Due to the increasing importance of energy and environmental issues, for the small and medium-sized asynchronous motors, the main power equipment in the industrial field, there has been a so-called "super high efficiency motor" with higher efficiency in foreign countries. It is also necessary in China to consider the development and application of ultra-high efficiency motors.
1. Energy-saving potential and economic benefits of ultra-high efficiency motors
According to domestic and international surveys, the average annual operating time of motors in the industrial field is about 3000h, but in the petroleum, chemical, paper, metallurgy, electric power and other industries, the annual running time of motors often exceeds 6000h. For these long-running applications, the use of ultra-high efficiency motors will have a more significant effect on energy savings. China's power generation in 2003 was 180 billion kwh. Since 50% of the power generation is transmitted through the motor, and the three-phase asynchronous motor accounts for 90%, and the general-purpose Y series motor accounts for 70%, the Y series motor will transmit 31.5% of the total electric energy, that is, 580 billion kwh. If these motors are all replaced by high-efficiency motors, that is, the efficiency is increased by 2.75 percentage points and the loss is reduced by about 20% on average, saving energy of 16 billion kwh per year . If you consider that 30% of the motors are running above 6000h, change this part of the motor to an ultra-high efficiency motor, that is, increase the efficiency. 5 to 2 percentage points, the average loss of about 15%, can save 4.6 billion kwh of electricity, corresponding to saving 1.7 million tons of standard coal, about 2.4 million tons of raw coal. It can save another investment in the construction of a 1 million kw power station.
2. The application of ultra-efficient motors is also economically beneficial to users.
Buy an ultra-efficient motor, although it is more expensive to buy, but the motor life cycle is several years, even decades. Once used for a long time, it is economically beneficial for the user.
3, reduce losses, improve efficiency
In addition to increasing the amount of silicon steel sheet and copper wire and reducing the size of the fan, the ultra-high-efficiency motor must also take measures in the application of new materials, motor manufacturing processes and optimization design to reduce the sharp increase in manufacturing costs. Pressure and limits to the size of the motor structure.
Brook Hansen of the UK collaborated with a steel mill to develop a new electrical steel sheet of Polycor 420. After the general electrical steel sheet is processed into iron core and pressed into the machine base, the iron consumption is greatly increased, and the iron consumption of the motor made of the steel sheet does not change much before and after processing. Figure 4 shows a comparative test of the company using different magnetic materials on a 22kw motor.
Toshiba Corporation of Japan is one of the leading suppliers of high efficiency motors and ultra high efficiency motors in the United States. The company claims that the cost of high-efficiency motors has fallen by 30% due to improvements in manufacturing processes and the adoption of new materials. The measures taken include: applying special off-line tools, increasing the stator slot full rate, increasing the cross-sectional area of the copper wire, improving the manufacturing precision, shortening the air gap length, thereby reducing the excitation current and the copper loss caused by the rotor; The slot insulation process reduces stray losses; the laser core stacking tool is used to reduce the iron loss.
This is also advantageous for improving the efficiency of the motor.
In the case of China's increasingly tight energy supply, for some long-term continuous operation and high load rate, the use of more efficient motors is quite effective in saving energy, and at the same time economically reasonable.
In order to promote the development of motor energy conservation, it is recommended to revise the current motor energy efficiency standards: the motor energy efficiency standards are divided into three levels, the lowest level is the current high efficiency motor level, and the high level indicator is the current ultra high efficiency motor level. In order to enable a greater reduction in the energy consumption of China's motor systems. In addition, in order to promote the development of "Ultra High Efficiency Motor", it is necessary not only to increase the amount of effective materials (silicon steel sheets and copper wires), but also to take measures in the motor manufacturing process, new material application and optimization design, thereby reducing manufacturing costs. . In order to promote the application.