Which is the higher temperature between the stator and rotor during motor operation?

Temperature rise is a very important performance indicator for motor products, and the temperature of each part of the motor and the environmental conditions it is located in determine the level of temperature rise.

Analyzed from the point of view of measurement, the temperature measurement of the stator part is relatively direct, while the rotor part tends to be measured indirectly. However, the relative qualitative relationship between the two temperatures does not change much regardless of how they are detected.

From the analysis of the working principle of the motor, there are basically three hotspots of the motor, namely the stator winding, rotor conductor, and bearing system. If it is a wound rotor, there is also a collector ring or carbon brush part.

From the perspective of heat transfer, the temperature of each heat source varies, and it is inevitable that through the conduction and radiation of heat, the relative temperature balance of each part will be achieved, that is, each component will exhibit a relatively constant temperature.

For the stator and rotor parts of the motor, the heat from the stator can be directly dissipated outward through the casing. If the rotor temperature is relatively low, it can also effectively absorb the heat from the stator part. Therefore, the temperature of the stator and rotor parts may need to be comprehensively evaluated based on the magnitude of their own heat.

When the stator part of the motor heats severely while the rotor body heats less (such as permanent magnet motors), the stator heat is not only dissipated to the surrounding environment, but also transferred to other components in the inner cavity. It is highly likely that the temperature of the rotor will not be higher than that of the stator part; When the rotor part of the motor generates severe heat, based on the physical distribution analysis of the two components, the heat emitted by the rotor must be continuously dissipated through the stator and other components. In addition, the stator body is also a heating element, and as the main heat dissipation chain component of the rotor, the stator part receives heat while also dissipating it through the casing. The tendency for the rotor temperature to be higher than the stator temperature is greater.

There is also a limit case, when the stator and rotor are heating seriously, the stator or rotor may not be able to withstand the erosion of high temperature, resulting in the deterioration of winding insulation or rotor conductor deformation or liquefaction of the harsh consequences of the rotor, if it is the case of cast aluminum rotor, especially casting of aluminum process is not good, there will be a rotor partially bluish or blue or the whole blue or even flow of the aluminum of the undesirable appearance.