Why do air compressors need frequency converters

Nowadays, in the air compressor market, series such as variable frequency screw air compressors, permanent magnet variable frequency screw air compressors, and two-stage compression permanent magnet variable frequency air compressors all use variable frequency control to adjust the frequency of the air compressor, stabilize the outlet pressure of the air compressor, and achieve automatic switching of the frequency converter.

Air compressors are generally selected based on the actual demand for cooling capacity under design conditions. In general, compressors work year-round, spanning two extreme weather conditions of winter and summer, so they face relatively complex external environments. Moreover, there are inevitably certain deviations between actual working conditions and design schemes, so the compressor power has more appropriate surplus.

At present, the energy regulation of air compressors mainly includes intermittent control operation, suction regulation, cylinder unloading, bypass regulation, and stepless variable speed regulation. Intermittent operation of the compressor is a common operating mode. When the ambient temperature is higher than the set temperature, the compressor will start running. When the ambient temperature drops below the set temperature, the compressor will stop working. This working method is suitable for situations where the ambient temperature is relatively stable and the load is not large, but in actual use, the ambient temperature does not tend to stabilize at all times. Under extreme weather conditions and complex working environments, various production activities can cause changes in cooling load, frequent temperature fluctuations, and frequent engine start stop, resulting in significant energy waste.

The instantaneous current of the generator will pollute the power grid, increase grid fluctuations, and also affect the lifespan of the compressor. Therefore, frequency conversion technology has also been widely applied in compressors.

Under certain working conditions, the cooling capacity of the compressor is directly proportional to the mass flow rate. The basic idea of variable frequency regulation is to adjust the mass flow rate by changing the compressor motor speed, thereby changing the cooling capacity of the total unit.