Permanent magnet design and selection of permanent magnet motors

Permanent magnet motors have now become a mainstream product in today's world, and many companies are keen on it. However, when we use it, we must pay attention to its maintenance and upkeep. As for the maintenance of permanent magnet motors, the editor also introduced it last time. Everyone It should also be taken seriously. So what are the design and selection of permanent magnets in permanent magnet motors? The editor will explain it to you below!

The permanent magnet design of the permanent magnet motor is as follows:

(1) Shape of permanent magnet

The shape of the permanent magnet is related to the selected magnetic pole structure. For the external magnetic pole structure, it is recommended to use tile-shaped magnetic poles; for the built-in magnetic pole structure, it is recommended that you use rectangular permanent magnets.

(2) Structure of magnetic poles

In permanent magnet motors, permanent magnets are often connected in series and parallel. Similar to the series-parallel connection of batteries in a circuit, the magnetomotive force of two or more permanent magnets are connected in series along the magnetizing direction to jointly provide the magnetomotive force. At this moment, the magnetomotive force of the magnetic circuit is the sum of their magnetomotive forces. The area of ​​the surface pass is the area of ​​a permanent magnet. Two or more permanent magnets are connected in parallel along the magnetizing direction to jointly provide magnetic flux. The magnetic flux is the sum of their magnetic fluxes, and the magnetomotive force is equal to the magnetomotive force of one permanent magnet.

The selection of permanent magnets for permanent magnet motors is as follows:

Permanent magnet motors have various permanent magnets and their functions. How to choose the appropriate permanent magnet material is directly related to the function and economy of the motor. The selection of permanent magnets should meet the following requirements:

(1) The permanent magnet should be able to generate the required magnetic field in the designated working space.

(2) The magnetic field established by the permanent magnet should have stability, and the magnetic performance should be within the allowable range as the operating temperature and environment change.

(3) Has good corrosion resistance.

(4) It has good mechanical properties, such as good durability, high compressive strength, and processability.

(5) Reasonable price and good economy.

Specific to permanent magnet motors, the application ranges of various types of permanent magnets are as follows:

Ferrite permanent magnets are suitable for situations where the volume, weight and function of the motor are not high, but the economy of the motor is high. In recent years, with the decrease in the price of NdFeB permanent magnets and the increase in the price of magnetic and conductive materials, for the same motor, the use of NdFeB can reduce the size of the motor and the amount of copper and iron materials, sometimes economically. It's a good deal. In many cases, ferrite permanent magnets have a tendency to be gradually replaced by titanium iron boron permanent magnets.

Alnico permanent magnets are suitable for applications where the size, weight and performance of the motor are not high, but the operating temperature exceeds 300°C or where good temperature stability is required and the cost of the motor is not high. The use of Alnico permanent magnets in motors There are very few now.

NdFeB permanent magnets are suitable for situations where the volume, weight and performance of the motor are very high, the operating environment temperature is not high, and the temperature stability of the permanent magnet is not high.

Rare earth cobalt permanent magnets are suitable for situations where the size, weight and performance of the motor are high, the operating environment temperature is high, good temperature stability is required, and manufacturing cost is not the primary consideration.