Cooling system for electric motor and cooling control method

The invention relates to a cooling system for an electric motor, in which a failure is prevented by thermal fatigue due to the temperature cycle. The beginning and the end of the operation of the forced cooling motor fan (6) of the forced cooling system (Tis) controlled by using the difference between the temperature of the engine and the operation starting temperature of the power converter (3), whereby an extension of the temperature range is suppressed.