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Encyclopedia > Electric motor
Electric motors
Electric motors

An electric motor uses electrical energy to produce mechanical energy. The reverse process, that of using mechanical energy to produce electrical energy, is accomplished by a generator or dynamo. Traction motors used on locomotives often perform both tasks if the locomotive is equipped with dynamic brakes. Electric motors are found in household appliances such as fans, refrigerators, washing machines, pool pumps, floor vacuums, and fan-forced ovens. A motor is a device that converts energy into mechanical power, and is often synonymous with engine. ... Image File history File links Download high resolution version (707x768, 49 KB) Summary Largest motor: 1 Hp (750 W) Next largest: 25 W Small motors: CD player motor, toy motor, CD drive head traverse motor Licensing I, the creator of this work, hereby grant the permission to copy, distribute and... Image File history File links Download high resolution version (707x768, 49 KB) Summary Largest motor: 1 Hp (750 W) Next largest: 25 W Small motors: CD player motor, toy motor, CD drive head traverse motor Licensing I, the creator of this work, hereby grant the permission to copy, distribute and... Electrical energy can refer to several closely related things. ... In physics, mechanical energy describes the potential energy and kinetic energy present in the components of a mechanical system. ... This article is about machines that produce electricity. ... Traction motor typically refers to those motors that are used to power the driving wheels of a railroad locomotive, electrical multi-unit train (such as a subway or light rail vehicle train), or a tram. ... Great Western Railway No. ... Regenerative braking is any technology which allows a vehicle to recapture and store part of the kinetic energy that would ordinarily be lost when braking. ...

Contents

History and development

The principle of conversion of electrical energy into mechanical energy by electromagnetic means was demonstrated by the British scientist Michael Faraday in 1821 and consisted of a free-hanging wire dipping into a pool of mercury. A permanent magnet was placed in the middle of the pool of mercury. When a current was passed through the wire, the wire rotated around the magnet, showing that the current gave rise to a circular magnetic field around the wire. This motor is often demonstrated in school physics classes, but brine (salt water) is sometimes used in place of the toxic mercury. This is the simplest form of a class of electric motors called homopolar motors. A later refinement is the Barlow's Wheel. These were demonstration devices, unsuited to practical applications due to limited power. Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed to the fields of electromagnetism and electrochemistry. ... Year 1821 (MDCCCXXI) was a common year starting on Monday (link will display the full calendar) of the Gregorian Calendar (or a common year starting on Saturday of the 12-day slower Julian calendar). ... This article is about the element. ... For other uses, see Magnet (disambiguation). ... In electricity, current refers to electric current, which is the flow of electric charge. ... For the sports equipment manufacturer, see Brine, Corp. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... Barlows Wheel is the name given to an early demonstration of an electric motor, designed and built by English mathematician and physicist, Peter Barlow in 1822. ...



The first electric motor using electromagnets for both stationary and rotating parts was demonstrated by Ányos Jedlik in 1828 Hungary, who later developed a motor powerful enough to propel a vehicle. The first commutator-type direct-current electric motor capable of a practical application was invented by the British scientist William Sturgeon in 1832. Following Sturgeon's work, a commutator-type direct-current electric motor made with the intention of commercial use was built by the American Thomas Davenport and patented in 1837. Although several of these motors were built and used to operate equipment such as a printing press, due to the high cost of primary battery power, the motors were commercially unsuccessful and Davenport went bankrupt. Several inventors followed Sturgeon in the development of DC motors but all encountered the same cost issues with primary battery power. No electricity distribution had been developed at the time. Like Sturgeon's motor, there was no practical commercial market for these motors. photo of Jedlik Anyos Jedlik (Hungarian Jedlik István Ányos, Slovak Å tefan Anián Jedlík) (January 11, 1800, SzimÅ‘ – December 13, 1895, GyÅ‘r, Hungary) was a Hungarian inventor, engineer, physicist, and Roman Catholic priest of Slovak origin. ... Conventional continuous current flows from the battery. ... William Sturgeon (May 22, 1783 - December 4, 1850) was an English physicist and inventor who made the first electromagnets. ... Thomas Davenport (b. ... For other uses, see Battery. ...


The modern DC motor was invented by accident in 1873, when Zénobe Gramme connected the dynamo he had invented to a second similar unit, driving it as a motor. The Gramme machine was the first electric motor that was successful in the industry. Zénobe Gramme, by Mathurin Moreau Zénobe Théophile Gramme (April 4, 1826 - January 20, 1901) was a Belgian electrical engineer. ... This article is about machines that produce electricity. ... A Gramme machine or Gramme dynamo is kind of electric dynamo named for its Belgian/French inventor, Zénobe Gramme. ...


In 1888 Nikola Tesla invented the first practicable AC motor and with it the polyphase power transmission system. Tesla continued his work on the AC motor in the years to follow at the Westinghouse company. Nikola Tesla (Nih koh la TESS lah) [2](Serbian Cyrillic: ) (10 July 1856 – 7 January 1943) was an inventor, physicist, mechanical and electrical engineer. ... An AC motor is an electric motor that is driven by an alternating current. ...


Categorization of electric motors

The classic division of electric motors has been that of DC types vs AC types. This is more a de facto convention, rather than a rigid distinction. For example, many classic DC motors run happily on AC power.


The ongoing trend toward electronic control further muddles the distinction, as modern drivers have moved the commutator out of the motor shell. For this new breed of motor, driver circuits are relied upon to generate sinusoidal AC drive currents, or some approximation of. The two best examples are: the brushless DC motor, and the stepping motor, both being polyphase AC motors requiring external electronic control.


There is a clearer distinction between a synchronous motor and asynchronous types. In the synchronous types, the rotor rotates in synchrony with the oscillating field or current (eg. permanent magnet motors). In contrast, an asynchronous motor is designed to slip; the most ubiquitous example being the common AC induction motor which must slip in order to generate torque. A synchronous electric motor is distinguished by its rotor spinning at the same rate as the oscillating field which drives it. ... Induction Motor (IM) is one kind of AC motor where power is supplied to the rotating device by induction. ...


DC motors

A DC motor is designed to run on DC electric power. Two examples of pure DC designs are Michael Faraday's homopolar motor (which is uncommon), and the ball bearing motor, which is (so far) a novelty. By far the most common DC motor types are the brushed and brushless types, which use internal and external commutation respectively to create an oscillating AC current from the DC source -- so they are not purely DC machines in a strict sense. Michael Faraday, FRS (September 22, 1791 – August 25, 1867) was an English chemist and physicist (or natural philosopher, in the terminology of that time) who contributed to the fields of electromagnetism and electrochemistry. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... A ball bearing motor is an unusual electric motor that is constructed as follows: Take a short hollow copper pipe and fit 2 ball bearings on either end. ...


Brushed DC motors

Main article: Brushed DC Electric Motor

The classic DC motor design generates an oscillating current in a wound rotor with a split ring commutator, and either a wound or permanent magnet stator. A rotor consists of a coil wound around a rotor which is then powered by any type of battery. A brushed DC motor is a type of electric motor that, in contrast to a brushless DC motor, has two static electric contacts (brushes) that come in contact with different sections of a split disc (commutator) at different times, spinning the motor through electromagnets. ... Conventional continuous current flows from the battery. ...


Many of the limitations of the classic commutator DC motor are due to the need for brushes to press against the commutator. This creates friction. At higher speeds, brushes have increasing difficulty in maintaining contact. Brushes may bounce off the irregularities in the commutator surface, creating sparks. This limits the maximum speed of the machine. The current density per unit area of the brushes limits the output of the motor. The imperfect electric contact also causes electrical noise. Brushes eventually wear out and require replacement, and the commutator itself is subject to wear and maintenance. The commutator assembly on a large machine is a costly element, requiring precision assembly of many parts. Conventional continuous current flows from the battery. ... For other uses, see Friction (disambiguation). ... ...


Brushless DC motors

Some of the problems of the brushed DC motor are eliminated in the brushless design. In this motor, the mechanical "rotating switch" or commutator/brushgear assembly is replaced by an external electronic switch synchronised to the rotor's position. Brushless motors are typically 85-90% efficient, whereas DC motors with brushgear are typically 75-80% efficient. A brushless DC motor (BLDC) is an AC synchronous electric motor that from a modeling perspective looks very similar to a DC motor. ...


Midway between ordinary DC motors and stepper motors lies the realm of the brushless DC motor. Built in a fashion very similar to stepper motors, these often use a permanent magnet external rotor, three phases of driving coils, one or more Hall effect sensors to sense the position of the rotor, and the associated drive electronics. The coils are activated, one phase after the other, by the drive electronics as cued by the signals from the Hall effect sensors. In effect, they act as three-phase synchronous motors containing their own variable-frequency drive electronics. A specialized class of brushless DC motor controllers utilize EMF feedback through the main phase connections instead of Hall effect sensors to determine position and velocity. These motors are used extensively in electric radio-controlled vehicles. When configured with the magnets on the outside, these are referred to by modelists as outrunner motors. Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ... Because of induction of the windings, power requirements, and temperature management some glue circuitry is necessary between digital controller and motor. ... A brushless DC motor (BLDC) is an AC synchronous electric motor that from a modeling perspective looks very similar to a DC motor. ... The magnetic piston (1) in this pneumatic cylinder will cause the Hall effect sensors (2 and 3) mounted on its outer wall to activate when it is fully retracted or extended. ... Small Variable Frequency Drive (VFD) A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. ... This radio control airplane is carrying a scale model of X-33 and is taking part in NASA research. ...


Brushless DC motors are commonly used where precise speed control is necessary, as in computer disk drives or in video cassette recorders, the spindles within CD, CD-ROM (etc.) drives, and mechanisms within office products such as fans, laser printers and photocopiers. They have several advantages over conventional motors: Disk Drive is the afternoon show on CBC Radio Two. ... The video cassette recorder (or VCR, less popularly video tape recorder) is a type of video tape recorder that uses removable cassettes containing magnetic tape to record audio and video from a television broadcast so it can be played back later. ... CD may stand for: Compact Disc Canadian Forces Decoration Cash Dispenser (at least used in Japan) CD LPMud Driver Centrum-Demokraterne (Centre Democrats of Denmark) Certificate of Deposit České Dráhy (Czech Railways) Chad (NATO country code) Chalmers Datorförening (computer club of the Chalmers University of Technology) a 1960s... The CD-ROM (an abbreviation for Compact Disc Read-Only Memory (ROM)) is a non-volatile optical data storage medium using the same physical format as audio compact discs, readable by a computer with a CD-ROM drive. ... For other uses, see Fan. ... 1993 Apple LaserWriter Pro 630 laser printer A laser printer is a common type of computer printer that rapidly produces high quality text and graphics on plain paper. ... A small, much-used Xerox copier in a high school library. ...

  • Compared to AC fans using shaded-pole motors, they are very efficient, running much cooler than the equivalent AC motors. This cool operation leads to much-improved life of the fan's bearings.
  • Without a commutator to wear out, the life of a DC brushless motor can be significantly longer compared to a DC motor using brushes and a commutator. Commutation also tends to cause a great deal of electrical and RF noise; without a commutator or brushes, a brushless motor may be used in electrically sensitive devices like audio equipment or computers.
  • The same Hall effect sensors that provide the commutation can also provide a convenient tachometer signal for closed-loop control (servo-controlled) applications. In fans, the tachometer signal can be used to derive a "fan OK" signal.
  • The motor can be easily synchronized to an internal or external clock, leading to precise speed control.
  • Brushless motors have no chance of sparking, unlike brushed motors, making them better suited to environments with volatile chemicals and fuels.
  • Brushless motors are usually used in small equipment such as computers and are generally used to get rid of unwanted heat.
  • They are also very quiet motors which is an advantage if being used in equipment that is affected by vibrations.

Modern DC brushless motors range in power from a fraction of a watt to many kilowatts. Larger brushless motors up to about 100 kW rating are used in electric vehicles. They also find significant use in high-performance electric model aircraft. Bearing is the following: Often, bearing is the state of having something as a quality, characteristic, or permanent attribute. ... Conventional continuous current flows from the battery. ... Tachometer showing engine RPM (revolutions per minute), and a redline from 6000 and 7000 RPM. A tachometer is an instrument that measures the speed of rotation of a shaft or disk, as in a motor or other machine. ... For other uses, see Watt (disambiguation). ...


Coreless DC motors

Nothing in the design of any of the motors described above requires that the iron (steel) portions of the rotor actually rotate; torque is exerted only on the windings of the electromagnets. Taking advantage of this fact is the coreless DC motor, a specialized form of a brush or brushless DC motor. Optimized for rapid acceleration, these motors have a rotor that is constructed without any iron core. The rotor can take the form of a winding-filled cylinder inside the stator magnets, a basket surrounding the stator magnets, or a flat pancake (possibly formed on a printed wiring board) running between upper and lower stator magnets. The windings are typically stabilized by being impregnated with Electrical epoxy potting systems. Filled epoxies that have moderate mixed viscosity and a long gel time. These systems are highlighted by low shrinkage and low exotherm. Typically UL 1446 recognized as a potting compound for use up to 180C (Class H) UL File No. E 210549. Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... The stator is the fixed part of a rotating machine. ... Close-up photo of one side of a motherboard PCB, showing conductive traces, vias and solder points for through-hole components on the opposite side. ... In chemistry, epoxy or polyepoxide is a thermosetting epoxide polymer that cures (polymerizes and crosslinks) when mixed with a catalyzing agent or hardener. Most common epoxy resins are produced from a reaction between epichlorohydrin and bisphenol-A. The first commercial attempts to prepare resins from epichlorohydrin occurred in 1927 in...


Because the rotor is much lighter in weight (mass) than a conventional rotor formed from copper windings on steel laminations, the rotor can accelerate much more rapidly, often achieving a mechanical time constant under 1 ms. This is especially true if the windings use aluminum rather than the heavier copper. But because there is no metal mass in the rotor to act as a heat sink, even small coreless motors must often be cooled by forced air. For other uses, see Mass (disambiguation). ... For other uses, see Copper (disambiguation). ... For other uses, see Steel (disambiguation). ... In physics and engineering, the time constant usually denoted by the Greek letter , (tau), characterizes the frequency response of a first-order, linear time-invariant (LTI) system. ... One millisecond is one-thousandth of a second. ... Aluminum redirects here. ...


These motors were commonly used to drive the capstan(s) of magnetic tape drives and are still widely used in high-performance servo-controlled systems, like radio-controlled vehicles/aircraft, humanoid robotic systems, industrial automation, medical devices, etc. Nautical capstan A capstan is a rotating machine used to control or apply force to another element, usually linear. ... Compact audio cassette Magnetic tape is a non-volatile storage medium consisting of a magnetic coating on a thin plastic strip. ... In practical usage, a robot is a mechanical device which performs automated tasks, either according to direct human supervision, a pre-defined program or, a set of general guidelines, using artificial intelligence techniques. ...


Universal motors

A variant of the wound field DC motor is the universal motor. The name derives from the fact that it may use AC or DC supply current, although in practice they are nearly always used with AC supplies. The principle is that in a wound field DC motor the current in both the field and the armature (and hence the resultant magnetic fields) will alternate (reverse polarity) at the same time, and hence the mechanical force generated is always in the same direction. In practice, the motor must be specially designed to cope with the AC current (impedance must be taken into account, as must the pulsating force), and the resultant motor is generally less efficient than an equivalent pure DC motor. Operating at normal power line frequencies, the maximum output of universal motors is limited and motors exceeding one kilowatt are rare. But universal motors also form the basis of the traditional railway traction motor in electric railways. In this application, to keep their electrical efficiency high, they were operated from very low frequency AC supplies, with 25 Hz and 16 2/3 hertz operation being common. Because they are universal motors, locomotives using this design were also commonly capable of operating from a third rail powered by DC. In electrical engineering, an armature is usually the rotating part of an electric motor or dynamo. ... Electrical impedance, or simply impedance, is a measure of opposition to a sinusoidal alternating electric current. ... Traction motor typically refers to those motors that are used to power the driving wheels of a railroad locomotive, electrical multi-unit train (such as a subway or light rail vehicle train), or a tram. ... Overhead wire in Coventry, England Overhead wire and its suspension system in Bridgeport, Connecticut, USA A railway electrification system is a way of supplying electric power to electric locomotives and multiple units. ... Third rail at the West Falls Church Metro stop in Washington, D.C., electrified to 750 volts. ... Direct current (DC or continuous current) is the continuous flow of electricity through a conductor such as a wire from high to low potential. ...


The advantage of the universal motor is that AC supplies may be used on motors which have the typical characteristics of DC motors, specifically high starting torque and very compact design if high running speeds are used. The negative aspect is the maintenance and short life problems caused by the commutator. As a result such motors are usually used in AC devices such as food mixers and power tools which are used only intermittently. Continuous speed control of a universal motor running on AC is very easily accomplished using a thyristor circuit, while stepped speed control can be accomplished using multiple taps on the field coil. Household blenders that advertise many speeds frequently combine a field coil with several taps and a diode that can be inserted in series with the motor (causing the motor to run on half-wave rectified AC). Conventional continuous current flows from the battery. ... Circuit symbol for a thyristor The thyristor is a solid-state semiconductor device with four layers of alternating N and P-type material. ... Closeup of the image below, showing the square shaped semiconductor crystal various semiconductor diodes, below a bridge rectifier Structure of a vacuum tube diode In electronics, a diode is a two-terminal component, almost always one that has electrical properties which vary depending on the direction of flow of charge...


Universal motors can rotate at relatively high revolutions per minute (rpm). This makes them useful for appliances such as blenders, vacuum cleaners, and hair dryers where high-speed operation is desired. Many vacuum cleaner and weed trimmer motors exceed 10,000 rpm, Dremel and other similar miniature grinders will often exceed 30,000 rpm. Motor damage may occur due to overspeed (rpm in excess of design specifications) if the unit is operated with no significant load. On larger motors, sudden loss of load is to be avoided, and the possibility of such an occurrence is incorporated into the motor's protection and control schemes. Often, a small fan blade attached to the armature acts as an artificial load to limit the motor speed to a safe value, as well as provide cooling airflow to the armature and field windings. An electric blender. ... Regular canister vacuum cleaner for home use. ... Categories: Stub | Hairdressing ... // A string trimmer, also called a line trimmer, edge trimmer, Weedeater (a brandname), Weedwhacker, weedy, whipper snipper, strimmer, garden strimmer, or bush cutter is a powered handheld device that uses a flexible monofilament line instead of a blade for cutting grass and other plants near objects. ... A single-speed MultiPro Dremel Dremel Moto-Tool is the name given to rotary tools developed by Albert J. Dremel, who founded the Dremel Company in 1932 in Racine, Wisconsin. ...


With the very low cost of semiconductor rectifiers, some applications that would have previously used a universal motor now use a pure DC motor, sometimes with a permanent magnet field. A semiconductor is a solid material that has electrical conductivity in between that of a conductor and that of an insulator; it can vary over that wide range either permanently or dynamically. ... A rectifier is an electrical device that converts alternating current to rectified direct current, a process known as rectification. ...


AC motors

Main article: AC motor

In 1882, Nikola Tesla identified the rotating magnetic field principle, and pioneered the use of a rotary field of force to operate machines. He exploited the principle to design a unique two-phase induction motor in 1883. In 1885, Galileo Ferraris independently researched the concept. In 1888, Ferraris published his research in a paper to the Royal Academy of Sciences in Turin. An AC motor is an electric motor that is driven by an alternating current. ... Nikola Tesla (Nih koh la TESS lah) [2](Serbian Cyrillic: ) (10 July 1856 – 7 January 1943) was an inventor, physicist, mechanical and electrical engineer. ... Early 20th century Alternator made in Budapest, Hungary, in the power generating hall of a hydroelectric station. ... Galileo Ferraris (October 30, 1847 - February 7, 1897) was an Italian physicist and electrical engineer, noted mostly for his studies on alternating current. ...


Introduction of Tesla's motor from 1888 onwards initiated what is sometimes referred to as the Second Industrial Revolution, making possible the efficient generation and long distance distribution of electrical energy using the alternating current transmission system, also of Tesla's invention (1888).[1] Before the invention of the rotating magnetic field, motors operated by continually passing a conductor through a stationary magnetic field (as in homopolar motors). Bessemer converter The Second Industrial Revolution (1870–1914) is a phrase used by some historians to describe an assumed second phase of the Industrial Revolution. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...


Tesla had suggested that the commutators from a machine could be removed and the device could operate on a rotary field of force. Professor Poeschel, his teacher, stated that would be akin to building a perpetual motion machine.[2] Tesla would later attain U.S. Patent 0,416,194 , Electric Motor (December 1889), which resembles the motor seen in many of Tesla's photos. This classic alternating current electro-magnetic motor was an induction motor. Conventional continuous current flows from the battery. ... This article or section should include material from Parallel Path See also Perpetuum mobile as a musical term Perpetual motion machines (the Latin term perpetuum mobile is not uncommon) are a class of hypothetical machines which would produce useful energy in a way science cannot explain (yet). ...


Michail Osipovich Dolivo-Dobrovolsky later invented a three-phase "cage-rotor" in 1890. This type of motor is now used for the vast majority of commercial applications. Dolivo-Dobrovolsky, Michail Osipovich (Russian: ; January 2 [O.S. December 21, 1861] 1862 in Saint-Petersburg — November 15 [O.S. November 3] 1890), was a Russian engineer, electrician, inventor, developed the first three-phase generator and three-phase motor (1888), studied star and delta connections. ...


Components

A typical AC motor consists of two parts:

  1. An outside stationary stator having coils supplied with AC current to produce a rotating magnetic field, and;
  2. An inside rotor attached to the output shaft that is given a torque by the rotating field.

Torque motors

A torque motor is a specialized form of induction motor which is capable of operating indefinitely at stall (with the rotor blocked from turning) without damage. In this mode, the motor will apply a steady torque to the load (hence the name). A common application of a torque motor would be the supply- and take-up reel motors in a tape drive. In this application, driven from a low voltage, the characteristics of these motors allow a relatively-constant light tension to be applied to the tape whether or not the capstan is feeding tape past the tape heads. Driven from a higher voltage, (and so delivering a higher torque), the torque motors can also achieve fast-forward and rewind operation without requiring any additional mechanics such as gears or clutches. In the computer world, torque motors are used with force feedback steering wheels. Induction Motor (IM) is one kind of AC motor where power is supplied to the rotating device by induction. ... A stall is the slowing or stopping of a process. ... The rotor is the non-stationary part of a rotary electric motor or alternator, which rotates because the wires and magnetic field of the motor are arranged so that a torque is developed about the rotors axis. ... For other senses of this word, see torque (disambiguation). ... For other uses, see Reel (disambiguation). ... DDS tape drive. ... Capstans are found in the mechanisms of tape recorders in which they have a similar function to nautical capstans. ... For other uses, see Gear (disambiguation). ... For other uses, see Clutch (disambiguation). ... This article is about haptic technology. ...


Slip ring

The slip ring or wound rotor motor is an induction machine where the rotor comprises a set of coils that are terminated in slip rings to which external impedances can be connected. The stator is the same as is used with a standard squirrel cage motor. A slip ring (in electrical engineering terms) is a method of making an electrical connection through a rotating assembly. ...


By changing the impedance connected to the rotor circuit, the speed/current and speed/torque curves can be altered.


The slip ring motor is used primarily to start a high inertia load or a load that requires a very high starting torque across the full speed range. By correctly selecting the resistors used in the secondary resistance or slip ring starter, the motor is able to produce maximum torque at a relatively low current from zero speed to full speed. A secondary use of the slip ring motor is to provide a means of speed control. Because the torque curve of the motor is effectively modified by the resistance connected to the rotor circuit, the speed of the motor can be altered. Increasing the value of resistance on the rotor circuit will move the speed of maximum torque down. If the resistance connected to the rotor is increased beyond the point where the maximum torque occurs at zero speed, the torque will be further reduced.



When used with a load that has a torque curve that increases with speed, the motor will operate at the speed where the torque developed by the motor is equal to the load torque. Reducing the load will cause the motor to speed up, and increasing the load will cause the motor to slow down until the load and motor torque are equal. Operated in this manner, the slip losses are dissipated in the secondary resistors and can be very significant. The speed regulation is also very poor.


Stepper motors

Main article: Stepper motor

Closely related in design to three-phase AC synchronous motors are stepper motors, where an internal rotor containing permanent magnets or a large iron core with salient poles is controlled by a set of external magnets that are switched electronically. A stepper motor may also be thought of as a cross between a DC electric motor and a solenoid. As each coil is energized in turn, the rotor aligns itself with the magnetic field produced by the energized field winding. Unlike a synchronous motor, in its application, the motor may not rotate continuously; instead, it "steps" from one position to the next as field windings are energized and de-energized in sequence. Depending on the sequence, the rotor may turn forwards or backwards. Because of induction of the windings, power requirements, and temperature management some glue circuitry is necessary between digital controller and motor. ... Because of induction of the windings, power requirements, and temperature management some glue circuitry is necessary between digital controller and motor. ... For other uses, see Solenoid (disambiguation). ...


Simple stepper motor drivers entirely energize or entirely de-energize the field windings, leading the rotor to "cog" to a limited number of positions; more sophisticated drivers can proportionally control the power to the field windings, allowing the rotors to position between the cog points and thereby rotate extremely smoothly. Computer controlled stepper motors are one of the most versatile forms of positioning systems, particularly when part of a digital servo-controlled system. Cog is a term with several meanings: A part of a gear system cog (ship), a small sailing vessel A tenon that extends all the way through another piece of wood, in joinery Cynically Ochlocratic Governments The evil robots in Toontown Online The evil robot drones of the Machine Empire... Small R/C servo mechanism 1. ...


Stepper motors can be rotated to a specific angle with ease, and hence stepper motors are used in pre-gigabyte era computer disk drives, where the precision they offered was adequate for the correct positioning of the read/write head of a hard disk drive. As drive density increased, the precision limitations of stepper motors made them obsolete for hard drives, thus newer hard disk drives use read/write head control systems based on voice coils. A voice coil is the coil of wire attached to the apex of the moving cone of a loudspeaker. ...


Stepper motors were upscaled to be used in electric vehicles under the term SRM (switched reluctance machine).


Linear motors

Main article: Linear motor

A linear motor is essentially an electric motor that has been "unrolled" so that, instead of producing a torque (rotation), it produces a linear force along its length by setting up a traveling electromagnetic field. A linear motor is essentially a multi-phase alternating current (AC) electric motor that has had its stator unrolled so that instead of producing a torque (rotation) it produces a linear force along its length. ... A linear motor is essentially a multi-phase alternating current (AC) electric motor that has had its stator unrolled so that instead of producing a torque (rotation) it produces a linear force along its length. ... For other senses of this word, see torque (disambiguation). ...


Linear motors are most commonly induction motors or stepper motors. You can find a linear motor in a maglev (Transrapid) train, where the train "flies" over the ground, and in many roller-coasters where the rapid motion of the motorless railcar is controlled by the rail. Transrapid Shanghai Maglev Train stopping at terminus Longyang Road station Transrapid Shanghai Maglev Train Inside the Shanghai Transrapid maglev Inside the Shanghai Transrapid maglev VIP section Magnetic levitation transport, or maglev, is a form of transportation that suspends, guides and propels vehicles (especially trains) using electromagnetic force. ... Transrapid at the Emsland test facility Transrapid is a German monorail system using magnetic levitation. ...


Doubly-fed electric motor

Doubly-fed electric motors have two independent multiphase windings that actively participate in the energy conversion process with at least one of the winding sets electronically controlled for variable speed operation. Two is the most active multiphase winding sets possible without duplicating singly-fed or doubly-fed categories in the same package. As a result, doubly-fed electric motors are machines with an effective constant torque speed range that is twice synchronous speed for a given frequency of excitation. This is twice the constant torque speed range as singly-fed electric machines, which have only one active winding set. Doubly-fed electric machines (i. ... Singly-Fed Electric Machines (i. ...


A doubly-fed motor allows for a smaller electronic converter but the cost of the rotor winding and slip rings may offset the saving in the power electronics components. Difficulties with controlling speed near synchronous speed limit applications.[3]


Singly-fed electric motor

Singly-fed electric machines incorporate a single multiphase winding set that is connected to a power supply. Singly-fed electric machines may be either induction or synchronous. The active winding set can be electronically controlled. Induction machines develop starting torque at zero speed and can operate as standalone machines. Synchronous machines must have auxiliary means for startup, such as a starting induction squirrel-cage winding or an electronic controller. Singly-fed electric machines have an effective constant torque speed range up to synchronous speed for a given excitation frequency. Singly-Fed Electric Machines (i. ...


The induction (asynchronous) motors (i.e., squirrel cage rotor or wound rotor), synchronous motors (i.e., field-excited, permanent magnet or brushless DC motors, reluctance motors, etc.), which are discussed on the this page, are examples of singly-fed motors. By far, singly-fed motors are the predominantly installed type of motors.


Nanotube nanomotor

Main article: Nanomotor

Researchers at University of California, Berkeley, recently developed rotational bearings based upon multiwall carbon nanotubes. By attaching a gold plate (with dimensions of the order of 100nm) to the outer shell of a suspended multiwall carbon nanotube (like nested carbon cylinders), they are able to electrostatically rotate the outer shell relative to the inner core. These bearings are very robust; devices have been oscillated thousands of times with no indication of wear. These nanoelectromechanical systems (NEMS) are the next step in miniaturization that may find their way into commercial aspects in the future. A nanomotor is a molecular device capable of converting energy into movement and forces on the order of the pico-newtons. ... Sather Tower (the Campanile) looking out over the San Francisco Bay and Mount Tamalpais. ...


See also:

Molecular motors are biological nanomachines and are the essential agents of movement in living organisms. ... An electrostatic motor or capacitor motor is a type of electric motor based on the attraction and repulsion of electric charge. ...

Motor standards

The following are major design and manufacturing standards covering electric motors:

The International Electrotechnical Commission (IEC) is an international standards organization dealing with electrical, electronic and related technologies. ... This article is about the standards association NEMA. For other uses, see Nema. ...

See also

Electronics Portal
Energy Portal

Motor control: Image File history File links Nuvola_apps_ksim. ... Image File history File links Portal. ...

Components: A motor controller is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. ... Motor Soft Starter A motor soft starter (when in the context of AC electric motors) is an electronic device that reduces the torque in the power train of a motor. ... A direct on line starter is often abbreviated DOL starter and is a widely-used starting method of electric motors. ... Adjustable speed drive (ASD) is one of the most general terms applied to equipment used to control the speed of machinery. ... An electronic speed control or ESC is a device mounted onboard an electrically-powered R/C model in order to vary its drive motors speed, its direction and even to act as a dynamic brake in certain controllers. ... Small Variable Frequency Drive (VFD) A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. ... A thyristor drive is a motor and controller combination including the drive shaft,where AC supply current is regulated by a thyristor phase control to provide variable voltage to a DC motor. ... It has been suggested that this article or section be merged into Electric motor. ...

Scientists and engineers: A centrifugal switch is an electric switch that operates using the centrifugal force created from a rotating shaft, most commonly that of an electric motor or gasoline engine. ... Conventional continuous current flows from the battery. ... A slip ring (in electrical engineering terms) is a method of making an electrical connection through a rotating assembly. ...

Related subjects: Ottó Titusz Bláthy (1860-1939), was a Hungarian electrical engineer, co-inventor of the electric transformer, the tension regulator, the watt meter, the alternating current (AC) electric motor, the turbogenerator and high efficiency turbogenerator. ... Marconi Wireless Station in Somerset, New Jersey in 1921 Charles Proteus Steinmetz (April 9, 1865 – October 26, 1923) was an American mathematician and electrical engineer. ... Nikola Tesla (Nih koh la TESS lah) [2](Serbian Cyrillic: ) (10 July 1856 – 7 January 1943) was an inventor, physicist, mechanical and electrical engineer. ...

Electrical Engineers design power systems. ... Timeline of motor and engine technology 1698 - Thomas Savery builds a steam-powered water pump for pumping water out of mines 1712 - Thomas Newcomen builds a piston-and-cylinder steam-powered water pump for pumping water out of mines 1769 - James Watt patents his first improved steam engine 1816 - Robert... The power factor of an AC electric power system is defined as the ratio of the real power to the apparent power, and is a number between 0 and 1. ... A polyphase system is a means of distributing alternating current electrical power. ... Traction motor typically refers to those motors that are used to power the driving wheels of a railroad locomotive, electrical multi-unit train (such as a subway or light rail vehicle train), or a tram. ... Electric motors of various sizes. ... A synchronous electric motor is distinguished by its rotor spinning at the same rate as the oscillating field which drives it. ... An AC motor is an electric motor that is driven by an alternating current. ... Electric motors of various sizes. ... Image File history File links Download high resolution version (707x768, 49 KB) Summary Largest motor: 1 Hp (750 W) Next largest: 25 W Small motors: CD player motor, toy motor, CD drive head traverse motor Licensing I, the creator of this work, hereby grant the permission to copy, distribute and... Induction Motor (IM) is one kind of AC motor where power is supplied to the rotating device by induction. ... A brushed DC motor is a type of electric motor that, in contrast to a brushless DC motor, has two static electric contacts (brushes) that come in contact with different sections of a split disc (commutator) at different times, spinning the motor through electromagnets. ... A brushless DC motor (BLDC) is an AC synchronous electric motor that from a modeling perspective looks very similar to a DC motor. ... Because of induction of the windings, power requirements, and temperature management some glue circuitry is necessary between digital controller and motor. ... A linear motor is essentially a multi-phase alternating current (AC) electric motor that has had its stator unrolled so that instead of producing a torque (rotation) it produces a linear force along its length. ... There are very few or no other articles that link to this one. ... A reluctance motor is a type of synchronous electric motor which uses the phenomenon of reluctance to induce non-permanent magnetic poles on the rotor. ... A ball bearing motor is an unusual electric motor that is constructed as follows: Take a short hollow copper pipe and fit 2 ball bearings on either end. ... To meet Wikipedias quality standards, this article or section may require cleanup. ... 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. ... The electronic (gold-plated) contacts of an EF mount lens. ... An electrostatic motor or capacitor motor is a type of electric motor based on the attraction and repulsion of electric charge. ... A motor controller is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. ... Adjustable speed drive (ASD) is one of the most general terms applied to equipment used to control the speed of machinery. ... Generally, an amplifier is any device that uses a small amount of energy to control a larger amount of energy. ... Direct torque control is one method used in variable frequency drives to control the torque (and thus finally the speed) of the three-phase AC electric motors. ... A direct on line starter is often abbreviated DOL starter and is a widely-used starting method of electric motors. ... An electronic speed control or ESC is a device mounted onboard an electrically-powered R/C model in order to vary its drive motors speed, its direction and even to act as a dynamic brake in certain controllers. ... A motor controller is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. ... Small Variable Frequency Drive (VFD) A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. ... Barlows Wheel is the name given to an early demonstration of an electric motor, designed and built by English mathematician and physicist, Peter Barlow in 1822. ... A nanomotor is a molecular device capable of converting energy into movement and forces on the order of the pico-newtons. ... Traction motor typically refers to those motors that are used to power the driving wheels of a railroad locomotive, electrical multi-unit train (such as a subway or light rail vehicle train), or a tram. ... The Lynch Motor is a unique axial gap permanent magnet brushed DC motor invented by Cedric Lynch, U.S. patent 4823039. ... The Mendocino motor is a solar powered magnetically levitated motor. ... A Repulsion motor is a type of electric motor for use on alternating current. ... The inchworm motor is a device using piezoelectric actuators to move a shaft with nanometer precision. ... A Booster was a motor-generator (MG) set used for voltage regulation in direct current (DC) electrical power circuits. ... A pair of carbon brushes In electrical engineering, brushes conduct current between stationary wires and moving parts, most commonly in a rotating shaft. ...

References and further reading

Citations
  1. ^ [1][dead link]
  2. ^ "Tesla's Early Years". PBS.
  3. ^ Cyril W. Lander, Power Electronics 3rd Edition, Mc Graw Hill International UK Limited, London 1993 ISBN 0-07-707714-8 Chapter 9-8 Slip Ring Induction Motor Control
General references
  • Donald G. Fink and H. Wayne Beaty, Standard Handbook for Electrical Engineers, Eleventh Edition, McGraw-Hill, New York, 1978, ISBN 0-07-020974-X.
  • Edwin J. Houston and Arthur Kennelly, Recent Types of Dynamo-Electric Machinery, copyright American Technical Book Company 1897, published by P.F. Collier and Sons New York, 1902
  • Kuphaldt, Tony R. (2000-2006). "Chapter 13 AC MOTORS", Lessons In Electric Circuits — Volume II. Retrieved on 2006-04-11. 
  • A.O.Smith: The AC's and DC's of Electric Motors. Retrieved on 2006-04-11.
  • Resenblat & Frienman DC and AC machinery
Further reading
  • Shanefield D. J., Industrial Electronics for Engineers, Chemists, and Technicians, William Andrew Publishing, Norwich, NY, 2001. A self-teaching textbook that briefly covers electric motors, transformers, speed controllers, wiring codes and grounding, transistors, digital, etc. Easy to read and understand, up to an elementary level on each subject, not a suitable reference book for technologists already working in any of those fields.
  • Fitzgerald/Kingsley/Kusko (Fitzgerald/Kingsley/Umans in later years), *Electric Machinery, classic text for junior and senior electrical engineering students. Originally published in 1952, 6th edition published in 2002. Authors still listed as Fitzgerald/Kingsley/Umans although Fitzgerald and Kingsley are now deceased.
  • Bedford, B. D.; Hoft, R. G. et al (1964). Principles of Inverter Circuits. New York: John Wiley & Sons, Inc.. 0 471 06134 4.  (Inverter circuits are used for variable-frequency motor speed control)
  • B. R. Pelly, "Thyristor Phase-Controlled Converters and Cycloconverters: Operation, Control, and Performance" (New York: John Wiley, 1971).
  • John N. Chiasson, Modeling and High Performance Control of Electric Machines, Wiley-IEEE Press, New York, 2005, ISBN 0-471-68449-X.

Not to be confused with Public Broadcasting Services in Malta. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 101st day of the year (102nd in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 101st day of the year (102nd in leap years) in the Gregorian calendar. ... Assorted discrete transistors A transistor is a semiconductor device, commonly used as an amplifier or an electrically controlled switch. ... Small Variable Frequency Drive (VFD) A variable-frequency drive (VFD) is a system for controlling the rotational speed of an alternating current (AC) electric motor by controlling the frequency of the electrical power supplied to the motor. ...

External links

HowStuffWorks is a website created by Marshall Brain but now owned by the Convex Group. ...

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Electric motors are used in many applications and many industries instead of fuel engines because they are cleaner and less expensive to run.
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The modern DC motor was invented by accident in 1873, when Zénobe Gramme connected a spinning dynamo to a second similar unit, driving it as a motor.
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