Based on the method of reducing the energy consumption of air compressor based on frequency conversion technology, the WangWei WangWei scheme of China Sun Oil Company was designed to design the control method of the variable speed speed air compression pressure sensor 10 governor operation. In order to solve the key problem of the speed regulation performance efficiency and operational reliability improvement of the motor in the air compressor frequency conversion transformation. This study provides a theoretical basis for the use of frequency converters to control the application and popularization of motors on air compressors. For the energy saving and environmental protection of air compressors, it is of great significance to improve product performance and competitiveness. 1 Introduction In the working process, the air compressor motor must constantly overcome the huge moment of inertia generated by the rotor from static to rated speed. Especially when starting with load, the starting torque is many times higher than the running torque. The result is not only the result. It consumes extra power and can exacerbate the wear and tear of moving parts of the air compressor. In addition, this mode of operation will also generate large vibration noise and inrush current during the starting process, and the fluctuation of the power supply voltage. Therefore, the variable frequency air compressor should be used instead of the constant speed air compressor to avoid such frequent start and stop. process. The main features of the inverter control motor First, the reliability is high, the failure rate of the AC motor frequency conversion speed regulation is very low, compared with the DC speed regulation, the motor has no commutator and other vulnerable links, its advantages are very obvious, and the protection function is perfect. The reliability is much higher than other speed control methods. This is the fundamental reason for the rapid development of frequency conversion speed regulation. Secondly, the speed regulation range is wide. The minimum working frequency of the frequency converter can range from zero hertz to 4 or more. It can meet different speed regulation occasions and is widely used. Again, the speed regulation is good, the speed between the two gears can be as low as zero to several revolutions. For some control systems, the impact on the system can be reduced, and the controlled parameters are more stable and improved. Reliability and economy have extended the life of the equipment. Finally, the working characteristics are good. In terms of working characteristics, whether it is static or dynamic, the frequency conversion speed regulation is comparable to the DC speed control system. 2 Air compressor frequency conversion control scheme The system is driven by a frequency converter to drive two air compressor motors. After the pressure signal of the pressure sensor sampling pipe network is intelligently processed, the control signal is transmitted to the frequency converter, and the frequency converter adjusts the motor speed according to the control signal to realize the air volume adjustment of the air compressor to ensure the stability of the pipe network pressure. No.1 motor No.2 motor KM1 upper limit switching lower limit switch RST inverter industrial change start-stop work change start-stop frequency frequency stop frequency frequency stop, to add intermediate relay between output port and AC contactor, through intermediate relay to control motor Actions, to achieve isolation between weak current and strong electricity, protect the system to enhance the reliability of system operation. The interlocking of the circuit that is controlled again, because the control system is internally automatic, it is strictly forbidden to connect the motor to the power frequency power supply and the variable frequency power supply at the same time, and the inverter is always connected with the motor. The selection principle of the inverter is as described above. In the frequency conversion transformation of the air compressor system, it is necessary to select the inverter according to the specific project requirements and carry out the operation design. The selection of the inverter of the electric drive variable frequency speed control system is a relatively complicated question, which is an experimental process with multiple steps. Mainly consider the following aspects, such as the choice of the type of inverter 1 to the application object division, the inverter can be divided into general-purpose inverter and special inverter, in order to meet the needs of most production machinery speed regulation, general-purpose inverter control, It can also be used for control methods such as slip frequency control current limit control, square voltage-to-frequency ratio control, and sagittal control. It is widely used and has a wide range of contents. The dedicated inverter is developed for specific application fields and has excellent performance in a specific demand. Some special functions, such as fan-type load-specific inverters, have special functions in them. 2 Inverter capacity selection The capacity of the inverter should be optimized with the power of the motor, but the frequency of the motor cannot be determined only by the power of the motor. The capacity of the device. The rated output current of the inverter is also an important factor that must be considered when selecting the capacity of the inverter. In addition to this, the number of starting and retarding motors of the motor and the load should be considered. Based on the control operation mode of this paper, the capacity of the inverter only needs to comply with the capacity of the inverter control motor. The main purpose of the air compressor is to obtain the compressed air of constant pressure. Therefore, the control of the outlet pressure of the compression host is the key to the energy-saving control of the entire air compressor system. For the user, since the outlet pressure requirement remains unchanged and remains basically constant, the control system can be designed to control the inlet and outlet pressure difference of the compressor according to the process pipe wind pressure as a control parameter. The control principle controller constitutes a closed-loop control system. Pressure transmitter power air compressor 3 air compressor frequency conversion control design In the air compressor system, the two are generally operated in parallel. In order to realize the continuous adjustment of the speed of the two motors, the motor speed is set according to the actual load, thereby saving energy. At the same time, in order to save the initial investment of the inverter and other equipment, the design of the operation of the two air compressors is as follows: Each time you run, you only need one at most, and the other is standby. Any station can be selected as the main control unit. In operation, the first machine is used as the main control unit to carry out frequency conversion operation. If the frequency rises to the upper limit and the pressure difference is still too large, the No. 1 machine is switched to the power frequency operation, and the inverter will be connected to the No. 2 machine. So that the No. 2 machine is in the inverter running state. When the working efficiency of the inverter drops to the lower limit and the differential pressure is still too small, the No. 1 machine is stopped, and the No. 2 machine is still in the variable frequency operation state. The control circuit is used to control. By adding the digital modulo 0 conversion module, the 1 digital signal is converted into a voltage or current according to the setting of the inverter, and input to the analog control terminal of the inverter to control the operation of the inverter. Each motor can select the power frequency operation mode and the frequency conversion operation mode. When the switch is switched to the frequency conversion position, the motor will be used as the main control unit to realize the above control. When the switch is switched to the power frequency, the motor can also be manually controlled by the start and stop buttons, and the motor can be switched at the power frequency. In the design of the control circuit, we must first consider the isolation between weak current and strong power. In this control system, all the actions of controlling the motor contactor are completed according to the program logic of 0. In order to protect the force sense transmitter system, the selection principle of the selection amount of the inverter is applied. Generally calculate the required power of the load, then the power of the motor is set to be greater than the required power of the load, thereby determining the power of the motor; and then determining the output power of the shaft under the following three conditions by the power of the motor. ; cos6 is the power factor of the motor is usually about 75; UM motor voltage 00; L motor according to the power frequency power supply; Pai Chu rated Rong Lin A; lCN inverter rated current. The calculation formula of the three inverter capacities is suitable for the case where a single inverter is continuously operated by a single motor. The above three equations are unified. When selecting the inverter, the relationship of the three equations should be satisfied at the same time, especially the more critical amount of the inverter current. If the maximum current in the actual operation of the motor is less than the rated current of the motor, the capacity of the inverter can be appropriately reduced when the inverter is selected. For constant torque loads, the capacity of the selected frequency converter should not be less than 80% of the motor power; for constant power loads, the capacity of the selected frequency converter should not be less than the power of the motor. It can also be estimated by the flow or motor nameplate. Current. 3 Switching between the power grid and the inverter When switching the motor in the power frequency grid rotation to the inverter rotation, once the power frequency grid is disconnected, the motor must be completely stopped before switching to the inverter side to start. However, when switching from the power grid to the inverter, for a device that cannot be stopped immediately, it is necessary to select a model having such a control device, that is, to switch to the inverter side without completely stopping the motor. Generally, after the power grid is cut off, the free running motor is synchronized with the inverter, and then the inverter output power. This is effectively avoided in the switching method of this article. (4) Instantaneous power failure restart The instantaneous power failure causes the inverter to stop working. However, after the power is restored, the operation cannot be started immediately. It is necessary to wait for the motor to stop completely and then start again. This is because the frequency at the time of restarting is not appropriate, which may cause an overvoltage and overcurrent protection action, causing a malfunction and stopping. The use of the inverter mode will avoid this situation, because it has the power supply instantaneous stop or the automatic restart function after the large step-down, effectively avoiding the above situation. 5 Inverter peripheral equipment and its selection Inverter peripheral equipment can be divided into conventional accessories and special accessories. Among them, the conventional accessories include a power transformer arrester power supply side circuit breaker power supply side AC contactor motor side electromagnetic contactor and a power frequency grid switching contactor and a thermal relay. Special accessories have a reactor filter braking resistor. In order to adapt to the needs of variable frequency speed control in this paper, the control cabinet also needs to be equipped with various types of circuit breakers. Swiss 8 contactor France Schneider relay Taiwan Guoxing and other low-voltage electrical equipment, complete the hard connection of the electrical main circuit and control loop The function is to realize the reliable and correct connection of the hard-wired line. 5 Energy-saving effect calculation Take the transformation of our company's air compressor as an example. The test parameters are as follows: The motor power line time is 8 hours, the annual operation is 300 days, and the loading time is 155. The load time is 158; the load current is 218, and the load-shedding current is 90. After the modification, the load current is 186, and the power-saving rate is about 30. The annual power consumption is calculated as 30. The conclusion is 6, the power saving effect is obvious, and the transformation is obvious. There are other advantages to the rear system. First, the noise of the machine is reduced. The use and the frequency converter realize the soft start of the soft start of the machine, avoiding the impact on the power grid when the air compressor starts, and reducing the maintenance amount of the equipment. Second, two sets of control loops ensure normal and safe operation of the system. Finally, the degree of automation is high, overcoming the shortcomings of manual adjustment of the original system. Wang Wei 1963 male engineer, now working for China Sun Oil Company. Chen Hongwei. The piston compressor uses the technical manualæ™·. Beijing Machinery Industry Press. 199217. Yang Geng, Luo Yingli. Motor and motion control systemæ™·. Beijing Tsinghua University Press. 20063. Kang Mei, Julie, Chen Shan. Inverter usage guide. Beijing Chemical Industry Press. 200933. Small Autoclave,Composite Material Autoclave,Composite Treatment Autoclave,Civil Use Autoclave JIANGSU OLYMSPAN THERMAL ENERGY EQUIPMENT CO.,LTD , https://www.compositesautoclave.com