In fields such as industrial automation, drones, and electric vehicles, sensored motors are widely used for their stable startup performance and precise speed control. However, during prolonged operation or under high load conditions, users may encounter severe motor overheating. If not properly addressed, this issue can lead to reduced efficiency, demagnetization of magnets, or even coil burnout. This article analyzes the main causes, diagnostic methods, and effective countermeasures to help users manage motor overheating more scientifically.
Common Causes of Overheating
The most frequent cause is excessive load. When the motor continuously operates beyond its rated power, the current rises significantly, increasing copper losses and heat accumulation. Another common cause is poor ventilation and heat dissipation. Limited installation space or dust-clogged air ducts can prevent proper cooling. Additionally, improper driver parameter settings—such as incorrect Hall sensor angle calibration or distorted PWM waveforms—can result in unbalanced currents, increasing iron losses and heat generation. Other contributing factors include aging coil insulation, bearing friction, and voltage fluctuations.
Diagnostic Methods
To determine the heat source, users can use an infrared thermometer or temperature sensor to monitor the motor surface and winding temperatures. If the temperature exceeds the design limit (typically 80°C–120°C), the motor should be shut down for inspection. A rapidly rising stator temperature with a normal rotor temperature often indicates coil current imbalance or local short-circuiting. Conversely, a high rotor temperature usually points to poor bearing lubrication or magnet demagnetization. The current waveform and Hall signal data monitored by the driver can also reveal whether the motor is running abnormally.
Effective Solutions
Control load and operating time – Keep the motor within its rated power range and avoid prolonged full-load or frequent start-stop operation.
Improve cooling and ventilation – Regularly clean fans, vents, and filters. Install aluminum heat sinks or a forced air-cooling system to enhance heat dissipation.
Optimize driver parameters – Use a compatible controller and recalibrate the Hall sensor angle for precise commutation. Employing a Field-Oriented Control (FOC) algorithm can also reduce current harmonics and heat generation.
Perform regular maintenance – Check bearing lubrication and ensure smooth rotation. Inspect coil insulation resistance to prevent aging or short circuits.
Monitor motor temperature – Integrate thermal sensors or temperature switches for automatic overheating protection that can reduce load or stop operation when necessary.
If the overheating persists after applying these measures, users should consult a professional technician for a detailed inspection, which may include rewinding the coils or redesigning the cooling structure.
In conclusion, severe heating in sensored motors is not caused by a single factor but rather by a combination of electrical, mechanical, and environmental influences. By properly identifying the cause, adjusting control parameters, and performing regular maintenance, users can effectively reduce temperature rise, extend motor lifespan, and ensure long-term, efficient, and stable performance across various industrial and control applications.