I. Comparison of Core Structure and Principles
| Comparison items | Industrial frequency Screw Air Compressor | Permanent magnet variable frequency screw air compressor |
| Motor type | Three-phase asynchronous motor | Permanent magnet synchronous motor |
| Drive control | Star-delta start, constant speed operation | Inverter drive, continuously variable speed (0~ rated speed) |
| Execution logic | Load - Unload: Shut down when pressure reaches the limit, restart when pressure reaches the limit. | Constant pressure variable flow: real-time speed adjustment, constant pressure, minimal unloading. |
| Starting current | Large (5 to 7 times the rated current), impacting the power grid. | Small (1.2 times the rated current), soft start without impact. |
II. Key Performance Differences
1. Energy Saving Effect (The Most Core Difference)
Power Frequency: when the motor idles under no-load conditions, energy consumption can reach 30%~50% of that at full load, resulting in significant waste.
Permanent Magnet: Automatically reduces speed or enters sleep mode under light load/no-load conditions, resulting in extremely low energy consumption.
Motor Efficiency: ≥95% (approximately 88%~92% at power frequency).
Overall Energy Savings: 20%~40%, with greater energy savings depending on gas usage fluctuations.
2. Gas Pressure Stability
Power Frequency: Pressure fluctuates within the upper and lower limits (e.g., 0.7~0.85MPa), affecting gas-consuming equipment.
Permanent Magnet: Pressure remains constant (e.g., 0.75MPa±0.01MPa), resulting in high-quality gas supply.
3. Noise and Lifespan
Power Frequency: Noise 80~85dB(A), large start-stop shock, rapid component wear.
Permanent Magnet: Noise 65~75dB(A), smooth operation, 30%+ longer lifespan.
4. Maintenance and Cost
Power Frequency: Simple structure, inexpensive maintenance; low initial purchase cost.
Permanent Magnet: Requires inverter maintenance; 30%~50% more expensive to purchase, but the cost can be recouped through electricity bills within 2~3 years.
