Patent ID: 9172320
Filing Date: 2015-10-27
Classification: H02P

Abstract:
1. A method of driving, with a motor control circuit, a multi-phase motor having a plurality of motor windings, the method comprising: generating, with the motor control circuit, a plurality of drive signals comprising determined start-up signal characteristics to start the multi-phase motor spinning, wherein the determined start-up signal characteristics of the plurality of drive signals comprise a ramped start-up of the electric motor during a ramp-up time period during a start-up mode of operation, wherein the plurality of drive signals results in a corresponding plurality of sinusoidal current signals carried by the plurality of motor windings, and wherein the generating comprises generating the plurality of drive signals such that, at an end of the ramp-up time period, a last one of the plurality of cycles of the sinusoidal current signal ends at a zero current, the method further comprising stopping the plurality of drive signals for a coasting time period following the end of the ramp-up time period; detecting a back EMF signal indicative of a zero back EMF voltage on the selected one of the plurality of motor windings while the plurality of drive signals are stopped, the detected back EMF signal indicative of an end of the coasting time period; and driving the plurality of motor windings with the plurality of sinusoidal current signals in a normal mode of operation in response to the detecting.