High-efficiency and energy-saving motor technology and its significance to industry development

From the perspective of energy conservation and environmental protection, high-efficiency motors are the current international development trend. The United States, Canada, and Europe have successively promulgated relevant regulations. According to the running time of the motor, the CEMEP standard formulated by Europe divides the efficiency into three levels: eff1 (high), eff2, and eff3 (low), which was implemented in steps from 2003 to 2006. The newly issued IEC60034-30 standard divides the motor efficiency into four levels: IE1 (corresponding to eff2), IE2 (corresponding to eff1), IE3, and IE4 (high). my country promises to implement IE2 and above standards from July 1, 2011.

At present, my country's industrial energy consumption accounts for about 70% of the total energy consumption, of which motor energy consumption accounts for about 60% to 70% of industrial energy consumption. Together with non-industrial motor energy consumption, the actual energy consumption of motors accounts for more than 50% of the total energy consumption, and the current application ratio of high-efficiency energy-saving motors is low. According to the sampling survey of 198 motors of key domestic enterprises by the National Small and Medium-sized Motor Quality Supervision and Inspection Center, only 8% of them have reached level 2 or above. This has caused a great waste of social resources.

Energy-saving measures for high-efficiency motors

Energy saving for motors is a systematic project, involving the entire life cycle of motors. From the design and manufacture of motors to the selection, operation, adjustment, maintenance and scrapping of motors, the effect of energy-saving measures should be considered from the entire life cycle of motors. In this regard, domestic and foreign countries mainly consider improving efficiency from the following aspects.

The design of energy-saving motors refers to the use of modern design methods such as optimization design technology, new material technology, control technology, integration technology, and test and detection technology to reduce the power loss of motors, improve the efficiency of motors, and design high-efficiency motors.

While converting electrical energy into mechanical energy, the motor itself also loses some energy. Typical AC motor losses can generally be divided into three parts: fixed loss, variable loss and stray loss. Variable loss changes with load, including stator resistance loss (copper loss), rotor resistance loss and brush resistance loss; fixed loss is independent of load, including core loss and mechanical loss. Iron loss is composed of hysteresis loss and eddy current loss, which is proportional to the square of the voltage, and hysteresis loss is inversely proportional to the frequency; other stray losses are mechanical losses and other losses, including friction losses of bearings and windage losses caused by the rotation of fans and rotors.

Features of high-efficiency motors

1. Save energy and reduce long-term operating costs. It is very suitable for textile, fan, water pump, compressor use. The motor purchase cost can be recovered by saving electricity in one year;

2. Direct start or speed regulation with frequency converter can fully replace asynchronous motors;

3. Rare earth permanent magnet high-efficiency energy-saving motors can save more than 15℅ of electricity compared with ordinary motors;

4. The motor power factor is close to 1, which improves the quality factor of the power grid and does not require a power factor compensator;

5. The motor current is small, saving power transmission and distribution capacity and extending the overall operating life of the system;

6. Power saving budget: Taking a 55-kilowatt motor as an example, a high-efficiency motor saves 15% of electricity compared with a general motor. The electricity fee is calculated at 0.5 yuan per kilowatt hour. The cost of replacing the motor can be recovered by saving electricity within one year by using energy-saving motors.

Advantages of high-efficiency motors

˙ Direct start, can fully replace asynchronous motors.

˙ Rare earth permanent magnet high-efficiency energy-saving motors can save more than 3% of electricity compared with ordinary motors.

˙The power factor of the motor is generally higher than 0.90, which improves the quality factor of the power grid without adding a power factor compensator.

˙The motor current is small, which saves power transmission and distribution capacity and extends the overall operating life of the system.

˙Adding a driver can achieve soft start, soft stop, and stepless speed regulation, and the power saving effect is further improved.

Development of the high-efficiency motor industry

The integration and reorganization of the country in the coal, mining, equipment manufacturing and other industries will further promote the demand and development of medium-sized motor products. The in-depth implementation of the national energy conservation and emission reduction policy has put forward new and higher requirements for the energy conservation of motor systems. The simple pursuit of high efficiency of motors is shifting to high efficiency of system operation, and ultimately promoting the further segmentation of the motor product market and promoting the development of special and dedicated products and complete systems. This not only puts higher requirements on the design and production of small and medium-sized motors, but also provides a broader product application space, economic profit space and industry development space. In the next five years, the country will use fiscal subsidies to promote small and medium-sized energy-saving and high-efficiency motors and other products. It is expected that the output of small and medium-sized energy-saving and high-efficiency motors will grow explosively in the next five years, with an average annual growth rate of 58.07%. After the rapid development in 2013, the output of small and medium-sized energy-saving and efficient motors stabilized in 2014, with a slight decline in the growth rate. However, it is difficult to change the trend of substantial growth in the output of small and medium-sized energy-saving and efficient motors. In 2016, the output of small and medium-sized energy-saving and efficient motors will increase to 218.4 million kilowatts.