1, fixed-speed drive
Industrial and agricultural production, there are a large number of production machinery required to run continuously in a single direction at a roughly constant speed, such as fans, pumps, compressors, general machine tools and so on. In the past, most of these machines were driven by three-phase or single-phase asynchronous motors. Asynchronous motor cost is low, the structure is simple and reliable, easy to maintain, very suitable for this type of mechanical drive. However, asynchronous motor efficiency, low power factor, loss, and the use of such motors in a wide range of large quantities, so there is a large amount of power in use is wasted. Secondly, agriculture and industry in the use of a large number of fans, pumps often also need to adjust the flow, usually by adjusting the dampers, valves to complete, which wasted a lot of power. 70 years, people use frequency converters to adjust the fans, pumps in the asynchronous motor speed to regulate the flow of their considerable energy-saving effect, but the cost of the frequency converter to limit the use of its own asynchronous motor, and the low efficiency still exists. Low efficiency still exists.
For example, household air-conditioning compressor originally used single-phase asynchronous motor, switching control of its operation, noise and higher temperature variation is its shortcomings. the early 1990s, Japan's Toshiba first in the compressor control of asynchronous motor speed control, the advantages of frequency conversion speed control to promote the development of frequency conversion air conditioning. In recent years, Japan's Hitachi, Sanyo and other companies began to use permanent magnet brushless motors to replace the asynchronous motor frequency regulation, significantly improving efficiency, obtaining better energy saving and further reducing the noise, in the same rated power and rated speed, set the volume and weight of the single-phase asynchronous motor to be 100%, then the volume of the permanent magnet brushless DC motors for the volume of 38.6%, the weight of 34.8%, and the amount of copper used is 20.9%. The amount of copper is 20.9%, the amount of iron is 36.5%, the efficiency is increased by more than 10%, and the speed control is convenient, the price and asynchronous motor frequency control is comparable. Permanent magnet brushless DC motor in the air conditioning applications to promote the upgrading of air conditioning agent.
Re-such as instrumentation and other equipment used in large quantities on the cooling fan, in the past are used in single-phase asynchronous motor external rotor structure of the drive, it is large in size and weight, low efficiency. In recent years it has been completely replaced by permanent magnet brushless DC motor driven brushless fan. In modern times, brushless fans are used without exception on a variety of rapidly developing information equipment such as computers. Over the years, the use of brushless fan has formed a complete series, a variety of specifications, frame size from 15mm to 120mm *** there are 12 kinds, frame thickness of 6mm to 18mm *** 7 kinds, voltage specifications of DC 1.5V, 3V, 5V, 12V, 24V, 48V, the speed range from 2100rpm to 14,000rpm, is divided into a low-speed, medium speed, High speed and ultra-high speed 4 kinds, life expectancy of more than 30,000 hours, the motor is a permanent magnet brushless DC motor with external rotor.
In recent years, practice shows that in the power is not greater than 10kW and continuous operation of the occasion, in order to reduce the size, save materials, improve efficiency and reduce energy consumption and other factors, more and more asynchronous motor drive is being permanent magnet brushless DC motor gradually replaced. In the occasion of larger power, due to a larger cost and investment, in addition to permanent magnet materials, but also a larger power drive, so there are fewer applications.
2, speed drive
There are quite a lot of work machinery, its operating speed needs to be arbitrarily set and adjusted, but the speed control accuracy requirements are not very high. This type of drive system in packaging machinery, food machinery, printing machinery, material handling machinery, textile machinery and transportation vehicles have a large number of applications.
In this type of speed applications initially used the most DC motor speed control system, after the 70's with the development of power electronics and control technology, asynchronous motor frequency control quickly penetrate into the original DC speed control system applications. This is because on the one hand, asynchronous motor frequency control system performance and price can be fully comparable with the DC speed control system, on the other hand, asynchronous motors and DC motors compared with a large capacity, high reliability, low interference, long life and other advantages. Therefore, asynchronous motor frequency control in many occasions quickly replaced the DC speed control system.
AC permanent magnet synchronous motor due to its small size, light weight, high efficiency and energy saving and a series of advantages, more and more people pay attention to its control technology is becoming more mature, the controller has been productized. Small and medium power asynchronous motor frequency control is gradually replaced by permanent magnet synchronous motor speed control system. Elevator drive is a typical example. The drive system of elevator has certain requirements for acceleration, speed stabilization, braking and positioning of the motor. In the early days, people used DC motor speed control system, and its shortcomings are self-evident. 70's inverter technology development is mature, asynchronous motor inverter speed control drive quickly replaced the DC speed control system in the elevator industry. In these years, the latest drive technology in the elevator industry is the permanent magnet synchronous motor speed control system, which is small in size, energy-saving, good in control performance and easy to be made into low-speed direct drive, eliminating the gear reducer; its low noise, leveling accuracy and comfort are better than the previous drive system, and it is suitable to be used in the elevator without machine room. The permanent magnet synchronous motor drive system will soon be favored by major elevator companies, and its supporting special inverter series products have been listed in a variety of grades. It can be foreseen that in the occasion of speed regulation drive, it will be the world of permanent magnet synchronous motor. Japan's Fuji has launched a series of permanent magnet synchronous motor products with frequency converter controller, power from 0.4kW ~ 300kW, volume than the same capacity asynchronous motor is smaller than 1 ~ 2 seat number, the force energy index is significantly higher than the asynchronous motor can be used for pumps, transport machinery, mixers, winches, lifts, cranes, and other occasions we.
3, precision control drive
① High-precision servo control system
Servo motors in the field of industrial automation play a very important role in the operation and control of the application of different occasions on the control performance of servo motors are not the same requirements. In practice, servo motors have a variety of different control methods, such as torque control/current control, speed control, position control and so on. Servo motor system has also experienced the DC servo system, AC servo system, stepper motor drive system, until the most notable permanent magnet motor AC servo system in recent years. In recent years, the import of various types of automation equipment, automatic processing equipment and robots, the vast majority of permanent magnet synchronous motor AC servo system.
② information technology permanent magnet synchronous motor
Today's information technology is highly developed, a variety of computer peripherals and office automation equipment is also highly developed, and its supporting key components of the micro-motor demand, precision and performance requirements are increasingly high. Requirements for such micro-motor is miniaturization, thin, high-speed, long life, high reliability, low noise and low vibration, precision requirements are particularly high. For example, hard disk drive spindle drive motor is a permanent magnet brushless DC motor, it is nearly 10,000 rpm high speed drive disk rotation, disk on the implementation of the data read and write function of the magnetic head from the disk surface is only 0.1 ~ 0.3 microns for the suspension of the movement, the high precision requirements can be imagined. Information technology in a variety of equipment such as printers, floppy disk drives, CD-ROM drives, fax machines, copiers, etc. The vast majority of drive motors used in the permanent magnet brushless DC motors. Restricted by the level of technology, these micro-motors can not be manufactured at home, some of the products in the domestic assembly.