Auto-Correction Commutation Method Based on Phase Voltage Threshold for Position Sensorless Brushless DC Motor

This article explores a novel auto-correction commutation method based on phase voltage threshold for position sensorless brushless DC motor. In order to generate the commutation signal and correct the commutation error, three key technique contributions are made: 1) Proposing a phase voltage threshold comparison (PVTC) circuit, which generates the commutation signals that can be drifted in phase by a threshold voltage. 2) Designing a commutation property identification (CPI) circuit to generate a logic level, which indicates the commutation error type. 3) Introducing a bipolar voltage modulation (BVM) circuit, which generates an auto-adjusted threshold voltage to feed the PVTC circuit according to the logic level from CPI circuit. Because a hardware-based closed-loop regulation is actually established through the configuration of PVTC, CPI and BVM circuits, the auto-correction commutation signals are generated. Experimental results on a magnetically suspended control moment gyroscope verify the auto-correction commutation method.