Method and circuitry for drag braking a polyphase DC motor
First Claim
1. A method for braking a forward rotation of a rotor of a rotor of a polyphase DC motor, comprising the steps of:
- incrementing a commutation sequencer by several phases to produce an incremented commutation sequence to produce a magnetic flux vector that lags a magnetic pole of said motor; and
applying driving currents to coils of said motor in accordance with said incremented commutation sequence.
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Accused Products
Abstract
A method and circuit for braking a forward rotation of a rotor of a polyphase DC motor. A commutation sequencer is incremented by several phases to produce an incremented commutation sequence to produce a magnetic flux vector that lags a magnetic pole of the motor. Driving currents are applied to coils of the motor in accordance with the incremented commutation sequence to brake the rotor. The method is implemented in a circuit that has a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate the rotor. A power stage to which the commutation signals are applied energizes the selected coils in accordance with the commutation signals. A circuit interrupts the energization of the selected coils and the commutation sequence is altered to produce a sequence that produces a negative torque on the rotor. Circuits are also provided to inhibit application of the altered commutation sequence until recirculation currents in the power stage caused by the coils in response to the reduction of the input voltage have fallen below a predetermined level, and to inhibit application of the altered commutation sequence until a voltage on a sense resistor between the power stage and a reference potential has fallen below a predetermined level after an operation of the circuit for interrupting the energization of the selected coils.
45 Citations
33 Claims
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1. A method for braking a forward rotation of a rotor of a rotor of a polyphase DC motor, comprising the steps of:
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incrementing a commutation sequencer by several phases to produce an incremented commutation sequence to produce a magnetic flux vector that lags a magnetic pole of said motor; and applying driving currents to coils of said motor in accordance with said incremented commutation sequence. - View Dependent Claims (2, 3, 4, 5)
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6. A method for braking a rotation of a rotor of a brushless and sensorless DC motor from moving in a forward direction, the DC motor having the rotor, a stator with at least three coils, and a circuit having a sequencer which controls three top transistor switches and three bottom transistor switches connected in a half H-bridge configuration, said circuit controlling a current flowing through said at least three coils which forms positive torque on said rotor, the method comprising the steps of:
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opening said three bottom transistor switches to stop the current flowing through the coils; monitoring the recirculation current formed in the three top transistor switches; commutating said sequencer by several phases so that the current flowing through said at least three coils will produce a negative torque; applying an output of said sequencer to close one of said three top transistor switches and one of said three bottom transistor switches so that negative torque is applied to said rotor. - View Dependent Claims (7, 8, 9, 10)
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11. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate said rotor according to a commutation sequence that increments in a forward direction and generates a flux vector that leads the rotor; a power stage to which said commutation signals are applied to energize the selected coils in accordance with said commutation signals; a circuit for interrupting the energization of the selected coil; a circuit for producing an altered commutation sequence that increments in a forward direction and generates a flux vector that lags the rotor; and a circuit for applying the altered commutation sequence to said power stage to brake the rotation of the rotor. - View Dependent Claims (12, 13)
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14. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate said rotor; a power stage to which said commutation signals are applied to energize the selected coils in accordance with said commutation signals; a circuit for interrupting the energization of the selected coil; a circuit for altering the commutation sequence to produce an altered commutation sequence that produces a negative torque on the rotor; and a circuit for applying the altered commutation sequence to said power stage to brake the rotation of the rotor; a circuit for removing an input voltage from the power stage in response to a signal to brake the rotor, and for reapplying the input voltage after the altered commutation sequence has been applied; and a circuit for inhibiting application of said altered commutation sequence until recirculation currents in said power stage caused by the coils in response to the reduction of the input voltage have fallen below a predetermined level.
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15. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate said rotor; a power stage to which said commutation signals are applied to energize the selected coils in accordance with said commutation signals; a circuit for interrupting the energization of the selected coil; a circuit for altering the commutation sequence to produce an altered commutation sequence that produces a negative torque on the rotor; and a circuit for applying the altered commutation sequence to said power stage to brake the rotation of the rotor; a circuit for removing an input voltage from the power stage in response to a signal to brake the rotor, and for reapplying the input voltage after the altered commutation sequence has been applied; and a circuit for inhibiting application of said altered commutation sequence until a voltage on a sense resistor between the power stage and a reference potential has fallen below a predetermined level after an operation of the circuit for interrupting the energization of the selected coils.
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16. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate said rotor; a power stage to which said commutation signals are applied to energize the selected coils in accordance with said commutation signals; a circuit for interrupting the energization of the selected coil; a circuit for altering the commutation sequence to produce an altered commutation sequence that produces a negative torque on the rotor; and a circuit for applying the altered commutation sequence to said power stage to brake the rotation of the rotor; a circuit for removing an input voltage from the power stage in response to a signal to brake the rotor, and for reapplying the input voltage after the altered commutation sequence has been applied; and a circuit for inhibiting application of said altered commutation sequence until recirculation currents in said power stage caused by the coils in response to the reduction of the input voltage have fallen below a predetermined level; and a circuit for inhibiting application of said altered commutation sequence until a voltage on a sense resistor between the power stage and a reference potential has fallen below a predetermined level after an operation of the circuit for interrupting the energization of the selected coils.
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17. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate said rotor; a power stage to which said commutation signals are applied to energize the selected coils in accordance with said commutation signals; a circuit for interrupting the energization of the selected coil; a circuit for altering the commutation sequence to produce an altered commutation sequence that produces a negative torque on the rotor, comprising a plurality of multiplexers connected to output the sets of commutation signals in a first order in the absence of a reverse torque signal, and to output the sets of commutation signals in a second order in the presence of a reverse torque signal; and a circuit for applying the altered commutation sequence to said power stage to brake the rotation of the rotor.
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18. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a sequencer for incrementally generating sets of commutation signals to select stator coils for energization to rotate said rotor; a power stage to which said commutation signals are applied to energize the selected coils in accordance with said commutation signals; a circuit for interrupting the energization of the selected coil; a circuit for altering the commutation sequence to produce an altered commutation sequence that produces a negative torque on the rotor; a circuit for applying the altered commutation sequence to said power stage to brake the rotation of the rotor and circuitry for incrementing said sequencer in response to a back emf signal from at least one of said stator coils.
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19. A circuit for braking rotation of a rotor of a polyphase DC motor having a plurality of stator coils, comprising:
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a power stage to energize selected stator coils; a sequencer for incrementally generating sets of commutation signals for application to said power stage to select stator coils for energization to rotate said rotor; said commutation signals being selected to create a magnetic flux vector that moves in advance of a pole of said rotor to cause said rotor to rotate in a forward direction; a circuit for interrupting the energization of the stator coils; a circuit for altering the commutation sequence to produce an altered commutation sequence that creates a flux vector that moves behind the pole of the rotor to apply a negative torque to the rotor. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27)
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28. A control circuit for braking a rotor of a brushless and sensorless DC motor from forward rotation, said motor having the rotor and a stator with at least three coils, said control circuit comprising:
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energizing means for energizing said at least three coils in accordance with sequential commutation sequences; interrupting means for interrupting the energizing of said at least three coils; monitoring means for monitoring the voltage outputs of said at least three coils after the interrupting means has interrupted the energizing of said at least three coils; and altering means for producing an altered commutation sequence that produces a negative torque on the rotor. - View Dependent Claims (29, 30, 31, 32, 33)
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Specification