Electric motor, any of a class of devices that convert electrical energy to mechanical energy, usually by using electromagnetic phenomena.
What is a power motor?
How do you bring stuff in motion and maintain them moving without moving a muscle tissue? While steam engines create mechanical energy using hot steam or, more precisely, steam pressure, electric motors use electric energy as their resource. 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 movement into electric power. The physical basis of both processes may be the electromagnetic induction. In a generator, current is induced and electricity is created when a conductor is at a moving magnetic field. Meanwhile, in an electric engine a current-having 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
In general, the heart of a power motor contains a stator and a rotor. The word “stator” is derived from the Latin verb “stare” = “to stand still”. The stator is the immobile component of an electric motor. It is firmly attached to the equally immobile casing. The rotor on the contrary is mounted to the engine shaft and can move (rotate).
In case of AC motors, the stator includes the so-called laminated core, which is wrapped in copper wires. The winding acts as a coil and generates a rotating magnetic field when current is definitely flowing through the wires. This magnetic field created 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 motor shaft) rotate to follow the rotating magnetic field of the stator.
The electric electric motor serves to use the created rotary motion to be able to drive a equipment unit (as torque converter and speed variator) or to directly drive a credit card applicatoin as line motor.
What types of electric motors can be found?
All inventions started with the DC engine. Nowadays however, AC motors of various designs are the most commonly used electric motors in the industry. They all have got a common result: The rotary motion of the engine axis. The function of AC motors is founded on the electromagnetic working basic principle of the DC electric motor.
As with most electric motors, DC motors contain an immobile component, the stator, and a moving element, the rotor. The stator consists either of an electric magnet utilized to induce the magnetic field, or of long term Ac Induction Motor magnets that consistently generate a magnetic field. Inside of the stator is where in fact the rotor is certainly located, also known as armature, that is covered by a coil. If the coil is connected to a source of direct current (a battery, accumulator, or DC voltage supply unit), it creates a magnetic field and the ferromagnetic core of the rotor turns into an electromagnet. The rotor is usually movable installed via bearings and can rotate so that it aligns with the attracting, i.e. opposing poles of the magnetic field – with the north pole of the armature reverse of the south pole of the stator, and the other way round.
In order to established the rotor in a continuous rotary movement, the magnetic alignment should be reversed again and again. This is achieved by changing the current path in the coil. The motor has a so-called commutator for this function. Both supply contacts are connected to the commutator and it assumes the task of polarity reversal. The changing attraction and repulsion forces ensure that the armature/rotor proceeds to rotate.
DC motors are mainly utilized 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 current. In asynchronous motors, the rotor is a so-called squirrel cage rotor. Turning outcomes from electromagnetic induction of this rotor. The stator consists of windings (coils) offset by 120° (triangular) for each stage of the three-stage current. When connected to the three-phase current, these coils each build-up a magnetic field which rotates in the rhythm of the temporally offset series frequency. The electromagnetically induced rotor can be carried along by these magnetic areas and rotates. A commutator as with the DC engine is not needed in this way.
Asynchronous motors are also called induction motors, because they function only via the electromagnetically induced voltage. They run asynchronously since the circumferential quickness of the electromagnetically induced rotor by no means reaches the rotational quickness of the magnetic field (rotating field). Due to this slip, the efficiency of asynchronous AC motors is leaner than that of DC motors.
More on the framework of AC motors / asynchronous motors and upon what we offer
AC synchronous motors
In synchronous motors, the rotor has permanent magnets rather than windings or conductor rods. In this manner the electromagnetic induction of the rotor can be omitted and the rotor rotates synchronously without slip at the same circumferential acceleration as that of the stator magnetic field. Efficiency, power density and the possible speeds are thus significantly higher with synchronous motors than with asynchronous motors. However, the look of synchronous motors can be a lot more complex and time-consuming.
Additional information about synchronous motors and our portfolio
In addition to the rotating machines that are mainly used on the market, drives for motions on directly or curved tracks are also required. Such motion profiles occur mainly in machine tools along with positioning and managing systems.
Rotating electric motors may also convert their rotary movement into a linear movement with the aid of a gear unit, i.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.
This is where linear motors enter into play that generate the translational motion directly (direct drives). Their function can be produced from the rotating electrical motors. To get this done, imagine a rotating motor “exposed”: The previously round stator becomes a set travel distance (track or rail) which is 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 motor and rotates in a circle there, is pulled over the travel distance in a straight range or in curves by the longitudinally shifting magnetic field of the stator as a so-called carriage or translator.
More information about linear motors and our drive solutions