Patent ID: 8436564
Filing Date: 2013-05-07
Classification: H02K,H02P

Abstract:
1. A method for operating a motor comprising a rotor, wherein the motor further comprises a plurality of electromagnets, the method comprising: (a) calculating a pulse-width modulation (PWM) duty cycle; (b) sampling a voltage induced by rotation of the rotor at a first expected zero crossing value, wherein said sampling produces a first sampled voltage value; (c) calculating an average of a plurality of sampled voltage values, wherein the plurality of sampled voltage values comprise the first sampled voltage value and voltage values sampled at a plurality of prior expected zero crossing values; (d) subtracting the first sampled voltage value from the calculated average of the plurality of sampled voltage values to produce a delta zero crossing error; (e) determining a sign associated with the delta zero crossing error; (f) updating an integral term according to the determined sign associated with the delta zero crossing error, wherein the integral term is associated with a specified rotational period; (g) subtracting the delta zero crossing error from the updated integral term to produce an updated rotational period value; (h) generating one or more time values based on the updated rotational period value; and (i) controlling operation of the motor based on the one or more time values and the PWM duty cycle.