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US5872434: Systems and methods for actuator power failure response

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Filing Information

Inventor(s) Michael L. Hill ·
Assignee(s) Barber Colman Company ·
Attorney/Agent(s) David Barron ·
Primary Examiner Brian Sircus ·
Application Number US8920051
Filing date 08/28/1997
Issue date 02/16/1999
Predicted expiration date 08/28/2017
U.S. Classifications 318/159  · 318/160  ·
International Classifications H02K 710  ·
Kind CodeA
International Classifications 318159;160 ·
11 Claims, No Drawings


Abstract

A brushless DC motor is controlled by determining a speed of the motor and a line voltage supplying drivers of the motor. Based upon these determined values and predetermined motor performance data, a maximum PWM on-time is determined for drive signals supplied to windings of the motor. This maximum PWM on-time thereby limits motor torque output to a predetermined maximum. Stopping the motor is performed in sequential phases including a loaded generator phase, an active braking phase and a holding phase. During holding, the amount of energy supplied to the motor is reduced to the point just before slippage such that holding energy is minimized. Upon power failure, the motor is driven toward a spring return home position overcoming static friction that may prevent the spring return mechanism from functioning properly. These techniques are applied to a motor in an actuator.

Independent Claims | See all claims (11)

  1. 1. A method of operating an actuator including an output member and a brushless DC motor mechanically coupled thereto, said output member having a spring return mechanism coupled to it, said spring return mechanism biasing said output member toward a home position thereof, said method comprising:detecting a power failure of power supplied to said actuator;upon said power failure driving said brushless DC motor to move said output member of said actuator toward said home position.
  2. 5. A method of operating an actuator including an output member and a brushless DC motor mechanically coupled thereto, said output member having a spring return mechanism coupled to it, said spring return mechanism biasing said output member toward a home position thereof, said method comprising:detecting a power failure of power supplied to said actuator;upon said power failure driving said brushless DC motor to move said output member of said actuator toward said home position if said output member is not at said home position.
  3. 6. A method of operating an actuator including a output member and a brushless DC motor mechanically coupled thereto, said output member having a spring return mechanism coupled to it, said spring return mechanism biasing said output member toward a home position thereof, said method comprising:monitoring a power supply voltage of said actuator;detecting a power failure when said power supply voltage falls below a predetermined voltage level;upon said power failure driving said brushless DC motor to move said output member of said actuator toward said home position; andwherein said driving said motor overcomes static friction.
  4. 7. An apparatus for operating an actuator including an output member and a brushless DC motor mechanically coupled thereto, said output member having a spring return mechanism coupled to it, said spring return mechanism biasing said output member toward a home position thereof, said apparatus comprising:means for detecting a power failure of power supplied to said actuator;means for, upon said power failure, driving said brushless DC motor to move said output member of said actuator toward said home position.
  5. 11.11. An actuator comprising:an output member;a brushless DC motor mechanically coupled to said output member;a spring return mechanism coupled to said output member and biasing said output member toward a home position;means for detecting a power failure of power supplied to said actuator;means for, upon said power failure, driving said brushless DC motor to move said output member of said actuator toward said home position if said output member is not at said home position.

References Cited

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Other Publications

Linear Interface ICs Device Data, Motorola Inc., 1993 pp. 1,57, 63-67, 70-74.
Unitrode, Data Book, Switchmode Driver for 3-0 Brushless DC Motors, Jun. 1993, pp. 103, 105.
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