The selection of rated gear motor power is a very important and complex issue. When the load is too high, if the rated power of the motor is too large, the motor tends to be in the light load operation state, the capacity of the motor itself will not give full play to, and it will become a "big horse-drawn" car "motor operating efficiency is low. The efficiency of the motor is low, and the performance is not good, which will increase. Operating costs. On the contrary, the rated power of the motor is very small, that is, "small horse pulling the car", the motor current exceeds the rated current, the motor loss increases, low efficiency, it is important to affect the service life of the motor, even if the overload is not too much, the service life of the motor will be reduced by more; overloading will destroy the insulation of the motor insulating material insulation performance or even burned. Of course, the motor is rated so small that the load may not be towed at all, which may result in the motor being left in the starting state for a long time and damaged due to overheating. Therefore, the power rating of the motor should be selected in strict accordance with the operation of the electric vehicle.