The world's oldest motor prototype is a permanent magnet motor

- Nov 09, 2017 -

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The world's first prototype motor is a permanent magnet motor, when the performance of the permanent magnet material is poor, and accounted for by the electromagnetic motor mainstream. Alnico permanent magnets come out so that the development of permanent magnet motor, but its relatively high price, Alnico permanent magnet motor is not widely used. Since the advent of inexpensive ferrite magnets, the application of permanent magnet motors has increased dramatically. Applications have ranged from toy motors, audio-visual motors, automotive micromotors to industrial low-power drives and servo drives. According to statistics, below 500W in permanent magnet motor permanent magnet motor accounted for more than 92%, of which the vast majority of ferrite permanent magnet motor. Ferrite used to date, but its poor magnetic properties, not suitable for high-performance motor needs, appeared in the 20th century, 60 rare earth samarium cobalt permanent magnet, the maximum energy product is AlNiCu four times, is more than five times the ferrite . Samarium cobalt permanent magnets appear to enable high-performance servo motor to achieve?

But samarium cobalt permanent magnet price is too high, limiting its application. The 20th century, 80 appear neodymium iron boron permanent magnet materials,

Working temperature and magnetic temperature coefficient less than the SmCo permanent magnet, the other properties are more than SmCo, NdFeB permanent magnet far lower than the SmCo price. The emergence of high-performance permanent magnets and the continuous improvement of their performance will cause tremendous changes in the motor industry. A variety of servo motors are expected to be DC and AC, the final stepper motor will eventually transition to permanent magnet motor, in the field of application of AC induction motor is eventually to be replaced by various types of permanent magnet motor.

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1, economic permanent magnet DC motor

Micro-permanent magnet DC motor to economical and high-performance type in both directions. The so-called economic, mainly refers to the audio equipment, such as micro-DC micro-motor, such as all kinds of recorders, VCRs, combo audio, record player, Walkman, radios, CD players, digital laser disc players and car audio. It is characterized by a large number of low prices, generally only a few dollars each. Japan's Mabuchi company is the world's largest producer of permanent magnet DC motors business, annual production of billions of units. However, the appreciation of the yen, Japan basically do not produce such a motor local, most of the transfer of mainland China and Southeast Asian countries. Its output accounted for the vast majority of the Company. At present, the output of economical miniature DC motors in domestic enterprises is 200 million units, while the output of wholly-owned enterprises is estimated at about 1 billion units. The production of economical miniature DC motors in mainland China accounts for the vast majority of the total amount in the world. This economical motor technically difficult, production must have a scale, with an annual output of 1 million level is not enough, we must reach tens of millions of output orders of magnitude, huge investment in equipment.

Economic development trend of DC motor is the development of its requirements, such as audio motor, the whole motor is the pursuit of smaller, ultra-thin, high-speed, high precision and low noise to meet their needs. The development trend of this type of motor is:

⑴ flat light and small. Such as tape recorders ?, record players, Walkman, tape recorders and other equipment, sheet motor favored.

⑵ brushless. Such as video recorders, drums and spindle motor put forward higher requirements, and it is to ensure the quality of key components, most of them are now using brushless DC motor to improve operational reliability, high efficiency and reduce noise.

⑶ high speed. 2000 Japan small motor seminar and exhibition, Sanjia, Canon, Panasonic and other companies have exhibited DVD spindle motor, CD-ROM motor, speed 2000r / min or more, to overcome the high-speed bearing and noise problems, the use of The dynamic pressure bearing structure. Compared with ball bearings, the use of air and oil hydrodynamic bearings are improved in terms of volume, speed, noise and cleanliness, and the production cost is low, and its application fields are gradually expanding.

⑷ high precision. Such as recorder motor steady-state error requirements of not more than 0.75%, the noise is not more than 32dB, shaking less than 0.03%. Another example drum motor is the main part of the drum servo system of video recorder, drum motor requires less torque fluctuations, low noise, high mechanical installation accuracy, good dynamic characteristics. The requirements of the DVD spindle motor and the disc with the motor end turntable machining accuracy and high precision, turntable end beating not more than 20μm. It is an inevitable trend in the future to require miniature permanent magnet motors to be more precise.

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2, high-performance rare earth permanent magnet DC motor

Rare earth permanent magnet materials research and development of the development of micro-motor has played a significant role in promoting. The United States, Japan and Western Europe and other developed countries, rare earth permanent magnet motor applications accounted for more than 60% of total sales of rare earth permanent magnet. Rare earth permanent magnet materials with high remanence and coercivity and magnetic energy product, and has good dynamic response characteristics, especially for high performance micro-motor.

Isotropic NdFeB bonded permanent magnets have some favored advantages favored by producers and users, such as from electricity

Machine producer perspective, the advantages of this bonded permanent magnet are:

⑴ size, weight, performance than bonded ferrite several times;

⑵ artifacts in the production process is not magnetized, less use of computer peripherals pollution;

⑶ isotropic magnetization can remove the rotor core, reducing rotor inertia and production costs;

⑷ multi-pole motor design high anti-demagnetization capacity;

⑸ Stable motor performance under dynamic load;

⑹Hcj temperature coefficient lower than the anisotropic NdFeB bonded permanent magnet.

Abroad, NdFeB motor applications more and more. German Siemens company with an annual output of CNC machine tools, industrial robots with more than 100,000 permanent magnet motor. In 1995, the western countries produced 3.2 million voice coil motors for computer peripherals and reached 6 million in 2000. General Motors Corporation of the United States for the automotive rare earth permanent magnet motor is extremely optimistic about the development of the company Neodymium Iron boron motor needs up to 200 million units as much. The EC decided to allocate special funds entrusted to the United States Field University developed NdFeB motor. Japan is a large country producing NdFeB permanent magnet, permanent monopoly motor market has been monopolized.

In recent years, a foreign country has developed a small low-speed, high torque motor, even if the HD motor (High? Density? Motor?) It uses high-performance rare earth permanent magnet materials and special magnetic circuit DD motor (Direct? Drive? Motor) Made with a small, high-performance servo drive. Motor for the outer rotor structure, the motor part, bearings, rotor position output part, directly connected with the rotor. HD motor magnetic circuit

In the outer rotor iron core groove embedded in sheet-shaped high-performance rare earth permanent magnet, motor built-in electromagnetic deceleration gear, to achieve low-speed large torque head. Compared with the traditional direct drive motor, the core utilization rate has more than doubled, the output torque is 2 times higher. This motor vertical grinder spindle drive, industrial robots and other fields have a wide range of applications. Rare earth permanent magnet motor development direction is miniaturization and ultra-thin. NdFeB maximum energy product of high, in particular, can be made of ultra-thin, so difficult to do in the past ultra-thin structure motor to achieve. Such as foreign countries with small stereo player, thin VCR flaky brushless DC motor, the entire motor thickness of only 4.3mm, the rotor with NdFeB, the magnetic field for the axial direction, the control part of a printed on the board to achieve a high degree of integration Modular, greatly improving the reliability of the motor.

High temperature, high vacuum and other special circumstances, the application of samarium cobalt permanent magnet motor is still the dominant position. Samarium cobalt permanent magnet with high temperature, low temperature coefficient and corrosion resistance characteristics, aerospace equipment, atomic energy equipment, underwater robots, NC machines and other special occasions widely used. British Muihead? Vaetric company to develop submarine radar wireless drive permanent magnet motor, the insulation level H (180 ℃), the motor with a Hall sensor brushless DC motor, encoder and temperature sensor of three parts, the power of up to 800W, speed 80r / min case, the peak torque of 40N.m. American Simonds precision products company with a small samarium cobalt permanent magnet generator as the aviation ignition system and engine control system power? To meet the stringent requirements of aero-engine vibration and high temperature, F-15 fighter and F-100 jet engines are applied . German Siemens company developed for CNC machine tool feed system drive motor is a SmCo permanent magnet motor. Swiss Interelectric company developed high-performance hollow cup rotor permanent magnet DC motor has S, A, RE, F four series, power from 2.5W to 250W, diameter from 10 ~ 75mm, varieties of thousands, and equipped with precision gears and Encoders, tachometer and other combinations of motor. 

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3, brushless DC motor

Brushless DC motor is a combination of motor technology and electronic technology with the new micro-motor electromechanical integration. It is one of the most promising motors. The main characteristic of brushless DC motor is that it has similar mechanical characteristics to ordinary brush DC motor and must have electronic commutation circuit. Brushless DC motor completely cancel the mechanical commutator and brush, but with the same linear mechanical properties of the traditional DC motor, speed range, starting torque, high efficiency, but also has the following characteristics:

⑴ high reliability, long life, working time mainly depends on the bearing and lubrication, high-performance motor life of up to tens of thousands of hours.

⑵ do not need regular maintenance.

⑶ no electrical contact with sparks, safety, explosion-proof, radio interference small?

⑷ low mechanical noise.

⑸ can work in high vacuum, corrosive gas medium and liquid medium environment, such as aerospace equipment.

⑹ can work at high speed or super speed. There are 100000r / min products.

⑺ Adopt the inside-out structure, the winding stator, easy to heat, the rotor permanent magnet excitation, no winding, almost no loss and fever.

结 combined with electronic circuits, greater flexibility of use. For example: the use of low-power logic control signal can control the motor starting and stopping, reversing or adjusting speed, suitable for digital control, easy to interface with the computer. It is, brushless DC motor industry and home and defense and other fields has been widely used.

The aerospace industry, high vacuum, brushless DC motor advantage is the most obvious. Such as the spacecraft with a variety of pumps, the use of many brushless motor.


Article from NdFeB Industry Network

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