Maximum Torque Per Ampere Control of Brushless DC Motors with Misaligned Hall Sensors

Three-Phase Hall-Sensor-controlled brushless DC (BLDC) motors are widely used in many industrial and electric mobility applications due to their high efficiency, power density, and cost-effectiveness. A typical voltage-source inverter (VSI) with the 120° commutation controls the motor's stator currents based on the Hall sensor signals that give the rotor position at discrete intervals. However, many low-cost motors often have misaligned Hall sensors, leading to distorted switching sequences and degraded performance. Furthermore, the BLDC motors with large winding inductance have non-negligible commutation intervals that shift the operation angle away from the desirable maximum torque-per-Ampere (MTPA) operation. This paper extends the previous research in this area and combines the filtering of Hall sensor signals with the automatic correction of the commutation angle to maintain the MTPA operation. The effectiveness of the proposed method is demonstrated on a typical industrial motor with a large electrical time constant and misalignment of Hall sensors.