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Frequency Control Technology fan and pump energy saving applications

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In the production process of the enterprise, the application of pumps and fan equipment is very extensive, and the power consumption of such equipment is very large, and its energy consumption accounts for a large proportion of the total energy consumption of the enterprise. At present, our country is deepening the reform of the market economy system and the market competition can already be described as the word "brutal." Therefore, in order to enhance its own competitiveness, enterprises must optimize production techniques and processes, reduce energy consumption in production and reduce production Cost, improve product price competitiveness.
1 frequency changer function
In the realization of motor control equipment often used is the inverter, the device to achieve the motor control is to change the frequency of the power output. In the process of enterprise production, we must pursue better control of the motor, and to achieve better control of the entire motor, you must use the inverter, through the device to achieve AC motor overcurrent voltage protection, overload protection and frequency Speed, at the same time the overall system of energy utilization and efficiency of the inverter is also responsible for regulation.
2 different types of frequency converter
2.1 different switching mode under the inverter classification
Different switches, the type of inverter is also different, according to the switch classification, the inverter can be divided into four categories: First, SPWM control inverter; second, PAM control inverter; third, SVPWM control inverter; Fourth, PWM inverter. In these four different types of frequency converter, PAM control is a pulse amplitude modulation, which by changing the pulse width of the pulse column to achieve the waveform and the output value of the modulation, in order to achieve the variable frequency inverter functions; and PAM control, PWM control is pulse width modulation control, that is, when adjusting the waveform and output, it can be used to change the pulse width of the way, in order to achieve the inverter frequency conversion function; on the basis of PWM, change the modulation pulse is the SPWM control , In order to achieve the sine wave output, you need to follow the law of sine, arranged in the appropriate pulse width to filter and output waveforms, often used in production to the tributary AC inverter; and SVPWM control is space vector pulse width modulation, PWM A method of technical modulation, the PWM is inserted into the three-phase stator windings of the motor, to promote the generation of rotating magnetic field in the stator, so as to drive the motor to rotate.
2.2 According to the working principle of the inverter classification
In accordance with the working principle of split, the inverter can be divided into three types: the first is vector control inverter, the second is V / f control inverter, the third is slip frequency control inverter. V / f control inverter can ensure that the frequency and output voltage is a positive correlation, so you can achieve the consistency of the motor flux, effectively avoiding the weak magnetic and magnetic saturation problems; the so-called Slip Speed ​​is in the speed Adopting the method of changing the slip of induction motor, the speed determines the slip requirement, and the slip frequency control technology can improve the dynamic performance and static performance of the system to a certain extent. The most important feature of vector control inverter is the DC motor Speed ​​control, according to vector changes in the method of decomposition of stator winding current induction motor, DC motor can achieve the magnetic field current component.
3 fan, pump frequency energy-saving analysis of the working principle
Fan, pump frequency To achieve energy efficiency, there are two ways: one is soft-start energy saving, one is energy-saving inverter. The following specific introduction of these two energy-saving methods of energy-saving principle:
3.1 About soft start Energy saving
As the motor is Y / D start or start directly, the rated current of 4 to 7 times is the starting current, which will have a huge impact on the power supply grid and mechanical and electrical equipment, if the power supply capacity is very high, it will be activated Resulting in great damage, such as the valve and the baffle was the current and vibration damage, thereby shortening the life of the equipment and so on. After installing the inverter energy-saving device, the soft-start function of the inverter can automatically adjust the starting current at the beginning to zero, so that you do not have to worry about the current generated will exceed the rated current, to a certain extent, reduce the impact on the grid, played Extend the life of your valve and equipment so you can save on frequency converter maintenance
3.2 About energy-saving inverter
There is a formula in hydrodynamics, namely P = H × Q. Professionals all know that there is a certain relationship between P, H and Q, and they are all in direct proportion to each other, only in different sizes. If the efficiency of the pump is a fixed value, then as the flow rate is reduced, the rotational speed N will also decrease, and the output power P will also decrease, and the cubic relationship will decrease. This means that the pump speed and pump motor power consumption rate is a cubic relationship.
4 frequency control and fan, pump energy saving
4.1 adjust fan, pump flow method
There are many ways to adjust the flow of the fan and the pump. Each method has its advantages. There are three commonly used methods: (1) AC motor speed control; (2) When the speed of the pump, fan is adjusted Electromagnetic slip clutch way, but the motor in this case the operation is constant speed; (3) In the regulation of the fan baffle, if the use of traditional mechanical methods, can enable the realization of the pump, the deflector valve Adjustment of the opening degree. In the case of the same percentage of saving rate, the installed capacity and electric energy saving will become the maximum, therefore, in the production process, should be widely used high-voltage variable frequency speed control technology, and the variable speed control applied to large capacity compressors, Pumps and fans, in order to achieve energy-saving purposes.
4.2 frequency control in the fan, pump energy saving applications
The fluid theory as a basic starting point, you can use the cubic function to represent the centrifugal fan, pump shaft power and speed relationship. In the study, it is shown that the efficiency of hydraulic speed control after slip will decrease with the efficiency of the speed regulation scheme. When the speed drops to 50%, the frequency converter will show a higher efficiency. In this way, Will find that everything basically did not happen any change. Therefore, all speed control program is the best energy-saving solutions. A practical example shows that when the speed and shaft power of the same pump and fan are all 100%, the rotational speed is adjusted to 50% and the shaft power is reduced to 50%. However, if the slip is adjusted to 50%, then only about 25% of the power drawn from the power grid; if by frequency conversion, the flow dropped to 50%, only about 10% of the power drawn from the grid. Therefore, we find it easy to find that VVVF has unparalleled advantages.
5 frequency control and environmental protection
In the total power consumption of enterprises, motor-driven energy consumption accounts for a large proportion. We have reason to believe that the depletion of natural gas, coal, oil and other fuels is largely due to excessive electricity consumption. Excessive emissions of nitrogen dioxide and carbon dioxide can cause serious air pollution, cause irreparable serious damage to the atmospheric ozone layer, and cause extremely adverse effects on human life. At present, the environmental problems have become increasingly serious and have affected people's daily life. However, as people's awareness of environmental protection continues to increase, more and more people are beginning to pay attention to environmental issues and are actively involved in environmental protection. Therefore, in the production process of the enterprise, the enterprise should widely adopt the frequency conversion speed regulation and energy conservation technology, thus not only saving energy effectively, but also reducing the emission of pollution and playing the role of protecting the environment.
6 Conclusion
To sum up, energy-saving operation of pumps, fans and other equipment is realized through frequency control technology, and has been generally valued by the state and the government. The practice shows that the use of frequency converters in the drive control of pumps and fans can receive significant energy savings and is a widely available speed control method. Frequency control technology has many advantages, not only can improve the operating efficiency of equipment, but also to maximize the business for high-efficiency production needs. At the same time, it can actually reduce the cost of equipment maintenance and repair, effectively extending its life expectancy. At home and abroad, frequency control technology has been and will continue to receive the attention of people in our country's economic construction, it will also play an important role.
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