EMU traction motor cooling designs
The fast-growing economy and people's growing demand have promoted the rapid development of China's high-speed rail industry. China has a vast territory and a large population, and there is a great demand for travel. "High speed" and "heavy load" have become a new direction for the development of EMUs. In order to meet the demand of high-speed heavy load, higher power traction motors have become the preferred replacement parts. Higher power brings huge traction force, but also generates a lot of heat, It brings pressure to the normal operation of traction motor.
Traction motor structure：
The traction motor is composed of stator, rotor, bearing, end cover and other components. The stator is of iron core structure after being processed by casting machine base; The motor rotor is of squirrel cage structure, which is composed of high-strength forged alloy steel rotating shaft, insulated cold-rolled silicon steel laminated core, copper guide bar squirrel cage winding and other components; Motor bearings are used to bear radial and axial forces. Cylindrical rolling bearings are used at the driving end of the motor and ball rolling bearings are used at the non driving end.
Motor Cooling:
At present, the structural forms of traction motors mainly include self ventilation cooling structure, fully enclosed structure, water cooling structure and oil cooling structure, while EMU trains mostly adopt self ventilation cooling structure.
Surface layer cooling:
In order to achieve greater heat dissipation, some fins or rib plates will be designed inside or outside the traction motor to increase the cooling area and achieve better heat dissipation effect.
Force air cooling:
The heat inside the motor is taken away by the constantly circulating gas, which is an important way for the motor to dissipate heat. The uniformity of air volume and pressure at the air outlet of the traction motor fan is the design focus of the traction air duct. Usually, a deflector can be added inside the air duct to evenly distribute the air volume. The material, structural size, speed and power of the fan air duct have a great impact on the heat dissipation capacity of the motor. The ventilation air duct sends the required air volume to the designated position, It is of great significance to motor cooling.
The improvement of the speed level and axle load of high-speed EMU trains has led to the continuous emergence of higher power motors. At present, the traction motor adopts the methods of increasing the cooling area and improving the air cooling capacity to achieve cooling. However, with the further improvement of the speed and axle load of EMU trains, the traction motor releases more heat, and the required cooling methods also need to be further updated, such as high-performance liquid cooling, high-power semiconductor cooling, etc.
