Mitigating Misaligned Hall-Sensors in Brushless DC Motors Using Calibration Routine

Hall-Sensor-controlled brushless DC (BLDC) motors are commonly used in many applications due to their low cost and simple control. In a typical BLDC motor, a permanent magnet synchronous machine (PMSM) is controlled by a voltage source inverter (VSI) using the Hall sensor signals. Ideally, the three Hall sensors are spaced 120 degrees apart. However, due to manufacturing tolerances, the sensors’ actual position may differ, resulting in uneven conduction intervals and degradation of motor performance. To mitigate the misaligned Hall sensors, previous research proposed averaging the Hall sensor signals to achieve a steady state performance close to ideal. However, such averaging filters have a memory and may degrade the dynamic performance in fast transients. To ensure fast dynamic performance, this paper proposes a calibration routine and a correction lookup table that records and stores the identified errors, which are then corrected in run-time without compromising the dynamic performance. The proposed method is demonstrated on a typical industrial BLDC motor and has been shown to be very effective compared to previous methods.