Learn the major effect of temperature on stepper motors in this article. Also, learn the temperature and humidity requirements that Smooth Motor has stated for you.
Stepper motors play an essential part in the field of precise motion control. When rapid acceleration, precise control of angle linear position, or both are needed, these motors are a must-have. Temperature is the most important environmental element influencing the performance of stepper motors, but this is true of all electromechanical systems. The effect of temperature on stepper motors, both the changes that occur inside and the practical effects on the motor's functioning, are explored in this article.
Stepper Motors' Thermal Properties
Stepper motors' efficiency is highly dependent on their thermal properties. In transforming electrical energy into mechanical motion, these motors produce heat. The efficiency, current, and voltage of the motor all directly correlate to the heat it produces.
Effects on Current and Resistance
The temperature has an immediate impact on the resistance of the motor windings. The windings' resistance grows directly to the temperature under the classical law of electrical conductivity in metals. When the resistance rises, the motor's current draw changes. As the motor's resistance increases with temperature, it draws less current at a given voltage, which might decrease torque production.
Efficiency and Thermodynamic Derating
Another factor that is the effect of temperature on stepper motors is the torque output of stepper motors. Torque derating is a feature of stepper motors that means the torque production decreases as the temperature increases. The derating happens because the increasing winding resistance makes the current less efficient at producing magnetic fields within the motor. Therefore, as the motor's temperature rises, its torque-producing capabilities decrease.
In addition to other aspects, temperature affects efficiency. Running a stepper motor at its ideal temperature maximizes its efficiency. When all three parameters—resistance, current, and magnetic field generation—are in harmony, we have an ideal range. Reduced efficiency results from operating outside of this temperature range.
Grade UL B is the industry standard for stepper motor insulation, meaning that the motor insulation system must withstand temperatures of up to 130℃. The surface temperature of the motor must be less than 100℃ to account for the safety coefficient and the temperature differential between the inside and outside of the motor. The typical ambient temperature is about 40℃. Thus, it is important to keep the motor coil's temperature increase within 80K. Motor failure (often an open circuit, but sometimes a short circuit) may happen if the temperature of the motor coil rises over the insulation system's limit value.
This can happen because the motor coil's enameled wire, the insulation slot, the printed circuit board, and other components are susceptible to burnout. The motor's heat absorption capacity is key in determining the rated current. If the motor's working temperature is too high, lowering the motor's running current will bring it down to an acceptable range, and then adjusting the motor's internal heat control will bring it down to a suitable level for the insulation system.
The temperature increase of the motor, for instance, should not exceed 60K if the surrounding temperature is 60℃. In areas where stepper motors are used, where the operating temperature is high, it is more practical to control the rise in temperature of the motor. This can be done by either reducing the operating current of the motor or improving the heat dissipation conditions since most insulating materials used by stepper motor manufacturers meet grade B standards.
The insulating system's safety and the stability of the permanent magnet are compromised when the temperature of the stepper motor is very high. A decrease in operating torque occurs when the permanent magnet becomes demagnetized due to increased temperature. If the temperature of the stepper motor is too low, the grease on the bearings will solidify, rendering the bearings unusable for lubrication. In such a case, consider using cryogenic bearings. The user may use an existing technique to get the motor up to working temperature by turning it on and waiting for it to warm up; after that, they can spin the motor to get it started running, but this requires them to adjust the settings on the equipment's start procedure accordingly.
To prevent condensation from forming within the motor, the stepper motor has to withstand certain humidity levels. Stepper motors rely only on using anti-rust oil during manufacturing to protect the silicon steel plates that cover the rotor's outside and the stator's inside from rust. Condensation forms readily on surfaces when relative humidity is too high, leading to rust. Rusty areas may cause the rotor to seize, leading to motor failure in stepper motors due to the tiny space between the rotor and stator. Conversely, for small-sized stepper motors with low normal operating voltages, excessive humidity can have little effect on insulation material properties; however, for large-sized stepper motors with high drive voltages, this condition has a noticeable influence.
If you found this guide helpful, let Smooth Motor make your Stepper Motor work smoothly! Our products are durable and built with top-notch materials. Visit our website to learn more about the effect of temperature on stepper motors.
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