In fact, an electric motor converts electricity into mechanical motion. Reverse action that converts Mechanical motion to electricity Is done by the generator.
The two devices are similar except in function. Most electric motors by ElectromagnetismThey work, but there are also motors that work on the basis of other phenomena such as electrostatic force and piezoelectric effect.
The general scheme is that when a current-carrying substance is affected by a Magnetic field Is placed, a force is applied to that material by the field.
In a cylindrical motor, the rotor due Torque Which is due to the force applied to the rotor at certain distances from the rotor axis.
Most electric motors are rotary, but there are linear motors. In a rotating motor, the moving part (usually inside the motor) is called the rotor and the fixed part is called the stator.
The rotor consists of electric magnets that are wound on a frame. Although this frame is often referred to as armature, the term is often misused.
The armature is the part of the motor to which the input voltage is applied or the part of the generator where the output voltage is generated. Depending on the design of the machine, any part of the rotor or stator can be used as an armature. Kits are used in schools to build very simple engines.
General information about electric motors Types of electric motors
General information about DC electric motors
One of the first rotary motors, if not the first, was built by Michael Faraday in 1821 and included a loose hanging wire immersed in a container of mercury. A permanent magnet was placed in the middle of the container. As a current passed through the wire, the wire revolved around the magnet, indicating that the current would increase a circular magnetic field around the wire. This engine is often shown in school physics classes, but sometimes salt water is used instead of the toxic substance mercury.
Classic DC motor with armature from Electric magnet Is. A rotary switch called a commutator reverses the direction of the electric current twice per cycle to flow in the armature, and the electric magnets absorb and dissipate the permanent magnet outside the motor.
DC motor speed depends on the set of voltage and current passing through the motor windings and the motor load or braking torque.
DC motor speed It depends on the voltage and the torque depends on the current. The speed is usually controlled by variable voltage or current flow, using pulses (a type of winding switch) in the motor winding or by having a variable voltage source. Because this type of engine can produce high torque at low speeds, it is commonly used in traction applications such as locomotives.
However, there are several limitations to classical design, many of which are due to the need for brushes to connect to the commutator. The wear of the brushes and commutator causes friction, and the higher the engine speed, the harder the brushes must be pressed to make a good connection.
Not only does this friction lead to engine noise, but it also places a higher speed limit, which means that the brushes are eventually gone and need to be replaced. Incomplete electrical connection also generates electrical noise in the connected circuit. These problems are eliminated by moving the motor from the outside to the outside, and by placing permanent magnets inside and coils on the outside, we arrive at a brushless design.
General information about electromotors for winding field motors
Permanent magnets on the outside (stator) of a DC motor can be replaced with electric magnets. By changing the field current (winding on the electric magnet) we can determine the velocity ratio /Engine torque Change. If the field winding is placed in series with the armature winding, we will have a high-speed low-torque motor, and if it is placed in parallel, we will have a high-speed low-torque motor. We can reduce the field current to get even faster but with the same amount of torque. This technique is ideal for electric traction and many similar applications, and the application of this technique can lead to the removal of equipment from a mechanically variable gearbox.
General information about electric motors of universal motors
One type of DC motor is the winding field of the universal motor. The name of these motors is derived from the fact that these motors can be used with both DC and AC current, although most of these motors actually operate on AC power. The principle of operation of these motors is based on the fact that when a coiled field DC motor is connected to alternating current, the current in both the field winding and the armature winding (and in the resulting magnetic fields) changes simultaneously, thus creating mechanical force. Will always be unchanged. In practice, the motor must be specially designed to be compatible with AC current (impedance / reactance must be considered) and the final motor will generally be less efficient than a pure DC equivalent motor.
The advantage of these motors is that AC power can be applied to motors that have the characteristics of a DC motor, especially since these motors have very high starting torque and a very compact design at high speeds. The downside of these motors is the maintenance and reliability problems caused by the commutator, which is why these motors are rarely seen in industry, but the most common AC motors are in devices such as mixers and power tools that are sometimes used.
General information about AC motor electromotors
General information about single-phase AC motor electromotors
The most common single-phase motor is the slotted pole synchronous motor, which is often used in devices that require low torque, such as electric fans, microwave ovens and other small appliances. Another type of AC motor is the single-phase induction motor, which is often used in large appliances such as washing machines and dryers. Generally, these motors can generate larger starting torque by using a starter coil with a starter capacitor and a centrifugal switch.
During start-up, the capacitor and start-up coil are connected to the power supply via a series of contacts under spring-loaded pressure on a rotary centrifugal switch. The capacitor helps to increase the starting torque of the motor. When the motor reaches the rated speed, the centrifugal switch is activated, the contacts handle is activated, disconnecting the capacitor and the series starter coil from the power supply, in which case the motor operates only with the main coil.
General information about three-phase AC motors
For applications requiring higher power, three-phase AC (or multi-phase) induction motors are used. These motors use the phase difference between the electrical phases of a multi-phase power supply to create a rotating electromagnetic field within them. Often, the rotor consists of a number of copper conductors embedded in steel. Through electromagnetic induction, a rotating magnetic field is induced in these conductors, which in turn creates a balancing magnetic field and causes the motor to move in the direction of rotation of the field.
This type of motor is known as induction motor. In order for this engine to move, the engine must always be with Speed Rotate less than the frequency of the power supply applied to the motor, otherwise a balancing field will not be created in the rotor. The use of this type of engine in traction applications such as locomotives, where it is known as asynchronous traction motor, is increasing day by day. Separation field current is applied to the rotor windings to create a continuous magnetic field, which is present in the synchronous motor, the motor rotates simultaneously with the rotating magnetic field caused by three-phase AC power. Synchronous motors can also be used as current generators. The speed of an AC motor depends primarily on the supply frequency, and the amount of slip, or the difference in rotational speed between the rotor and the stator field, determines the torque produced by the motor. Speed change in this type of motor can be made possible by having a bunch of coils or poles in the motor that turn the speed of the magnetic rotating field on and off.
General information about electric motors for stepper motors
Another type of electric motor is a stepper motor, in which an internal rotor, consisting of permanent magnets, is controlled by a set of external magnets that are switched on and off electronically. A stepper motor is a combination of a DC electric motor and a solenoid. Simple stepper motors are positioned in certain positions by part of a gear system, but relatively controlled stepper motors can rotate very slowly. Computer-controlled stepper motors are a form of positioning systems, especially when part of a digital system has steering control.
General information about electric motors for linear motors
A linear motor is essentially an electric motor that rotates to generate a linear force by generating a moving electromagnetic field along its length, instead of generating a rotational torque. Linear motors are often induction or stepper motors. You can see a linear motor on a Maglev high-speed train in which the train flies on the ground.
An AC motor is an electric machine that is fed by AC power and converts electrical power into rotational or linear mechanical power. AC AC motor consists of two main parts:
Stator: An external, usually fixed, core that generates a rotating field using alternating current.
* Rotor: An internal and movable core that is connected to the output shaft and produces torque according to the rotating field produced by the stator.
According to the type of rotor used in motors, AC motors are classified into two types:
* Synchronous motor in which the rotor rotates exactly at the speed of the rotating field. In this type of motor, the electric field of the rotor is supplied by an external source.
* Synchronous motor or induction in which the electric field of the rotor arises from the induction of the stator field.