Sensored motors, equipped with built-in Hall sensors for precise commutation and smooth startup, are widely used in drones, electric vehicles, and automation systems. However, during operation, users may encounter starting difficulties — such as the motor failing to rotate smoothly, excessive vibration, or abnormally high current. These issues not only affect system performance but may also cause driver overload or motor damage. This article analyzes the common causes of starting problems in sensored motors and offers practical solutions.
Common Causes of Starting Problems
The first and most frequent cause is abnormal Hall sensor signals. The Hall sensors are key components that detect rotor position and feed it back to the driver. If the Hall angle is incorrect, the signal wiring is reversed, or the sensors are affected by magnetic interference, commutation timing errors can occur, resulting in “jittering” or reverse rotation.
Second, improper driver parameter settings can prevent smooth startup. Each motor model requires specific configurations for pole pairs, Hall angle, and startup current. If these settings do not match the motor specifications, the driver cannot correctly identify the rotor position, leading to startup failure.
Third, insufficient or unstable power supply can cause the motor to fail to generate enough starting torque to overcome static friction. Voltage fluctuations can also trigger overcurrent or undervoltage protection in the driver.
Fourth, excessive load or mechanical blockage can hinder startup. If the motor is connected to a high-resistance mechanism, or if the bearings or gears are jammed, the motor will struggle to rotate.
Finally, driver malfunction — such as damaged driver chips, bridge circuit faults, or sampling errors — can also cause startup failure.
Effective Solutions
Check Hall signals. Use an oscilloscope to verify whether the Hall waveforms are complete and correctly phased. If signal misalignment or interference is detected, recalibrate the Hall sensors to ensure accurate 120° or 60° phase separation.
Set correct driver parameters. In the driver configuration software, input the correct motor pole pairs, Hall sequence, and startup current limit according to the motor’s specifications. If unsure, use the driver’s auto-identification or test mode to calibrate.
Ensure stable power supply. Verify that the power output meets the required specifications. Use a power module with sufficient capacity and add filter capacitors to reduce voltage fluctuations.
Reduce mechanical load. Disconnect the motor from the mechanical system and test whether it can start under no-load conditions. If it starts normally, inspect the transmission system for friction, misalignment, or blockage.
Inspect the driver. Check for overcurrent, overvoltage, or undervoltage protection states. Replace damaged power modules or reflash the firmware if necessary.
In addition, regular maintenance and testing can prevent starting difficulties. Keep the motor clean to avoid dust or oil contamination around the Hall sensors. Check all wiring connections for looseness or poor contact. Measure winding insulation and resistance regularly to prevent internal damage.
In conclusion, sensored motor starting problems are usually caused by electrical signal errors, incorrect parameter settings, or excessive mechanical load. By systematically diagnosing and adjusting these factors, users can restore smooth startup and improve long-term reliability. For high-precision applications, it is recommended to use professional tuning software to perform automatic calibration and startup optimization, thereby eliminating startup issues at the source.