Control system for brushless DC motor
First Claim
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1. A control system for brushless DC motors comprising:
- a brushless DC motor having a field rotor and a plurality of stator windings;
a position detecting circuit for detecting counter electromotive force voltage signals generated in said stator windings as said field rotor rotates and generating rotor position detection signals on the basis of said counter electromotive force voltage signals;
a driver circuit connected to said stator windings of said motor and being responsive to said rotor position detection signals to control conduction of current from a DC power supply to said stator windings;
a current detecting circuit for detecting an input current to said driver circuit from said DC power supply;
a hold circuit for holding a maximum value of the detected input current; and
a phase correcting circuit for correcting the phase of said rotor position detection signal in accordance with the held value of said input current.
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Abstract
A control system for brushless DC motors detects counter electromotive force voltages induced in motor windings and produces rotor position detection signals from the counter electromotive force voltages. The maximum value of an input DC current to a motor drive circuit is held and the phase of the rotor position detection signals is changed in accordance with the held value of the input DC current to prevent the phase of the position detection signals from varying with the load on the brushless DC motor.
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Citations
11 Claims
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1. A control system for brushless DC motors comprising:
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a brushless DC motor having a field rotor and a plurality of stator windings; a position detecting circuit for detecting counter electromotive force voltage signals generated in said stator windings as said field rotor rotates and generating rotor position detection signals on the basis of said counter electromotive force voltage signals; a driver circuit connected to said stator windings of said motor and being responsive to said rotor position detection signals to control conduction of current from a DC power supply to said stator windings; a current detecting circuit for detecting an input current to said driver circuit from said DC power supply; a hold circuit for holding a maximum value of the detected input current; and a phase correcting circuit for correcting the phase of said rotor position detection signal in accordance with the held value of said input current. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A motor control system for inverter-controlled air conditioners comprising:
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a brushless DC motor having a field rotor and a plurality of stator windings and driving a compressor of an air conditioner; a position detecting circuit for detecting counter electromotive force voltage signals generated in said stator windings as said field rotor rotates and generating rotor position detection signals on the basis of said counter electromotive force voltage signals; a driver circuit connected to said stator windings of said motor and being responsive to said rotor position detection signals to control a voltage supplied from a DC power supply to said stator windings; a current detecting circuit for detecting an input current to said driver circuit from said DC power supply; a hold circuit for holding a maximum value of the detected input current; a phase correcting circuit for correcting the phase of said rotor position detection signal in accordance with the held value of said input current; a first temperature sensor for detecting ambient temperatures; a second temperature sensor for detecting temperatures in a heat exchanger of said air conditioner; and means for changing the amount of phase correction obtained from said phase correcting circuit either when the temperature detected by said first temperature sensor falls below a first predetermined temperature or when the temperature detected by said second temperature sensor falls below a second predetermined temperature. - View Dependent Claims (11)
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Specification