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 can you bring things in motion and maintain them moving without moving a muscle? While steam engines create mechanical energy using sizzling steam or, more precisely, steam pressure, electrical motors use electric energy as their supply. For this reason, electric motors are also known as 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 processes may be the electromagnetic induction. In a generator, current can be induced and electricity is created when a conductor is within a shifting magnetic field. Meanwhile, within an electric engine a current-holding conductor induces magnetic areas. Their alternating forces of attraction and repulsion develop the basis for generating motion.
How does an electric motor work?
Motor housing with stator
Motor housing with stator
In general, the heart of an electric motor includes a stator and a rotor. The term “stator” is derived from the Latin verb “stare” = “to stand still”. The stator is the immobile component of an electric motor. It is firmly mounted on the equally immobile housing. The rotor on the contrary is mounted 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 works as a coil and generates a rotating magnetic field when current is definitely flowing through the wires. This magnetic field developed by the stator induces a current in the rotor. This current then generates an electromagnetic field around the rotor. As a result, the rotor (and the attached engine shaft) rotate to check out 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 even to directly drive an application as line motor.
What forms of electric motors are available?
All inventions started with the DC motor. Nowadays however, AC motors of varied designs are the most commonly used electric motors in the industry. They all possess a common result: The rotary movement of the motor axis. The function of AC motors is founded on the electromagnetic working principle of the DC electric motor.
As with most electric motors, DC motors consist of an immobile component, the stator, and a moving element, the rotor. The stator consists either of a power magnet used to induce the magnetic field, or of long term magnets that continuously generate a magnetic field. Within the stator is where the rotor can be located, also known as armature, that is wrapped by a coil. If the coil is connected 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 becomes an electromagnet. The rotor is definitely movable mounted via bearings and may rotate so 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 continuing rotary motion, the magnetic alignment should be reversed again and again. This is attained by changing the current path in the coil. The engine has a so-known as commutator for this function. Both supply contacts are linked 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 used in applications with low power ratings. 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 usually a so-known as squirrel cage rotor. Turning results from electromagnetic induction of this rotor. The stator includes windings (coils) offset by 120° (triangular) for every stage of the three-stage current. When linked to the three-stage current, these coils each build up a magnetic field which rotates in the rhythm of the temporally offset range frequency. The electromagnetically induced rotor is usually carried along by these magnetic fields and rotates. A commutator as with the DC engine is not needed in this way.
Asynchronous motors are also called induction motors, as they function only via the electromagnetically induced voltage. They run asynchronously since the Ac Induction Motor circumferential acceleration of the electromagnetically induced rotor never reaches the rotational rate of the magnetic field (rotating field). For this reason slip, the efficiency 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 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 swiftness as that of the stator magnetic field. Effectiveness, power density and the feasible 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 devices that are mainly used on the market, drives for motions on straight or curved tracks are also required. Such movement profiles occur mainly in machine tools and also positioning and managing systems.
Rotating electric motors may also convert their rotary motion into a linear motion using a gear unit, i.e. they are able to cause it indirectly. Frequently, however, they do not have the required dynamics to realize particularly demanding 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 produced from the rotating electric motors. To get this done, imagine a rotating motor “exposed”: The previously round stator becomes a flat travel distance (monitor or rail) which is protected. The magnetic field then forms along this path. In the linear engine, 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.
More information regarding linear motors and our drive solutions