ã€China Aluminum Industry Network】Cixi Fei Nade Electrical Appliance Factory (referred to as “Finnard Electricâ€) is a company specializing in the production and sales of motor protectors, power protection relays, and phase sequence relays. The main products are: three-phase power protection, motor protection, phase protection, phase failure protection, phase and phase sequence protection, three-phase overload protection, intelligent motor protection, microcomputer motor protection, motor Comprehensive protector, power protection relay, surge protector, thermostat, explosion-proof switch, explosion-proof control box, escalator synchronization rate tester, stand-alone automotive air conditioning controller, automotive fan stepless speed regulator, boiler liquid level meter Etc., supporting the major domestic elevator plants, thermal power plants, and automobile plants
As the main electromechanical energy conversion device, the motor protector has been applied to various fields of the national economy and people's daily life. Whether it is in industrial and agricultural production, transportation, national defense, aerospace, medical and health, business and office equipment, or household appliances and consumer electronics products (such as refrigerators, air conditioners, DVDs, etc.) in daily life, they are used in large quantities. A variety of electric motors. According to statistics, over 90% of all power resources come from electric motors. Similarly, 60 percent of the electricity produced in China is used for electric motors. The motor is closely related to people's life. In the electric age, the speed control of electric motors generally adopts simulation methods, and there are many applications for the simple control of electric motors. Simple control refers to starting, braking, forward and reverse control and sequential control of the motor. This type of control can be implemented with relays, programmable controllers and switching elements. There is also a class of control called complex control, which refers to the control of the physical quantities such as the rotational speed, rotation angle, torque, voltage, current, and power of the motor.
The development history of DC motor control There are several kinds of commonly used DC motors for control: In the front, the earlier DC speed control system uses a constant DC voltage to supply power to the armature of the DC motor, and the adjustment is achieved by changing the resistance in the armature circuit. speed. This method is simple and easy to manufacture equipment, low prices. However, the disadvantages are that it is inefficient, its mechanical properties are soft, and it is not possible to smoothly regulate the speed in a wide range, so it is rarely used at present.
In the second and the late thirties, generator-motors (also known as rotating converters) emerged. Using magnetic amplifiers, motor amplifiers, thyristors, and other control devices, excellent speed control performance was achieved. Wide speed range (ten to one to several tens to one), small speed change rate, smooth speed regulation, etc. Especially when the motor is decelerating, the flywheel inertia on the motor shaft can be easily feedbacked by the generator. To the power grid, on the one hand, smooth braking characteristics can be obtained, on the other hand, energy losses can be reduced and efficiency can be improved. However, the main disadvantage of the generator and motor speed control system is the need to increase the number of rotary motors and some auxiliary excitation equipment that are equivalent to the speed control motor, which is large and difficult to maintain.
With the advent of microcomputers, ultra-large-scale integrated circuits, new types of electronic power switching devices and new sensors, as well as the in-depth development of automatic control theory, power electronics, and computer control technologies, DC motor control devices have also continued to evolve. The application of the microcomputer makes the DC electric drive control system tend to be digitized and intelligent, which greatly promotes the development of the electric drive. In recent years, some advanced countries have successively introduced and used a large number of direct-current electric drives with a microcomputer as their control core, such as Siemens' SIMOREG K 6RA24 and ABB's PAD/PSD. With the acceleration of modernization and the continuous improvement of people’s living standards, the demand for automation is also increasing, and the application of DC motors is also expanding.
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