The reason why the permanent magnet variable frequency air compressor is called "permanent magnet" is because the "permanent magnet synchronous motor" is also called permanent magnet motor, rare earth permanent magnet synchronous motor, AC permanent magnet synchronous motor and so on.

Knowledgeable people must know that the permanent magnet synchronous motor in the permanent magnet variable frequency air compressor will produce irreversible demagnetization in the case of high current, high temperature or violent vibration. Today, Xiaobian teaches you three ways to solve the demagnetization problem.

The first trick: the correct choice of permanent magnet motor power

Demagnetization is related to the power selection of permanent magnet motor. The correct selection of the power of the permanent magnet motor can prevent or delay demagnetization. The main reason for the demagnetization of permanent magnet synchronous motor is that the temperature is too high, and overload is the main reason for the temperature is too high. Therefore, in the selection of permanent magnet motor power to leave a certain margin, according to the actual situation of the load, generally about 20% is more appropriate.

Tip # 2: Improve your design

a. Appropriately increase the thickness of permanent magnet

From the point of view 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 cause demagnetization under the joint action of the magnetic flux generated by the torque winding current and the magnetic flux generated by the radial force winding. In the case that the motor air gap is unchanged, the most effective way to ensure that the permanent magnet is not demagnetized is to appropriately increase the thickness of the permanent magnet.

b. There is a ventilation groove loop inside the rotor to reduce the temperature rise of the rotor

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

Tip 3: Avoid heavy starting and frequent starting

Cage asynchronous start synchronous permanent magnet motor to avoid heavy direct start or frequent start. In the process of asynchronous starting, the starting torque is oscillating. In the starting torque trough, the stator magnetic field has demagnetization effect on the rotor magnetic pole. Therefore, try to avoid heavy load and frequent start of asynchronous permanent magnet synchronous motor.