The structure of permanent magnet synchronous motor

Permanent magnet synchronous motor is mainly composed of rotor, end cover, stator and other components. Generally speaking, the biggest feature of a permanent magnet synchronous motor is that its stator structure is very similar to that of an ordinary induction motor, mainly because the unique structure of the rotor is different from other motors. The biggest difference from the commonly used asynchronous motor is the unique structure of the rotor, where high-quality permanent magnet poles are placed on the rotor. Since there are many options for the placement of permanent magnets on the rotor, PMSMs are generally divided into three categories: inline, surface mount, and plug-in. The running performance of the permanent magnet synchronous motor is the most concerned, and there are many factors that affect its performance, but the most important is the structure of the permanent magnet synchronous motor. In terms of surface mount, plug-in and embedded, each structure has its own advantages.

The surface-mounted permanent magnet synchronous motor is the most widely used in the industry. The main reason is that it has many advantages that other forms of motors cannot match, such as its convenient manufacturing, relatively small rotational inertia and simple structure. And this type of permanent magnet synchronous motor is easier for designers to optimize its design. The most important method is to change its distribution structure to sinusoidal distribution, which can bring many advantages, such as applying the above methods. It can improve the running performance of the motor very well. The reason why the plug-in motor can be greatly improved compared with the surface-mounted motor is that it makes full use of the unique reluctance torque energy generated by the asymmetry of the magnetic link structure it designed. The power density of the motor is greatly improved, and it can be easily manufactured. Therefore, the structure of the permanent magnet synchronous motor is widely used in the transmission system, but its shortcomings are also very prominent, such as the production cost. Compared with the magnetic flux leakage coefficient and the surface mount type, it is much larger. The permanent magnet in the permanent magnet synchronous motor is placed inside the rotor. Although its structure is relatively complex, there are several obvious advantages that are beyond doubt, because it is obviously similar to the surface-mounted type. Compared with other motors, it will generate a large torque; because the installation method of the permanent magnets in the rotor is embedded, the possibility of a series of dangers brought by the permanent magnets after being demagnetized will be very small. , so the motor can run at a higher rotational speed but does not need to consider whether the permanent magnets in the rotor will be damaged due to excessive centrifugal force.

In order to reflect the superior performance of the permanent magnet synchronous motor, compared with the traditional asynchronous motor, the permanent magnet synchronous motor, especially the most commonly used rare earth type permanent magnet synchronous motor, has the advantages of simple structure and high operation reliability; It is particularly light; the loss is relatively small, and the efficiency is relatively high; the shape and size of the motor can be flexibly changed and other obvious advantages. It is precisely because it has so many advantages that its application range is very wide, covering almost all fields such as aerospace, national defense, industrial and agricultural production and daily life. Compared with the induction motor, the permanent magnet synchronous motor can be considered not to input reactive excitation current, so its power factor can be significantly improved, thereby reducing the current on the stator and the loss of the resistance on the stator, and there is no need for stable operation. The loss on the rotor resistance, and then the fan can be reduced due to the reduction of the total loss (small-capacity motors can even do not need a fan) and the corresponding wind wear loss, so that the efficiency can be improved 2-8 compared with the induction motor of the same specification percent.