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With the continuous development of economy and technology, the air compressor, as an important mechanical power equipment, has been widely used in many industrial fields such as machinery, metallurgy, building materials, electric power, chemical industry, food, and textile. However, air compressors are equipped with high energy consumption. In some industries, power consumption accounts for more than 30% of the total power consumption in production. Permanent magnet frequency conversion air compressor has become a hot spot and bright spot in the industry because of their energy-saving and high efficiency. Gradually replace the original air compressor with large power consumption with a permanent magnet variable frequency air compressor, which can directly save users 20%-40% of the cost! So what is the working principle of the permanent magnet variable frequency air compressor? Why is it favored by the market? Let’s find out together.
The permanent magnet variable frequency air compressor is a new concept, and its working principle depends on the permanent magnet synchronous motor. The working principle of the rare earth permanent magnet variable frequency air compressor is the same as that of the electric excitation synchronous motor. The former uses permanent magnets instead of excitation coils as excitation. When the three-phase alternating current with frequency f is introduced into the three-phase stator winding of the permanent magnet motor, a synchronous rotating magnetic field will be generated. In a steady state, the main pole field rotates synchronously with the rotating magnetic field, so the speed of the rotor is also synchronous speed. The main pole magnetic field composed of permanent magnets and stator rotating magnetic field is always relatively static and interacts to generate electromagnetic torque to drive the motor to rotate and convert energy.
The frequency converter screw air compressor adopts the continuously variable speed characteristic of the frequency converter and realizes smooth starting through the internal controller or PID regulator. When there is a large fluctuation in gas consumption, the operation can be quickly adjusted. Compared with the power frequency lower limit switch control, the system has higher stability.
Most of the working conditions of the frequency converter are below the rated speed, which reduces the mechanical noise and wear of the main engine, and prolongs the maintenance and service life. If the fan also adopts frequency conversion speed regulation, it can significantly reduce the noise during the operation of the air compressor.
Because the inverter itself has the function of a soft starter, the starting current can be controlled within 1.2 times the rated current. In comparison, the starting current of power frequency is usually more than 6 times, and the starting impact is small. It is not just a problem of the grid, but a problem of the entire mechanical system.
The frequency conversion air compressor can only work under the specified displacement, and the displacement of the frequency conversion air compressor can be adjusted within a wide range. Frequency conversion speed regulation can adjust the speed of the motor in real time according to the actual gas consumption, and adjust and control the displacement. The air compressor can automatically sleep when the air consumption is low, which greatly reduces energy consumption. Improve the control method to further improve the energy-saving effect.
Because the frequency converter adopts overmodulation technology (converting the baseband signal into a transmission signal), even if the AC power supply voltage is slightly low, it can output enough torque to drive the motor to work. When the voltage is slightly higher, the output voltage to the motor will not be too high. For self-generating enterprises, frequency control can give full play to its advantages. According to the characteristics of motor frequency converter (frequency conversion air compressor works energy-saving under rated voltage), it has an obvious effect on places with low grid voltage.
