Energy Conversion in Electric Machines
Conversion of electrical and mechanical energy through electromagnetic interaction is the basis for the operation of modern electric machines. These machines typically consist of a rotating rotor and a stationary stator. In the case of motors, electrical energy is converted into mechanical work and heat, while in generators, mechanical energy is transformed into electrical energy. Electric drives that operate on electricity and provide mechanical energy are represented by a wide range of electrical equipment and automation. They can vary in the type of rotation of the magnetic field and rotor, as well as being either alternating or direct current.
Asynchronous Motor
Asynchronous motors are among the most common electric machines. They are named for the fact that the rotor rotates at a lower speed than the magnetic field of the stator. This results in the generation of electromotive force (EMF), which creates torque. In the design of such motors, a squirrel-cage rotor is usually used, as this ensures simplicity, low cost, and reliability in operation. Asynchronous motors can operate from the grid without additional converters.
Synchronous Motor
The principle of operation of a synchronous motor is that the rotor rotates at the same speed as the magnetic field in the air gap between the rotor and stator. A synchronous motor consists of an armature and excitation winding and can operate both as a motor and a generator. The main advantage of synchronous motors is their low dependence on voltage fluctuations in the grid, making them ideal for machines with complex operating modes.
Permanent Magnet Motor
In permanent magnet motors, the rotating magnetic field is created by permanent magnets placed in the rotor. These motors have less heating of the excitation winding of the electromagnet, as permanent magnets provide a stable torque. However, the main disadvantage of such machines is the inability to adjust the rotational frequency with the change of the inducer.
Hybrid Motor
A hybrid motor combines several types of engines, allowing for the use of the best features of each. Its principle of operation is that an internal combustion engine powers an electric generator, which in turn drives electric motors that transfer torque to the wheels of vehicles. The use of battery packs in such systems allows for fuel savings of up to 55% and provides starting acceleration that is 60% faster.
Servo Drive
A servo drive is an electric drive controlled through negative feedback. It ensures the accuracy of the output of a specified parameter on the output shaft, achieved through the use of position and speed sensors. Servo drives are applied in control systems, particularly in automotive steering and braking systems. Modern servo drives can perform complex control tasks.