Patent ID: 8164291
Filing Date: 2012-04-24
Classification: H02P

Abstract:
1. A method for starting a direct current (DC) brushless motor, the DC brushless motor comprising a plurality of windings jointly connected to each other through a joint juncture, the method comprising the following steps of: (a) exciting a first phase by supplying a current to the windings at a first winding and a second winding thereof; (b) measuring a first back electromotive force (BEMF) of a third winding that has not conducted the current through yet; (c) calculating a differential value of the first BEMF; (d) switching to a second phase by switching the current to the second winding and the third winding according to the differential value and in response to a start-time period; (e) measuring a second BEMF of the first winding; and (f) switching to a third phase by switching the current to the first winding and the third winding while the second BEMF crosses a negative zero-crossing point.