Engine classification is based on various parameters. According to one of them, a synchronous and asynchronous motor are distinguished. Differences of devices, general characteristics and the principle of operation are described in the article.
Synchronous motor
This type of engine is capable of working both as a generator and, as a matter of fact, as an engine. His device is akin to a synchronous generator. A characteristic feature of the engine is the unchanged rotary speed of the load.
These types of motors are widely used in many fields, for example, for electric wires that need a constant speed.
The principle of operation of the synchronous motor
The basis of its functioning is the interaction of the rotating magnetic field of the armature and the magnetic fields of the inductor poles. Typically, the anchor is in the stator, and the inductor is located in the rotor. For powerful motors, electric magnets are used for poles, and for weak ones - permanent.
The principle of operation of a synchronous motor includes (briefly) and an asynchronous mode, which is usually used to accelerate to the required (i.e., rated) rotation speed. At this time, the inductor windings are short-circuited or through a rheostat. After reaching the required speed, the inductor begins to supply direct current.
Advantages and disadvantages
The main disadvantages of this type of engine are:
- the need to supply DC windings;
- launch complexity
- sliding contact.
Most generators, wherever they are used, are synchronous. The advantages of such engines in general are:
- highest reliability;
- the highest coefficient of performance ;
- ease of maintenance.
Induction motor
This type of device is a mechanism aimed at transforming electrical energy of alternating current into mechanical. From the name "asynchronous" itself, we can conclude that we are talking about a non-simultaneous process. Indeed, the rotation frequency of the stator magnetic field here is always higher than the rotary one.
Such a device consists of a cylindrical stator and a rotor, depending on the type of which short-circuited asynchronous motors can be with a phase rotor.
Operating principle
The motor operation is based on the interaction of the magnetic stator field and the currents induced in the rotor by the same field. Torque appears when there is a difference in the rotation frequency of the fields.
We now summarize how the synchronous motor differs from the asynchronous motor . What explains the widespread use of one type and the limited use of another?
Synchronous and asynchronous motors: differences
The difference between the operation of the engines is in the rotor. In the synchronous type, it consists of a permanent or electric magnet. Due to the attraction of opposite poles, the rotating stator field also attracts a magnetic rotor. Their speed is the same. Hence the name - synchronous.
In it, it is possible to achieve, in contrast to asynchronous, even phase voltage advance. Then the device, like capacitor banks, can be used to increase power.
Asynchronous motors, in turn, are simple and reliable, but their disadvantage is the difficulty in adjusting the speed. To reverse a three-phase asynchronous motor (that is, change the direction of its rotation in the opposite direction), the arrangement of two phases or two linear wires approaching the stator winding is changed.
If we consider the speed, then they have here a synchronous and asynchronous motor differences. In the synchronous type, this indicator is constant, in contrast to the asynchronous one. Therefore, the first is used where constant speed and complete controllability are needed, for example, in pumps, fans and compressors.
It is very simple to identify the presence of the considered types of devices on a particular device. An asynchronous motor will not have a round number of revolutions (for example, nine hundred thirty per minute), while a synchronous motor will have a round number (for example, one thousand revolutions per minute).
And those and other motors are controlled quite difficult. The synchronous type has a rigid characteristic of mechanics: for any changing load on the motor shaft, the speed will be the same. In this case, the load, of course, must change, taking into account that the engine is able to withstand it, otherwise this will lead to a breakdown of the mechanism.
This is how a synchronous and asynchronous motor works. Differences between both species determine the scope of their use, when one species copes with the task in an optimal way, for the other it will be problematic. At the same time, you can find combined mechanisms.