How to deal with the problem of servo motor overheating?

As the executive element of mechanical equipment, servo motor is used widely in servo system. When using servo motor, there is a phonomena of overheating when working. As you are not familiar with the principle and structure of servo motor, how to judge whether the heating value is normal or not? And how to reduce the heating value of servo motor?

The allowable heating level of motor is mainly determined by motor inner insulation grade. Inner insulation performance can be destroyed only under high temperature (above 130℃), so if the temperature inside is not above 130℃, the motor cannot be damaged while the current surface temperature is below 90℃. Therefore, it is normal if the surface temperature is between 70 and 80℃. The simple temperature measurement way is to use thermometer, or use rough judgment: use hand to contact it and you can keep 1 -2 s or above, which indicates the temperature is under 60℃; use hand to contact it and you cannot remain, which indicates the temperature is about 70 – 80℃; if some drops of water are quickly vaporized after dripping, it indicates that the temperature is above 90℃. Certainly, temperature gun also can be used for detection.

There are some reasons for servo motor overheating as following: too large load, phase failure, air duct obstruction, low speed running time too long, excessive power supply harmonic and so on.

Based on the principle of servo motor, in order to reduce the motor overheating, it is necessary to reduce copper loss and iron loss. There are two ways to reduce copper loss: reduce the resistance and the current, which requires us to choose the motor with small rated current as much as possible. For two-phase motor, do not use parallel-motor unless serial-motor cannot use, but this often contradicts the requirements of torque and speed. For selected motor, automatic half-flow control function and offline function of the driver should be fully utilized. The former will reduce the current automatically while the latter will cut off the current directly when the motor is in static condition. Besides, the current waveform is close to sine, so harmonic of subdividing driver is less and heat radiated from motor is less. There are not many ways to reduce iron loss and voltage grade is related with the iron loss, so it is suggested to select the proper drive voltage grade, meanwhile, the indexes such as high-speed performance, smoothness and heating, noise, etc. are also should be taken into account.