The hottest frequency conversion system brings you

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The frequency conversion system brings you a new experience of safety and green

through the analysis of the problems exposed by the lubricating oil injection in the rotating part of the motor and electrical appliance supporting the FBCDZ series large-scale pair cyclone in the development process, a technical solution to the problem is found. The research and application of frequency conversion technology and special motor technology have made a major breakthrough in the development of large-scale cyclones. The implementation of the new scheme has played a positive role in promoting the safety production of coal mines, improving the environment, and saving energy and reducing consumption

fbcdz series fans are explosion-proof extraction counter rotating shaft flow fans, which are mainly used for main ventilation in underground coal mines. The structural principle is shown in the figure. Two motors with the same power are installed in the center of the fan channel, and two large fans are directly connected on the motor shaft extension arranged face to face, which are called class I fans and class II fans. The rotation directions of the two fans are opposite. During the operation of the fan, the gas containing air from the underground will be extracted, and the air will flow out through the channels around the outer baffle of the motor. The cooling of the motor enters the motor from ports 1 and 2 and flows out from ports 3 and 4 by the air in the atmospheric environment. Due to the high wind pressure and efficiency of the fan function of this structure, and the small floor area, there is no need to build a fan room, the construction cycle is short, and the capital construction investment is small, so it has been widely used in the main ventilation of coal mines in recent years, especially in the small and medium-sized fans

with the development of the coal industry, more and more fans are used, and their power is also developing in a larger direction. However, this also brings a series of problems, such as the common problems that the motor is not easy to maintain, the bearing is easy to damage, the air volume cannot be adjusted to save energy, and the starting of high-power fans

the existence of the above problems limits the development of such fans, especially in the direction of high power. Therefore, the key to the development of fans lies in the improvement and promotion of motor technology and electrical control technology. In recent years, colleagues in the industry have also invested a lot of research in this area, but the effect is not ideal, especially the research on the special motor and electrical supporting the fan

explore and research solutions

how to improve the technical level of motor and electrical control technology is the key to whether this kind of fan is reliable and energy-saving. According to the needs of the research topic and market research, a state-owned coal mine fan expansion and reconstruction project is selected as the research object, and fruitful research has been carried out and important results have been achieved

the original fan of the mine is a pair of cyclones with a total power of 2630kw. According to the development planning of the mine, the use of air volume will be maximized within five years, and the total power of air supply is 21850kw, which is the current maximum power pair of cyclones. If this project is successful, it will meet the current domestic demand for cyclones

the general technical scheme of this project selects the world's most advanced frequency converter suitable for fan working conditions to develop a large-scale special motor for cyclone. The specific technical scheme is briefly analyzed as follows:

1 Selection of frequency converter

considering the possible impact of high-power motor starting on the old power of the old mine, as well as the working conditions of the fan at different air volumes, the frequency converter control technology is selected. One is to reduce the influence of motor starting on old electricity; Second, energy saving can be achieved under different working conditions. After repeated demonstration, 2. Load accuracy: 0.01%. Acs5000 frequency converter with international advanced technology is selected for this project, with continuous output power of 400 ~ 25 and an average annual growth rate of 27.6% 00kw; The output voltage of each phase is 4KV; The cooling method is air cooling. The frequency converter adopts direct torque control (DTC) technology to control the torque and speed of the motor. The semiconductor switching device adopts IGCT, which has control mode, simplified power module and more compact and reasonable structure, so that the controlled motor can obtain excellent torque characteristics and speed characteristics

2. Frequency converter direct torque control technology

this frequency converter adopts direct torque control (DTC) technology, which is a new AC variable frequency speed regulation technology after vector control (VC) technology. The switching state of the inverter is directly controlled by the core variables flux and torque of the motor. The measured motor current and DC voltage are used as inputs to the adaptive motor model, which generates a set of accurate actual values of torque and magnetic flux every 25 M. The motor torque comparator compares the actual torque value with the given value of the torque given regulator, and the magnetic flux comparator compares the actual magnetic flux value with the given value of the magnetic flux given regulator. Depending on the output from the two comparators, the optimal pulse selector determines the optimal switching state of the inverter, eliminating the complex vector transformation and the simplification of the mathematical model of the motor

3. Acs5000 high voltage inverter power module

the inverter adopts 36 pulse multiple rectification mode. It is required to be equipped with a shift transformer. Six sets of secondary windings are used for the secondary side winding, and the zigzag connection method is adopted along the side triangle to meet the requirements of 36 pulse input rectifier bridge. The harmonics fully meet IEEE-519 and gb/t14549 harmonic standards

the inverter is voltage type nine level fusionless (vsi-mf) design. The acs5000 frequency converter based on DTC control technology can provide accurate speed and torque control without adding a code disk on the motor side

4. Special function

based on the data on the motor nameplate, all parameters of acs5000 internal DTC motor model will be calculated automatically. This program usually only needs to be run once during debugging (no-load identification time is 5min). If necessary (for example, acs5000 frequency converter drives other motors), the motor identification operation can be carried out at any time

acs5000 frequency converter can set multiple groups of dangerous frequency bands, which can quickly cross all dangerous frequency bands of the fan during the acceleration process of the motor controlled by the frequency converter

when the motor load is not saturated, acs5000 automatically optimizes the motor magnetic flux to reduce the overall energy consumption and motor noise. For example, carbon fiber reinforced plastic with extremely light weight and excellent performance is used to replace the aluminum based material noise of the aircraft. According to the load torque and speed, the overall efficiency (frequency converter and motor) can be increased by 1% - 10%

implementation and results

after nearly a year of product development, the equipment began trial operation in July 2009. After measurement, all performance indicators meet the technical requirements of the design

the harmonics at the electric side and motor side of the frequency converter meet the requirements of gb/t14549

during the starting process, the current is only 1.1 times of the rated current, there is no strong current impact, and the electricity in the mining area is used normally and is not affected

the system can adjust the speed as required, avoid the resonance point of the fan, and smoothly cross the dangerous speed

the switching of the fan is smooth, the time between start and stop is reduced, and the fan stops by energy consumption braking, which is more reliable and simple to operate than the original mechanical braking

it effectively meets the requirements of air volume under different working conditions underground. When the motor is at 60% load, there is no need to adjust the size of the air valve, which can reduce the input power by 135kW

the bearing of the motor runs at a low and stable temperature with good lubrication. When the local maximum ambient temperature is 37 ℃, the temperature does not exceed 60 ℃. There is no need to worry about the accident of poor bearing lubrication caused by too much or too little grease

the motor winding temperature has been kept below 65 ℃

the noise of the whole system is 15dB lower than that of the original fan, which improves the working environment

frequency conversion technology becomes the best choice

fbcdz series develops towards higher power for cyclones, and electrical control technology and special motor technology are the key. The frequency conversion technology is easy to realize stable starting and convenient speed regulation. In order to meet the requirements of air volume under different working conditions, the main shaft ventilation of coal mine often chooses larger motor power, and the frequency conversion technology makes its energy saving the best choice. Secondly, the research of fan specific motor is the key to improve the reliability of fan operation, especially the design of bearing structure, the selection of lubrication mode and sealing mode, as well as the design of motor cooling system, we must consider the special environment of motor use, and cannot use general motor to replace it. After continuous improvement and improvement, the technology of large-scale pair of cyclones will become more and more mature. A better, safer and more reliable coal mine ventilation equipment will become a strong support for coal mine safety production, energy conservation and consumption reduction

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