- Michael Xu
- Issue Time
- Dec 24,2021
What is the difference between PM VSD screw air compressor and fixed speed screw air compressor?
In the frequency conversion control screw air compressor, it can be divided into two types: ordinary frequency conversion and permanent magnet frequency conversion. It is also controlled by inverter, so what is the difference between the two? Which energy saving effect is higher and lower?
The same frequency converter is used, but the permanent magnet variable frequency motor does not require reactive excitation current, can significantly improve the power factor (up to 1, even capacitive), reduce the stator current and stator resistance loss, and there is no rotor during stable operation Copper consumption can reduce the fan (small-capacity motors can even remove the fan) and the corresponding wind friction loss, and the efficiency can be increased by 2 to 8 percentage points compared with the ordinary variable frequency motors of the same specification. Moreover, the permanent magnet variable frequency motor uses rare earth permanent magnet materials, while the ordinary variable frequency motor is an ordinary three-phase asynchronous motor. The permanent magnet variable frequency motor can maintain high efficiency and power within the range of 25% to 120% of the rated load. This factor makes the energy-saving effect more significant during light-load operation, and the work efficiency is high, which is 5%-7% higher than the ordinary frequency conversion motor of the same power on average, and saves energy and electricity than the ordinary frequency conversion motor.
1. The life span is different.
From the perspective of the service life of the machine, the permanent magnet variable frequency screw air compressor is better. Because it is driven by a variable frequency converter, the air compressor adopts a "soft start" when it starts, which has a certain protective effect on the motor and reduces the possibility of burning the motor.
2. The parts are different.
From the perspective of parts, the permanent magnet variable frequency air compressor adopts high-efficiency rare earth permanent magnet motors and frequency converters. These two components are of great help to the energy saving of the air compressor.
3. The maintenance cost is different.
From the perspective of maintenance costs, permanent magnet motors do not need bearings and no need to add grease, which eliminates the point of failure and reduces maintenance costs.
In addition, the permanent magnet variable frequency motor will automatically adjust the frequency of the motor to change the motor power according to the changes of the user-end equipment, and well match the motor output power. Its working efficiency remains at a high level no matter it is under light load or overload.