Li Chongjian, the most popular electric drive, put

Li Chongjian: new requirements for intelligent electrical appliances put forward by electric drive energy conservation and efficiency increase

Dr. Li Chongjian, chief engineer of metallurgical automation research and Design Institute, delivered a speech at the "intelligent electrical appliances and equipment manufacturing forum". He mainly talked about several aspects: first, the development history of intelligent technology; 2、 Intellectualization of electric drive system; 3、 Energy saving and intellectualization of motor system; 4、 Electrical equipment for steel production process; 5、 Some problems of motor frequency conversion energy saving

development history of intelligent technology

the intelligent technology we are talking about now is actually Leeb hardness tester, Rockwell hardness tester, Brinell hardness tester, shore hardness tester, shore hardness tester, Babbitt hardness tester, microhardness tester, Mohs hardness tester, Vickers hardness tester, Wechsler hardness tester, etc. it is a generalized intelligent control, which is composed of three parts: detection (instrument), control (computer), execution (power electronics and electrical transmission)

the development of automation technology in China began with industrial reform. From the control of clock and windmill, to the control of steam engine and speed, to astronomical telescope and hydropower generation, and finally to feedback control. From 1940s to 1960s, classical control theory appeared. It is mainly described by mathematical equations. In the 1960s and 1970s, modern control theory appeared, emphasizing nonlinear time-varying systems and time-domain analysis. In 1956, American psychologists, mathematicians, computer scientists and information theorists established intelligent science through joint discussion. Intelligent control emphasizes three points: unstructured, uncertain and highly autonomous

the development of automation system hardware has experienced four stages. The first stage, 1900, began the electrical age; In the second stage, in 1941, the world's first electronic computer, a behemoth, was born; The third stage, simulation system, manual recording; The fourth stage is modern personal computer

at present, power and electronics are facing changes in technology and application. Energy is a major problem facing mankind today, which allows reliable and rapid impregnation of fibers without fiber displacement. Information technology has developed the fastest. Power electronics is the key link of energy conversion and information control. Therefore, power electronics has been highly valued and developed. Now the main problem is that different countries and different fields have different understanding of smart electricity. But in general, it is a very big development opportunity for our electrical industry

intellectualization of electric drive system

with the perfection and maturity of single computer digital control speed regulation system, modern automation system engineering has begun to strengthen the communication with digital speed regulation system. International electric drive products are required to have the function of communication with basic automation system. As the executive part of automation system, electric drive has become the intelligent terminal of automation network with the development of computer technology and automatic control technology. Automation system has been developing continuously in the past 100 years, and relay logic control has gradually developed to programmable control, namely PLC. In addition, chemical and petrochemical instrument control systems have gradually developed into distributed control systems, namely DCS. The electric drive realizes digital speed regulation control, namely DSC. This year, these three control systems began to integrate gradually

fieldbus realizes this kind of joint control. In particular, the recent development of energy interconnection and IOT has provided a development space for the electrical industry. I think there are different understandings of Fieldbus in different industries

now there are companies specializing in Fieldbus exchange, such as Chint electric. The development of these industries needs our careful study

it is particularly worth mentioning that the electric drive system has undergone fundamental changes. Now inside the function cabinet is the computer, which is also intelligent and connected by optical fiber. The electric drive system is constantly intelligent, and then connected with optical fiber. Even though it may only be an ordinary shunt in the eyes of laymen, it is actually a voltage detector

the United States proposed that the interface of the point in the intelligent power module is called PEBB. Further development is the integration of devices (IPM), which integrates power chips and control circuits to meet the requirements of low cost, flexural modulus of elasticity, miniaturization, high reliability and ease of use

intelligent electrical appliances supporting the electric drive system should be electrical equipment with automatic control and information connection functions. There is also intelligent motor. Intelligent motor integrates frequency converter, motor and control system to form an intelligent motor integrating information transmission, energy transformation and motion control

energy saving and intellectualization of motor system

the national development and Reform Commission launched the ten key energy-saving projects proposed in the planning in 2006, among which the fifth one is energy saving of towering motor system. Every year, the state subsidizes about 100 motor system energy-saving projects. The goal of the 11th five year plan is to improve the operating efficiency of the motor system by 2 percentage points and save 20billion kwh of electricity annually (equivalent to the power generation of Two Three Gorges power stations) 。 Energy saving of motor system. I am also a member of motor transformation

this is an overall motor system, which mainly adopts the frequency conversion speed regulation mode to change the running speed of the fan, water pump, compressor and other drive motors, and the efficiency can be increased by 15-30% from the power supply to the transformer, and then realize the fan. This is a generalized stage, which achieves the maximum efficiency with the minimum electric energy. We should constantly adjust the efficiency of the motor system according to the changes of this process. The ventilator of the coal mine was designed 15 years later, and the wind level of this air duct needs 2 kilowatts. After 15 years, it was only 3 kilowatts larger. In the first 15 years, a large number of our fans were used in this way. There is also a change in wind power. The situation is different in summer and winter. But the design is based on the most complex situation

from the perspective of existing problems, there are four points. 1、 At present, the motor system in China has low operating efficiency and high energy consumption, mainly due to the low efficiency of the motor and the driven equipment itself. In addition, the system efficiency is low due to unreasonable system matching and adjustment methods. 2、 The equipment is old and inefficient. Motors, fans, pumps and other equipment are backward, and the efficiency is lower than that of developed countries by an average of percentage points. 3、 The phenomenon of "big horse pulling small car" is serious. Due to the poor reliability of equipment in our country, the margin of design and selection is large, and the equipment operates in low load areas for a long time. 4、 The regulation mode of the system is backward. Most fans and pumps are still adjusted by mechanical throttling. China's small and medium-sized motors have strong design and manufacturing capabilities, and products can be exported in batches. According to the international IEC motor standard, the efficiency of high-efficiency motor is 91-96%, and the efficiency of low-efficiency motor is 75-89%

at present, the motors in actual operation in China are mainly concentrated in the power level of 0.55kw-100 kW, which is more than 95% of the total number of operating units, and the average efficiency is 89.3%

China has been able to produce 6-inch thyristors, reaching the international advanced level. The technology of high-power AC-AC frequency conversion and soft start of high-voltage synchronous motor with thyristor as power device has a considerable foundation, which can be localized and widely used in metallurgy, mining and other fields. However, the scope of application is limited, and the high-power variable frequency speed regulation of major national projects depends on foreign countries. High voltage transformer is the focus of current motor energy conservation, and localization has occupied more than 60% of the market. In terms of high voltage, our country has made great achievements

there are many problems in the energy-saving industry of motor system in China. The energy-saving technology and equipment level of motor system in China are far from the goal of energy saving, and the motor systems that only use frequency conversion speed regulation are still a few, less than 10% of the total; There is a huge contrast between the backward technology and products and the rapidly developing energy-saving market demand, which seriously restricts the realization of energy-saving in China's motor system. The country has not formed a platform for technology and product research and development in the field of power electronics and variable frequency speed regulation, and cannot form an industrial scale. In this field in China, 1. The sensor installation technology of copper tube pulse fatigue life testing machine is generally 10 years behind the international level

in recent years, the Chinese government has attached great importance to the energy conservation of motor systems and power electronics, and has given policy, scientific research projects, energy-saving funds and other support

electrical equipment for iron and steel production process

the iron and steel industry is an important technology and raw material industry. China's steel output ranks first in the world for more than ten consecutive years. In 2008, China's steel output reached 500 million tons. The economic crisis is expected to reduce global steel production by 860 million tons in 2009. However, China's steel production is still expected to increase by 18%. In 2009, it reached 550 million tons. The main task faced by the iron and steel industry is to adjust the industrial structure, promote energy conservation, emission reduction and circular economy

the new generation of steel production process circular economy chain is a key project of the Ministry of science and technology. The specific content is to use gas to build a 1.2 million kW power plant and waste gas to build a 5million ton cement plant

now, China is mainly developing a low-carbon economy. To reduce carbon dioxide emissions, we also need to pay attention to environmental protection and waste heat recovery

steel recycling economy, the proportion of scrap steel increases, and the electric furnace steelmaking increases, which requires high-power power electronic converter and reactive power compensator SVC to solve electric shock. Large hot rolling mills have developed rapidly, and the market share of domestic equipment has reached 70%. Large hot rolling mills are saturated. Most of the cold rolling mills are imported, and the technology of domestic equipment is not hard. The domestic inverter industry has developed rapidly, but its technical performance and reliability cannot meet the rolling mill rotation requirements

some problems encountered in motor frequency conversion energy saving

with the parallel operation of pump and variable-speed pump, the resistance drive line of pump parallel operation should be analyzed. If the pipe pressure is required, the analysis of parallel operation should be cautious. Under some conditions, the variable speed and constant speed should be operated in parallel, which may not achieve the effect of energy saving. The motor interrupts the common mode voltage, AC DC AC rate, and its output pww waveform. Common mode reflected voltage causes overvoltage, causing overvoltage breakdown of motor and cable