An electric motor is an electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a wire winding to generate force in the form of torque applied on the motor's shaft. An electric generator is mechanically identical to an electric motor, but operates in reverse, converting mechanical energy into electrical energy.
In electricity generation, a generator is a device that converts motion-based power or fuel-based power into electric power for use in an external circuit. Sources of mechanical energy include steam turbines, gas turbines, water turbines, internal combustion engines, wind turbines and even hand cranks. The first electromagnetic generator, the Faraday disk, was invented in 1831 by British scientist Michael Faraday. Generators provide nearly all the power for electrical grids.
An induction motor or asynchronous motor is an AC electric motor in which the electric current in the rotor that produces torque is obtained by electromagnetic induction from the magnetic field of the stator winding. An induction motor therefore needs no electrical connections to the rotor. An induction motor's rotor can be either wound type or squirrel-cage type.
A rotating magnetic field is the resultant magnetic field produced by a system of coils symmetrically placed and supplied with polyphase currents. A rotating magnetic field can be produced by a poly-phase current or by a single phase current provided that, in the latter case, two field windings are supplied and are so designed that the two resulting magnetic fields generated thereby are out of phase.
A synchronous electric motor is an AC electric 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 integer number of AC cycles. Synchronous motors use electromagnets as the stator of the motor which create a magnetic field that rotates in time with the oscillations of the current. The rotor with permanent magnets or electromagnets turns in step with the stator field at the same rate and as a result, provides the second synchronized rotating magnet field. A synchronous motor is termed doubly fed if it is supplied with independently excited multiphase AC electromagnets on both the rotor and stator.
A magnetic bearing is a type of bearing that supports a load using magnetic levitation. Magnetic bearings support moving parts without physical contact. For instance, they are able to levitate a rotating shaft and permit relative motion with very low friction and no mechanical wear. Magnetic bearings support the highest speeds of any kind of bearing and have no maximum relative speed.
An ultrasonic motor is a type of piezoelectric 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. Ultrasonic motors differ from other piezoelectric motors in several ways, though both typically use some form of piezoelectric material, most often lead zirconate titanate and occasionally lithium niobate or other single-crystal materials. The most obvious difference is the use of resonance to amplify the vibration of the stator in contact with the rotor in ultrasonic motors. Ultrasonic motors also offer arbitrarily large rotation or sliding distances, while piezoelectric actuators are limited by the static strain that may be induced in the piezoelectric element.
Direct torque control (DTC) is one method used in variable-frequency drives to control the torque of three-phase AC electric motors. This involves calculating an estimate of the motor's magnetic flux and torque based on the measured voltage and current of the motor.
Doubly fed electric machines, also slip-ring generators, are electric motors or electric generators, where both the field magnet windings and armature windings are separately connected to equipment outside the machine.
A dynamo is an electrical generator that creates direct current using a commutator. Dynamos were the first electrical generators capable of delivering power for industry, and the foundation upon which many other later electric-power conversion devices were based, including the electric motor, the alternating-current alternator, and the rotary converter.
In electrical engineering, electric machine is a general term for machines using electromagnetic forces, such as electric motors, electric generators, and others. They are electromechanical energy converters: an electric motor converts electricity to mechanical power while an electric generator converts mechanical power to electricity. The moving parts in a machine can be rotating or linear. While transformers are occasionally called "static electric machines", since they do not have moving parts, generally they are not considered "machines", but as electrical devices "closely related" to the electrical machines.
In electromagnetism, excitation is the process of generating a magnetic field by means of an electric current.
Motor-CAD is an Electromagnetic and Thermal analysis package for electric motors and generators, developed and sold by Motor Design Ltd. It was initially released in 1999.
A magnet motor or magnetic motor is a type of perpetual motion machine, which is intended to generate a rotation by means of permanent magnets in stator and rotor without external energy supply. Such a motor is theoretically as well as practically not realizable. The idea of functioning magnetic motors has been promoted by various hobbyists. It can be regarded as pseudoscience. There are frequent references to free energy and sometimes even links to esotericism.
A magnetic gear resembles the traditional mechanical gear in geometry and function, using magnets instead of teeth. As two opposing magnets approach each other, they repel; when placed on two rings the magnets will act like teeth. As opposed to conventional hard contact backlash in a spur gear, where a gear may rotate freely until in contact with the next gear, the magnetic gear has a springy backlash. As a result magnetic gears are able to apply pressure no matter the relative angle. Although they provide a motion ratio as a traditional gear, such gears work without touching and are immune to wear of mating surfaces, have no noise, and may slip without damage.
A permanent magnet motor is a type of electric motor that uses permanent magnets for the field excitation and a wound armature. The permanent magnets can either be stationary or rotating; interior or exterior to the armature for a radial flux machine or layered with the armature for an axial flux topology. The schematic shows a permanent magnet motor with stationary magnets outside of a brushed armature.
Electromagnetically induced acoustic noise, electromagnetically excited acoustic noise, or more commonly known as coil whine, is audible sound directly produced by materials vibrating under the excitation of electromagnetic forces. Some examples of this noise include the mains hum, hum of transformers, the whine of some rotating electric machines, or the buzz of fluorescent lamps. The hissing of high voltage transmission lines is due to corona discharge, not magnetism.
Md. Azizur (Aziz) Rahman was a Bangladeshi born Canadian inventor of modern energy-efficient electric motors that span multiple industry applications. He was an electrical engineer, professor, researcher and scientist. He is internationally recognized as one of the founding innovators of modern power engineering and a pioneer in the development and application of interior permanent magnet motors and associated drive technology-used in the world's first mass-produced hybrid vehicle, the Toyota Prius. Since launching the Prius in 1997, Toyota surpassed global sales of 15 million hybrid vehicles in 2020, all of which use Dr. Rahman's IPM motor drive. His research contributions were broad and adopted in a wide range of electric motor applications ranging from vacuum cleaners, air conditioners, elevators to aircraft.
An axial flux motor is a geometry of electric motor construction where the gap between the rotor and stator, and therefore the direction of magnetic flux between the two, is aligned parallel with the axis of rotation, rather than radially as with the concentric cylindrical geometry of the more common radial flux motor. With axial flux geometry torque increases with the cube of the rotor diameter, whereas in a radial flux the increase is only quadratic. Axial flux motors have a larger magnetic surface and overall surface area than radial flux motors for a given volume.
Switched reluctance linear motors (SRLMs) are a type of electric machines called linear motors which work based on the principle of a varying magnetic reluctance for force generation. The system can be used in reversed mode and then is called Switched Reluctance Linear Generator. The SRLMs consist of two parts: the active part or primary part and the passive or secondary. The active part contains the windings and defines two main types of LSRMs: transverse and longitudinal. It is longitudinal when the plane that contains the flux lines is parallel to the line of movement and transverse when it is perpendicular. Other classifications are considering the windings totally concentrated in one coil per phase or partially concentrated in two poles per phase or four poles per phase (double-sided). Switched Reluctance motors have been used extensively in clocks and phonograph turntables before, but nowadays, with the rising emphasis on energy efficiency, SR motors are taking more prominent roles in appliances, industrial uses, and commercial and vehicular applications and they are getting traction in the linear applications due to their simplicity, robustness, economic rationality, and high fault tolerance ability as compared with the Linear Synchronous and Linear Induction motors. The SRLM has been researched widely and there are applications of SRLMs and generators for example in wave energy conversion or hyperloop ultra high speed transportation system. One of the main advantages of the SRLM is that it does not require the use of permanent magnets, which are considered a scarce material, so it enables it to be deployed over long distances.
