Could someone please explain to me what excitation, synchronization, and asynchronous mean?

Excitation is the device that provides power to the generator rotor. Depending on the method of excitation in a DC motor, it can be classified into separately excited, self-excited, series-excited, and compound-excited types. During the operation of a DC motor, excitation involves controlling the voltage of the stator in order to vary the magnetic field generated, thereby changing the speed of the motor. An AC motor whose rotor speed is identical to the speed of the rotating magnetic field in the stator is called a synchronous motor; whereas a motor whose rotor speed is lower than that of the rotating magnetic field is called an asynchronous motor. The original poster can look up more relevant information to supplement this knowledge

The motor of a compressor is usually a synchronous motor, which means that its speed remains constant at all times. If the line voltage suddenly drops, the motor’s speed changes; this is known as motor loss of synchronization. The excitation cabinet then immediately increases the excitation current to the rotor. If the line voltage does not recover after a certain period of time, the motor trips. An asynchronous motor, on the other hand, has its speed change depending on the level of the line voltage

1. The main difference between synchronous and asynchronous motors lies in whether the rotor speed is identical to the speed of the magnetic field rotating in the stator. If the rotor rotates at the same speed as the stator, it is called a synchronous motor; if not, it is called an asynchronous motor. . . 2. When the number of pole pairs is constant, there is a strict relationship between the motor’s speed and frequency; in motor terminology, this is referred to as synchronization. An asynchronous motor, also known as an induction motor, is primarily used as an electric motor, and its rotor speed during operation is always lower than that of a synchronous motor. 3. The so-called “synchronization” means that when current flows through the armature (stator) windings, a rotating magnetic field is generated in the air gap. The direction and speed of rotation of this magnetic field are identical to those of the rotor’s rotation, which is why it is called synchronization. In an asynchronous motor, there is a relative speed between its rotating magnetic field and the rotor, which results in torque being generated. As for why there is such a difference between asynchronous motors and synchronous motors, I’ll summarize it as follows: the fundamental reason lies in whether excitation is applied to the stator. When no excitation is applied, it is an asynchronous motor; this is because only when relative motion occurs does cutting through magnetic flux lines take place (or in other words, magnetic flux changes), which in turn generates electromagnetic force (i.e., the Ampere force). With excitation applied, the stator can be regarded as a magnet with fixed N and S poles, which rotate in sync with the rotating magnetic field; hence it is called a synchronous motor. (The magnetic attraction)

After reading the responses from those above, I can only share here a passage from the \"Motor Design Manual\" that defines a synchronous motor, for everyone’s reference*: Synchronous motors are primarily used to operate as generators. The electrical power used for communication in modern society is almost entirely generated by synchronous generators. Synchronous motors can also be used as electric motors; for high-power manufacturing machines where speed control is not required, synchronous motors are commonly employed for driving purposes. By adjusting the excitation, synchronous motors can help improve the power factor of the electrical grid. Furthermore, synchronous motors can also be used as synchronous compensators; they are essentially synchronous motors that operate at idle in an AC power grid, dedicated to supplying inductive or capacitive reactive power to the grid in order to meet its requirements for such power. Over the past decade or so, thanks to the development of power electronics technology, inverters and synchronous motors have been combined to create brushless motors. These motors lack the mechanical commutator found in DC motors; instead, electronic commutation is used, allowing them to achieve performance similar to that of DC motors. Moreover, they can have a larger capacity, higher voltage, and higher speed than DC motors, opening up new applications in industry. In synchronous motors, the armature windings are generally placed on the stator, while the rotors are equipped with magnetic poles; excitation windings are installed on these magnetic poles (if the magnetic poles are made of permanent magnets, then no excitation windings are needed). When operating as a generator, a direct current is passed through the excitation winding, creating a magnetic field inside the motor. The rotor of the motor is rotated by a prime mover, and the relative motion between this magnetic field and the stator conductors induces an alternating voltage in the stator windings. The frequency f of the alternating electromotive force is determined by the number of pole pairs p and the rotor speed n, that is, f = pn/60. Here, the unit of frequency is Hz, while the unit of speed is r/min. As can be seen from the formula, when the number of pole pairs and the speed of the motor are constant, the frequency of the alternating voltage generated is also fixed. In our country’s power system, the frequency of alternating current is specified to be 50Hz. Therefore, when the motor has one pair of poles, its speed is necessarily 3000 r/min; when it has two pairs of poles, the speed is necessarily 1500 r/min, and so on. When operating as a synchronous motor, three-phase alternating current must be applied to the stator windings of the motor, which generates a rotating magnetic field within the motor. When direct current is applied to the excitation winding of the rotor, the rotor behaves like a magnet. Thus, the rotating magnetic field causes the magnet to spin, and the speed of the rotor is given by n = 60f/p. It can be seen that in a synchronous motor, whether it is used as a generator or a motor, when the number of pole pairs remains constant, there is a strict relationship between its speed n and frequency f; this phenomenon is referred to in electrical engineering terms as \"synchronization\". All types of synchronous motors consist of two basic components: the stator and the rotor. The rotor section consists of the rotor core, excitation winding, slip ring, and shaft, among other components. The stator part consists of the stator core and the stator armature windings.

Both synchronous and asynchronous motors belong to AC electric motors, and they rotate by being powered by a 50-hertz AC power supply. In an asynchronous motor, alternating current is supplied to the stator, which generates a rotating magnetic field; the rotor then induces its own magnetic field, and it is the interaction of these two magnetic fields that causes the rotor to rotate in tandem with the stator’s rotating magnetic field. The rotor rotates more slowly than the stator’s magnetic field, resulting in a difference in speed; this lack of synchronization is what gives it the name “asynchronous” motor. In a synchronous motor, similar to the stator in an asynchronous motor, a constant magnetic field is created by applying direct current to the rotor, allowing it to rotate in sync with the stator’s rotating magnetic field, which is why it is called a synchronous motor. Asynchronous motors are simple, cost-effective, and easy to install, use, and maintain, which is why they are widely used. However, their disadvantages include low efficiency and a low power factor, which can be detrimental to the power grid. Synchronous motors, on the other hand, have high efficiency and can handle capacitive loads, helping to improve the power factor of the power grid. They are commonly used in large industrial and mining equipment. This describes the methods used to generate magnetic fields in rotating motors. Most modern motors are based on electromagnetic induction, and a magnetic field is required in them. This magnetic field can be generated by permanent magnets, or it can be produced by passing an electric current through a coil using an electromagnet. The set of coils in a motor that are specifically designed to generate a magnetic field is called the excitation winding. Due to the limitations of permanent magnet materials, the magnetic field generated by permanent magnets is relatively weak; they are mainly used in small-capacity motors. However, with the emergence of new types of permanent magnet materials, especially rare earth materials with high magnetic energy products such as rare earth cobalt and neodymium-iron-boron, permanent magnet motors with capacities in the hundreds of kilowatts have begun to be developed. Most motors use current excitation. Excitation methods are divided into two main categories: externally excited and self-excited.