Cooling problem at low motor speed

Update:28 Feb 2019
Summary:

First of all, the impedance of the asynchronous motor i […]

First of all, the impedance of the asynchronous motor is not ideal. When the power frequency is lower, the loss caused by the higher harmonics in the power supply is larger.

Secondly, when the normal asynchronous motor is reduced in speed, the cooling air volume is proportional to the cube of the rotational speed, which causes the low-speed cooling condition of the motor to deteriorate, and the temperature rise sharply increases, making it difficult to achieve constant torque output.