Method and apparatus for driving a DC motor
First Claim
1. A control circuit for an electric motor, the electric motor comprising a rotor, a stator and windings, the control circuit having a feedback loop regulator to generate a control signal (TL or TR) to control a current drive circuit to control the amplitude of current (iw) in the windings, the feedback loop regulator being arranged to compare the amplitude of the current (iw) in the windings with a reference value (iset), the control circuit also having circuitry to extract a characteristic (DC) of the control signal, said characteristic varying in function of time as the back electromotive force in the windings,the control circuitry further having circuitry to determine cinematic quantities and/or to determine the direction of rotation of the motor.
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Accused Products
Abstract
A circuit for determining a direction of rotation of an electric motor, the motor having asymmetry and/or eccentricity in a profile of back electromotive force as a function of angular position of a rotor with respect to a stator, the circuit receiving a signal representing the BEMF, and use the corresponding asymmetry and/or eccentricity in the signal to derive the direction of rotation. The signal representing the back emf can be generated by a control circuit. The control circuit can have a feedback loop regulator to generate a control signal (TL or TR) to control a current drive circuit (11,12) to control an amplitude of current (iw) in the windings, the feedback loop regulator being arranged to compare the amplitude of the current (iw) in the windings with a reference value (iset), and use the control signal to provide the signal representing the back electromotive force.
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Citations
21 Claims
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1. A control circuit for an electric motor, the electric motor comprising a rotor, a stator and windings, the control circuit having a feedback loop regulator to generate a control signal (TL or TR) to control a current drive circuit to control the amplitude of current (iw) in the windings, the feedback loop regulator being arranged to compare the amplitude of the current (iw) in the windings with a reference value (iset), the control circuit also having circuitry to extract a characteristic (DC) of the control signal, said characteristic varying in function of time as the back electromotive force in the windings,
the control circuitry further having circuitry to determine cinematic quantities and/or to determine the direction of rotation of the motor.
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13. A method for determining the angular position of an electric motor, the motor having windings at a stator and a permanent magnet at the rotor, the amplitude of the current in the windings being controlled by a feedback loop regulator controlling a current drive circuit connected to the windings, the method comprising:
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obtaining a characteristic (DC) of a control signal (TL, TR) generated by the feedback loop regulator; and monitoring the characteristic (DC) of the control signal; and determining the angular position of the electric motor. - View Dependent Claims (14, 15, 16)
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17. A method for determining a direction of rotation of an electric motor, the motor having windings at a stator and a permanent magnet at a rotor and having asymmetry and/or eccentricity in a profile of back electromotive force as a function of the angular position of the rotor of the motor with respect to the stator of the motor, the amplitude of the current in the windings being controlled by a feedback loop regulator controlling a current drive circuit connected to the windings, the method comprising:
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obtaining a characteristic of a control signal generated by the feedback loop regulator at more than two instants in time; and determining a direction of rotation of an electric motor. - View Dependent Claims (18, 19, 20, 21)
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Specification