Current control in brushless DC motors
First Claim
1. An apparatus comprising:
- an H-bridge configured to couple a direct current power source to windings of a motor, wherein the H-bridge comprises a plurality of switches; and
a motor controller configured to;
close one of the plurality of switches to put the H-bridge in a coast configuration, wherein the windings are short circuited,identify a desired direction for a current impulse to the windings, wherein identifying the desired direction comprises indicating to increase or decrease a magnitude of a current in the windings while maintaining a positive direction of the current,open the one of the plurality of switches in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings, andclose another of the plurality of switches in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings,wherein;
the close of one of the plurality of switches, the open of the one of the plurality of switches, and the close of another of the plurality of switches are configured to reduce ripple currents relative to the ripple currents that would be present with pulse width modulation, andthe current impulse increases or decreases the magnitude of the current in the windings once per a duty cycle while maintaining the positive direction of the current.
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Abstract
A method and apparatus for controlling a brushless direct current motor. An H-bridge is configured to couple a direct current power source to windings of the brushless direct current motor. The H-bridge comprises a plurality of switches. A motor controller is configured to close one of the plurality of switches to put the H-bridge in a coast configuration, wherein the windings of the motor are short circuited. A desired direction for a current impulse to the windings is identified. The one of the plurality of switches is opened in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings. Another of the plurality of switches is closed in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings.
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Citations
20 Claims
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1. An apparatus comprising:
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an H-bridge configured to couple a direct current power source to windings of a motor, wherein the H-bridge comprises a plurality of switches; and a motor controller configured to; close one of the plurality of switches to put the H-bridge in a coast configuration, wherein the windings are short circuited, identify a desired direction for a current impulse to the windings, wherein identifying the desired direction comprises indicating to increase or decrease a magnitude of a current in the windings while maintaining a positive direction of the current, open the one of the plurality of switches in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings, and close another of the plurality of switches in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings, wherein; the close of one of the plurality of switches, the open of the one of the plurality of switches, and the close of another of the plurality of switches are configured to reduce ripple currents relative to the ripple currents that would be present with pulse width modulation, and the current impulse increases or decreases the magnitude of the current in the windings once per a duty cycle while maintaining the positive direction of the current. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A method for controlling a brushless direct current motor, the method comprising:
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closing one of a plurality of switches in an H-bridge to put the H-bridge in a coast configuration, wherein windings of the brushless direct current motor are short circuited and wherein the H-bridge is configured to couple a direct current power source to the windings; identifying a desired direction for a current impulse to the windings, wherein identifying the desired direction comprises indicating to increase or decrease a magnitude of a current in the windings while maintaining a positive direction of the current; opening the one of the plurality of switches in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings; and closing another of the plurality of switches in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings, wherein; the close of one of the plurality of switches, the open of the one of the plurality of switches, and the close of another of the plurality of switches are configured to reduce ripple currents relative to the ripple currents that would be present with pulse width modulation, and the current impulse increases or decreases the magnitude of the current in the windings once per a duty cycle while maintaining the positive direction of the current. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. A computer program product for controlling a brushless direct current motor, the computer program product comprising:
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a non-transitory computer readable storage medium; first program instructions for closing one of a plurality of switches in an H-bridge to put the H-bridge in a coast configuration, wherein windings of the brushless direct current motor are short circuited and wherein the H-bridge is configured to couple a direct current power source to the windings; second program instructions for identifying a desired direction for a current impulse to the windings, wherein identifying the desired direction comprises indicating to increase or decrease a magnitude of a current in the windings while maintaining a positive direction of the current; third program instructions for opening the one of the plurality of switches in response to identifying a first desired direction for the current impulse to provide the current impulse in the first desired direction to the windings; and fourth program instructions for closing another of the plurality of switches in response to identifying a second desired direction for the current impulse to provide the current impulse in the second desired direction to the windings; wherein; the first program instructions, the second program instructions, the third program instructions, and the fourth program instructions are stored on the non-transitory computer readable storage medium, the close of one of the plurality of switches, the open of the one of the plurality of switches, and the close of another of the plurality of switches are configured to reduce ripple currents relative to the ripple currents that would be present with pulse width modulation, and the current impulse increases or decreases the magnitude of the current in the windings once per a duty cycle while maintaining the positive direction of the current. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification