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# Electric motor

An electric motor is an electrical machine that converts electrical energy into mechanical energy. [1]

## Acceleration

Acceleration, in physics, is the rate of change of velocity of an object.

## Alternating current

Alternating current (AC), is an electric current in which the flow of electric charge periodically reverses direction, whereas in direct current (DC, also dc), the flow of electric charge is only in one direction.

## Aluminium

Aluminium (or aluminum; see) is a chemical element in the boron group with symbol Al and atomic number 13.

## American Institute of Electrical Engineers

The American Institute of Electrical Engineers (AIEE) was a United States based organization of electrical engineers that existed from 1884 through 1962.

## American Petroleum Institute

The American Petroleum Institute (API) is the largest U.S trade association for the oil and natural gas industry.

## Ampère's force law

In magnetostatics, the force of attraction or repulsion between two current-carrying wires (see first figure below) is often called Ampère's force law.

## André-Marie Ampère

André-Marie Ampère (20 January 1775 – 10 June 1836) was a French physicist and mathematician who was one of the founders of the science of classical electromagnetism, which he referred to as "electrodynamics".

## Andrew Gordon (Benedictine)

Andrew Gordon (15 June 1712 - 22 August 1751) was a Scottish Benedictine monk, physicist and inventor.

## Angular frequency

In physics, angular frequency ω (also referred to by the terms angular speed, radial frequency, circular frequency, orbital frequency, radian frequency, and pulsatance) is a scalar measure of rotation rate.

## Arago's rotations

Arago's rotations is an observable phenomenon and effect discovered by François Arago in 1824.

## Armature (electrical engineering)

In electrical engineering, an armature generally refers to one of the two principal electrical components of an electromechanical machine &mdash; generally in a motor or generator &mdash; but it may also mean the pole piece of a permanent magnet or electromagnet, or the moving iron part of a solenoid or relay.

## Ányos Jedlik

Ányos István Jedlik (Jedlik Ányos István; Štefan Anián Jedlík; in older texts and publications: Stephanus Anianus Jedlik; 11 January 1800 – 13 December 1895) was a Hungarian inventor, engineer, physicist, and Benedictine priest of Slovak origin.

## Barlow's wheel

An 1842 diagram of Barlow's wheel Barlow's wheel was an early demonstration of a homopolar motor, designed and built by English mathematician and physicist, Peter Barlow in 1822.

## Battery (electricity)

An electric battery is a device consisting of two or more electrochemical cells that convert stored chemical energy into electrical energy.

## Benjamin G. Lamme

Benjamin Garver Lamme (January 12, 1864 – July 8, 1924) was an American electrical engineer and chief engineer at Westinghouse, where he was responsible for the design of electrical power machines.

## Brine

Brine is a solution of salt (usually sodium chloride) in water.

## Brush (electric)

A brush is a device which conducts current between stationary wires and moving parts, most commonly in a rotating shaft.

## Brushed DC electric motor

A brushed DC motor is an internally commutated electric motor designed to be run from a direct current power source.

## Brushless DC electric motor

Brushless DC electric motor (BLDC motors, BL motors) also known as electronically commutated motors (ECMs, EC motors) are synchronous motors that are powered by a DC electric source via an integrated inverter/switching power supply, which produces an AC electric signal to drive the motor.

## Brushless electric motor

A brushless electric motor is an electric motor driven by an electrical input, which lacks any form of commutator or slip ring.

## Charles F. Scott (engineer)

Charles Felton Scott (September 19, 1864 in Athens, Ohio &ndash; December 17, 1944) was an electrical engineer, professor at Yale University and known for the Scott connection.

## Coercivity

In electrical engineering and materials science, the coercivity, also called the magnetic coercivity, coercive field or coercive force, is a measure of the ability of a ferromagnetic material to withstand an external magnetic field without becoming demagnetized.

## Cogging torque

Cogging torque of electrical motors is the torque due to the interaction between the permanent magnets of the rotor and the stator slots of a Permanent Magnet (PM) machine.

## Commutator (electric)

A commutator is the moving part of a rotary electrical switch in certain types of electric motors and electrical generators that periodically reverses the current direction between the rotor and the external circuit.

## Control theory

Control theory is an interdisciplinary branch of engineering and mathematics that deals with the behavior of dynamical systems with inputs, and how their behavior is modified by feedback.

## Copper

Copper is a chemical element with symbol Cu (from cuprum) and atomic number 29.

## Current source

A current source is an electronic circuit that delivers or absorbs an electric current which is independent of the voltage across it.

## Direct current

Direct current (DC) is the unidirectional flow of electric charge.

## Direct torque control

Direct torque control (DTC) is one method used in variable frequency drives to control the torque (and thus finally the speed) of three-phase AC electric motors.

## Donald G. Fink

Donald Glen Fink (November 8, 1911 &ndash; May 3, 1996) was an American electrical engineer, a pioneer in the development of radio navigation systems and television standards, vice president for research of Philco, president of the Institute of Radio Engineers, General Manager of the IEEE, and an editor of many important publications in electrical engineering.

## Double-T armature

Double-T armature - Shape of armature used in some motors and generators.

## Doubly fed electric machine

Doubly fed electric machines are electric motors or electric generators that have windings on both stationary and rotating parts, where both windings transfer significant active power between shaft and electrical system.

## Eddy current

Eddy currents (also called Foucault currents) are circular electric currents induced within conductors by a changing magnetic field in the conductor, due to Faraday's law of induction.

## Electric field

The electric field is a component of the electromagnetic field.

## Electric generator

In electricity generation, a generator is a device that converts mechanical energy to electrical energy for use in an external circuit.

## Electric machine

The academic study of electric machines is the universal study of electric motors and electric generators.

## Electric power distribution

An electric power distribution system is the final stage in the delivery of electric power; it carries electricity from the transmission system to individual consumers.

## Electric vehicle

An electric vehicle (EV), also referred to as an electric drive vehicle, uses one or more electric motors or traction motors for propulsion.

## Electrical conductor

In physics and electrical engineering, a conductor is an object or type of material that allows the flow of electrical current in one or more directions.

## Electrical energy

Electrical energy is the energy newly derived from electric potential energy.

## Electrical resistivity and conductivity

Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is an intrinsic property that quantifies how strongly a given material opposes the flow of electric current.

## Electrodynamic tether

Electrodynamic tethers (EDTs) are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electrical energy, or as motors, converting electrical energy to kinetic energy.

## Electromagnet

An electromagnet is a type of magnet in which the magnetic field is produced by an electric current.

## Electromagnetic coil

An electromagnetic coil is an electrical conductor such as a wire in the shape of a coil, spiral or helix.

## Electromagnetic induction

Electromagnetic induction is the production of an electromotive force across a conductor when it is exposed to a time varying magnetic field.

## Electromagnetic interference

Electromagnetic interference (EMI), also called radio-frequency interference (RFI) when in the radio frequency spectrum, is a disturbance generated by an external source that affects an electrical circuit by electromagnetic induction, electrostatic coupling, or conduction.

## Electromagnetism

Electromagnetism is a branch of physics which involves the study of the electromagnetic force, a type of physical interaction that occurs between electrically charged particles.

## Electromechanics

In engineering, electromechanics combines electrical and mechanical processes and procedures drawn from electrical engineering and mechanical engineering.

## Electromotive force

Electromotive force, also called emf (denoted \mathcal and measured in volt), is the voltage developed by any source of electrical energy such as a battery or dynamo.

## Electrostatic motor

An electrostatic motor or capacitor motor is a type of electric motor based on the attraction and repulsion of electric charge.

## Energy conversion efficiency

Energy conversion efficiency (η) is the ratio between the useful output of an energy conversion machine and the input, in energy terms.

## Eric Laithwaite

Eric Roberts Laithwaite (14 June 1921 &ndash; 27 November 1997) was an English electrical engineer, known as the "Father of Maglev" for his development of the linear induction motor and maglev rail system.

## Fractional horsepower motor

A fractional horsepower motor (FHP) is an electric motor with a rated output power of 746 Watts or less.

## François Arago

Dominique François Jean Arago (Domènec Francesc Joan Aragó), known simply as François Arago (Catalan: Francesc Aragó) (1786–1853), was a French mathematician, physicist, astronomer, freemason, supporter of the carbonari and politician.

## Frank J. Sprague

Frank Julian Sprague (July 25, 1857 in Milford, Connecticut – October 25, 1934) was an American naval officer and inventor who contributed to the development of the electric motor, electric railways, and electric elevators.

## Galileo Ferraris

Galileo Ferraris (31 October 1847 – 7 February 1897) was an Italian physicist and electrical engineer, noted mostly for the studies and independent discovery of the rotating magnetic field, a basic working principle of the induction motor.

## General Electric

General Electric (GE) is an American multinational conglomerate corporation incorporated in New York.

## George Westinghouse

George Westinghouse, Jr. (October 6, 1846 – March 12, 1914) was an American entrepreneur and engineer who invented the railway air brake and was a pioneer of the electrical industry, gaining his first patent at the age of 22.

## Goodness factor

Goodness factor is a metric developed by Eric Laithwaite to determine the 'goodness' of an electric motor.

## Gramme machine

A Gramme machine, Gramme ring, Gramme magneto, or Gramme dynamo is an electrical generator that produces direct current, named for its Belgian inventor, Zénobe Gramme, and was built as either a dynamo or a magneto.

## Hall effect sensor

A Hall effect sensor is a transducer that varies its output voltage in response to a magnetic field.

## Homopolar motor

A homopolar motor is a direct current electric motor with two magnetic poles, the conductors of which always cut unidirectional lines of magnetic flux by rotating a conductor around a fixed axis that is parallel to the magnetic field.

## Horsepower

Horsepower (hp) is a unit of measurement of power (the rate at which work is done).

## Hungary

Hungary (Magyarország) is a landlocked country in Central Europe.

## Inductance

In electromagnetism and electronics, inductance is the property of an electrical conductor by which a change in current flowing through it induces an electromotive force in both the conductor itselfSears and Zemansky 1964:743 and in any nearby conductors by mutual inductance.

## Induction motor

An induction or asynchronous motor is an AC electric motor in which the electric current in the rotor needed to produce torque is obtained by electromagnetic induction from the magnetic field of the stator winding.

## Institute of Electrical and Electronics Engineers

The Institute of Electrical and Electronics Engineers (IEEE) is a professional association with its corporate office in New York City and its operations center in Piscataway, New Jersey.

## International Electrotechnical Commission

The International Electrotechnical Commission (in French: Commission électrotechnique internationale) is a non-profit, non-governmental international standards organization that prepares and publishes International Standards for all electrical, electronic and related technologies – collectively known as "electrotechnology".

## International System of Units

The International System of Units (Système International d'Unités, SI) is the modern form of the metric system, and is the most widely used system of measurement.

## Joule heating

Joule heating, also known as ohmic heating and resistive heating, is the process by which the passage of an electric current through a conductor releases heat.

## Linear induction motor

A linear induction motor (LIM) is an alternating current (AC), asynchronous linear motor that works by the same general principles as other induction motors but is typically designed to directly produce motion in a straight line.

## Maglev

Maglev (derived from magnetic levitation) is a transport method that uses magnetic levitation to move vehicles without touching the ground.

## Magnet

A magnet (from Greek λίθος magnḗtis líthos, "Magnesian stone") is a material or object that produces a magnetic field.

## Magnetic core

A magnetic core is a piece of magnetic material with a high permeability used to confine and guide magnetic fields in electrical, electromechanical and magnetic devices such as electromagnets, transformers, electric motors, generators, inductors, magnetic recording heads, and magnetic assemblies.

## Magnetic field

A magnetic field is the magnetic effect of electric currents and magnetic materials.

## Magnetism

Magnetism is a class of physical phenomena that are mediated by magnetic fields.

## Mechanical energy

In the physical sciences, mechanical energy is the sum of potential energy and kinetic energy.

Michael Faraday FRS (22 September 1791 – 25 August 1867) was an English scientist who contributed to the fields of electromagnetism and electrochemistry.

## Microelectromechanical systems

Microelectromechanical systems (MEMS) (also written as micro-electro-mechanical, MicroElectroMechanical or microelectronic and microelectromechanical systems and the related micromechatronics) is the technology of very small devices; it merges at the nano-scale into nanoelectromechanical systems (NEMS) and nanotechnology.

## Mikhail Dolivo-Dobrovolsky

Mikhail Osipovich Dolivo-Dobrovolsky (Михаи́л О́сипович Доли́во-Доброво́льский; Michail von Dolivo-Dobrowolsky or Michail Ossipowitsch Doliwo-Dobrowolski; Michał Doliwo-Dobrowolski; in Gatchina near Saint Petersburg &mdash; in Heidelberg, Germany), was a Polish-Russian engineer, electrician, and inventor.

## Moritz von Jacobi

Moritz Hermann (Boris Semyonovich) von Jacobi (Борис Семёнович (Морис-Герман) Якоби) (21 September 1801 – 10 March 1874) was a German Jewish engineer and physicist born in Potsdam.

## Motor capacitor

A motor capacitor, such as a start capacitor or run capacitor (including a dual run capacitor) is an electrical capacitor that alters the current to one or more windings of a single phase AC induction motor to create a rotating magnetic field.

## National Electrical Manufacturers Association

The National Electrical Manufacturers Association (NEMA) is the association of electrical equipment and medical imaging manufacturers in the United States.

## Nature (journal)

Nature is a British interdisciplinary scientific journal, first published on 4 November 1869.

## Neodymium

Neodymium is a chemical element with symbol Nd and atomic number 60.

## Nikola Tesla

Nikola Tesla (Никола Тесла; 10 July 1856 – 7 January 1943) was a Serbian American inventor, electrical engineer, mechanical engineer, physicist, and futurist best known for his contributions to the design of the modern alternating current (AC) electricity supply system.

## Noise (electronics)

In electronics, noise is a random fluctuation in an electrical signal, a characteristic of all electronic circuits.

## Numerical control

Numerical control (NC) is the automation of machine tools that are operated by precisely programmed commands encoded on a storage medium, as opposed to controlled manually by hand wheels or levers, or mechanically automated by cams alone.

## Operating temperature

An operating temperature is the temperature at which an electrical or mechanical device operates.

## Original equipment manufacturer

Original equipment manufacturer (OEM) is a term used when one company makes a part or subsystem that is used in another company's end product.

## Physicist

A physicist is a scientist who specializes in physics research.

## Piezoelectric motor

A piezoelectric motor or piezo motor is a type of electric motor based upon the change in shape of a piezoelectric material when an electric field is applied.

## Piezoelectricity

Piezoelectricity is the electric charge that accumulates in certain solid materials (such as crystals, certain ceramics, and biological matter such as bone, DNA and various proteins) in response to applied mechanical stress.

## Power inverter

A power inverter, or inverter, is an electronic device or circuitry that changes direct current (DC) to alternating current (AC).

## Pulse-width modulation

Pulse-width modulation (PWM), or pulse-duration modulation (PDM), is a modulation technique used to encode a message into a pulsing signal.

## Pumped-storage hydroelectricity

Pumped-storage hydroelectricity (PSH, or PHES) is a type of hydroelectric energy storage used by electric power systems for load balancing.

## Regenerative brake

A regenerative brake is an energy recovery mechanism which slows a vehicle or object by converting its kinetic energy into a form which can be either used immediately or stored until needed.

## Reluctance motor

A reluctance motor is a type of electric motor that induces non-permanent magnetic poles on the ferromagnetic rotor.

## Repulsion motor

A repulsion motor is a type of electric motor for use on alternating current (AC).

## Revolutions per minute

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min) is a measure of the frequency of rotation, specifically the number of rotations around a fixed axis in one minute.

## Rotating magnetic field

A rotating magnetic field is a magnetic field that has moving polarities in which its opposite poles rotate about a central point or axis.

## Rotor (electric)

The rotor is a moving component of an electromagnetic system in the electric motor, electric generator, or alternator.

## Saturation (magnetic)

Seen in some magnetic materials, saturation is the state reached when an increase in applied external magnetic field H cannot increase the magnetization of the material further, so the total magnetic flux density B more or less levels off.

## Scalar (mathematics)

In linear algebra, real numbers are called scalars and relate to vectors in a vector space through the operation of scalar multiplication, in which a vector can be multiplied by a number to produce another vector.

## Servomechanism

A servomechanism, sometimes shortened to servo, is an automatic device that uses error-sensing negative feedback to correct the performance of a mechanism and is defined by its function.

Shaded-pole motors are the original type of AC single-phase induction motor.

## Silvanus P. Thompson

Silvanus Phillips Thompson FRS (19 June 1851 – 12 June 1916) was a professor of physics at the City and Guilds Technical College in Finsbury, England.

## Singly fed electric machine

Singly fed electric machines (electric motors or electric generators) belong to a category of electric machines that incorporate only one multiphase winding set that is independently excited and as a result, actively participates in the energy conversion process and determines the full electro-mechanical conversion power rating of the machine.

## Skin effect

Skin effect is the tendency of an alternating electric current (AC) to become distributed within a conductor such that the current density is largest near the surface of the conductor, and decreases with greater depths in the conductor.

## Slip ring

A slip ring is an electromechanical device that allows the transmission of power and electrical signals from a stationary to a rotating structure.

## Squirrel-cage rotor

A squirrel-cage rotor is the rotating part (rotor) used in the most common form of AC induction motor.

## Stall torque

Stall torque is the torque produced by a mechanical device whose output rotational speed is zero.

## Stator

The stator is the stationary part of a rotary system, found in electric generators, electric motors, sirens, or biological rotors.

## Stepper motor

A stepper motor or step motor or stepping motor is a brushless DC electric motor that divides a full rotation into a number of equal steps.

## Switch

In electrical engineering, a switch is an electrical component that can break an electrical circuit, interrupting the current or diverting it from one conductor to another.

## Switched reluctance motor

The switched reluctance motor (SRM) is a type of a stepper motor, an electric motor that runs by reluctance torque.

## Synchronous motor

A synchronous electric motor is an AC motor in which, at steady state, the rotation of the shaft is synchronized with the frequency of the supply current; the rotation period is exactly equal to an integral number of AC cycles.

## Tachometer

A tachometer (revolution-counter, tach, rev-counter, RPM gauge) is an instrument measuring the rotation speed of a shaft or disk, as in a motor or other machine.

## Thomas Davenport (inventor)

Thomas Davenport (9 July 1802 &ndash; 6 July 1851) was a Vermont blacksmith who constructed the first American DC electric motor in 1834.

## Thomas Edison

Thomas Alva Edison (February 11, 1847 – October 18, 1931) was an American inventor and businessman.

## Time constant

In physics and engineering, the time constant, usually denoted by the Greek letter τ (tau), is the parameter characterizing the response to a step input of a first-order, linear time-invariant (LTI) system.

## Torque

Torque, moment, or moment of force (see the terminology below) is the tendency of a force to rotate an object about an axis, fulcrum, or pivot.

## Traction motor

A traction motor is an electric motor used for propulsion of a vehicle, such as an electric locomotive or electric roadway vehicle.

## Transformer

A transformer is an electrical device that transfers electrical energy between two or more circuits through electromagnetic induction.

## Two-phase electric power

Two-phase electrical power was an early 20th-century polyphase alternating current electric power distribution system.

## UL (safety organization)

UL (Underwriters Laboratories) is an American worldwide safety consulting and certification company headquartered in Northbrook, Illinois.

## Ultrasonic motor

An ultrasonic motor is a type of electric motor powered by the ultrasonic vibration of a component, the stator, placed against another component, the rotor or slider depending on the scheme of operation (rotation or linear translation).

## Universal motor

The universal motor is so named because it is a type of electric motor that can operate on both AC and DC power.

## University of Regensburg

The University of Regensburg (Universität Regensburg) is a public research university located in the medieval city of Regensburg, Bavaria, a city that is listed as a UNESCO World Heritage Site.

## Utility frequency

The utility frequency, (power) line frequency (American English) or mains frequency (British English) is the frequency of the oscillations of alternating current (AC) in an electric power grid transmitted from a power plant to the end-user.

## Variable-frequency drive

A variable-frequency drive (VFD) (also termed adjustable-frequency drive, variable-speed drive, AC drive, micro drive or inverter drive) is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage.

## Vector control (motor)

Vector control, also called field-oriented control (FOC), is a variable-frequency drive (VFD) control method where the stator currents of a three-phase AC electric motor are identified as two orthogonal components that can be visualized with a vector.

## Voltage source

A voltage source is a two terminal device which can maintain a fixed voltage.

## William Sturgeon

William Sturgeon (22 May 1783 – 4 December 1850) was an English physicist and inventor who made the first electromagnets, and invented the first practical English electric motor.

## Wound rotor motor

A wound-rotor motor is a type of induction motor where the rotor windings are connected through slip rings to external resistances.

## Zénobe Gramme

Zénobe Théophile Gramme was a Belgian electrical engineer.

## References

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