Can a brushless motor still work if its magnet has a misaligned N S pole?

In the rotor structure of brushless motors, the position, angle, and N/S polarity arrangement of magnets are among the core factors determining motor performance. Under normal conditions, magnets should be arranged with fixed pole pitch and strictly alternating N and S pole directions. Once magnet misalignment occurs—such as reversed polarity, uneven pole pitch causing NS position shifts, or disordered polarity sequence—motor performance is directly affected. So, can the motor still be used after such issues occur?

First, if magnets are installed with reversed polarity (N installed as S, or two adjacent poles both as N or S), the motor will almost certainly fail to start normally. Symptoms include vibration, overheating, and frequent overcurrent protection triggers. This constitutes a critical error, rendering the motor essentially unusable. Continued operation not only results in extremely low efficiency but may also burn out the driver board. Therefore, a brushless motor with reversed polarity must never be used further and requires either rework or rotor replacement.

Arc-shaped segmented neodymium magnets commonly used in brushless motors

Secondly, if the magnetic poles exhibit angular deviation (where the magnetic orientation rotates by a certain degree), the motor may still start but will exhibit noticeable issues such as increased noise, unstable low-speed operation, reduced torque, and decreased efficiency.

If the magnetic poles are unevenly spaced or arranged, causing the overall N-S positions to shift, the motor may experience difficulties starting, increased vibration, elevated temperature rise, and reduced load capacity. While less severe than reversed polarity installation, this still compromises operational quality and may trigger structural risks like magnet loosening or abnormal noise.

The above covers whether brushless motors with misaligned N/S poles on magnets can remain operational. N/S pole misalignment ranks among the most critical defects in brushless motors and must be strictly avoided in any high-speed application.

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