An electric motor is an electric machine that converts electrical energy into mechanical energy.
In modern life, an electric motor drives most of the mechanisms that are powered by electric current.
The scope of use of electric motors is very diverse from everyday life to industry.
Depending on the type of power supply, electric motors are divided into:
- DC electric motors;
- Electric motors of alternating current.
In turn, AC motors are divided into:
- Stepper (type of synchronous).
The principle of operation of any electric motor is based on the interaction of magnetic fields. If you bring one magnet closer to another, then their opposite poles will attract each other, and the like poles will repel each other.
DC motor characterized in that it is powered by a DC source. It allows smoothly, over a wide range, to regulate the speed of rotation, changing the current in the rotor circuit with the help of additional electrical resistance, to a change in the supply voltage, as well as to a change in magnetic flux.
Asynchronous motor is characterized in that the rotating part of the engine - the rotor, always rotates at a speed not equal to the speed of the magnetic flux, that is not in synchronism with it. They are used where it is not necessary to maintain a constant speed of rotation, as well as in everyday life, in a single-phase design at low power.
The synchronous motor is characterized in that the rotating part of the engine - a rotor, which rotates at a speed equal to the frequency of the magnetic field of revolutions per unit structure.
The difference between a synchronous motor and an asynchronous motor is in the ratio of the rotor speed to the magnetic field. In the synchronous motor both are identical. In asynchronous - different.
The stepper motor is characterized in that the power surge electric current leads to the fact that its rotor does not rotate continuously, and each time performs a rotational movement by a predetermined angle.
The electric motor is the main element that drives the electric mechanisms, but nevertheless there is a need to control the electric motor.
In the simplest cases, simple and relatively cheap electromechanical contactors or relays are used to drive the electric motor. But often the engine needs a smooth control of rotation speed and torque, then controlled motors (thyristor or transistor) for DC motors and frequency converters for AC motors are used to power the motors.