Electric motor
Electric motor, some of a class of devices that convert electrical energy to mechanical energy, usually by using electromagnetic phenomena.

What is an electric motor?
How do you bring points in motion and keep them moving without moving a muscle tissue? While steam engines create mechanical energy using warm steam or, more specifically, steam pressure, electric motors use electric energy as their source. For this reason, electrical motors are also called electromechanical transducers.

The counter piece to the electric motor is the generator, which has a similar structure. Generators transform mechanic movement into electric power. The physical basis of both processes is the electromagnetic induction. In a generator, current is certainly induced and electrical energy is created whenever a conductor is within a moving magnetic field. Meanwhile, within an electric motor a current-carrying conductor induces magnetic fields. Their alternating forces of appeal and repulsion produce 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 term “stator” comes from the Latin verb “stare” = “to stand still”. The stator may be the immobile component of an electric motor. It is firmly attached to the equally immobile casing. The rotor on the other hand is mounted to the 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 cables. This magnetic field created by the stator induces a current in the rotor. This current then generates an electromagnetic field around the rotor. Because of this, the rotor (and the attached engine shaft) rotate to check out the rotating magnetic field of the stator.

The electric engine serves to use the created rotary movement in order to drive a gear unit (as torque converter and speed variator) or to directly drive a credit card applicatoin 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 mostly 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 operating theory of the DC electric motor.

DC motors
As with most electrical motors, DC motors consist of an immobile component, the stator, and a moving component, the rotor. The stator consists either of an electric magnet utilized to induce the magnetic field, or of permanent magnets that continuously generate a magnetic field. Within the stator is where the rotor can be located, also called 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 device), it creates a magnetic field and the ferromagnetic primary of the rotor turns into an electromagnet. The rotor can be movable mounted via bearings and will rotate to ensure that it aligns with the attracting, i.e. opposing poles of the magnetic field – with the north pole of the armature reverse of the southern pole of the stator, and the other way round.

In order to established the rotor in a continuous rotary movement, the magnetic alignment must 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 purpose. The two 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 proceeds to rotate.

DC motors are mainly utilized in applications with low power ratings. These include smaller equipment, hoists, elevators or electrical 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 outcomes from electromagnetic induction of the rotor. The stator includes windings (coils) offset by 120° (triangular) for each stage of the three-phase 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 line frequency. The electromagnetically induced rotor can be carried along by these magnetic areas and rotates. A commutator as with the DC motor is not needed in this way.

Asynchronous motors are also called induction motors, as they function only via the electromagnetically induced voltage. They operate asynchronously because the circumferential rate of the electromagnetically induced rotor by no means reaches the rotational velocity of the magnetic field (rotating field). For this reason slip, the effectiveness of asynchronous AC motors is leaner than that of DC motors.

More on the structure 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 way the electromagnetic induction of the rotor could be omitted and the rotor rotates synchronously without slip at the same circumferential quickness 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 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 utilized on the market, Ac Induction Motor drives for motions on straight or curved tracks are also required. Such motion profiles occur primarily in machine tools and also positioning and managing systems.

Rotating electric motors can also convert their rotary motion into a linear movement using a gear unit, we.e. they can cause it indirectly. Frequently, however, they don’t have the necessary dynamics to realize particularly challenging and fast “translational” movements or positioning.

That’s where linear motors come 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 electric motor “opened up”: The previously round stator becomes a flat travel distance (monitor or rail) which is usually covered. The magnetic field after that forms along this path. In the linear engine, the rotor, which corresponds to the rotor in the three-phase motor and rotates in a circle there, is pulled over the travel range in a straight series or in curves by the longitudinally moving magnetic field of the stator as a so-called carriage or translator.

More information regarding linear motors and our drive solutions