CLOSED LOOP STARTUP CONTROL FOR A SENSORLESS, BRUSHLESS DC MOTOR

摘要

A method for driving a brushless direct current (DC) motor is provided. The brushless DC motor has a first phase that is coupled between a first terminal and a common node, a second phase that is coupled between a second terminal and the common node, and a third phase that is coupled between a third terminal and the common node. The first and second phases are coupled to a first supply rail and a second supply rail, respectively, such that the brushless DC motor is in a first commutation state. The first phase is then decoupled from the first supply rail so as to allow first terminal to float during a window period. A first voltage difference between the first terminal and the second terminal is compared to a second voltage difference between the third terminal and the second terminal during the window period, and the brushless DC motor is commuted to a second commutation state if the first voltage difference is approximately equal to the second voltage difference.