As we all know, hub motor is a device that integrates transmission, braking system and motor in the hub, and it is also a research hotspot of new energy vehicle technology. When the motor and the hub rotate together, the unavoidable problem is the temperature. If the temperature is too high, the stability and safety of the motor will be damaged. If it is serious, it may be burned. At this time, it is necessary to heat the hub motor in time. How to heat the hub motor? The following small series of global wind turbine will introduce the heat dissipation mode of hub motor.
1、 Air cooling
1. Natural cooling
Natural cooling motor does not use fan, but through heat exchange, convection, heat radiation and other forms of heat transfer from the object to the environment medium to reduce the temperature of the object, so as to achieve the same spontaneous process as the ambient temperature.
2. Forced air cooling
Forced air cooling is usually done by using an electric fan to blow air through the motor. The forced air cooling method can reduce the heat conduction to the machine structure and allow the motor to run under higher load. Forced air cooling is divided into open air cooling and closed air cooling.
(1) Open air cooling refers to the heat exchange between the internal and external air of the motor. It has ventilation inlet and outlet. The wind takes away heat along the through-hole direction. It can not only directly heat the stator, but also directly heat the rotor.
(2) Closed air cooling refers to that the air circulates inside the motor and carries out heat exchange between the shell and the outside. The internal fan of the motor blows the air into the air duct of the casing. The wind reaches one end of the motor along the air duct of the casing, and then reaches the other end of the motor through the ventilation hole of the rotor and the air gap between the stator and the rotor to complete a cycle. The heat can be dissipated by the heat sink on the casing.
2、 Liquid cooling
1. Oil cooled
Oil cooling, as the name implies, is to use cooling oil to cool the motor. There are heat exchangers on the outer surface of some motors, which take away the heat of motors by circulating cooling oil. The cooling parts can be soaked in cooling grease with good insulation performance, which is a suitable cooling form for external rotor motor. Oil cooling can be divided into direct cooling and indirect cooling according to the contact form with coolant. Direct cooling is the direct cooling of the motor stator and rotor, indirect cooling is to soak the sealed motor in the oil tank and take away the heat through the casing.
2. Water cooling
Water cooling is similar to oil cooling, except that it uses water as the cooling medium. The cooling water conduit can be placed inside the stator winding, or the cooling channel can be designed in the stator casing. There are two forms of water cooling and heat dissipation design, one is to use the water jacket form, the water circuit is designed in the shell; the other is to adopt the form of water pipe, which is designed on the stator.
3、 Mixed cooling
The mixed cooling mode generally uses liquid cooling in the motor and air cooling at the same time. Compared with the first two cooling methods, this cooling method has better heat dissipation effect compared with air cooling, and makes better use of air compared with liquid cooling, so that the heat exchange of internal equipment of hub motor is more sufficient. If the motor is cooled by oil and air, the heat dissipation efficiency of hub motor is improved.
The above content is the answer to how to heat the hub motor. Simply speaking, the heat dissipation methods of the wheel hub motor include air cooling, liquid cooling and mixed cooling. Therefore, appropriate heat dissipation methods should be adopted to heat the wheel hub motor so as to ensure the stable operation of the motor within the controllable temperature range and avoid failure due to excessive temperature.
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