Introduction
Modern electric machines are capable of converting mechanical energy into electrical energy and vice versa. This means they can perform the functions of both a motor and a generator.
Asynchronous Motor
Asynchronous motors are among the most common types of electric motors that convert electrical energy into mechanical energy. Torque is generated when there is no induction of a magnetic field in the rotor windings.
The design of an asynchronous motor necessarily includes a stator and a rotor, separated by an air gap. The windings serve as the active parts of the motor. Other important parameters, such as cooling, rotation, strength, and rigidity, depend on the structural features of the device.
Depending on the type of winding, there are short-circuited and phase rotors. Phase rotors are used where the maximum possible starting torque is required.
Synchronous Motor
The synchronous motor is structurally similar to the asynchronous motor. The three-phase stator winding creates a rotating magnetic field. The rotor has excitation windings connected to a direct current source.
The synchronous motor can maintain a constant speed if the supply current value does not change.
Advantages of the synchronous motor compared to the asynchronous one:
- lower sensitivity to voltage spikes;
- torque is directly proportional to voltage, not the square of the voltage;
- its performance is influenced only by the magnetic flux generated in the stator field.
Permanent Magnet Motor
The main components of such motors are: a stator with windings and a rotor with permanent magnets. Permanent magnet motors can provide greater torque compared to motors that operate on the principle of magnetic resistance. The characteristic step during the operation of these motors is 30°.
Continuous rotation of the shaft is achieved by alternating the phase connections, with an average of 24 to 48 cycles per revolution.
The maximum speed of such motors is limited by the capabilities of the rotor and the influence of electromotive force.
Hybrid Motor
Hybrid motors represent a different price category and significantly outperform previous types in specifications. They are capable of providing:
- a smaller step size (from 100 to 400 steps per revolution);
- high torque and speed values.
Particular attention should be paid to the stator of the hybrid drive, which, like the rotor, is equipped with special teeth to maximize the number of equivalent poles. This leads to improved static and dynamic torque indicators thanks to the optimal arrangement of the teeth.
Servo Drive
A servo drive is a complex technical device that precisely controls the movement parameters using negative feedback. The term "valve motor," which is controlled by valves (various switching devices), is also known.
Main advantages of servo drives:
- low system inertia;
- precise positioning;
- maximum dynamic characteristics.