Talking about the temperature distribution law in the motor

11/10/2019

Temperature rise is a very important performance parameter of the motor. There are some differences in the temperature rise requirements of the motor with different heat resistance levels. The temperature rise is positively correlated with the temperature, but the temperature of different parts of the motor is not the same, but its distribution is very regular. Sex.

In the calculation of the temperature rise of the motor, the most important thing is to calculate the temperature rise of the winding and the core. These components are both heat-conducting media, and there are distributed heat sources. Their temperatures are generally spatially distributed in a regular pattern, so that there is a maximum temperature rise and an average temperature rise. Although the heating limit of each part of the motor should be based on the highest temperature rise, in the calculation, as a whole, it is usually possible to calculate only the average temperature rise of the heat-generating component; there is a certain regularity between the average temperature rise and the highest temperature rise. The temperature of the motor can also be measured by the average temperature rise.

1. Axial temperature distribution of stator windings of symmetric radial ventilation motor

With this ventilation system, the air volume through each radial air duct is substantially the same, and the maximum temperature of the winding and the iron core occurs in the middle of the motor. The middle part of the stator winding is converted into heat by copper (aluminum) consumption, part of which is dissipated into the air through the core and the air passage, and the other part is conducted along the winding to both ends and is dispersed from the end of the winding into the air. In a type of motor where the effective length is not long, the heat dissipation at the ends plays a significant role in cooling the windings.

2. Axial temperature distribution of stator windings of axial or hybrid ventilation motors

In general, when such an asymmetrical ventilation system is used, the position at which the highest temperature occurs is moved from the middle of the symmetrical ventilation system to the exit of the hot air escape motor.

3, surface cooling closed AC motor stator winding temperature axial distribution

In this type of motor, the losses in the stator windings are mainly dissipated through the core and the frame. The heat dissipation conditions at the ends of the windings are poor, so that part of the heat loss at the ends is also transmitted through the slots and scattered through the core. Thus, the temperature distribution of the stator windings forms a case where the ends are high and the middle is low.

4, the excitation winding temperature distribution

In a concentrated multi-layer field winding, heat is mainly dissipated from the surface because the height is much larger than the thickness. Such windings typically have different heat dissipation conditions on the inner and outer surfaces of the windings, so the temperature distribution is asymmetrical.

5, the temperature distribution of the iron core laminated group

Since the thermal conductivity of the silicon steel sheet laminate group in the radial direction and the axial direction is many times different (for example, the thermal conductivity of the laminated silicon steel sheet in the layered direction is 42.5, and the vertical direction is 0.62), it can be approximated. The temperature distribution in the radial direction of the lamination stack is uniform, while the temperature distribution in the axial direction is not uniform. If the air volume through the radial air passages on both sides is different, the temperature distribution of the core in the axial direction will also be asymmetrical.

The transverse thermal conductivity of the laminated silicon steel sheet is related not only to the silicon content of the silicon steel sheet, but also to the inter-sheet insulation material and the degree of compaction.