Automatic Phase Sequence Detection in BLDC Motor Drives with Hall Sensors

Brushless DC (BLDC) motors with hall effect sensors are one of the most common arrangements in electric vehicle drives, particularly in E-rickshaw type of applications. The drive operation is dependent on the hall sensor signals that correspond to particular rotor position in an electrical cycle. Each hall is placed in fixed spatial configuration against the three phase stator windings. Thus, hall signal pattern is fixed against fixed motor phase sequence in clockwise or counterclockwise rotation. This sequence locking is necessary for the drive operation. If correct sequencing is not used for connecting motor phase or hall terminals with controller terminals, the phase sequence detected by the controller is different from the actual sequence. The switching pattern implemented by the controller is incorrect in such a case. This paper presents a scheme for automatic phase detection and subsequent correction in controller without requiring physical reconnection of motor phase windings.