How much power consumption difference between frequency conversion compressor and power frequency compressor

The difference between the power consumption of the inverter compressor and the power frequency compressor varies with the operating conditions. Under low load or fluctuating conditions, the inverter compressor can save 10%-50% of the power; under full load conditions, The power consumption of the two is close, and the inverter compressor may have a slightly higher loss due to the inverter. The following is a specific analysis:

low load or fluctuating condition

• power frequency compressor: Fixed frequency operation, output fixed displacement. When the actual gas consumption is lower than the rated displacement, the equipment cannot adjust the speed and can only operate in the "load-unload" mode. When the motor is idling, it still consumes 30%-50% of the rated power, resulting in a large amount of power waste.
• Inverter compressor: Adjust the motor speed in real time through the frequency converter to achieve accurate matching between the displacement and the actual gas consumption. When the gas consumption decreases, the frequency converter reduces the motor frequency, the speed slows down, and the energy consumption decreases with the speed drop in a cubic relationship (according to the principle of fluid mechanics, the motor power is proportional to the third power of the speed). When the load is low, there is no need to unload, and the motor keeps running at a low speed and only consumes the electric energy required to maintain the current gas volume.
• Difference in electricity consumption: Take 75kW screw air compressor as an example. Under the scenario of low load (the gas consumption load accounts for 50% of the rated displacement), the monthly power consumption of the power frequency compressor may be as high as 12480 degrees, while the variable frequency compressor only needs 6240 degrees, with a monthly energy saving of 6240 degrees, an energy saving cost of 4992 yuan, and an annual energy saving income of 59904 yuan.

Full load condition

• power frequency compressor: When running at full load, it can stably output the rated displacement without frequent adjustment of the speed, so the energy consumption is relatively stable.
• Inverter compressor when running at full load, although the rated displacement can be output stably, due to the need to drive the inverter, a certain amount of energy consumption may be increased (usually 5%-8% of the rated power). However, this increase in energy consumption is usually small, and in practical applications, because the inverter compressor can more accurately match the actual gas consumption, the overall energy consumption may still be lower than that of the power frequency compressor (especially in the case of long-term operation or slight fluctuations in gas consumption). However, if only the ideal state of full load and constant gas consumption is considered, the power consumption of the two is close, and the inverter compressor may have a slightly higher loss due to the inverter.
• Difference in electricity consumption: Under the scenario of full load (the gas consumption load accounts for 100 of the rated displacement), the monthly power consumption of the power frequency screw air compressor is about 15600 degrees, while the monthly power consumption of the variable frequency screw air compressor can be reduced to 14820 degrees, which can save 780 degrees of electricity per month, corresponding to the energy saving cost of 624 yuan, and the annual energy saving income can reach 7488 yuan. Although the inverter compressor can still save a certain amount of electricity when running at full load, the energy-saving effect is much smaller than that of low load or fluctuating conditions.