1. Introduction and development of variable frequency air compressors: With the rapid development of my country's economy, the country is paying more and more attention to high-speed and low-consumption technology, and this technology has attracted people's attention. Whether variable frequency speed regulation technology can be applied in the field of air compressor air supply to save electricity while improving the performance of air compressors and improving the quality of air supply has become a topic of concern to us.
2. Working principle of variable frequency air compressor: Since the speed of the air compressor motor is in a square relationship with the actual power consumption of the air compressor, reducing the motor speed will reduce the actual power consumption. The variable frequency machine uses a pressure sensor to instantly sense the actual air pressure and gas consumption in the system. Through the precise coordination of electrical control and variable frequency control, the motor speed (that is, output power) is instantly controlled without changing the air compressor motor torque (that is, the ability to drag the load). By changing the compressor speed, it responds to changes in system pressure and maintains a stable system pressure (set value) to achieve on-demand output of high-quality compressed air. When the air volume consumed by the system decreases, the compressed air provided by the compressor is greater than the system consumption. The variable frequency compressor will reduce the speed and reduce the output compressed air volume; otherwise, the motor speed will be increased to increase the compressed air volume to maintain a stable system pressure value. It is the same as the fan motor water pump power saving. According to the load change, the input voltage frequency is controlled, which is the same as the inverter principle.
3. What are the advantages of variable frequency air compressors compared with ordinary industrial frequency air compressors?
1. Stable air pressure:
● Compared with the upper and lower limit switch control of industrial frequency operation, the air pressure stability is improved exponentially.
● Since the variable frequency screw air compressor utilizes the stepless speed regulation characteristics of the inverter, it can start smoothly through the controller or the PID regulator inside the inverter; for occasions with large fluctuations in air consumption, it can quickly adjust and respond;
2. No shock at start-up:
● This shock is not only to the power grid, but also greatly reduced to the entire mechanical system.
● Since the inverter itself includes the function of soft starter, the starting current is within 1.2 times of the rated current. Compared with the power frequency starting which is generally more than 6 times of the rated current, the starting impact is very small.
3. Variable flow control:
● Optimized control strategy can further improve the energy saving effect.
● When the gas consumption is low, the air compressor can also be automatically put into sleep mode, which greatly reduces the energy loss.
● The power frequency driven air compressor can only work at one exhaust volume, while the variable frequency air compressor can work in a wider range of exhaust volume. The inverter adjusts the motor speed in real time according to the actual gas consumption to control the exhaust volume.
4. Better voltage adaptability of AC power supply:
● For self-generated occasions, variable frequency drive can better show its advantages;
● According to the characteristics of motor VF (variable frequency air compressor works below the rated voltage in energy-saving state), the effect is obvious for sites with low grid voltage.
● Due to the overmodulation technology adopted by the frequency converter, when the AC power supply voltage is slightly low, it can still output sufficient torque to drive the motor to work; when the voltage is slightly high, it will not cause the voltage output to the motor to be too high;
5. Low noise:
● If the fan also adopts variable frequency drive, the noise of the air compressor can be significantly reduced;
● Most working conditions of the variable frequency system are working below the rated speed, the mechanical noise and wear of the main machine are reduced, and the maintenance and service life are extended;
IV. Energy saving effect of variable frequency air compressor:
1. The pressure setting of the variable frequency air compressor can be one point, that is, the low pressure that meets the requirements of the production equipment can be used as the set pressure. The variable frequency air compressor will adjust the speed of the air compressor according to the trend of the up and down fluctuation of the pipeline pressure, and even eliminate the unloading operation of the air compressor, saving electricity.
2. Since the variable frequency air compressor stabilizes the pressure of the pipeline network, it can reduce or even eliminate the pressure fluctuation, so that all the running air compressors in the system are operated at a lower pressure that meets the production requirements, reducing the power loss caused by the upward pressure fluctuation.
3. Since the air compressor cannot exclude the possibility of long-term operation under full load, the capacity of the motor can only be determined according to the maximum demand, so the design capacity is generally larger. In actual operation, the proportion of light-load operation time is very high. If variable frequency speed regulation is adopted, the working efficiency during operation can be greatly improved. Therefore, the energy-saving potential is very large.
4. Some adjustment methods (such as adjusting the valve opening and changing the angle of the blade, etc.) cannot reduce the operating power of the motor even when the demand is small. After adopting variable frequency speed regulation, when the demand is small, the speed of the motor can be reduced, and the operating power of the motor can be reduced, thereby further realizing energy saving.
5. Most single-motor traction systems cannot be adjusted continuously according to the weight of the load. After adopting variable frequency speed regulation, it is very convenient to make continuous adjustments, which can keep the pressure, flow, temperature and other parameters stable, thereby greatly improving the working performance of the compressor.