[heating of the motor]
The various losses generated by the motor eventually turn into heat energy, which makes some parts of the motor, such as the iron core and windings, heat up and the temperature rises. Temperature has a great influence on the insulation and service life of the motor, so the electrical engineer has certain restrictions on the temperature rise and operating temperature of the motor.
【Insulation Materials】
The temperature limit of the motor mainly depends on the insulating material. Excessive temperature will cause rapid aging of insulating materials. The problems caused by insulation aging are: the electrical insulation performance is reduced, the mechanical strength is reduced, the parts wrinkle and break under the conditions of vibration, shock and damp heat, and the service life is greatly reduced. Lao Zhang attached a table of insulation materials and heat resistance commonly used in motors for your reference.
【cooling method】
Having discussed heat generation, it is necessary to discuss heat dissipation and cooling. The structure of the motor is various, the operation mode is not the same, there are many varieties and different uses, so their cooling methods are also different, which can be summarized as follows:
[Small enclosed self-cooling general-purpose micromotor]
l The power is generally not large, mainly small permanent magnet DC motors and small AC motors;
l The motor structure adopts a fully enclosed structure, and the heat load is designed to be low. Generally, no special heat calculation is performed, and the temperature rise is not high during normal operation;
l The insulation level of the motor is not high, most of which are B-class insulation, and some even use E-class insulation
l Mainly used in toys, small household appliances, office equipment, audio, entertainment and health fields;
【Micromotor for fully enclosed drive】
l Most of the motors are of standard structure, serialized design, and excellent performance;
l The insulation grade is generally F grade, the temperature rise is high, the temperature rise requirements are strict, and the heat load design is also high;
l In individual cases, H-level or even C-level insulation is also used according to actual needs;
l Mainly used in industrial automation equipment, robots, intelligent machinery, military equipment and production lines where certain driving control requirements are required, generally there is no special cooling equipment or driving device;
【Separate type micro motor】
l The motor does not form a whole. According to the user's needs, install the various parts of the motor on the corresponding machinery and equipment. Generally, it is mainly in the form of providing a separate stator and rotor;
l The temperature rise and heat dissipation of the motor should be considered in combination with the occasion. Generally, the heat dissipation conditions are good, so a higher power density can be designed;
l If there is a cooling device, it is necessary to carry out special temperature rise design and experiment according to the type of cooling medium, flow rate, and the size of the contact surface with the heating part of the motor;
l Usually used in high-end home appliances, such as compressors, electric vehicles, aviation equipment and machine tools;
【Micromotor for cooling】
l This type of micro-motor itself is used for cooling various equipment or systems, such as computer cooling axial fans, air-conditioning fans, etc.;
l Generally, special thermal design is not considered, it should be considered together with cooling equipment such as fans, and its shape and structure design should consider the impact on cooling medium resistance;
【Micro-motor components and systems】
l Motor assembly is a combination of multiple motors to provide better performance and more uses to meet high-precision drives or special requirements;
l For heat dissipation or temperature rise, the weak links should be considered, and the components with the lowest insulation level should meet the demand through reasonable distribution of the thermal field;
l Especially when the motor body and the drive system are integrated, the heat dissipation of the power components in the driver and the heat resistance level of the electronic components need to be considered;
After reading this article, I believe if most of your problems with motor heating can be explained. This chapter discusses the common types of motors, but for special customized micromotors used in special occasions, such as high-power, high-torque motors, the heating and cooling methods cannot be so roughly understood, but should be based on special circumstances. special analysis. In the next article, Lao Zhang will explain the commonly used cooling methods of special motors, as well as the very important motor working system.
