Why is the variable frequency motor equipped with a separate cooling fan?

It is used for cooling the motor. Not only "variable frequency motors", but "ordinary motors" also need to be equipped with a "cooling fan".

Because the motor generates heat when it is working, in order to ensure that the motor does not overheat, the heat emitted must be taken away by wind, water or other carriers to achieve a cooling effect. The simple method is ventilation and cooling. The motor generally has its own fan blades (that is, installed on the motor shaft), but when the motor is slowed down by some means, the air volume blown by the fan blades is not enough to cool down the motor. Effect. Therefore, another "cooling fan" must be installed. In order to ensure the air supply volume of the "cooling fan", the power supply connected to it is full voltage.