Stall protection circuit for an electronically commutated motor
First Claim
1. A control circuit for a system including an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage and having a rotatable assembly associated with the stationary assembly in selective magnetic coupling relation therewith for rotation at a motor speed in response to a magnetic field generated by the winding stages, a commutating circuit for the motor responsive to a control signal for applying the voltage to one or more of the winding stages at a time to commutate the winding stages in a preselected sequence to rotate the rotatable assembly, and tachometer pulse signal generating means for generating a pulsed signal representative of the rotational speed of the rotatable assembly and having a duty cycle, said control circuit comprising:
- first means for inhibiting application of the motor voltage to the winding stages in response to the tachometer pulse signal when the motor speed is below a preset minimum speed; and
second means for inhibiting application of the motor voltage to the winding stages in response to the tachometer pulse signal when the duty cycle of the tachometer pulse signal is outside a preselected acceptable range whereby application of the motor voltage to the winding stages is inhibited when the motor is stalling as indicated by the motor speed being below the preset minimum speed or as indicated by the duty cycle of the tachometer pulse signal being outside the preselected acceptable range.
1 Assignment
0 Petitions
Accused Products
Abstract
A control circuit for a system including an electronically commutated motor. A tachometer pulse signal generator generates a signal representative of the rotational speed of the rotatable assembly of the motor and having a duty cycle. The control circuit includes first and second motor voltage inhibiting circuits. The first inhibiting circuit inhibits application of the motor voltage to the winding stages of the motor in response to the tachometer pulse signal when the motor speed is below the preset minimum speed. The second inhibiting circuit inhibits application of the motor voltage to the winding stages in response to the tachometer pulse signal when the duty cycle of the tachometer pulse signal is outside a preselected acceptable range. Application of the motor voltage to the winding stages is inhibited when the motor is stalling as indicated by the motor speed being below the preset minimum speed or as indicated by the duty cycle of the tachometer pulse signal being outside the preselected acceptable range.
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Citations
28 Claims
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1. A control circuit for a system including an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage and having a rotatable assembly associated with the stationary assembly in selective magnetic coupling relation therewith for rotation at a motor speed in response to a magnetic field generated by the winding stages, a commutating circuit for the motor responsive to a control signal for applying the voltage to one or more of the winding stages at a time to commutate the winding stages in a preselected sequence to rotate the rotatable assembly, and tachometer pulse signal generating means for generating a pulsed signal representative of the rotational speed of the rotatable assembly and having a duty cycle, said control circuit comprising:
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first means for inhibiting application of the motor voltage to the winding stages in response to the tachometer pulse signal when the motor speed is below a preset minimum speed; and second means for inhibiting application of the motor voltage to the winding stages in response to the tachometer pulse signal when the duty cycle of the tachometer pulse signal is outside a preselected acceptable range whereby application of the motor voltage to the winding stages is inhibited when the motor is stalling as indicated by the motor speed being below the preset minimum speed or as indicated by the duty cycle of the tachometer pulse signal being outside the preselected acceptable range. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A control circuit for a system including an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage and having a rotatable assembly associated with the stationary assembly in selective magnetic coupling relation therewith for rotation at a motor speed in response to a magnetic field generated by the winding stages, and a commutating circuit for the motor responsive to a control signal for applying the voltage to one or more of the winding stages at a time to commutate the winding stages in a preselected sequence to rotate the rotatable assembly, said control circuit comprising:
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means for generating a pulsed motor speed signal having a pulse rate representative of the motor speed; means for defining a minimum motor speed; means for comparing the motor speed represented by the pulsed motor speed signal to the minimum motor speed; and means, responsive to the comparing means, for inhibiting application of the motor voltage to the winding stages when the motor speed is below the minimum motor speed whereby application of the motor voltage to the winding stages is inhibited when the motor is stalling as indicated by motor speed being below the minimum motor speed. - View Dependent Claims (21, 22, 23)
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24. A control circuit for a system including an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage and having a rotatable assembly associated with the stationary assembly in selective magnetic coupling relation therewith for rotation at a motor speed in response to a magnetic field generated by the winding stages, a commutating circuit for the motor responsive to a control signal for applying the voltage to one or more of the winding stages at a time to commutate the winding stages in a preselected sequence to rotate the rotatable assembly, and tachometer pulse signal generating means for generating a signal representative of the rotational speed of the rotatable assembly and having a duty cycle, said control circuit comprising:
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means for generating a signal representative of the duty cycle of the tachometer pulse signal; means for defining a preselected duty cycle range; means for comparing the magnitude of the duty cycle representative signal to the preselected duty cycle range; and means, responsive to the comparing means, for inhibiting application of the motor voltage to the winding stages when the magnitude of the duty cycle signal is not within the preselected duty cycle range whereby application of the motor voltage to the winding stages is inhibited when the motor is stalling as indicated by the duty cycle of the tachometer pulse signal being outside the preselected duty cycle range. - View Dependent Claims (25, 26, 27)
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28. A stall protection control for a system including an electronically commutated motor having a stationary assembly with a plurality of winding stages for carrying a motor current in response to application of a voltage and having a rotatable assembly associated with the stationary assembly in selective magnetic coupling relation therewith for rotation at a motor speed in response to a magnetic field generated by the winding stages, the control comprising:
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means for applying the voltage to one or more of the winding stages at a time to commutate the winding stages in a preselected sequence to rotate the rotatable assembly; means for generating a tachometer pulse signal representative of the rotational speed of the rotatable assembly and having a duty cycle; means for defining a preset minimum speed below which the motor is considered to be in a stall; first means, responsive to the tachometer pulse signal, for inhibiting application of the motor voltage to the winding stages when the rotational speed is below the preset minimum speed; and means for defining a preselected duty cycle range for the tachometer pulse signal outside of which the motor is considered to be in a stall; second means, responsive to the tachometer pulse signal, for inhibiting application of the motor voltage to the winding stages when the duty cycle of the tachometer pulse signal is outside the preselected duty cycle range whereby application of the motor voltage to the winding stages is inhibited when the motor is stalled as indicated by the motor speed being below the preset minimum speed or by the duty cycle of the tachometer pulse signal being outside the preselected acceptable range.
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Specification