Electric motor, some of a class of devices that convert electrical energy to mechanical energy, usually by employing electromagnetic phenomena.
What is an electric motor?
How do you bring issues in motion and maintain them moving without moving a muscle tissue? While steam engines create mechanical energy using sizzling steam or, more precisely, steam pressure, electric motors use electric energy as their source. For this reason, electric motors are also called electromechanical transducers.
The counter piece to the electric engine is the generator, that includes a similar structure. Generators transform mechanic motion into energy. The physical basis of both procedures is the electromagnetic induction. In a generator, current can be induced and electricity is created when a conductor is at a moving magnetic field. Meanwhile, within an electric electric motor a current-transporting conductor induces magnetic areas. Their alternating forces of attraction and repulsion create the basis for generating motion.
How does an electric motor work?
Motor housing with stator
Motor housing with stator
Generally, the heart of an electric motor contains a stator and a rotor. The word “stator” is derived from the Latin verb “stare” = “to stand still”. The stator may be the immobile part of an electric motor. It really is firmly mounted on the equally immobile casing. The rotor on the contrary is mounted to the engine shaft and may move (rotate).
In case of AC motors, the stator includes the so-called laminated core, which is wrapped in copper wires. The winding functions as a coil and generates a rotating magnetic field when current can be flowing through the cables. This magnetic field developed by the stator induces a current in the rotor. This current then generates an electromagnetic field around the rotor. Consequently, the rotor (and the attached engine shaft) rotate to follow the rotating magnetic field of the stator.
The electric engine serves to apply the created rotary motion in order to drive a equipment unit (as torque converter and speed variator) or to directly drive an application as line motor.
What types of electric motors are available?
All inventions started with the DC engine. Nowadays nevertheless, AC motors of various designs are the most commonly used electrical motors in the industry. They all possess a common result: The rotary movement of the engine axis. The function of AC motors is based on the electromagnetic working theory of the DC motor.
As with most electrical motors, DC motors consist of an immobile part, the stator, and a moving element, the rotor. The stator consists either of a power magnet utilized to induce the magnetic field, or of long term magnets that consistently generate a magnetic field. Inside of the stator is where in fact the rotor is usually located, also known as armature, that is wrapped by a coil. If the coil is linked to a source of direct current (a electric battery, accumulator, or DC voltage supply unit), it creates a magnetic field and the ferromagnetic primary of the rotor becomes an electromagnet. The rotor is certainly movable installed via bearings and can rotate so that it aligns with the attracting, i.electronic. opposing poles of the magnetic field – with the north pole of the armature opposing of the southern pole of the stator, and the other way round.
In order to arranged the rotor in a continuous rotary movement, the magnetic alignment should be reversed over and over. This is attained by changing the current direction in the coil. The motor has a so-called commutator for this function. Both supply contacts are linked to the commutator and it assumes the duty of polarity reversal. The changing attraction and repulsion forces make sure that the armature/rotor continues to rotate.
DC motors are mainly used in applications with low power rankings. These include smaller equipment, hoists, elevators or electric vehicles.
Asynchronous AC motors
Instead of direct current, an AC motor requires three-phase alternating electric current. In asynchronous motors, the rotor is definitely a so-known as squirrel cage rotor. Turning results from electromagnetic induction of the rotor. The stator consists of windings (coils) offset by 120° (triangular) for each phase of the three-stage current. When connected to the three-stage current, these coils each build-up a magnetic field which rotates in the rhythm of the temporally offset collection frequency. The electromagnetically induced rotor can be carried along by these magnetic areas and rotates. A commutator much like the DC engine is not required in this way.
Asynchronous motors are also known as induction motors, Ac Induction Motor Because they function only via the electromagnetically induced voltage. They run asynchronously since the circumferential velocity of the electromagnetically induced rotor by no means reaches the rotational velocity of the magnetic field (rotating field). Because of this slip, the performance of asynchronous AC motors is leaner than that of DC motors.
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AC synchronous motors
In synchronous motors, the rotor has permanent magnets rather than windings or conductor rods. In this way the electromagnetic induction of the rotor could be omitted and the rotor rotates synchronously without slip at the same circumferential velocity as that of the stator magnetic field. Efficiency, power density and the possible speeds are thus considerably higher with synchronous motors than with asynchronous motors. However, the look of synchronous motors is also much more complex and time-consuming.
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As well as the rotating machines that are mainly utilized in the industry, drives for actions on straight or curved tracks are also required. Such motion profiles occur mainly in machine tools and also positioning and managing systems.
Rotating electric motors may also convert their rotary movement into a linear movement using a gear unit, we.e. they are able to cause it indirectly. Frequently, however, they do not have the required dynamics to realize particularly challenging and fast “translational” movements or positioning.
That’s where linear motors enter into play that generate the translational motion directly (direct drives). Their function could be derived from the rotating electrical motors. To do this, imagine a rotating motor “exposed”: The previously circular stator becomes a flat travel distance (monitor or rail) which can be covered. The magnetic field then forms along this route. In the linear electric motor, the rotor, which corresponds to the rotor in the three-phase electric motor and rotates in a circle there, is pulled over the travel range in a straight collection or in curves by the longitudinally shifting magnetic field of the stator as a so-known as carriage or translator.
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