Nanyang explosion-proof motor | Which condition is prone to heating during no-load operation or load operation

2023-11-22 10:21:29

The manufacturer of explosion-proof motors in Nanyang stated that some users will install new motors on the equipment for no-load testing after purchasing them. There is also a method called load operation, which of these two methods is simpler to make the motor heat up?

As long as it is within the normal load range, there is no difference between the speed of the stepper motor with load and no load. The stepper motor controller operates in a constant current chopping environment. When the power supply, controller, and motor are connected, the load of the power supply is stable. No matter how the load of the motor is changed, the voltage and current of the power supply will not change (assuming the power supply is a regulated power supply). The so-called constant current chopping only achieves the purpose of constant current through chopping, that is, the energy supplied by the power supply is consumed by the controller and motor together, The energy taken by the motor is only a part of the power supply, and a portion is consumed by the controller. The no-load heat source of the stepper motor suffers from copper loss, iron loss, and the damping load of the motor shaft; On load heating also originates from copper loss, iron loss, and damping load of the motor shaft.

Under the premise of the same driving current/voltage and speed, the heating capacity of the loaded drive should be greater than that of the unloaded drive. The reason for this is:

1. Because the apparent driving current is the same, the contribution of copper loss on the surface to heating is fundamentally the same;

2. However, due to the fact that the current change rate of the motor winding under loaded driving conditions is higher than that under no-load conditions, it can lead to increased iron loss in practice;

3. Moreover, high modification rate current will exacerbate the skin effect of winding current, increasing copper loss from the other side;

4. The manufacturer of Nanyang explosion-proof motors stated that during load operation, the motor shaft is often affected by axial load, resulting in increased damping and heating.

At the micro level, when the motor is unloaded, the external work done by the motor is very small, and there is no need to draw more energy from the power supply. At this time, from the power supply side, in addition to a small part of the supplied energy defeating the no-load damping, it is mainly used to compensate for the loss of Joule energy in the winding. Correspondingly, the current flowing through the winding mainly comes from the inductance energy storage and continuous current effect of the winding, while the current directly supplied by the power supply only accounts for a small portion, which is much smaller than the total current of the winding. Therefore, the current modification rate is very small at this time.

6. After being loaded, the motor starts to work externally, and the amount of work done depends on the load torque and speed. At this time, it is necessary for the motor to draw enough energy from the power supply to output energy composed of hostile loads. As long as the load is large enough, from the power supply side, except for a small part of the energy that defeats the no-load damping and the loss of Joule energy used to compensate for the winding, most of the energy is used to defeat the load and do work, And this part of energy is injected into the winding by the power supply during each PWM cycle or chopping cycle. Correspondingly, a significant portion of the current flowing through the winding comes directly from the periodic supply of the power supply, resulting in an increase in the micro modification rate of the current in the winding.

7. This process can also be explained through hard angles. When unloaded, the power angle of the stepper motor is very small, and the dot product of the winding current vector and the back electromotive force vector is very small. The winding current is fundamentally derived from the continuous current effect of the winding inductance, with minimal consumption and minimal micro current modification rate; When loaded, the power angle of the stepper motor expands, and the dot product of the winding current vector and the back electromotive force vector increases. As external work is required, the winding current consumption increases, and the periodic current injection and compensation from the power source increase, resulting in a higher rate of micro current modification.

The above information was compiled and released by the Nanyang explosion-proof motor manufacturer. Thank you for watching.