Patent ID: 8766572
Filing Date: 2014-07-01
Classification: A47L,H02P

Abstract:
1. A method of controlling pulse-width modulation (PWM) for an electric motor, the method comprising: applying PWM pulses of a fixed width to a plurality of stator windings of a stator of the electric motor when a rotational speed of the electric motor is below a pre-determined threshold; applying, to at least one subset of the plurality of stator windings, at least one PWM pulse having a phase advance with respect to the fixed-width PWM pulses when the rotational speed of the electric motor exceeds the pre-determined threshold; determining that the rotational speed of the electric motor has dropped from being above the pre-determined threshold to being below the pre-determined threshold; and disabling power to the plurality of stator windings when it is determined that the rotational speed of the electric motor has dropped below the pre-determined threshold.