Supplier of energy feedback device for frequency converter: The frequency conversion and speed regulation function of the frequency converter is to convert a three-phase AC power supply (or any power supply) with adjustable voltage and frequency into a three-phase AC power supply. Sometimes, the frequency converter is also referred to as a variable voltage variable frequency device VVVF. Mainly used for regulating the speed of AC motors (asynchronous or synchronous).
An AC motor variable frequency speed regulation system consists of three main parts: a variable frequency speed controller, an AC motor driver, and a controller. The key core equipment is the frequency converter, which is used to achieve smooth changes in motor voltage and frequency.
Variable frequency speed regulation is incomparable to previous methods such as voltage regulation, variable pole speed regulation, cascade speed regulation, slip speed regulation, and hydraulic coupling speed regulation in terms of frequency range, static accuracy, dynamic quality, system efficiency, comprehensive protection functions, and easy implementation of automatic control and process control. It is widely recognized as a promising speed control solution for AC motors, representing the future direction of electrical transmission development.
Over the past thirty years, frequency converter speed regulation has been widely used in industries such as steel, metallurgy, petroleum, chemical, textile, chemical fiber, light industry, papermaking, rubber, plastics, power, and water management. The application of variable frequency speed regulation for low-voltage motors has become very popular and mature. The variable frequency speed regulation of high-voltage electric motors is also receiving attention and gradually being applied. In addition to its excellent speed regulation performance, AC motor variable frequency speed regulation also plays a significant role in saving electricity and protecting the environment. It is an ideal speed regulation device for enterprise technological transformation and product upgrading.
The energy-saving effect of frequency converter on fan and water pump
There is a significant power gap due to the contradiction between power supply and demand (supply exceeds demand), and energy conservation is needed. According to relevant departments' statistics, in 2002, China's installed power generation capacity was 31.9 billion kW, with an annual power generation of 1346.6 billion kWh. Although it ranks second in the world in terms of electricity scale, its per capita electricity consumption is among the lowest in the world. Moreover, the rapid development of our country's economy requires more electricity. If calculated based on the requirement of an 8% increase in national economic growth and an 11% increase in electricity, China's power generation capacity should be between 570 and 600 million kW by 2010, with an annual power generation of 28000-2900 billion kWh. In the summer of 2003, the sustained high temperatures caused a shortage of power supply in some provinces and cities, forcing the adoption of power rationing measures. Due to the heavy burden on the power grid, local power system instability has occurred. The above explanation shows that China's electricity supply and demand are unbalanced, with supply being less than demand. Therefore, it is necessary to save electricity.
Energy saving benefits of variable frequency speed regulation for fans and water pumps:
The total installed capacity of electric motors in China has reached 450 million kW, consuming approximately 65% of the country's electricity generation. Therefore, it is very important to achieve power saving for electric motors. There are two ways to save energy for general motors: one is to improve the efficiency of the motor itself to achieve long-term efficient operation, mainly used for constant speed machinery; Another is to improve the control accuracy of motor speed, so that the motor can operate at the most energy-efficient speed.
Fans, water pumps, and compressors are widely used electric motor driven equipment in the national economy, with a total motor capacity of 150 million and a power consumption of about 35% of the country's electricity generation. About 20% to 30% of fans and water pumps require speed regulation.
Variable frequency drive is an optional energy-saving solution for fans and water pumps. According to fluid theory, the shaft power of a centrifugal fan pump is a cubic function of the rotational speed. When the speed decreases, its power consumption will significantly decrease, for example, at 50% speed, the mechanical power of the shaft is only 12.5%. Of course, the efficiency of speed regulation schemes varies greatly, and the efficiency of hydraulic speed regulation devices after slip is not high, η≈(1-S)， At 50% rotational speed, ηvs≈50%， And the efficiency of the frequency converter is high, with a high efficiency factor, ηvvvF≈95%～98%， And it remains approximately unchanged.