stepper motor Motion control system
Stepping motor as a digital actuator, in the motion control system has been widely used. Many users friends in the use of stepper motor, the feeling of motor work when there is a big fever, doubts, I do not know whether this phenomenon is normal. In fact, fever is a common phenomenon of stepper motor, but what kind of heat is normal, and how to minimize the stepper motor fever? First of all, to understand why stepper motor heat for a variety of stepper motor , The internal are composed of iron core and winding coil. The winding has a resistance, power will produce loss, the size of the loss and resistance and current is proportional to the square, which is what we often say that the copper loss, if the current is not a standard DC or sine wave, but also produce harmonic loss; Eddy current effect, in the alternating magnetic field will produce loss, its size and material, current, frequency, voltage, called iron loss. Copper loss and iron loss will be expressed in the form of heat, thus affecting the efficiency of the motor. Stepper motor is generally the pursuit of positioning accuracy and torque output, the efficiency is relatively low, the current is generally large, and the harmonic component is high, the frequency of alternating current also changes with the speed, and thus stepper motor prevalence of heat, and the situation than the general AC motor is serious. In the case of
Moreover, the stepper motor heating control in a reasonable range of motor heating to what extent, mainly depends on the internal insulation level of the motor. Internal insulation performance at high temperatures (130 degrees or more) will be destroyed. So as long as the internal does not exceed 130 degrees, the motor will not be damaged, and then the surface temperature will be below 90 degrees. Therefore, the stepper motor surface temperature at 70-80 degrees are normal. Simple temperature measurement method useful temperature meter, you can also roughly judge: hand can touch more than 1-2 seconds, not more than 60 degrees; hand can only touch about 70-80 degrees; drop a few drops of water quickly gas Of the 90 degrees or more; of course, can also be used to detect the temperature gun. Third, the stepper motor with the speed of the case of constant current drive technology, the stepper motor in the static and low speed, the current will remain relatively constant, to maintain constant torque output. Speed to a certain extent, the motor internal back electromotive force increases, the current will gradually decline, the torque will decline. Therefore, the heat caused by copper loss is related to speed. Static and low speed when the general high fever, high fever when low. But the iron loss (although the proportion of smaller) changes in the situation is not the case, and the whole heat of the motor is the sum of the two, so the above is only the general situation. Fourth, the heat caused by the heat Although the motor does not generally affect the life of the motor, for most customers do not have to ignore. However, severe heat will have some negative effects. If the internal thermal expansion coefficient of the various parts of the internal structure of the stress changes and changes in the internal air gap will affect the dynamic response of the motor, high speed will be easy to get out of step. And if some occasions do not allow the motor overheating, such as medical equipment and high-precision test equipment. So the heat of the motor should be the necessary control.