Micro motor refers to the principle, structure, performance, function and so on are different from the conventional motor, and the volume and output power are very small motor. In general, the outer diameter of the micro motor is not greater than 130mm, and the power is between hundreds of milliwatts and hundreds of watts. It has been widely used in military and civil modern equipment and its control system, such as artillery control, missile guidance, aircraft automatic piloting, CNC machine tools, shuttleless loom control, industrial sewing machine control, telemetry and remote control, audio and video equipment, automatic instruments and computer peripherals, etc., all of which use a large number of micro motors.
Today, in practical applications, micro motors have been developed from the past simple starting control, the purpose of providing power, to the precise control of its speed, position, torque, etc., especially in industrial automation, office automation and home automation, almost all use motor technology, microelectronics technology and power electronics technology combined mechatronics products. Electronization is an inevitable trend in the development of micro motors.
2 Application field of micro motor（hollow cup motor)
Modern micro motor technology integrates a number of high and new technologies such as motors, computers, control theory, and new materials, and is moving from military and industrial to daily life. Therefore, the development of micro motor technology should be adapted to the development needs of pillar industries and high-tech industries. Micro motor is mainly used in the following aspects:
2.1 Micro special motors for home appliances
In order to continuously meet user requirements and adapt to the needs of the information age, to achieve energy saving, comfort, networking, intelligence, and even network home appliances (information home appliances), the replacement cycle of home appliances is very fast, and the requirements of high efficiency, low noise, low vibration, low price, adjustable speed and intelligence are put forward for the supporting motor. Micro motors for household appliances account for 8% of the total number of micro motors: including air conditioners, washing machines, refrigerators, microwave ovens, electric fans, vacuum cleaners, dewatering machines, etc.
The world's annual demand for 450 to 500 million units (sets), such motor power is not large, but a wide variety. The development trends of micro motors for home appliances are: ① permanent magnet brushless motors will gradually replace single-phase asynchronous motors; ② Optimize design, improve product quality and efficiency; ③ Adopt new structure and new technology to improve production efficiency.
2.2 Micro motor for information processing equipment
Information processing equipment with micro motors accounted for 29%: including information input, storage, processing, output, conduction and other links, including communication equipment. The world needs 1.5 billion (sets) per year, mainly permanent magnet DC motors, brushless DC motors, stepper motors, micro synchronous motors and so on. Microcomputer (PC) annual output of about 100 million units in 2000,2005 is expected to be 200 million units, for its supporting key components of the micro-motor demand, increasingly high requirements. Most of these motors are precision permanent magnet brushless motors and precision stepper motors.
Their characteristics and development directions are:
(1) High investment products This type of motor has very high requirements for the stability of the speed and the runout of the rotating shaft, so this type of motor is a combination of advanced manufacturing technology and emerging power electronics technology of high-tech, high investment products, generally concentrated in the international development and production of large companies.
(2) Miniaturization and flaky In order to meet the needs of miniaturization and portability of information products, miniaturization and flaky requirements are put forward for their supporting motors.
(3) High speed With the continuous improvement of the storage density of computer peripherals, it is required that the supporting motor speed should be above 8000r/ min.
2.3 Micro motor for automobile
Micro motors for automobiles accounted for 13%, including starter generators, wiper motors, motors for air conditioning and cooling fans, electric speedometers, window lifters and door lock motors. In 2000, the world's automobile production was about 54 million, with an average of 15 motors per vehicle, and 810 million were needed worldwide.
Automotive micro motor technology development focus:
(1) High efficiency, high force, energy saving through high-speed, high-performance magnetic material selection, high efficiency cooling means and improve the efficiency of the controller and other measures to improve its operation efficiency.
(2) Intelligent to achieve intelligent motor and controller of the car, so that the car runs in the best state, to achieve the minimum energy consumption.
2.4 Micro motor for audio equipment
Audio equipment with micro motors accounted for 18%, including record players, recorders, VCD and DVD video discs. Worldwide demand is more than 1 billion units per year. At present, the domestic production has accounted for about 60%, mainly printed winding motor, winding disk motor and so on.
2.5 Micro motor for video equipment
Video equipment with micro motors accounted for 7%, including cameras, cameras and so on. The world's annual demand in 350 to 400 million units (sets), such motors are precision, manufacturing and processing is difficult, especially after entering the digital, the motor put forward more demanding requirements.
2.6 Micro motor for industrial electric drive and control
This kind of micro motor accounts for 2%, including CNC machine tools, manipulators, robots, etc. Mainly for AC servo motor, power stepper motor, wide speed DC motor, AC brushless motor and so on. This kind of motor has many varieties, high technical requirements, and is a class of motor with faster domestic demand.
2.7 Special purpose micro motor
This type of motor accounts for about 23%, including aerospace flight, various aircraft, automated weapons and equipment, medical equipment and so on. Such motors are mostly special motors or new motors, including motors that are different from the general electromagnetic principle in principle, structure and operation mode, mainly low-speed synchronous motors, harmonic motors, limited Angle motors, ultrasonic motors, microwave motors, capacitive motors, electrostatic motors, etc. Among them, ultrasonic motor, microwave motor, capacitive motor and electrostatic motor are special motors which are different from general motors in principle, structure and operation. The emergence and development of these motors are closely related to the development of electronic technology and control technology.
3 Micro motor new product technology
With the continuous progress of science and technology and the new requirements of practical applications, there have been a variety of micro-special motors that are different from traditional electromagnetic motors. They adopt novel design concepts, methods, structures and principles.
3.1 Permanent magnet brushless motor
Brushless motor is the development direction of micro motor, which has been applied in the fields of information, home appliances, audio and video, transportation and so on. With the rapid development of permanent magnet materials and power electronics technology, performance continues to improve, the price continues to decrease, brushless motor will be further developed, the demand will be more and more large, compared with the general asynchronous motor, the new brushless motor power consumption decreased by 30% ~ 35%, to meet the requirements of high efficiency, energy saving, small, light weight.
Although the cost price of brushless motors is higher than that of asynchronous motors, due to small power consumption, high efficiency and reduced operating costs, from the point of view of energy conservation, the popularity of brushless motors is bound to be the trend of The Times. The world's major companies have launched a fierce competition in the field of brushless motors. Therefore, with the improvement of the performance of components and materials, the performance of brushless motors will also be greatly improved, and the speed competition of technology development will be more prominent.
3.2 Ultrasonic motor
ultrasonicmotor (ultrasonicmotor, ultrasonicmotor, Abbreviation USM) is the use of the inverse piezoelectric effect of piezoelectric materials, so that the elastic body (stator) in the ultrasonic frequency band to produce microscopic mechanical vibration (vibration frequency above 20kHz), through the friction between the stator and the rotor (or movable), the stator's microscopic vibration into the rotor (or movable) macro single-direction rotation (or linear motion). It breaks the concept of the traditional motor that the speed and torque are obtained by the electromagnetic effect, and is another remarkable new technology in the development of micro motor technology.
Compared with the traditional motor, ultrasonic motor has a series of advantages: (1) simple structure, it is composed of two basic components: vibration parts and moving parts; (2) the unit volume torque is large, which is 10 times that of the traditional motor of the same volume; (3) Low speed performance is good, the speed can be adjusted to zero, can directly output large torque at low speed; (4) Large braking torque, no additional brake is required; (5) Small mechanical time constant, good fast performance; (6) No magnetic and electric fields, no electromagnetic interference and electromagnetic noise.
At present, many companies in some foreign countries such as Japan have obtained commercial practical application. New products of ultrasonic motors from Canon, Panasonic, Hitachi and other companies have been used in advanced cameras, camcorders, and optical instruments. The development direction of ultrasonic motor technology is to further improve efficiency.
Ultrasonic motor adopts a new principle and structure, does not need magnets and coils, but uses the inverse piezoelectric effect of piezoelectric materials and ultrasonic vibration to directly obtain motion and force (moment). It breaks the concept of the motor that the speed and torque are obtained by the electromagnetic effect so far, and is a high-tech technology at the forefront of the current world science. Due to ultrasound, the motor has many characteristics that the electromagnetic motor does not have, although its invention and development is only 20 years of history, but in aerospace, robotics, automobiles, precision positioning, medical equipment, micro machinery and other fields have been successfully applied.
3.3 High-speed dynamic pressure bearing motor
With the development of information products in the direction of high efficiency, high density and micro thin, the precision permanent magnet brushless motor supporting it has a speed of up to 8000 ~ 50000r/ min. The bearings of high-speed motors will also replace traditional plain bearings with dynamic pressure bearings to overcome many technical problems caused by high speed. Compared with ball bearing and plain bearing, dynamic pressure bearing has many advantages. It can inhibit irregular shaft swing, improve impact resistance, long life, low noise and so on.
Dynamic pressure bearing motor has two types of fluid and air, the general speed is low with fluid dynamic pressure bearing, high speed with air dynamic pressure bearing. Although there are still some technical problems to be further solved, the development direction of high-speed dynamic pressure bearing motors has been generally confirmed.
3.4 Linear Motor
With the rapid development of automatic control technology, the positioning accuracy requirements of various automatic control systems are getting higher and higher, and the traditional rotary motor coupled with a set of transformation mechanism composed of linear motion devices can not meet the accuracy requirements, direct linear drive is one of the contents of modern servo drive technology research, linear motor is one of the key technologies. The application field of linear motor is also wide, in the need for linear motion of the device, the use of direct drive linear motor will be superior to the rotary motor. The control precision can be improved because the motion transformation mechanism is omitted.
3.5 Supermicro motor
Micro motor technology is a new high-tech field of micro-electromechanical system technology (MEMS) developed in the past 20 years, which is characterized by micro-machining technology based on semiconductor material silicon, used to manufacture devices with energy conversion and transmission functions in the size range from millimeter to micron. The emergence of MEMS technology has made a revolutionary leap in traditional mechanical manufacturing technology.
Ultramicromotor has the electrostatic principle of ultramicromotor and electromagnetic ultramicromotor, because the electromagnetic ultramicromotor is larger than the electrostatic ultramicromotor torque, high conversion efficiency, long life, it has been applied in many fields such as endoscopes, microrobots and so on. At present, the United States, Japan, Russia, Germany and other countries have invested a lot of manpower, material and financial resources to carry out the research and application of this technology, and have made great progress, and some have reached practical. For example, Japan Toshiba company developed a weight of 40mg, speed 60 ~ 1000r/ min, voltage 1.7V, diameter of only 0.8mm in the world's smallest micro motor, such as Shanghai Jiao Tong University is also developing a diameter of 1mm micro motor. It can be expected that with the development and application of nanofabrication technology, supermicro motors will also be greatly developed, so that they have more application fields.
3.6 Molecular Motor
Appeared with the development of MEMS, nano electrical system (na2noelectromechanicalsystems, NEMS), feature sizes may be from a few hundred to a few nanometers, some of which have important potential applications in biomedical field. RickyK. Soong et al. from Cornell University in the United States integrated a single biomolecular motor with a nanoscale inorganic system to form a hybrid nanomechanical device driven by a molecular motor. By hydrolyzing ATP(adenosine triphosphate) in an active system, the biomolecular (less than 8nm in diameter and 14nm in length) motor is capable of generating a maximum torque of 80 to 100pN·nm, compatible with the size and mechanical constants of nanomechanical structures that can be produced today. This new technology is expected to play a role in blood vessel cleaning.
4 micro motor development trend
After entering the 21st century, the sustainable development of the world economy is facing two key issues ———— energy and environmental protection, on the one hand, the progress of human society, people have higher and higher requirements for the quality of life, and the awareness of environmental protection is becoming stronger and stronger, because the micro motor is not only used in industrial and mining enterprises, but also used in commercial and service industries, especially more products have entered the family In the live, so the safety of the motor directly endangers the safety of personal property; The vibration, noise and electromagnetic interference of the motor will become the public hazard of polluting the environment. The efficiency of the motor is directly related to energy consumption and harmful gas emissions, so the international requirements for these technical indicators are more and more stringent, has attracted the attention of the motor industry at home and abroad, from the motor structure, process, materials, electronic components, control lines and electromagnetic design and other aspects of energy conservation research, micro motor new round of products in the basis of excellent technical performance On the other hand, it will implement relevant international standards for the purpose of energy saving and environmental protection, and promote relevant technological progress, such as new motor stamping, winding design, ventilation structure improvement and low loss and high permeability magnetic materials, rare earth permanent magnet materials, noise and vibration reduction technology, power electronics technology, control technology, reduce electromagnetic interference technology and other application research.
Under the premise of accelerating the trend of economic globalization, countries pay more attention to the two major issues of energy saving and environmental protection, strengthen international technical exchanges and cooperation, and accelerate the pace of technological innovation, the development trend of micro motor technology is: (1) adopt high and new technology and develop in the direction of electronic; (2) High efficiency, energy saving and green development; (3) To high reliability, electromagnetic compatibility development; (4) To low noise, low vibration, low cost, price development; (5) To specialized, diversified, intelligent development.
In addition, micro motor is modularization, combination, intelligent mechatronics direction and brushless, no iron core, permanent magnetization direction, especially noteworthy is that with the application of micro motor, the environment changes, the traditional electromagnetic principle of the motor can not be fully satisfied. With the new achievements of related disciplines, including new principles and new materials, the development of micro-special motors with non-electromagnetic principles has become an important direction of motor development.
