Is well known, the DC motor having a superior speed performance, speed convenient mainly in (infinitely speed), wide speed range, low-speed performance (high starting torque, starting current), smooth operation, low noise, High efficiency, application occasions from industrial to civilian (such as home appliances, cars, etc.) are extremely widespread. However, it is very efficient nor rotor losses, the rotor speed strictly synchronized with the power frequency, to the field generated by the rotor brushless DC motor <> high power factor by using a permanent magnet. Magnets now use rare earth permanent magnet materials. The storage of rare earth materials in China accounts for about 70% of the world's storage . The development of permanent magnet type '> brushless DC motors is a resource advantage that we should give full play to. This kind of motor is widely used at present. In the feed drive of CNC machine tools, the servo drive of robots and the variable-speed drive of new generation home appliances , the application prospects are very promising due to the high-efficiency, wide-range, and high-precision speed control performance of the variable-frequency speed control methods.
Permanent magnet brushless DC motor speed control system generally used in the drive voltage source Pulse Width Modulation (PWM) AC - DC - AC inverter. The merits of the inverter performance, a look at the impact of its harmonic output AC voltage of the motor: the motor heating caused by harmonics, increase energy consumption, caused by electromagnetic and mechanical noise. Second, we must look at the harmonic pollution of the power grid and the input power factor. These two aspects are particularly important for the application of a wide range of household appliances. It is directly related to the energy saving, the impact of noise on the environment and the pollution of the power grid . PWM AC - DC - AC frequency converter composed of high switching frequency self-turn-off devices plus reasonable control can achieve higher performance.
As far as the system controller is concerned, because the motion control system is a rapid system, especially the high-performance control of the AC motor requires real-time rapid processing of a variety of signals, in order to further improve the overall performance of the control system, in recent years, some large foreign companies have introduced MCU superior performance compared to a DSP (digital signal processor) monolithic motor controllers, such as the series of ADI ADMC3xx, TI's TMS320C24 DSP56F8xx series and Motorola's family. All of these are based on a DSP -based core and are equipped with peripheral functional circuits required for motor control. They are integrated in a single chip, which greatly reduces the price, reduces the size, and has a compact structure, convenient use, and improved reliability. Great speed up to now the DSP 20 ~ 40MIPS above, instruction execution time or completion time of a quick action of tens of nanoseconds, as compared to its ordinary MCU, computing and increased processing power of 10 to 50 times, to ensure that the system has more Superior control performance.
In summary, the permanent magnet brushless DC motor is equipped with a high-speed high-speed real-time digital controller. The system control is relatively simple, low cost, high efficiency and energy saving, stable speed, low noise, energy-saving green products, especially suitable Applied in home appliances products. It can also be extended to other industrial applications such as machine tools, robots and elevator drives.
My country is one of the world's major production and sales of household electrical appliances market, our appliances in the past 20 years has been rapid development, some company's products have become well-known international brands. From 1998 to today the rapid development of inverter air conditioner, began to develop a DC brushless motor by the AC induction motor variable frequency. In 2000 , sales of air conditioners in China were 11 million units, of which inverter air conditioners sold nearly 1 million units. The DC process of air conditioners in China is rapidly progressing. Through the prediction of domestic and foreign markets, China will use 5 million permanent magnets in 3 to 5 years , and DC brushless motors can achieve higher speeds within a larger speed range. Efficiency, more suitable for the needs of home appliances, Japan's inverter DC full DC production has already been mass production, China's inverter compressor manufacturers have begun to use DC brushless motor to replace the three-phase AC induction motor, in the next two years will appear permanent magnet Toilet brush dc motor compressor.
In 2000 sales of refrigerators for the 1100-1200 million, of which sales of brushless DC motor using refrigerator for 10-15 million units this kind of refrigerator 24 hours of power consumption (0 to 58 degrees) than the same models Ordinary refrigerator (0 to 70 degrees ) less 15% .
In 2000 sales of washing machines in our country is 11 million units, the second half of the year the country introduced the use of a washing machine brushless DC motor, smooth operation of the kind of washing machine, to achieve a smooth start, acceleration and deceleration braking, washing dehydration stepless variable speed, from Cashmere to denim, different clothes, different speeds, different washing methods. Compared with ordinary washing machines, the noise is reduced by 10 decibels, saving 50% of electrical energy and saving 20% of water . The sales of this type of washing machine in 2001 will be greatly increased.
In addition to the above home appliance products, permanent magnet brushless DC motors can also be used for electric bicycles, electric cars, elevators, range hoods, soya-bean milk makers, small cleaning machines, CNC machine tools, and robots.
Requirements for high-performance motor of a needle of refrigerators, air conditioners, washing machines and other new appliances, in particular a permanent magnet brushless DC motor all the advantages of the new permanent magnet brushless DC permanent magnet motor, high efficiency, large starting torque, starter current, low noise, no mechanical commutator, a long working life, particularly easily adjusted, can be variable speed, especially for consumer products, in addition, it can be used as a servo motor for controlling industrial occasions .
At present, there is no big difference between the stator and rotor structure of the brushless DC motor and the conventional DC motor. Since the cost of the electronic commutation circuit is higher than that of the mechanical commutator, the cost and the selling price of the brushless DC motor are increased, thus limiting the Its application. In particular, the current application of DC motors has expanded to the field of consumer products, and the price of brushless DC motors is a major factor limiting their application.
Aiming at the increasing demand for low-cost brushless DC motors in the automotive industry, home appliance industry and office automation industry at home and abroad, the new permanent magnet brushless DC motor is designed to provide a simple structure and easy manufacture. The brushless DC motor with reliable performance, convenient control and low cost can be applied to the fields of industrial control and various civil products.
(1) The motor can be steplessly speed-regulated, and the working speed range is very large, which can meet the speed requirements under various operating modes. Because the DSP chip is used to integrate the driver and the controller in one, the user can easily program on the driver to achieve various speed changes and even positioning actions.
(2) Brushless DC motors can work at ultra-low speeds, which exceeds the performance of AC drives, so new brushless DC motors can completely replace low-power AC drives.
(3) The brushless DC motor has a large starting torque and is almost unaffected by the fluctuation of the power grid voltage.
(4) Brushless DC motors are more efficient than AC frequency conversion systems.
(5 ) The temperature rise of the brushless DC motor is lower, and the temperature rise can be about 30% lower than that of the AC motor with the same power . Therefore, the life of the brushless DC motor is much higher than that of the AC motor.
(6) Brushless DC motor noise is low. |