Variable-frequency Drive (VFD) is a power control device that applies frequency conversion technology and microelectronics technology to control ac motor by changing the mode of working power supply frequency.
The frequency converter is mainly composed of rectifier (ac to dc), filter, inverter (dc to ac), braking unit, driving unit, detection unit microprocessing unit and so on.Frequency converter by internal IGBT off to adjust the voltage and frequency of the output power supply, according to the actual needs of the motor to provide its needed power voltage, and then achieve the purpose of energy saving, speed regulation, in addition, the converter has a lot of protection functions, such as over current, over voltage, overload protection and so on.With the continuous improvement of industrial automation, frequency converter has been widely used.
Application of frequency converter
1. Air conditioning load
Office buildings, shopping malls, some supermarkets and factories all have central air conditioning, which USES a lot of electricity during the peak summer season.In hot weather, Beijing, Shanghai and shenzhen all account for more than 40% of the peak electricity consumption.Therefore, it is a very good power-saving technology to drag the refrigerating pump, cooling water pump and fan of air conditioning system with frequency conversion device.At present, there are many companies specializing in air-conditioning energy-saving, the main technology is frequency conversion speed regulation energy-saving.
2. Crusher load
Many crushers and ball mills are used in metallurgical mines and building materials.
3. Load of calcining furnace for large kilns
Metallurgy, building materials, caustic soda and other large industrial kiln (converter) before the majority of dc, commutator motor, slip motor, cascade speed regulation or if unit speed regulation.In recent years, many units adopt frequency conversion control, and the effect is very good.
4. Compressor load
Compressor is also a widely used load.Low pressure compressors are widely used in various industrial sectors, high pressure compressors with large capacity in steel (such as oxygen generator), mines, fertilizers, ethylene have more applications.Using frequency conversion speed regulation, all bring the advantages of small starting current, saving electricity and optimizing the service life of the equipment.
5. Mill load
In metallurgical industry, the past large mill multi-purpose pay - frequency converter, in recent years, the cross - straight - frequency converter, mill communication is a kind of trend, especially in light load rolling mill, aluminum products factory of many nationalities have such as ningxia frame aluminum mill USES the general frequency converter, meet low frequency load startup, frame synchronization between running, constant tension control, simple operation and reliable.
6. Hoist load
The hoist load adopts frequency conversion speed regulation, stable and reliable.Blast furnace winch equipment in iron works is the main equipment for conveying iron raw materials.It requires smooth starting and braking, uniform acceleration and deceleration, and high reliability.The original use of cascade, dc or rotor series resistance speed regulation mode, low efficiency, poor reliability.The ideal effect can be obtained by replacing the above mentioned speed regulation mode with ac frequency converter.
7. Converter load
Converter load, ac frequency conversion instead of dc unit simple and reliable, stable operation.
8. Roller table load
Roller load, mainly used in iron and steel metallurgical industry, ac motor frequency control, can improve the reliability and stability of equipment.
9. Pump load
Pump load, large capacity, including pumps, pumps, chemical pumps, mud pumps, sand pumps, etc.Many water pump companies, chemical and fertilizer industry, reciprocating pump, non - ferrous metals and other industries such as the use of variable frequency speed control, have produced very good results.
10. Load of crane and dumper
Crane, dumper and other load torque large and stable, positive and negative frequent and reliable requirements.The frequency conversion device can control crane and dumper to meet these requirements.
11. Wire-drawing machine load
Production of wire drawing machine, high-speed, continuous production requirements.Steel wire strength of 200Kg/mm2, speed regulation system requires high precision, stability and synchronization.
12. Transport truck load
The application of frequency conversion technology in raw coal transport truck of coal mine or liquid steel transport truck of steel mill is very effective.Fast start and stop, strong overload capacity, and flexible positive and negative rotation, achieving smooth coal surface, correct weight (less or less loading), basically no need for manual operation, improve the production efficiency of raw coal, and save electricity.
13. Lift overhead bus load
As the elevator is a manned tool, it requires a highly reliable drag system and frequent acceleration, deceleration and positive and negative rotation. The improvement of the dynamic characteristics and reliability of the elevator increases the safety, comfort and efficiency of the elevator ride.In the past, dc elevator speed regulation, in recent years, gradually converted to ac motor frequency control, no matter Japan or Germany.Many elevator factories in our country fall over each other with frequency control to equip the elevator.Such as Shanghai mitsubishi, guangzhou Hitachi, Qingdao Fuji, tianjin Otis, etc. all adopt ac frequency conversion.Many of the original production of the elevator also carried out frequency conversion transformation.
14. Feeder load
Metallurgical, electric power, coal, chemical and other industries, there are many feeder, no matter the disk feeder or vibration feeder, using frequency control effect is very significant.The disc feeder of sulfuric acid production line in dye factory of jihua company is used for slip speed regulation, low frequency torque is small, fault is frequent, and it often stultiates.After using frequency conversion speed regulation, because it is asynchronous machine, high reliability, electricity saving, and more importantly, closed loop with temperature transmitter to ensure the accuracy of conveying materials, so as not to make the oxidant conveying excessive excessive temperature and cause accidents, to ensure the orderliness of production.
15. Load of stacker and reclaimer
Stacker and reclaimer is the main equipment for material stacker and reclaimer in coal yard, wharf and mine.Automatic piling and semi-automatic feeding, improve the reliability of the equipment, equipment running smoothly, without impact and shaking phenomenon, feeding process according to 1/cos rotation speed regulation, improve the bucket reincarnation feeding efficiency and belt coal uniformity, very popular with workers.
16. Fan load
Fan type load, is a large range of equipment, steel mills, power plants, nonferrous metals, mining, chemical, textile, chemical fiber, cement, paper and other industries used more.Most of the use of adjusting baffle open degree open regulation of air volume, waste a lot of electrical energy, using frequency control, can save electricity and reduce mechanical wear, extend the life of the equipment.
17. Mixer load
Chemical, pharmaceutical industry mixer is very much, using frequency control instead of other speed regulation mode, the benefits of special.
18. Load of spinning machine
The spinning process is complex, the work station is many, requests the tension control, some requests the position control.The effect of frequency conversion is good.
19. Special power supply load
Many power sources, such as experimental power source and aircraft drag power source (400Hz), can be completed with frequency conversion device, which has the advantages of low investment, quick effect, small size and simple operation.
20, paper machine load
The paper machine of our country papermaking industry, require high precision to adopt SCR dc speed regulation mode, some use slip motor, commutator motor.The reliability and accuracy are not high due to the existence of slip ring and carbon brush.As a result, papermaking machinery lags behind. Generally, the speed is only 200m/min, which is difficult to compare with that of foreign countries at 2000m/min.Therefore, the frequency conversion of papermaking machinery has been the general trend.
21. Load of washing and ironing equipment
The washing machine of bigger hotel and ironing equipment used to be more mechanical speed regulation or pole regulation, can only provide a speed or several speed, the need for repeated washing and ironing fabric is not ideal.Adopt frequency conversion speed regulation, greatly improve the efficiency of washing machine.
22. Music fountain load
Very touting music fountain, the height and amount of water is controlled by frequency conversion.
23, grinding machine and other mechanical load
The spindle of grinder has a high caring speed, and the frequency of power supply is also high, including 200Hz, 400Hz and even 800Hz.In the past, the power supply of spindle motor was mainly driven by if generator set.The intermediate frequency unit has large volume, low efficiency, high noise and poor accuracy.
24. Cigarette machine load
The cigarette machine imported by the cigarette industry in the past, no matter Maureen 8 or Maureen 0, is not stepless speed regulation.Therefore in the cigarette industry is mainly to solve the stepless speed regulation and reliability problems, simple technology, frequency converter usage is simple, great effect.
Vibration reduction and noise reduction load
Many loads, such as large air compressor, if frequency units, such as noise, vibration.Using frequency conversion technology, can reduce vibration and noise, up to standard.
Printing and dyeing machine load
Most printing and dyeing machines are multi-unit equipment.The process requires each unit to run synchronously at the same linear speed and maintain constant tension, otherwise it will break cloth, wrap cloth, uneven color, color degree is not enough, shrinkage rate is too large and other quality problems.In the past, the printing and dyeing machinery is used dc speed regulating system whether in common power mode or in partial power mode.Because of the inherent shortcomings of dc, the printing and dyeing industry has gradually adopted ac frequency conversion technology.The rotary screen printing machine is composed of feeding unit, printing unit, drying room guide belt unit and falling cloth unit.Speed chain control is formed by frequency conversion.Good synchronization performance, high precision, high reliability.
27. Load of injection molding machine
Injection molding machine is the key equipment of plastic processing and forming.In the past, the mode of power saving is often through delta (triangle) into Y (star) to save electricity, the general effect.Adopts frequency control of motor speed without changing the original structure, injection molding process that control pump pressure or flow (such as clamping, clamping, glue, pressure, stripping, back mould, etc.), power saving 20% ~ 52%, the proportion of good replaced the past valve throttle speed control mode, greatly reduce the energy consumption and the pearl river delta inverter were carried out a lot of injection molding factory.When reforming the injection molding machine, attention should be paid to the acceleration of mold closing, otherwise the output will be reduced, and attention should be paid to the harmonic interference at the input and output ends.
28, sewage treatment and other environmental protection load
More and more attention is paid to environmental protection, which is related to the living environment of human beings.So clean energy and green cities are emerging.Frequency conversion speed regulation can be used in three aspects of environmental load.The first is the industrial sewage treatment, the second is the garbage power plant, the third is the industrial smoke exhaust, dust control.
Glass, ceramics, pharmaceutical, beverage, food, packaging and other production line load
Glass, ceramics, pharmaceutical, beverage, food, packaging and other production lines using frequency control, have achieved good results.
30. Load of offshore oil production platform
Oil drilling using ac motor frequency conversion speed regulation is much better than dc speed regulation, especially in the sand, dust, because the ac motor is reliable.Offshore oil drilling platform needs frequency control device.
31. Submersible electric pump load
Electric submersible pump is a method of oil production in oilfield.Most of the submersible electric pumps work in Wells below 1800m, and most of them start at full pressure of power frequency and operate at constant speed, which has the following disadvantages:
(1) start the current is too large, will damage the motor insulation
(2) produce impact torque, damage the pump structure;
(3) the pump suddenly produced a larger suction, easy to suction sand, causing the pump.In addition, there is no stable voltage system and large fluctuation of downhole liquid level, which leads to unstable voltage and current, overexcitation and underexcitation of the submersible motor and causes faults.
32. Polyester chip type load
Polyester chip is one of the main products in the petrochemical industry, due to the high accuracy of frequency conversion speed regulation, easy to control multiple control points, stable and reliable, using frequency conversion speed regulation can increase product quality, bring great benefits to enterprises.Many enterprises in capacity expansion are using frequency control technology.
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