The difference between air compressor power frequency and frequency conversion

The main difference between air compressor power frequency and frequency conversion is reflected in the following aspects:

1. working principle and energy consumption control

1. power frequency air compressor:

   • working principle: The motor is directly connected to the compressor and driven by the power frequency power supply (usually 50Hz or 60Hz) provided by the power grid. Since the motor speed is fixed, the operating speed and output power of the air compressor are also constant.
   • energy consumption control: No matter how the actual air consumption changes, the air compressor will run at the rated speed. When the gas consumption is less than the rated displacement, the system pressure will rise, resulting in the unloading of the air compressor and no-load operation, or even shutdown and restart. This frequent start and stop not only increases energy consumption, but also shortens the life of the equipment.

2. Variable frequency air compressor:

   • working principle: The precise control of the motor speed is realized by introducing a frequency converter. The frequency converter can automatically adjust the power frequency according to the actual gas demand, and then change the speed of the motor, so as to adjust the displacement of the air compressor.
   • energy consumption control this on-demand gas supply mode effectively avoids energy waste and has a significant energy saving effect. According to statistics, compared with the power frequency air compressor, the energy saving effect of the variable frequency air compressor can reach 20% ~ 40%. In addition, the soft start function of the inverter also significantly reduces the starting current, reduces the impact on the power grid, and extends the service life of the equipment.

2. operation stability and pressure control

1. power frequency air compressor:

   • operation stability: Because its operating speed and output power are fixed, it is difficult to keep the system pressure constant when facing working conditions with large fluctuations in gas consumption. In order to alleviate this problem, it is usually necessary to have a larger gas tank to buffer the pressure fluctuation, but this increases the complexity and cost of the system.
   • Pressure control: The pressure is adjusted mainly through start-stop control, and the control accuracy is relatively low.

2. Variable frequency air compressor:

   • operation stability using the stepless speed regulation characteristics of the frequency converter, combined with the PID regulator, the precise control of the system pressure is realized. No matter how the air consumption changes, the variable frequency air compressor can quickly adjust the motor speed to maintain the stability of the system pressure.
   • Pressure control: The pressure control accuracy is high, and it can be adjusted in real time according to the actual gas consumption to ensure the stability of the production process and product quality.

3. Startup Characteristics

1. power frequency air compressor:

   • start mode: Usually use direct start or star delta step-down start, the starting current is larger, generally 5 to 7 times the rated current, the power grid and the equipment itself will cause a greater impact.

2. Variable frequency air compressor:

   • start mode: The soft start is realized through the frequency converter, and the maximum starting current is within 1.2 times of the rated current, which greatly reduces the impact on the power grid and other electrical equipment.

4. noise and vibration

1. power frequency air compressor:

   • noise and vibration: Due to the constant and high speed of the motor, coupled with the mechanical impact caused by frequent start and stop, the noise and vibration of the power frequency air compressor are relatively large, which has a certain impact on the working environment and the health of the operators.

2. Variable frequency air compressor:

   • noise and vibration: Because the motor speed is adjustable and mostly lower than the rated speed, and the soft start function of the inverter effectively reduces the starting impact, the noise and vibration of the inverter air compressor are significantly reduced, providing a more comfortable working environment for the operator.

5. adaptability and scope of application

1. power frequency air compressor:

   • adaptability: Because of its fixed operating speed and output power, the scope of application is relatively limited, and generally can only meet the working requirements under specific pressure and flow. In the need for frequent adjustment of gas occasions, its performance may not be satisfactory.
   • Scope of application: Because of its low price, simple structure and convenient maintenance, it is widely used in the fields of family, small car shop, medical treatment and chemical industry.

2. Variable frequency air compressor:

   • adaptability: It has good adaptability and flexibility, can intelligently adjust the working state according to actual needs, and meet the gas and power needs of different users.
   • Scope of application: It is suitable for occasions that require atmospheric volume, high pressure, frequent start and stop, and long-term operation, such as automobiles, manufacturing, and construction.

6. maintenance costs

1. power frequency air compressor:

   • maintenance costs: The structure is relatively simple and the maintenance is convenient, but due to frequent start and stop and mechanical impact, the equipment life is relatively short, and the long-term operation and maintenance cost is high.

2. Variable frequency air compressor:

   • maintenance costs: Although the initial investment is high, due to stable operation, low wear and tear, low failure rate, long equipment life, and low maintenance costs in the long run.

To sum up, variable frequency air compressors have significant advantages in energy efficiency, noise control, pressure stability, and maintenance costs, but the cost is relatively high; while power frequency air compressors have lower costs, but relatively insufficient energy efficiency and flexibility. When choosing an air compressor, it should be considered comprehensively according to the actual use scenario and needs to choose the most suitable type.