FINE RESOLUTION MOTOR CONTROL
First Claim
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1. A method of generating a motor control signal for a motor having a rotor that rotates at a rotational rate, the method comprising the steps of:
- generating first, second, and third sinusoidal signals, each sinusoidal signal being 120-degrees out of phase with the other sinusoidal signals;
differentiating the first, second, and third sinusoidal signals to obtain first, second, and third cosine signals, respectively;
subtracting the first sinusoidal signal from the third sinusoidal signal to obtain a first sinusoidal difference signal;
subtracting the second sinusoidal signal from the first sinusoidal signal to obtain a second sinusoidal difference signal;
subtracting the third sinusoidal signal from the second sinusoidal signal to obtain a third sinusoidal difference signal;
multiplying the first sinusoidal difference signal and the second cosine signal to obtain a first product signal;
multiplying the second sinusoidal difference signal and the third cosine signal to obtain a second product signal;
multiplying the third sinusoidal difference signal and the first cosine signal to obtain a third product signal;
summing the first, second, and third product signals to obtain a summation signal; and
multiplying the summation signal by a constant to obtain a rate signal that is proportional to the rotational rate of the rotor.
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Abstract
Methods and apparatus are provided for deriving precision position and rate information for motors using relatively low precision analog sensors, and for implementing compensation techniques that overcome inherent sensor errors and rotor magnet flux tolerances.
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Citations
20 Claims
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1. A method of generating a motor control signal for a motor having a rotor that rotates at a rotational rate, the method comprising the steps of:
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generating first, second, and third sinusoidal signals, each sinusoidal signal being 120-degrees out of phase with the other sinusoidal signals; differentiating the first, second, and third sinusoidal signals to obtain first, second, and third cosine signals, respectively; subtracting the first sinusoidal signal from the third sinusoidal signal to obtain a first sinusoidal difference signal; subtracting the second sinusoidal signal from the first sinusoidal signal to obtain a second sinusoidal difference signal; subtracting the third sinusoidal signal from the second sinusoidal signal to obtain a third sinusoidal difference signal; multiplying the first sinusoidal difference signal and the second cosine signal to obtain a first product signal; multiplying the second sinusoidal difference signal and the third cosine signal to obtain a second product signal; multiplying the third sinusoidal difference signal and the first cosine signal to obtain a third product signal; summing the first, second, and third product signals to obtain a summation signal; and multiplying the summation signal by a constant to obtain a rate signal that is proportional to the rotational rate of the rotor. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A motor controller, comprising:
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first, second, and third sensor means for generating first, second, and third sinusoidal signals, respectively, each sinusoidal signal being 120-degrees out of phase with the other sinusoidal signals; first, second, and third differentiation means for differentiating the first, second, and third sinusoidal signals, respectively, to generate first, second, and third cosine signals, respectively; first subtraction means for subtracting the first sinusoidal signal from the third sinusoidal signal to generate a first sinusoidal difference signal; second subtraction means for subtracting the second sinusoidal signal from the first sinusoidal signal to generate a second sinusoidal difference signal; third subtraction means for subtracting the third sinusoidal signal from the second sinusoidal signal to generate a third sinusoidal difference signal; first multiplication means for multiplying the first sinusoidal difference signal and the second cosine signal to generate a first product signal; second multiplication means for multiplying the second sinusoidal difference signal and the third cosine signal to generate a second product signal; third multiplication means for multiplying the third sinusoidal difference signal and the first cosine signal to generate a third product signal; summing means for summing the first, second, and third product signals to generate a summation signal; and fourth multiplication means for multiplying the summation signal by a constant to generate a rate signal that is proportional to the rotational rate of the rotor. - View Dependent Claims (10, 11, 12, 13, 14)
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15. A motor control system, comprising:
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a motor including a stator and a rotationally mounted rotor, the rotor configured, upon the stator being controllably energized, to rotate to a rotational position at a rotational rate; first, second, and third sensors evenly spaced about the rotor to sense the rotational position thereof and supply first, second, and third sinusoidal sensor signals, respectively, each sinusoidal sensor signal being 120-degrees out of phase with the other sinusoidal sensor signals; and a motor controller coupled to receive each of the sinusoidal sensor signals and configured to controllably energize the stator from a power source, the motor controller comprising; first, second, and third differentiation means for differentiating the first, second, and third sinusoidal signals, respectively, to generate first, second, and third cosine signals, respectively; first subtraction means for subtracting the first sinusoidal signal from the third sinusoidal signal to generate a first sinusoidal difference signal; second subtraction means for subtracting the second sinusoidal signal from the first sinusoidal signal to generate a second sinusoidal difference signal; third subtraction means for subtracting the third sinusoidal signal from the second sinusoidal signal to generate a third sinusoidal difference signal; first multiplication means for multiplying the first sinusoidal difference signal and the second cosine signal to generate a first product signal; second multiplication means for multiplying the second sinusoidal difference signal and the third cosine signal to generate a second product signal; third multiplication means for multiplying the third sinusoidal difference signal and the first cosine signal to generate a third product signal; summing means for summing the first, second, and third product signals to generate a summation signal; and fourth multiplication means for multiplying the summation signal by a constant to generate a rate signal that is proportional to the rotational rate of the rotor. - View Dependent Claims (16, 17, 18, 19)
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20. A self-calibrating complementary filter, comprising:
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subtraction means for (i) receiving a filtered position signal and a position signal and (ii) subtracting the filtered position signal from the position signal to supply a position error signal; gain adjustment means for applying a predetermined gain to the position error signal to supply an adjusted position error signal; first integration means for integrating the position error signal and supplying a rate adjustment signal; multiplication means for (i) receiving a rate signal and the rate adjustment signal and (ii) multiplying the rate signal and the rate adjustment signal to generate an adjusted rate signal; summing means for summing the adjusted rate signal and the adjusted position error signal to generate the filtered rate signal; and second integration means for integrating the filtered rate signal to obtain the filtered position signal.
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Specification