1. The concept, classification, and application of frequency converters
A frequency converter, or AC motor variable frequency speed controller, is a power conversion device that transforms AC power with fixed voltage and frequency into AC power with adjustable voltage and frequency. A frequency converter mainly consists of a power conversion unit, a braking unit, a drive unit, a detection unit, and a microprocessor unit. During operation, the microprocessor unit outputs drive pulses based on system settings and signals measured by the detection unit. After being amplified by the drive unit, these pulses directly control the on/off switching of the IGBTs in the power conversion unit to adjust the voltage and frequency of the output power supply, thereby regulating the motor speed (based on the characteristic that the speed of an AC induction/asynchronous motor is proportional to its frequency).
Inverters can be classified in various ways according to different standards. For example, according to the application scope, inverters can be divided into general-purpose inverters and special-purpose inverters; according to the conversion method, they can be divided into AC-AC inverters and AC-DC-AC inverters; among AC-DC-AC inverters, according to the energy storage method of the DC link, they can be divided into current-type inverters and voltage-type inverters; according to the voltage level, they can be divided into low-voltage inverters, medium-voltage inverters, and high-voltage inverters, etc.
The most important function of a frequency converter is to continuously and steplessly regulate the speed of a motor. Therefore, it has the following benefits: (1) It enables energy-saving operation of the motor. Since the output power of a motor is proportional to its speed, when the load remains unchanged, the output power of the motor decreases after it slows down, and the overall energy consumption also decreases, thereby achieving the goal of energy saving and emission reduction. (2) It enables soft starting and soft stopping of the motor, thereby reducing the starting current of the motor, reducing the demand of the motor on the grid capacity and the impact on the grid, avoiding the mechanical impact when the motor starts and stops, thereby reducing the initial investment in equipment, extending the life of the motor and the load equipment, and reducing equipment maintenance costs. (3) It replaces DC motors to meet the process requirements of various occasions and equipment, improve production efficiency or improve product quality. Due to the introduction of vector control technology, the frequency converter achieves a fast response and high-precision control comparable to DC motors. It can replace DC motors to achieve various process speed regulation, save space, and is more convenient to install, use and maintain. In addition, frequency converters have many application functions and protection functions. Application functions include PID regulation, brake function, and simple PLC, which enable frequency converters to be used in industries such as hoisting and textiles, thus expanding the application range of frequency converters. Protection functions such as overcurrent, overvoltage, short circuit, and overload protection make the operation of frequency converters and motors more reliable and safe.
Currently, frequency converters are widely used in various industries in my country, such as metallurgy, chemical industry, papermaking, and machinery. Specific applications are even broader, ranging from small-scale applications such as blowers, conveyors, feeders, mixers, grinders, crushers, paper cutters, calenders, extruders, valves, compressors, cooling towers, plastics machinery, elevators, and various textile machinery, to large-scale applications such as papermaking machines in paper mills, injection molding machines in mold factories, rolling mills in metallurgical plants, and large fans, pumps, cranes, and oil pipelines in industries such as chemicals.
2. Overview of the Variable Frequency Drive Industry
Compared to industrialized countries, my country's frequency converter industry started relatively late. Research and development of frequency converters in my country only began in the late 1970s and 1980s, primarily conducted by the Tianjin Electrical Transmission Institute (voltage type) and the Xi'an Power Electronics Technology Institute (current type) under the Ministry of Machinery Industry. The late 1980s and late 1990s saw the import of general-purpose frequency converters, initially from Japan's Sanken SVF and Fuji G5/P5 models. Subsequently, Mitsubishi, Yaskawa, Toshiba, Panasonic, ABB, AB, Siemens, and other manufacturers entered the Chinese market. Domestic manufacturers, with the help of technology imports, gradually developed their own frequency converters. Entering the 21st century, with the development of domestic power electronics and microelectronics technologies, the frequency converter industry expanded rapidly, domestic brands gradually rose to prominence, and their market share began to increase. Starting around 2006, the emergence and development of intelligent power modules enabled inverter manufacturers to produce mature products simply by manufacturing the control circuit, main power supply circuit, and casing. This led to a highly competitive domestic inverter market, with a large number of excellent domestic inverter brands emerging. Domestic brands further expanded their market share by leveraging localized production, service networks, and price advantages.
There are currently over 300 inverter manufacturers in my country, but their strength and scale vary greatly. Some companies still operate on a workshop-style production model, and the number of major brands remains around 20-30. In recent years, my country's inverter market has maintained a growth rate of 12%-15%, reaching approximately 28.5 billion yuan in 2013. It is projected that market demand will continue to grow at a rate exceeding 10%. Industry analysis indicates that the total potential market size for inverters in my country is approximately 120-180 billion yuan.
3. Overview of the Low-Voltage Frequency Converter Industry
Low-voltage frequency converters are adjustable-frequency AC motor drive devices with voltage levels below 690V. Originating in the United States in the late 1950s, my country's low-voltage frequency converter industry has gradually emerged in the 21st century. According to data from the China Automation Media Research Department, the market size of my country's low-voltage frequency converter industry was 9.26 billion yuan in 2006, and reached 21.405 billion yuan in 2013, with a compound annual growth rate of 12.72%. According to the "2013 my country Low-Voltage Frequency Converter Market Research Report" by the China Automation Media Research Department, the growth rate of my country's low-voltage frequency converter market will continue to maintain above 10%, and the total market size will exceed 26 billion yuan in 2016.
Low-voltage frequency converters are divided into four segments according to different user groups: <=7.5KW, 11-30KW, 37-90KW, and >=110KW, with those below 30KW being the most widely used. High-power converters are mainly used in project markets or large mechanical equipment, and manufacturers are primarily European and American, such as Siemens, ABB, and Afsen. Medium-power converters are the most common, including traditional fan and pump applications, complex mechanical applications, or project applications; all major suppliers offer products in this power range. Low-power converters are mainly used in mechanical applications, primarily by Japanese manufacturers and some European, American, and Taiwanese manufacturers, such as Delta, Fuji, and Mitsubishi. According to a report by the Zhongzi Media Research Department, the distribution of power segments in the low-voltage frequency converter market in 2012 is shown in the following figure:
Low-voltage frequency converters are categorized by application load into lifting loads, mechanical loads, and fan/pump applications. Lifting loads primarily refer to hoists and elevators, but also include lifting applications in other industries, with ABB, Siemens, Yaskawa, and Afsen being the main players. Mechanical loads account for more than half of the market, including mainstream machinery such as textile and packaging equipment, as well as non-OEM applications. According to a report by the Zhongzi Media Research Department, the low-voltage frequency converter market in 2012 was categorized by application load as shown in the following figure:
The development of low-voltage frequency converter products is closely related to industrial production, and the distribution of its downstream application market is basically consistent with the industrial distribution. According to the "2014 China Low-Voltage Frequency Converter Market Research Report", elevators, wind power, hoisting machinery, textiles, and municipal engineering are the five major application industries of low-voltage frequency converters.
(2) The market size of low-voltage frequency converters will continue to grow steadily.
A. Upgrading of the equipment manufacturing industry and rapid growth in the new energy sector are driving the continued expansion of the entire market.
Low-voltage frequency converter technology emphasizes precise and wide-range regulation. In the field of industrial automation, it is closely linked to front-end PLC control and back-end servo motors, forming an industrial automation control system. The 12th Five-Year Plan proposed to "transform and upgrade the manufacturing industry," including "developing advanced equipment manufacturing," with improving automation levels being a key focus. The demand for low-voltage frequency converters is directly related to the overall level of industrial development. As downstream equipment in the manufacturing industry upgrades, the low-voltage frequency converter industry will continue to maintain a growth rate of around 15%.
On the other hand, following the Copenhagen Conference, investment in new energy has become a global focus, with new energy and low-carbon economy becoming key development priorities for various countries. Wind energy, with its most mature technology, will be the preferred renewable energy source. Low-voltage frequency converters are widely used in the drive systems of the wind power industry, primarily functioning to integrate wind power with its variable frequency into the constant frequency power grid, ensuring the same direction, frequency, and voltage. Since frequency converter technology and wind power automation system control technology are crucial for wind turbine generators, the wind power industry has become a large-scale and rapidly growing downstream application sector for low-voltage frequency converters. By 2020, my country's installed wind power capacity will reach 100 million kilowatts, and this huge market potential will inevitably drive the continued rapid growth of the entire low-voltage frequency converter industry.
B. Import substitution has become a long-term driving force for domestic low-voltage frequency converter manufacturers to seize market share.
The low-voltage frequency converter industry is mainly dominated by European, American, and Japanese manufacturers. With the continuous improvement and maturation of domestic frequency converter technology, product price has become a primary consideration for downstream customers. Given the still significant price gap between domestic and international manufacturers, and the relatively dispersed strengths of major domestic low-voltage frequency converter manufacturers (e.g., INVT focuses on hoisting, wire drawing, and coal mining, while Huichuan Technology excels in elevators and injection molding machines), the domestic frequency converter manufacturers are unlikely to experience intense competition in the short term due to this differentiated market segmentation. Therefore, import substitution will be a major factor driving the high growth rate of domestic low-voltage frequency converter manufacturers for some time to come.
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