Low voltage VFD: a new opportunity for traditional upgrading
I.Low voltage VFD Industry Overview
- The concept, classification and application of VFD(frequency converter)
VFD, that is, AC motor variable frequency speed controller, is a kind of power conversion equipment. It converts fixed voltage and fixed frequency AC power into voltage and adjustable frequency AC power. The VFD is mainly composed of a power conversion unit, a braking unit, a drive unit, a detection unit, and a microprocessor unit. During operation, the microprocessor unit outputs driving pulses according to signals measured by the system setting and detection unit, and directly controls the on-off of the IGBTs in the power conversion unit after the driving unit amplifies to adjust the voltage and frequency of the output power supply, thereby achieving adjustment of the motor speed. The purpose (according to the characteristics of AC induction / asynchronous motor speed and frequency is proportional to).
VFD has a variety of classification methods according to different standards. For example, according to the application range, VFD can be divided into general-purpose VFD and special-purpose VFD; according to the conversion method, they can be divided into AC-AC VFD and AC-DC – AC VFD; In AC-DC-AC VFD, according to the energy storage method of DC link, it can be divided into current-type and voltage-type VFD; According to the voltage level, it can be divided into low-voltage VFD, medium voltage VFD and high voltage VFD.
The main function of the VFD is to continuously and steplessly adjust the speed of the motor. Therefore, there are the following aspects of effectiveness: (1) to achieve energy-saving motor operation. Because the output power of the motor is proportional to the rotation speed, the output power of the motor is reduced after the motor runs at a reduced speed, and the overall energy consumption is also reduced with the constant load, thereby achieving the purpose of energy saving and emission reduction. (2) Realize the soft start and soft stop of the motor to reduce the starting current of the motor, reduce the demand of the motor on the grid capacity and the impact on the grid, and avoid the mechanical impact when starting and stopping the motor, thereby reducing the funds of the early stage equipment. Invest, extend the life of motors and load equipment, reduce equipment maintenance costs. (3) to replace the DC motor to meet the process needs of various occasions, equipment, improve production efficiency or improve product quality. Thanks to the introduction of vector control technology, the VFD has achieved rapid response and high-precision control of the DC motor, which can replace the DC motor to realize various process speed adjustments. It also saves space, and is more convenient for installation and maintenance. In addition, the VFD also has many application functions and protection functions, application functions such as: PID adjustment, brake function, simple PLC, etc., so that the VFD can be applied in hoisting cranes, textiles and other industries, expanding the application of the VFD Protection functions such as over-current, over-voltage, short-circuit, and overload protection make the VFD and motor more reliable and safe.
At present, the VFD has been widely used in various industries in China, such as metallurgy, chemical industry, paper making, machinery and other industries. More specific applications, small applications such as blowers, conveyors, feeders, mixers, grinders, crushers, paper cutters, calenders, extruders, valves, compressors, cooling towers, plastic machinery in various industries , elevators, all kinds of textile machinery, large-scale applications such as paper mill paper machine, mold factory injection molding machine, metallurgical plant rolling mill, and chemical industry, such as large-scale fans, pumps, cranes, oil pipelines.
2.the development of the VFD industry
Compared to industrialized countries, China’s VFD industry started relatively late. In the late 1970s to the 1980s, China’s VFD development phase began. This stage is mainly the Ministry of Machinery Tianjin Electric Drive (voltage type) and the Ministry of Machinery Power Electronics Technology Institute (current type) research and development. From the end of the 1980s to the end of the 1990s, it was the stage of foreign import of general-purpose VFD. It was originally the Japan Sanken SVF type and Japan’s Fuji G5/p5 type, followed by Mitsubishi, Yaskawa, Toshiba, Panasonic, ABB, AB, Siemens, etc. Domestic manufacturers have also developed domestic VFD in the context of technology introduction. In the 21st century, with the development of domestic power electronics and microelectronics technologies, the VFD industry has rapidly expanded, domestic brands have gradually emerged, and the market share of domestic brands has also gradually increased. Since about 2006, due to the emergence and development of intelligent power modules, VFD companies can produce mature products by only controlling the circuit and the main power supply circuit and housing. The domestic VFD has seen a hundred contending situations. With rapid development, a large number of outstanding domestic VFD brands have emerged, and domestic brands have further expanded their market share with localized production, service networks and price advantages.
There are more than 300 VFD manufacturers in China, but their strength and scale are uneven. Individual companies still use workshop-style production models, and the main brands are maintained at 20-30. In recent years, China’s VFD market has maintained a growth rate of 12% to 15%. As of 2013, the national VFD market will be approximately 28.5 billion yuan. It is expected that the VFD market demand will still maintain a growth of more than 10%. According to the analysis of the VFD industry prospects, the total potential market space of the VFD in China is approximately 120 billion to 180 billion yuan.
3.the development of low voltage VFD industry
The low-voltage VFD is an adjustable output frequency AC motor drive device with a voltage level lower than 690V. It was first started in the United States in the late 1950s. Since the 21st century, China’s low-voltage VFD have gradually emerged. According to data from the Ministry of Media Research, the market size of China’s low-voltage VFD industry in 2006 was 9.26 billion yuan. In 2013, the scale of China’s low-voltage VFD industry has reached 21.405 billion yuan, with a compound annual growth rate of 12.72%. According to the 2013 China Low-voltage VFD Market Research Report published by the China-based media research department, the growth rate of China’s low-voltage VFD market will continue to exceed 10%, and the total market in 2016 will exceed RMB 26 billion.