Six-step commutation with round robin state machine to alleviate error in hall-effect-sensor reading for BLDC motor control

Hall-effect sensors are commonly applied in brushless direct current (BLDC) motor control for rotor position detection. By knowing the exact position of the rotor, inverter could supply energy in synchronize to the BLDC motor state. As the motor is categorized as synchronous motor, those sensors are vital. Working out of synchronization not only makes drive system less efficient but also threaten the inverter as current requirement will be increased. Unfortunately, the sensor works in harsh environment where high current, high temperature, and high vibration are exist. Those conditions result in some incorrect position detections. In order to improve the hall-effect position accuracy, in this paper, a simple finite state machine (FSM) called round robin technique is implemented. This technique along with conventional R-C filter in the sensor line successfully suppresses error in the rotor position detection. This results in higher inverter reliability and smoother motor operation.