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# Electric motor

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

## Acceleration

In physics, acceleration is the rate of change of velocity of an object with respect to time.

## Allen Kent

Allen Kent (October 24, 1921 – May 1, 2014) was an information scientist.

## Alternating current

Alternating current (AC) is an electric current which periodically reverses direction, in contrast to direct current (DC) which flows only in one direction.

## Aluminium

Aluminium or aluminum is a chemical element 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 177510 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.

## Antonio Pacinotti

Antonio Pacinotti (17 June 1841 &ndash; 24 March 1912) was an Italian physicist, who was Professor of Physics at the University of Pisa.

## Arago's rotations

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

## Armature (electrical engineering)

In electrical engineering, an armature is the power-producing component of an electric machine.

## 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.

## 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.

## Bearing (mechanical)

A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts.

## Benjamin Franklin

Benjamin Franklin (April 17, 1790) was an American polymath and one of the Founding Fathers of the United States.

## 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 high-concentration 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), or synchronous DC motors, are synchronous motors powered by DC electricity via an inverter or switching power supply which produces an AC electric current to drive each phase of the motor via a closed loop controller.

## 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.

## Chicago "L"

The Chicago "L" (short for "elevated") is the rapid transit system serving the city of Chicago and some of its surrounding suburbs in the U.S. state of Illinois.

## 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 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 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 in control systems engineering deals with the control of continuously operating dynamical systems in engineered processes and machines.

## 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.

## Eddy current

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

## Electric battery

An electric battery is a device consisting of one or more electrochemical cells with external connections provided to power electrical devices such as flashlights, smartphones, and electric cars.

## Electric field

An electric field is a vector field surrounding an electric charge that exerts force on other charges, attracting or repelling them.

## Electric generator

In electricity generation, a generator is a device that converts motive power (mechanical energy) into electrical power for use in an external circuit.

## Electric machine

In electrical engineering, electric machine is a general term for machines using electromagnetic forces, such as electric motors, electric generators, and others.

## Electric power distribution

Electric power distribution 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, also called an EV, 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 an electrical current in one or more directions.

## Electrical energy

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

## Electrical resistivity and conductivity

Electrical resistivity (also known as resistivity, specific electrical resistance, or volume resistivity) is a fundamental 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 or magnetic induction is the production of an electromotive force (i.e., voltage) across an electrical conductor in a changing 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.

## Electromagnetically excited acoustic noise and vibration

Electromagnetically excited acoustic noise is audible sound directly produced by materials vibrating under the excitation of electromagnetic forces.

## Electromagnetism

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

## Electromotive force

Electromotive force, abbreviated emf (denoted \mathcal and measured in volts), is the electrical intensity or "pressure" developed by a source of electrical energy such as a battery or generator.

## 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.

## Energy recovery

Energy recovery includes any technique or method of minimizing the input of energy to an overall system by the exchange of energy from one sub-system of the overall system with another.

## Engine

An engine or motor is a machine designed to convert one form of energy into mechanical energy.

## 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.

## Fan (machine)

A mechanical fan is a powered machine used to create flow within a fluid, typically a gas such as air.

## Fractional-horsepower motor

A fractional-horsepower motor (FHP) is an electric motor with a rated output power of 746.9 or 746 Watts or less.

## François Arago

Dominique François Jean Arago (Domènec Francesc Joan Aragó), known simply as François Arago (Catalan: Francesc Aragó) (26 February 17862 October 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, one of the pioneers of AC power system and an inventor of the three-phase induction motor.

## General Electric Company

The General Electric Company, or GEC, was a major UK-based industrial conglomerate involved in consumer and defence electronics, communications, and engineering.

## George Westinghouse

George Westinghouse Jr. (October 6, 1846 – March 12, 1914) was an American entrepreneur and engineer based in Pittsburgh, Pennsylvania who invented the railway air brake and was a pioneer of the electrical industry, gaining his first patent at the age of 19.

## Goodness factor

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

## 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 so that the conductor is at right angles to a static magnetic field.

## Horsepower

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

## Hungary

Hungary (Magyarország) is a country in Central Europe that covers an area of in the Carpathian Basin, bordered by Slovakia to the north, Ukraine to the northeast, Austria to the northwest, Romania to the east, Serbia to the south, Croatia to the southwest, and Slovenia to the west.

## Inductance

In electromagnetism and electronics, inductance is the property of an electrical conductor by which a change in electric current through it induces an electromotive force (voltage) in the conductor.

## Induction motor

An induction motor 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 (IEC; in French: Commission électrotechnique internationale) is an 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 (SI, abbreviated from the French Système international (d'unités)) 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 produces 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.

## Losses in electrical systems

In an electrical or electronic circuit or power system, losses can be classified into two categories: technical and non-technical losses.

## Maglev

Maglev (derived from magnetic levitation) is a system of train transportation that uses two sets of magnets, one set to repel and push the train up off the track as in levitation (hence Maglev, Magnetic-levitation), then another set to move the 'floating train' ahead at great speed taking advantage of the lack of friction.

## Magnet

A magnet is a material or object that produces a magnetic field.

## Magnetic core

A magnetic core is a piece of magnetic material with a high magnetic 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 a vector field that describes the magnetic influence of electrical currents and magnetized materials.

## Magnetism

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

## Magnetostriction

Magnetostriction (cf. electrostriction) is a property of ferromagnetic materials that causes them to change their shape or dimensions during the process of magnetization.

## Maxwell stress tensor

The Maxwell stress tensor (named after James Clerk Maxwell) is a symmetric second-order tensor used in classical electromagnetism to represent the interaction between electromagnetic forces and mechanical momentum.

## Mechanical energy

In 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 study 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 microscopic devices, particularly those with moving parts.

## Mikhail Dolivo-Dobrovolsky

Mikhail Osipovich Dolivo-Dobrovolsky (Михаи́л О́сипович Доли́во-Доброво́льский; Michail von Dolivo-Dobrowolsky or Michail Ossipowitsch Doliwo-Dobrowolski; Michał Doliwo-Dobrowolski; &ndash) 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 and Russian 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.

Motor-CAD is an Electromagnetic and Thermal analysis package for electric motors and generators, developed and sold by Motor Design Ltd.

## National Electrical Manufacturers Association

The National Electrical Manufacturers Association (NEMA) is the largest trade association of electrical equipment manufacturers in the United States.

## Nature (journal)

Nature is a British multidisciplinary 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 who is best known for his contributions to the design of the modern alternating current (AC) electricity supply system.

## Noise (electronics)

In electronics, noise is an unwanted disturbance in an electrical signal.

## Numerical control

Computer numerical control (CNC) is the automation of machine tools by means of computers executing pre-programmed sequences of machine control commands.

## Operating temperature

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

## Original equipment manufacturer

An Original Equipment Manufacturer (OEM) is a company that produces parts and equipment that may be marketed by another manufacturer.

## Physicist

A physicist is a scientist who has specialized knowledge in the field of physics, which encompasses the interactions of matter and energy at all length and time scales in the physical universe.

## Piezoelectric motor

A piezoelectric motor or piezo motor is a type of electric motor based on 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 pumped hydroelectric energy storage (PHES), is a type of hydroelectric energy storage used by electric power systems for load balancing.

## Regenerative brake

Regenerative braking 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 using on alternating current (AC).

## Revolutions per minute

Revolutions per minute (abbreviated rpm, RPM, rev/min, r/min) is the number of turns 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)

A scalar is an element of a field which is used to define a vector space.

## Servomechanism

In control engineering a servomechanism, sometimes shortened to servo, is an automatic device that uses error-sensing negative feedback to correct the action of a mechanism.

The shaded-pole motor is the original type of AC single-phase induction motor, dating back to at least as early as 1890.

## Silvanus P. Thompson

Silvanus Phillips Thompson (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 machine is a broad term which covers ordinary electric motors and electric generators.

## 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.

## Solenoid

A solenoid (/ˈsolə.nɔɪd/) (from the French solénoïde, derived in turn from the Greek solen ("pipe, channel") and eidos ("form, shape")) is a coil wound into a tightly packed helix.

The South Side Elevated Railroad (originally Chicago and South Side Rapid Transit Railroad) was the first elevated rapid transit line in Chicago, Illinois.

## Squirrel-cage rotor

A squirrel-cage rotor is the rotating part of the common squirrel-cage 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, mud motors 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 "make" or "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 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, 1847October 18, 1931) was an American inventor and businessman, who has been described as America's greatest inventor.

## 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 is rotational force.

## 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 a static electrical device that transfers electrical energy between two or more circuits through electromagnetic induction.

## UL (safety organization)

UL is a global 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 a type of electric motor that can operate on either AC or 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 nominal frequency of the oscillations of alternating current (AC) in an electric power grid transmitted from a power station to the end-user.

## Variable-frequency drive

A variable-frequency drive (VFD; also termed adjustable-frequency drive, “variable-voltage/variable-frequency (VVVF) 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 in which the stator currents of a three-phase AC electric motor are identified as two orthogonal components that can be visualized with a vector.

A vibrating alert is a feature of communications devices to notify the user of an incoming connection.

## 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 resistance.

## Zénobe Gramme

Zénobe Théophile Gramme (4 April 1826 – 20 January 1901) was a Belgian electrical engineer.

## References

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