Permanent magnet variable frequency air compressor is called permanent magnet because it is equipped with permanent magnet synchronous motor, also known as permanent magnet motor, rare earth permanent magnet synchronous motor, ac permanent magnet synchronous motor and so on.

Anyone who knows how to use the permanent magnet synchronous motor of the permanent magnet variable frequency air compressor will produce irreversible demagnetization in the case of large current, high temperature or violent vibration.

Step 1: choose the right permanent magnet motor power

Demagnetization is related to the power selection of permanent magnet motor. Proper selection of permanent magnet motor power can prevent or delay demagnetization. The main reason of demagnetization of permanent magnet synchronous motor is high temperature and overload is high temperature. Therefore, when selecting permanent magnet motor power, there should be a certain amount of margin. Generally, about 20% is more appropriate according to the actual load.

Tip 2: improve the design

A. Increase the thickness of permanent magnet appropriately

From the perspective of design and manufacture of permanent magnet synchronous motor, the relationship among armature reaction, electromagnetic torque and permanent magnet demagnetization should be considered. The permanent magnet on the rotor surface is easy to induce demagnetization under the combined action of magnetic flux generated by current of torque windings and magnetic flux generated by radial force windings. Under the condition of constant air gap of the motor, the most effective way to ensure the permanent magnet is to increase the permanent magnet thickness.

B. The rotor is provided with a ventilation groove loop inside to reduce the temperature rise of the rotor

Permanent magnet demagnetization is an important factor affecting the reliability of permanent magnet motor. If the rotor temperature rises too high, permanent magnet will produce irreversible magnetic loss. During the structural design, the rotor internal ventilation circuit can be designed to directly cool the magnetic steel. It not only reduces the temperature of magnetic steel, but also improves the efficiency.

Tip 3: avoid heavy-duty starting and frequent starting

Cage type asynchronous start synchronous permanent magnet motor try to avoid heavy load direct start or frequent start. In the asynchronous starting process, the starting torque is oscillating, and in the trough of the starting torque, the stator magnetic field is demagnetization to the rotor magnetic pole. So as far as possible avoid asynchronous permanent magnet synchronous motor overload and frequent start.