Motor AC is an electric motor driven by alternating current (AC). The AC motor generally consists of two base parts, an outer stator which has a coil supplied with alternating current to produce a rotating magnetic field, and an inner rotor attached to an output shaft that produces a second rotating magnetic field. The rotor magnetic field can be produced by permanent magnets, reluctant reluctance, or DC or AC power reels.
Less commonly, linear AC motors operate on the same principle as rotating motors but have stationary parts and their moves are arranged in a straight line configuration, resulting in linear motion rather than rotation.
Video AC motor
Principle of operation
The two main types of AC motors are induction motors and synchronous motors. The induction motor (or asynchronous motor) always depends on a small difference in velocity between the stator rotating magnetic field and the speed of the rotor axis called the slip to induce the rotor current in the winding AC rotor. As a result, induction motors can not produce near-sync speed of torque where induction (or slip) is irrelevant or does not exist anymore. In contrast, synchronous motors do not depend on induction-slip for operation and use permanent magnets, protruding poles (having a projected magnetic pole), or self-rotor winding windings. The synchronous motor produces its rated torque at exactly the same sync speed. The brushless wound-rotor two-feed synchronous motor system has a spirited independent rotor winding that does not rely on the current slip-induction principle. The brushless wound-rotor motor fed twice is a synchronous motor that can function right at the supply or sub frequencies for some super-frequency supply.
Other motor types include eddy current motors, and AC and DC mechanically mutated machines where speed depends on voltage and winding connection.
Maps AC motor
History
Alternating technology is now rooted in the invention of Michael Faraday and Joseph Henry in 1830-31 that the changing magnetic field can induce electrical currents in the circuit. Faraday is usually awarded for this discovery since he published his findings first.
In 1832, French instrument maker Hippolyte Pixii produced a rough form of alternating current when he designed and built the first alternator. It consists of a horseshoe magnet spinning through two wound wound rolls.
Due to the advantages of air conditioning in high-voltage long-distance transmission, there were many inventors in the United States and Europe at the end of the 19th century who tried to develop workable AC motors. The first person to imagine a rotating magnetic field was Walter Baily, who provided a workable demonstration of a battery-operated polyphase motor assisted by the commutator on 28 June 1879, to the Physical Society of London. Describing an almost identical tool to Baily, the French electrical engineer Marcel Deprez published a paper in 1880 that identified the principle of a rotating magnetic field and that of a two phase phase AC system to produce it. Practically never shown, the design is flawed, because one of the two currents is "equipped by the machine itself." In 1886, the English engineer Elihu Thomson built an AC motor by extending the principle of induction-repulsion and its wattmeter. In 1887, American inventor Charles Schenk Bradley was the first to patent a two-phase AC power transmission with four cables.
The direct current motors "without the commutator" appear to have been independently created by Galileo Ferraris and Nikola Tesla. Ferraris demonstrated the working model of a single-phase induction motor in 1885, and Tesla built his two-phase induction motor in 1887 and demonstrated it at the American Institute of Electrical Engineers in 1888 (though Tesla claimed he contained a rotating magnetic field in 1882). In 1888 Ferraris published his research to the Royal Academy of Sciences in Turin, where he detailed the basics of motor operation; Tesla, in the same year, was granted a US patent for his own motorcycle. Working from the Ferraris experiment, Mikhail Dolivo-Dobrovolsky introduced the first three-phase induction motor in 1890, a much more capable design that became the prototype used in Europe and the US He also invented the first three-phase generator and transformer and incorporated it into a complete three-phase AC system first in 1891. Three-phase motor design was also undertaken by Swiss engineer Charles Eugene Lancelot Brown, and another three-phase AC system developed by German engineer Friedrich August Haselwander and Swedish engineer Jonas WenstrÃÆ' ¶m.
Induction motor
Slip
If the squirrel cage motor rotor is run at the correct synchronous speed, the flux in the rotor at a particular spot on the rotor will not change, and no current will be made in the squirrel cage. For this reason, ordinary cage motors run at a few tens of times less RPM than synchronous speed. Since the rotating plane (or equivalent pulsed field) effectively rotates faster than the rotor, it can be said to slip through the rotor surface. The difference between sync speed and actual speed is called slip , and motor loading increases the number of slips as the motor slows down slightly. Even without load, internal mechanical losses prevent slippage from being zero.
Kecepatan motor AC ditentukan terutama oleh frekuensi pasokan AC dan jumlah kutub dalam gulungan stator, sesuai dengan relasinya:
Where
- F = frequency of AC power
- p = Number of poles per winding phase
The actual RPM for the induction motor will be smaller than this calculated sync speed with the amount known as slip , which increases with the resulting torque. Without the load, the speed will be very close to the sync. When loaded, the standard motor has a slip of between 2-3%, a special motor may have a slip of up to 7%, and a motor class known as torque motors is rated to operate on 100% slip (0 RPM)./full kiosk).
Slip motor AC dihitung oleh:
Where
- S = Slip Normalized, 0 to 1.
For example, a typical four-pole motor running at 60 Hz may have a nameplate rating of 1725 RPM at full load, while the calculated speed is 1800 RPM. Speeds on this type of motor have traditionally been altered by having an additional set of coils or poles on a motor that can be switched on and off to change the magnetic field rotation speed. However, developments in power electronics mean that the frequency of the power supply may also vary to provide smoother control over motor speed.
This type of rotor is the basic hardware for the induction regulator, which is the exception of the use of a rotating magnetic field as a pure (not electromechanical) electrical application.
Rotor enclosure polyphase
Most common AC motors use squirrel-cage rotors, which will be found in almost all domestic and light industrial current motors. The squirrels refer to a spinning practice cage for pets. The motor takes its name from its rotor "roll" shape - a ring at both ends of the rotor, with a rod connecting a ring that runs the length of the rotor. These are usually cast or copper aluminum which is poured in between the rotor iron laminates, and usually only the final rings will be visible. Most of the rotor currents will flow through the bars rather than the higher-the laminate resistance and lamination are usually varnished. Very low voltages at very high currents are typical in bars and end rings; High efficiency motors will often use cast copper to reduce resistance in the rotor.
In operation, the squirrel-cage motor can be seen as a transformer with a secondary spin. When the rotor does not rotate in sync with the magnetic field, a large rotor current is induced; large rotor currents move the rotor and interact with the stator magnetic field to bring the rotor almost into synchronization with the stator field. Non-loaded cage motors at no-load speed will consume electrical power only to maintain the rotor speed against friction and loss of resistance. As the mechanical load increases, the electrical load - the electrical load is inherently associated with the mechanical load. This is similar to a transformer, where the primary electrical load is related to secondary electrical loads.
This is why motor blower cage-squirrels can cause the home light to dim at start, but do not dim the lights at startup when its belt fan (and therefore mechanical load) is removed. Furthermore, motor cages that are jammed (overloaded or with a jammed axle) will consume a current that is limited only by the resistance of the circuit when it tries to start. Unless something else limits the flow (or cuts completely) overheating and destruction of the winding insulation is a possible outcome.
Almost every washing machine, dishwasher, stand-alone fan, record player, etc. Using several variants of squirrel-cage motors.
Polyphase wound rotor
An alternative design, called a wound rotor, is used when variable velocity is required. In this case, the rotor has the same number of poles as the stator and the roll is made of wire, connected to the slip ring on the shaft. Carbon brushes connect a slip ring to a controller such as a variable resistor that allows changing the slip rate of the motor. At high speed rotation of the rotor at a certain speed, the slip-frequency energy is captured, repaired, and returned to the power supply through the inverter. With a two-way controlled power, the wound rotor becomes an active participant in the energy conversion process, with a doubled wound rotor configured to show twice the power density.
Compared to squirrel cage rotor, motor rotor wounds are expensive and require the maintenance of slip rings and brushes, but they are the standard form for variable speed control before the advent of compact power electronic devices. Transistor inverters with variable-frequency drives can now be used for speed control, and wound motor rotor becomes less common.
Several methods for starting a polyphase motor are used. Where a large inrush and high initial torque can be allowed, the motor can start across the line, by applying a full line voltage to the terminal (direct-on-line, DOL). Where it is necessary to limit the initial inrush (where large motors are compared to short supply circuit capacities), the motor starts at a reduced voltage using a series inductor, autotransformer, thyristor, or other device. The technique that is sometimes used is the star-delta (Y?) Starts, where the motor coil is initially connected in the star configuration for the load acceleration, then switches to the delta configuration when the load goes up to speed. This technique is more common in Europe than in North America. Drives that are triggered by a transistor can directly vary the applied voltage according to the motor's initial characteristics and load.
This type of motor is becoming more common in traction applications such as locomotives, where it is known as an asynchronous traction motor.
Two-phase servo motor
The common two-phase AC servo motor has a squirrel cage rotor and a field consisting of two loops:
- the main coil of constant voltage (AC).
- a voltage regulator (AC) in quadrature (ie, 90 degrees of phase shift) with the main winding resulting in a rotating magnetic field. Reversal phase makes the motor backward.
An AC servo amplifier, a linear power amplifier, feeds the control coil. The electrical resistance of the rotor is made high intentionally so that the torque-speed curve is quite linear. Two-phase, high-speed in-phase servo motor, low torque device, is geared to push the load.
Single-phase induction motors
Single-phase motors do not have unique rotating magnetic fields such as multi-phase motors. The field alternates (reverses the polarity) between the polar pairs and can be seen as two rotating fields in the opposite direction. They require a secondary magnetic field that causes the rotor to move in a certain direction. Upon starting, the alternating stator field is in relative rotation with the rotor. Some commonly used methods:
Motor shaded-pole
The common single-phase motor is a shaded motor and is used in devices that require low initial torque, such as electric fans, small pumps, or small household appliances. In this bike, a small single-turn copper "shading" creates a moving magnetic field. Part of each pole is encircled by a copper coil or rope; the induced current in the rope opposes the flux change through the coil. This causes a time lag in the flux passing through the shading coil, so that the maximum field intensity moves higher across the polar surface at each cycle. This produces a low-level rotating magnetic field large enough to change both the rotor and the load. When the rotor picks up speed, the torque accumulates to the full extent because the main magnetic field rotates relative to the rotating rotor.
A reversible shaded-pole motor was made by Barber-Colman decades ago. It has a single field coil, and two main poles, each split half way to create two pole pairs. Each of these four "half poles" carries a coil, and the diagonal semicircular coils are connected to a pair of terminals. One terminal of each pair is common, so only three terminals are needed.
The motor will not start with the terminal open; connecting the common to the other makes the motor go one way, and connecting the common with others makes it run the other way. These motors are used in industrial and scientific devices.
An unusual, high-speed, high-speed motor can be found in traffic light controllers and ad lighting. Polar faces are parallel and relatively close to each other, with discs centered between them, something like a disk in a watthour meter. Each pole of his face is split, and has a shading coil on one part; the shading coil is in the opposite sections. Both rolls of shading may be closer to the main roll; they can go much further, without affecting the principle of operation, just the direction of rotation.
Applying AC to coil creates a growing field in the gap between the poles. The stator core field is approximately tangential to the imaginary circle on the disk, so that the magnetic field around it drags the disk and makes it rotate.
The stator is mounted on the pivot so it can be positioned for the desired speed and then clamped in position. Given that the effective velocity of the perimeter magnetic field in the gap is constant, placing the poles closer to the center of the disc makes it run relatively faster, and to the edge, more slowly.
It is possible that this motor is still used in some older installations.
Motor phase-phase
Another common single-phase AC motor is a split-phase induction motor , commonly used in key appliances such as air conditioning and clothes dryers. Compared to the shaded pole motor, this bike gives a much larger initial torque.
The split-phase motor has a secondary startup bend that is 90 degrees of power to the main winding, always centered directly between the main reel pole, and connected to the main winding with a set of electrical contacts. This winding roll is wrapped with fewer wire loops smaller than the main coil, thus having lower inductance and higher resistance. The position of the entanglement creates a small phase shift between the flux of the main winding and the flux from the initial winding, causing the rotor to rotate. When motor speed is sufficient to overcome load inertia, contacts are opened automatically by centrifugal switch or electric relay. The direction of rotation is determined by the connection between the main winding and the starting circuit. In applications where motors require a fixed rotation, one end of the initial circuit is permanently connected to the main winding, with the contact making the connection at the other end.
Motor start capacitor
A start-capacitor motor is a split-phase induction motor with an initial capacitor inserted in series with the startup winding, creating an LC circuit that produces a larger phase shift (and thus a much larger initial torque) than the split phase and polar motor shadow.
Resistance starts motor
The starting motor of resistance is a split-phase induction motor with a starter inserted in series with the startup winding, resulting in reactance. This extra starter provides help in the early and early rotation directions. The initial scrolls are made mainly of thin wires with fewer turns to make them resistive and less inductive. the main coil is made with thick wire with larger number of rounds which makes it less resistive and more inductive.
Permanent separator capacitor motor
Another variation is the motor the permanent separator (or PSC) . Also known as capacitor driven motors, these motors use non-polarized capacitors with high voltage ratings to generate electrical phase shifts between the run and start windings. PSC motors are the dominant type of split-phase motors in Europe and most of the world, but in North America, they are most commonly used in variable torque applications (such as blowers, fans, and pumps) and other cases where variable velocity is desired.
The capacitor with relatively low capacitance, and a relatively high voltage rating, is connected in series with the start winding and stays on the circuit for the entire cycle. Like other split-phase motors, the primary winding is used with smaller initial winding, and the rotation is changed by reversing the connection between the main winding and the starting circuit, or by having the primary winding polarity activated when the winding starts always connected to a capacitor. But there are significant differences; the use of speed sensitive centrifugal switches requires that other phase-split motors must operate at, or very close to, full speed. PSC motors can operate at various speeds, much lower than the electric speed of the motor. Also, for applications such as automatic door openers that require motors to reverse rotation frequently, the use of mechanisms requires that the motor must be slow to stop close before contact with the initial winding rebuilt. The 'permanent' connection to the capacitor in the PSC motor means that the rotational change is instantaneous.
Three phase motors can be converted to PSC motors by making two common windings and connecting the third through a capacitor to act as a winding start. However, the power rating must be at least 50% greater than for a single phase motor that is comparable because of unused rolls.
Sync motor
Sync Polyphase Motor
If the connection to the three-phase motor rotor coil is taken on the slip-rings and given a separate field current to create a continuous magnetic field (or if the rotor consists of a permanent magnet), the result is called a synchronous motor because the rotor will rotate simultaneously with the rotating magnetic field generated by polyphase power supply. Another synchronous motor system is a brushless wound-rotor that is fed twice as a synchronous motor system with an AC multi-phase rotor winding that can independently experience slip induction beyond synchronous speed but like all synchronous motors, independent of induction-slip for torsion production.
Synchronous motors can also be used as alternators.
Currently, synchronous motors are often driven by variable frequency drives transistorized. This greatly facilitates the problem of starting large rotor of large synchronous motors. They can also be started as induction motors using coils of squirrels that share a common rotor: once the motor reaches synchronous speed, no currents are induced in the crane windings so that it has little effect on the sync operation of the motor. In addition to stabilizing the motor speed on the change load.
Synchronous motors are sometimes used as traction motors; TGV is perhaps the most famous example of such use.
A large number of three phase synchronous motors are now installed in electric cars. They have Nd or other rare permanent magnets.
One use for this type of motor is its use in power factor correction schemes. They are referred to as synchronous condensers. It utilizes a feature engine in which it consumes power on a leading power factor when its rotor is overzealous. So the supply seems to be a capacitor, and thus can be used to improve the lagging power factor that is normally presented to the power supply by the inductive load. Excitation is adjusted until a close unity strength factor is obtained (often automatically). Machines used for this purpose are easy to identify because they do not have a shaft extension. Synchronous motors are appreciated in any case because the power factor is much better than the induction motor, making it more preferred for very high power applications.
Some of the largest AC motors are pumped hydroelectric generators that operate as synchronous motors to pump water into reservoirs at higher altitudes for later use to generate electricity using the same machine. Six 500-megawatt generators are installed at Bath County Pumped Storage Station in Virginia, USA. When pumping, each unit can generate 642,800 horsepower (479.3 megawatts). .
Single phase sync motor
Small single phase AC motors can also be designed with magnetic rotor (or some variation on the idea; see "Hysteresis synchronous motors" below).
If the conventional squirrel rotor has a foundation on it to create a protruding pole and increase reluctance, it will start conventionally, but will run simultaneously, though it can only provide simple torque at synchronous speed. This is known as the aversion motor.
Because inertia makes it difficult to quickly accelerate the rotor from stop to synchronous speed, these motors usually require some sort of special feature to start. Some include a squirrel-cage structure to bring the rotor closer to synchronous speed. Various other designs use small induction motors (which can share coils and rotor fields similar to synchronous motors) or very light rotor with one-way mechanisms (to ensure that the rotor starts in the "forward" direction). In the last example, applying AC power creates a chaotic (or seemingly chaotic) jumping motion back and forth; Such motors will always start, but have no anti-reversal mechanism, the direction it runs is unpredictable. Hammond's organ tone generator uses a non-self-starting sync motor (up until relatively recently), and has an additional conventional shaded starter motor. A manual start switch of spring auxiliary connects power to this second motor for a few seconds.
Hysteresis synchronous motor
These motors are relatively expensive, and are used where the correct speed (assuming a precise-frequency AC source) as well as a very small number of rotations of rapid variations in speed (called "flutter" in audio recordings) are essential. Applications include a roller recorder recorder drive (motor shaft can be a roller), and, before the advent of crystal controls, film cameras and recorders. Their distinguishing feature is their rotor, which is a fine cylinder of magnetic alloys that remain magnetized, but can suffer magnetic damage easily and re-magnetize with the poles at new locations. Hysteresis refers to how the magnetic flux in the metal lags behind the external magnetization forces; for example, to underestimate such a material, one may apply a polarity magnetization field opposite to the originally dazzling material. These motors have a stator such as an induction motor capacitor-run cage. At startup, when the slip is decreased enough, the rotor becomes magnetized by the stator field, and the poles remain in place. The motor then runs at a synchronous speed as if the rotor is a permanent magnet. When stopped and restarted, the poles tend to form in different locations. For a given design, the torque at synchronous speed is only relatively simple, and the motor can run under synchronous speed. In simple words, it is a magnetic field that lags behind the magnetic flux.
Other types of AC motors
Universal motor and series coil motor
The universal motor is a design that can operate on AC or DC power. In the universal motor the stator and rotor of the brushed DC motor are both split and supplied from an external source, with torque being the function of the rotor current multiplied by the stator current so as to reverse the current on the rotor and the stator does not reverse the rotation.. The universal motor can run on the AC and also the DC provides a not so high frequency so that the inductive reactance of the stator winding and eddy current loss becomes a problem. Almost all universal motors are series-wounded because their stators have relatively few turns, minimizing inductance. The compact universal motor, has high starting torque and can vary in wider speeds with relatively simple controls such as rheostats and PWM choppers. Compared to induction motors, universal motors do have some disadvantages attached to the brush and the commutator: relatively high levels of electrical and acoustic noise, low reliability, and more frequent maintenance.
Universal motors are widely used in small home appliances and hand power tools. Until the 1970s they dominated electric traction (electricity, including electric trains and highway vehicles); many traction electric networks still use special low frequencies such as 16.7 and 25 Hz to overcome such problems with losses and reactance. Still widely used, universal traction motors have been increasingly displaced by induction of polyphase air conditioners and permanent magnet motors with variable-frequency drives made possible by modern power semiconductor devices.
Motor drive
Motor repulse is a single phase phase-phase AC motor that is a type of induction motor. In repulsive motors, the armature brush is shortened together rather than connected in series with the field, as is done with a universal motor. With the action of the transformer, the stator induces the current in the rotor, which creates torque by repulsion rather than attraction as in other motors. Several types of repulsive motors have been produced, but motor start-repulsion-induction-run (RS-IR) has been most commonly used. The RS-IR motor has a centrifugal switch that cuts off all commutator segments so that the motor operates as an induction motor after approaching full speed. Some of these motors also lift the brush from contact with source voltage regulation. Motor repulse was developed before suitable starting motor capacitors were available, and some repulsion motors were sold in 2005.
Exterior rotor
Where speed stability is important, some AC motors (such as some Papst motors) have an inner stator and an outer rotor to optimize inertia and cooling.
Motor rotor sliding
A conical rotor brake motor incorporates the brake as an integral part of the conical slide rotor. When the motor is idle, the springs work on the sliding rotor and force the brake ring to adhere to the brake lid on the motor, holding the stationary rotor. When the motor is energized, its magnetic field produces axial and radial components. Axial components overcome the spring force, release the brakes; while the radial component causes the rotor to rotate. No additional brake control is required.
The high initial torque and low inertia of conical rotor brake motors have proven ideal for demanding high dynamic drive cycles in applications since motors were invented, designed and introduced more than 50 years ago. This type of motor configuration was first introduced in the United States in 1963.
Single-speed or two speed motors are designed to clutch into the gear motor gearbox system. The brake motor of the conical rotor is also used to drive the micro-speed drive.
This type of motor can also be found on cranes and overhead hoists. The micro-speed unit incorporates two motors and an intermediate gear reducer. This is used for applications where extreme mechanical positioning accuracy and high cycling capabilities are required. The micro-speed unit incorporates a "main" rotor brake motor for fast speed and "micro" conical rotor motor rotors for slow speed or positioning. The intermediate gearbox allows various ratios, and motors of different speeds can be combined to produce high ratios between high and low speeds.
Motor changed electronically
The electronically modified motor (EC) is an electric motor driven by a direct electric current (DC) and has an electronic replacement system, not a commutator and a mechanical brush. The current-to-torque and frequency-to-speed relationship of the BLDC motor is linear. While the motor coil is turned on by DC, the power can be rectified from the AC inside the casing.
Motor Watthour-meter
It is a two-phase induction motor with a permanent magnet to slow the rotor so that its speed is accurately proportional to the power passing through the meter. The rotor is an aluminum-alloy disc, and the induced currents therein react with the field of the stator.
A split meter watthour phase has a stator with three windings facing the disc. The magnetic circuit is equipped by a C-shaped core of transparent iron. The "tension" coil on the disk parallel with the supply; many bends have a high inductance/resistance ratio (Q) so that the magnetic field and current are the integral time of the applied voltage, which passes by 90 degrees. This magnetic field passes perpendicularly through the disk, pushing a circular eddy current in the field of disks centered in the field. The induced current is proportional to the time derivative of the magnetic field, guiding it to 90 degrees. This places the eddy current in phase with the applied voltage to the voltage coil, as the current induced on the secondary of the transformer with the resistive load is in phase with the applied voltage at its primer.
The eddy current passes just above the polar pieces of the two "current" coils under the disc, each wound with multiple rotations of the weight gauge whose inductive reactance is small compared to the load impedance. This coil connects the supply to the load, generating the magnetic field in phase with the load current. This field passes through the poles of one coil of the current perpendicular through the disk and back down through the disk to the other coil poles, with the magnetic circuit finished back to the first current coil. As these planes cross the disk, they pass through the eddy current induced in it by the voltage coils that produce Lorentz forces on the discs perpendicular to both. Assuming the power flows to the load, the flux from the left current coil crosses the disk upward where the eddy current flows radially toward the disk-producing center (by right hand rule) the torque that moves the front of the disk to the right. Similarly, the flux crosses through the disk to the right current coil where the eddy current flows radially away from the center of the disk, again producing a torque that moves the front of the disc to the right. When the AC polarity reverses, the eddy current in the disk and the direction of the magnetic flux of the current coil change, leaving the direction of the torque unchanged.
Such a torque is proportional to the instantaneous time line voltage of the instantaneous load, automatically correcting the power factor. The disc is braked with a permanent magnet so that the speed is proportional to the torque and the dish mechanically integrates the real power. The mechanical dial on the meter reads the rotation of the dish and the total net energy delivered to the load. (If the load supplies power to the grid, the disk rotates backward unless it is prevented by ratchet, thus enabling cleaner measurements.)
In the split phase watthour meter, the voltage coil is connected between two "hot" terminals (240V in North America) and two separate current coils connected between the corresponding line and the load terminal. No connection to a neutral system is required to properly handle line-to-neutral and line-to-line loads. Line-to-line takes the same current through the current coil and rotates the meter two times faster than the line-to-neutral charge drawing the same current only through a single current coil, correctly registering the power drawn by the line-to-load lines as doubled from line-to-neutral loads.
Other variations of the same design are used for polyphase strength (eg, three phases).
Motor low-speed sync timing
Representation is a low torque synchronous motor with a multi-polar hollow cylindrical magnet (internal pole) that surrounds the stator structure. The aluminum cup supports magnets. The stator has one coil, coaxial with a shaft. At each end of the coil are a pair of round plates with rectangular teeth at the edges, formed so that they are parallel to the shaft. They are stator poles. One of a pair of discs directly distributes the coil flux, while the other receives the flux that has passed through the general shading coil. The poles are rather narrow, and between the poles that point from one end of the coil is an identical set that leads from the other end. Overall, this creates a four-pole repetition sequence, alternating interchangeably with hatching, which creates a travel field where the rotor magnet poles are quickly synchronized. Some stepping motors have similar structures.
References
External links
- Short film AC MOTORS AND GENERATOR (1961) available for free download on the Internet Archive
- Short film AC MOTORS (1969) is available for free download on the Internet Archive
Source of the article : Wikipedia
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