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The difference between fixed speed screw air compressor and permanent magnet VSD screw air compressor

The difference between fixed speed screw air compressor and permanent magnet VSD screw air compressor

Jan 11,2022

The difference between fixed speed screw air compressor and permanent magnet VSD screw air compressor

Permanent magnet variable frequency screw air compressors are widely used in industry, and people can't help but remind people of industrial frequency-driven screw air compressors. Throughout the market, industrial frequency-driven air compressors have gradually withdrawn from people’s attention and replaced by permanent magnet variable frequency air compressors. So what is the difference between the two? Why is the permanent magnet variable frequency air compressor popular in the market?


1. The air pressure is stable:

Because the frequency conversion screw air compressor uses the stepless speed regulation characteristics of the frequency converter, it can be started smoothly through the controller or the PID regulator inside the frequency converter; it can also be adjusted quickly in the occasions where the air consumption fluctuates greatly. response;

Compared with the upper and lower limit switch control of power frequency operation, the air pressure stability is improved exponentially.


2. Start without impact:

 Since the frequency converter itself includes the function of a soft starter, the maximum 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 small.

This impact is not only on the power grid, but also on the entire mechanical system, which is also greatly reduced.


3. Variable flow control:

The air compressor driven by industrial frequency can only work at one displacement, and the variable frequency air compressor can work at a relatively wide range of displacement. The frequency converter adjusts the motor speed in real time according to the actual air consumption to control the air displacement.

When the air consumption is low, the air compressor can be automatically dormant, which greatly reduces the energy loss.

The optimized control strategy can further improve the energy-saving effect.


4.The voltage adaptability of the AC power supply is better:

Due to the over-modulation technology adopted by the frequency converter, it can still output enough torque to drive the motor when the AC power supply voltage is slightly lower; when the voltage is higher, it will not cause the output voltage to the motor to be too high;

For the occasion of self-generation, the variable frequency drive can show its advantages better;

According to the characteristics of the motor VF (variable frequency air compressors work below the rated voltage in the energy-saving state), the effect is obvious for sites with low grid voltage.


5. Low noise:

Most of the working conditions of the frequency conversion system work at lower than the rated speed, the mechanical noise and wear of the host machine are reduced, and the maintenance and service life are prolonged;

If the fan is also driven by frequency conversion, it can significantly reduce the noise of the air compressor when it is working.


The difference between frequency conversion and industrial frequency is obvious. The energy saving and efficiency advantages of permanent magnet frequency conversion air compressors are necessary means to win the market. It can also be seen that only by complying with market requirements can it be recognized by the market.

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