The magic of the permanent magnet motor is that it uses permanent magnets to generate a magnetic field, which requires neither an excitation coil nor an excitation current. The high power density and efficiency are even more remarkable, and the structure is relatively simple. It is reported that with the continuous advent of high-performance permanent magnet materials and the rapid development of control technology, the application of permanent magnet motors will become more extensive, bringing more and more efficient energy-saving changes, and bringing more positive impact to our society and life.

1. The development history of permanent magnet motor

In the development history of permanent magnet motors, permanent magnet materials play a vital role. As early as more than 2,000 years ago, my country discovered the magnetic properties of permanent magnet materials and applied them to the manufacture of compasses, which played a role that cannot be ignored in the fields of navigation and military affairs.

This has also become one of the four ancient inventions. one. However, it was not until the 1920s that the world’s first electric motor was born, which was a permanent magnet motor in which an excitation magnetic field was generated by a permanent magnet.

However, the permanent magnet material used at that time was only natural magnetite (Fe3O4), and its magnetic energy density was very low, so the motors made were bulky and were soon replaced by electric excitation motors.

Today, with the advent of high-performance permanent magnet materials and the rapid development of control technology, permanent magnet motors have regained their vitality and will play a wider role in various industries, becoming a leader in energy conservation and emission reduction.

With the need for industrial development and the promotion of scientific and technological innovation, people’s research on permanent magnet materials has entered a new stage.

From the ancient compass to the permanent magnet motor in the early 20th century, permanent magnet materials have been accompanying the development of human beings. However, the initial permanent magnet materials are not satisfactory, and the low magnetic energy density limits the further development of permanent magnet motors.

It was not until the 1930s that AlNiCo permanent magnets and ferrite permanent magnets came out in the 1950s that this problem was solved to a certain extent. But they are still too limited to meet the needs of higher power and smaller size motors.

Until the 1960s and 1980s, the appearance of rare earth cobalt permanent magnets and neodymium iron boron permanent magnets completely changed the appearance of permanent magnet motors.

These two permanent magnet materials have excellent magnetic properties such as high remanence density, high coercive force, high magnetic energy product, and linear demagnetization curve, which greatly expands the application range of permanent magnet motors.

Therefore, we can say that the advent of rare earth permanent magnets marks that permanent magnet motors have entered a new historical period, and also indicates that permanent magnet motors will have a broader future.

Characteristics and application of permanent magnet motor

Permanent magnet motors, especially rare earth permanent magnet motors, are a clear stream in the field of motors. Compared with traditional electric excitation motors, permanent magnet motors are not only simple in structure and reliable in operation but also small in size, light in weight, low in loss, and high in efficiency.

Therefore, permanent magnet motors are widely used in aerospace, national defense, industrial and agricultural production, and even in daily life.

Now, let’s take a look at the main characteristics of several typical permanent magnet motors and their main applications. First of all, the rare earth permanent magnet generator is a good choice. Compared with the traditional generator, it does not need a collector ring and a brush device, which not only simplifies the structure but also reduces the failure rate.

More importantly, the use of rare earth permanent magnets can also increase the air gap magnetic density, so that the motor speed can be increased to the optimum value, thereby improving the power-to-mass ratio.

Modern aviation and aerospace generators almost all use rare earth permanent magnet generators, such as 150 kVA 14 poles 12000 r/min ~ 21 000 r/min and 100 kVA 60000 r/min rare earth cobalt permanent magnet synchronous generators manufactured by General Electric Company of the United States.

Rare earth permanent magnet motors have a wide range of applications, from the textile and chemical fiber industry to coal mine transportation machinery, and then to the automotive field, everywhere. According to statistics, about 70% of vehicles use rare earth permanent magnet motors, and luxury cars are equipped with more than 70 sets of motors.

In the future, auto parts such as air conditioners, fans, and electric windows will also use motor magnets, while ignition coils, drives, and sensors will still use Sm-Co sintered magnets.

In addition, the application fields of rare earth permanent magnet motors are still expanding, such as the support in the frequency conversion and speed regulation system of small power rare earth permanent magnet synchronous motors for new air conditioners and refrigerators, and cordless electric gadgets for various rare earth permanent magnet DC micromotors.

The advantage of rare earth permanent magnet materials lies in their high performance and wide application fields, especially in the field of aerospace, which has important development prospects. Although the application of rare earth permanent magnet motors in the air is also involved, its main application direction is a new generation of aero engines.

However, high cost is still a challenge for rare-earth permanent magnet motors, while ferrite permanent magnet motors have been widely used because of their simple structure, lightweight, and lower total cost than electrically excited motors. However, on some special occasions, such as voice coil motors of computer disk drives, the use of NdFeB permanent magnet materials can improve performance, and reduce volume and quality, thereby reducing overall cost.

When designing and selecting motors, factors such as performance, price, and cost should be considered comprehensively, and innovation and design optimization should be carried out to achieve wider applications.

Types of permanent magnet motors

Compared with traditional electric excitation motors, permanent magnet motors have many advantages such as simple structure, reliable operation, small size, lightweight, low loss, and high efficiency. Even better, they can be flexibly molded into various shapes and sizes. In contrast, ordinary motors require current to maintain a magnetic field.

However, there is more than one type of permanent magnet motor. They also have permanent magnet DC motors， Asynchronous starter permanent magnet synchronous motors, permanent magnet brushless DC motors, speed regulating permanent magnet synchronous motors, and permanent magnet synchronous generators, etc.