Patent ID: 9106167
Filing Date: 2015-08-11
Classification: H02P

Abstract:
1. Method for driving a sensorless brushless DC motor or a permanent magnet synchronous motor in a predetermined direction, the motor comprising at least three stator windings connected in star configuration, and a permanent magnet rotor, the method comprising: a) determining a time period as the current time period, and energizing during the current time period two of the windings and leaving a third winding un-energized for rotating the rotor in a predetermined direction, based on a first motor state of an energizing sequence, corresponding to a known rotor position; b) measuring a first voltage representative for the back-EMF generated in the un-energized winding at a first time interval before expiry of the current time period; c) applying a commutation at expiry of the current time period so as to energize at least two of the windings while leaving a third winding un-energized according to a subsequent motor state of the energizing sequence; d) measuring a second voltage at a second time interval after the commutation, and calculating a subsequent time period based on at least the current time period and the measured first and second voltage; e) repeating steps b) and c) after replacing the current time period by the subsequent time period.