Electric motor

Electric motor
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 can you bring issues in motion and maintain them moving without moving a muscle tissue? While steam engines create mechanical energy using popular steam or, more exactly, steam pressure, electric motors use electrical energy as their supply. For this reason, electric motors are also called electromechanical transducers.

The counter piece to the electric electric motor is the generator, that includes a similar structure. Generators transform mechanic movement into electric power. The physical basis of both procedures is the electromagnetic induction. In a generator, current is induced and electrical energy is created whenever a conductor is within a shifting magnetic field. Meanwhile, within an electric engine a current-having conductor induces magnetic areas. Their alternating forces of appeal and repulsion make 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 consists of 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 a power motor. It really is firmly mounted on the equally immobile casing. The rotor on the contrary is installed to the electric motor shaft and can move (rotate).
In the event 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 usually flowing through the wires. This magnetic field produced by the stator induces a current in the rotor. This current after that generates an electromagnetic field around the rotor. Because of this, the rotor (and the attached motor shaft) rotate to follow the rotating magnetic field of the stator.

The electric engine serves to use the created rotary motion in order to drive a gear unit (as torque converter and speed variator) or even to directly drive an application as line motor.
What types of electric motors can be found?
All inventions began with the DC electric motor. Nowadays nevertheless, AC motors of varied designs are the mostly used electrical motors in the market. They all possess a common result: The rotary movement of the motor axis. The function of AC motors is founded on the electromagnetic working basic principle of the DC electric motor.

DC motors
As with most electrical motors, DC motors contain an immobile part, the stator, and a moving element, the rotor. The stator consists either of an electric magnet used to induce the magnetic field, or of permanent magnets that consistently generate a magnetic field. Inside of the stator is where the rotor is certainly located, also called armature, that is wrapped by a coil. If the coil is linked to a way to obtain direct current (a electric battery, accumulator, or DC voltage supply unit), it creates a magnetic field and the ferromagnetic core of the rotor becomes an electromagnet. The rotor is certainly movable installed via bearings and will rotate to ensure that it aligns with the attracting, i.electronic. opposing poles of the magnetic field – with the north pole of the armature opposite of the southern pole of the stator, and the other method round.

In order to established the rotor in a continuous rotary motion, the magnetic alignment should be reversed over and over. This is achieved by changing the current path in the coil. The engine has a so-known as commutator for this function. The two supply contacts are connected to the commutator and it assumes the task of polarity reversal. The changing attraction and repulsion forces make sure that the armature/rotor proceeds to rotate.

DC motors are mainly utilized in applications with low power ratings. These include smaller equipment, hoists, elevators or electrical vehicles.

AAc Induction Motor synchronous AC motors
Instead of direct current, an AC motor requires three-phase alternating electric current. In asynchronous motors, the rotor can be a so-called squirrel cage rotor. Turning results from electromagnetic induction of this rotor. The stator contains windings (coils) offset by 120° (triangular) for each phase of the three-stage current. When linked 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 is certainly carried along by these magnetic fields and rotates. A commutator as with the DC motor is not required in this way.

Asynchronous motors are also called induction motors, because they function just via the electromagnetically induced voltage. They run asynchronously because the circumferential speed of the electromagnetically induced rotor by no means reaches the rotational speed of the magnetic field (rotating field). Due to this slip, the effectiveness of asynchronous AC motors is leaner than that of DC motors.

More on the structure of AC motors / asynchronous motors and on what we offer

AC synchronous motors
In synchronous motors, the rotor is equipped with 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 slide at the same circumferential velocity as that of the stator magnetic field. Performance, power density and the possible speeds are thus considerably higher with synchronous motors than with asynchronous motors. However, the design of synchronous motors can be much more complex and time-consuming.

More details about synchronous motors and our portfolio

Linear motors
In addition to the rotating machines that are mainly used on the market, drives for movements on directly or curved tracks are also required. Such movement profiles occur mainly in machine tools along with positioning and handling systems.

Rotating electric motors can also convert their rotary movement into a linear movement using a gear unit, i.e. they can cause it indirectly. Frequently, however, they don’t have the necessary dynamics to realize especially 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 can be produced from the rotating electrical motors. To get this done, imagine a rotating engine “opened up”: The previously round stator becomes a flat travel distance (monitor or rail) which is covered. The magnetic field then forms along this route. In the linear engine, the rotor, which corresponds to the rotor in the three-phase engine and rotates in a circle there, is stopped the travel distance in a straight line or in curves by the longitudinally shifting magnetic field of the stator as a so-called carriage or translator.

More details about linear motors and our drive solutions


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