracy in designFire HazardsAdvantagesDisadvantagesCan utilize maximum torque from the startCan yield up to 90% efficiencyWide applicationsEnvironment-friendlyExtensive operating lifeLow maintenance requirementsPrice varies on functionElectrical energy is rarely available naturally

ReferencesA.E. Fitzgerald. Electric Machinery 6th EditionM.V. Bakshi, U.A. Bakshi. Electromechanical Energy Conversion Ihttp://www.ieeeghn.org/wiki/index.php/Generatorshttp://www.eti.kit.edu/english/1376.phphttp://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/motdct.htmlhttp://www.ece.lsu.edu/mendrela/EE3410ElMechEnergyConv.pdfhttp://www.vutbr.cz/www_base/priloha.php?dpid=73175