Speed or torque control circuit for an electronically commutated motor (ECM) and method of controlling the torque or speed of an ECM
First Claim
1. In a motor speed control circuit for an electronically commutated motor adapted to be energized from a DC power source, said motor having a multistage winding assembly and a magnetic assembly, the two arranged for mututl relative rotation upon application of a multi-stage energization sequence, the combination comprising:
- power input terminals for connection to a supply suitable for motor operation;
a waveform generator for supplying a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate;
means for producing a substantially smooth adjustable control voltage;
a modulating comparator having a first input to which said repetitive voltage waveform is supplied and a second input to which said adjustable control voltage is supplied, to produce output pulses when intersections occur between said inputs, said output pulses having an "active" on time equal to the interval between alternate pairs of intersections and occurring at said constant repetition rate; and
control logic means responsive to the "active" on time of said modulator pulses for providing pulse width modulated signals for control of the energization of the winding states in said multistate energization sequencewhereby adjustment of said control voltage, adjusts the active on time of each pulse and thereby the rate at which electrical energy is supplied to the motor for determination of the motor speed or torque.
1 Assignment
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Accused Products
Abstract
In a motor speed or torque control circuit for an electronically commutated motor (ECM) used in a ceiling fan, a pulse width modulator operating at an above audible pulse repetition rate is used in combination with means to adjust the motor voltage to achieve a large (20 to 1) range of smooth fan speed adjustment. The pulse width modulator, which takes the form of a comparator, has as inputs an invariant sawtooth voltage waveform, and a smooth, adjustable control voltage dependent on the voltage supplied to the motor. A steady state or pulsed output is produced dependent on whether intersections occur at the comparator input. The active output state of the pulse width modulator is used to control the application of power to the motor. The control circuit permits speed or torque control from a wall location, or on the ceiling fixture combining the motor. The speed or torque control circuitry is designed for use in a maximally integrated ECM control circuit. The invention also concerns a method of controlling the torque or speed of an ECM.
108 Citations
26 Claims
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1. In a motor speed control circuit for an electronically commutated motor adapted to be energized from a DC power source, said motor having a multistage winding assembly and a magnetic assembly, the two arranged for mututl relative rotation upon application of a multi-stage energization sequence, the combination comprising:
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power input terminals for connection to a supply suitable for motor operation; a waveform generator for supplying a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate; means for producing a substantially smooth adjustable control voltage; a modulating comparator having a first input to which said repetitive voltage waveform is supplied and a second input to which said adjustable control voltage is supplied, to produce output pulses when intersections occur between said inputs, said output pulses having an "active" on time equal to the interval between alternate pairs of intersections and occurring at said constant repetition rate; and control logic means responsive to the "active" on time of said modulator pulses for providing pulse width modulated signals for control of the energization of the winding states in said multistate energization sequence whereby adjustment of said control voltage, adjusts the active on time of each pulse and thereby the rate at which electrical energy is supplied to the motor for determination of the motor speed or torque.
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2. In a motor speed control circuit for an electronically commutated motor adapted to be energized from a DC power source, said motor having a multistage winding assembly, and a magnetic assembly, the two arranged for mutual relative rotation, said motor in a given state of a multistate energization sequence having an unenergized winding stage in which an induced back emf is integrated over time to determine the instant at which the mutual relative angular position has been attained suitable for commutation to the next state, and wherein in said given state, a second winding stage is energized in a first sense, and a third winding stage is energized in a second sense inverse to said first sense for serial energization of said second and third winding stages, the combination comprising:
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power input terminals for connection to a supply suitable for motor operation; a waveform generator for supplying a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate; means for producing a substantially smooth adjustable control voltage; a modulating comparator having a first input to which said repetitive low voltage waveform is supplied and a second input to which said adjustable control voltage is supplied, to produce output pulses when intersections occur between said inputs, said output pulses having an "active" on time equal to the interval between alternate pairs of intersections and occurring at said constant repetition rate; and control logic means responsive to the "active" on time of said modulator pulses for providing pulse width modulated signals for control of the energization of the winding stages in said multistate energization sequence. whereby adjustment of said control voltage, adjusts the active on time of each pulse and thereby the rate at which electrical energy is supplied to the motor for determination of the motor speed or torque. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. In a motor speed or torque control circuit for an electronically commutated motor adapted to be energized from a power source, said motor having a multistage winding assembly and a magnetic assembly, the two arranged for mutual relative rotation upon application of a multi-state energization sequence, the combination comprising:
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power input terminals for connection to a power supply suitable for motor operation; first adjustable voltage reduction means for serially connecting a load via said input terminals to the power supply to provide a variable output voltage suitable for variable torque or variable speed motor operation; a low voltage dc supply suitable for energization of said speed control circuit, said low voltage dc supply comprising a second voltage reduction means for serially connecting said speed control circuit via said first voltage reduction means and said power input terminals to the power supply; the speed or torque control circuit comprising; a modulating comparator having a first input to which a repetitive low voltage waveform is supplied and a second input to which an adjustable control voltage is supplied, said control voltage changing as said variable output voltage decreases to produce output pulses having an active on time which decreases as said adjustable control voltage decreases, said output pulses appearing when said repetitive voltage waveform and said adjustable voltage intersect, said output pulses occurring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections; control logic means responsive to the "active" on time of said modulator pulses for providing pulse width modulated signals for control of the energization of the winding stages in said multistate energization sequence; load output terminals for connection to the winding stages of said motor; and power switches responsive to said pulse width modulated signals for connecting the winding stages of the motor via said first adjustable voltage reduction means and via said power input terminals to the power supply for winding energization in said multi-state energization sequence, whereby upon operation of said first adjustable voltage reduction means, both the magnitude of the applied voltage and the active on time of the output pulses of the pulse width modulator are simultaneously reduced.
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15. In a motor speed or torque control circuit for an electronically commutated motor adapted to be energized from a power source, said motor having a multistage winding assembly and a magnetic assembly, the two arranged for mutual relative rotation upon application of a multi-state energization sequence, the combination comprising:
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power input terminals for connection to a power supply suitable for motor operation; first adjustable voltage reduction means for serially connecting a load via said input terminals to the power supply to provide a variable output voltage suitable for variable torque or variable speed motor operation; a low voltage dc supply suitable for energization of said speed control circuit, said low voltage dc supply comprising a second voltage reduction means for serially connecting said speed control circuit via said first voltage reduction means and said power input terminals to the power supply; the speed control circuit comprising; a modulating comparator having a first input to which a repetitive low voltage waveform is supplied and a second input to which an adjustable control voltage is supplied, said control voltage, after an initial reduction in motor operating voltage which occasions no change, changing as said variable output voltage decreases to produce output pulses having an active on time which decreases as said adjustable control voltage decreases, said output pulses appearing when said repetitive voltage waveform and said adjustable voltage intersect, said output pulses occurring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections, control logic means responsive to the active on time of said modulator pulses for providing pulse width modulated signals for control of the energization of the winding stages in said multi-state energization sequence; load output terminals for connection to the winding stages of said motor, and power switches responsive to said pulse width modulated signals for connecting the winding stages of the motor via said first adjustable voltage reduction means and via said power input terminals to the power supply for winding energization in said multi-state energization sequence, whereby after said initial reduction by operation of said first adjustable voltage reduction means, both the magnitude of the applied voltage and the active on time of the pulse width modulator are simultaneously reduced.
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16. In a motor speed or torque control circuit for an electronically commutated motor adapted to be energized from a power source, said motor having a multistage winding assembly, and a magnetic assembly, the two arranged for mutual relative rotation, said motor in a given state of a multistate energization sequence having an unenergized winding stage in which an induced back emf is intergrated over time to determine the instant at which the mutual relative angular position has been attained suitable for commutation to the next state, and wherein in said given state at least one other winding stage is energized in the appropriate sense to cause relative rotation, the combination comprising:
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power input terminals for connection to a power supply suitable for motor operation; first adjustable voltage reduction means for serially connecting a load via said input terminals to the power supply to provide a variable output voltage suitable for variable torque or variable speed motor operation; a low voltage dc supply suitable for energization of said speed control circuit, said low voltage dc supply comprising a second voltage reduction means for serially connecting said speed control circuit via said first voltage reduction means and said power input terminals to the power supply; the speed control circuit, comprising; a waveform generator for supplying a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate, means for producing an adjustable, substantially smooth control voltage, a modulating comparator having a first input to which said repetitive low voltage waveform is supplied and a second input to which said adjustable voltage is supplied, to produce output pulses when intersections occur between said repetitive low voltage waveform and said adjustable voltage, said output pulses occurring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections; control logic means responsive to the "active" on time of said modulator pulses for providing pulse width modulated signals for the winding stages in said multistate energization sequence; load output terminals for connection to the winding stages of said motor, and power switches responsive to said pulse width modulated signals for connecting the winding stages of the motor via said first adjustable voltage reduction means and said power input terminals to the power supply for winding energization in said multi-state energization sequence. - View Dependent Claims (17, 18, 19, 20, 21, 22)
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23. The method of controlling the speed or torque of an electronically commutated motor energized from a power source, said motor having a multistage winding assembly, and a magnetic assembly, the two arranged for mutual relative rotation, said motor in a given state of a multistate energization sequence having an unenergized winding stage in which an induced back emf is integrated over time to determine the instant at which the mutual relative angular position has been attained suitable for commutation to the next state, and wherein in said given state, at least one other winding stage is energized in the appropriate sense to cause relative rotation, comprising
generating a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate; -
adjusting a substantially smooth control voltage for speed or torque control; comparing said repetitive voltage waveform to said adjustable control voltage in a modulator to produce output pulses when intersections occur between said inputs, said output pulses occurring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections; and providing pulse width modulated signals during the active on time of said modulator pulses for control of the electrical energy supply in the energization of the winding stages in said multistate energization sequence.
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24. The method of controlling the speed or torque of an electronically commutated motor energized from a power source, said motor having a multistage winding assembly, and a magnetic assembly, the two arranged for mutual relative rotation, said motor in a given state of a multistate energization sequence having an unenergized winding stage in which an induced back emf is integrated over time to determine the instant at which the mutual relative angular position has been attained suitable for commutation to the next state, and wherein in said given state at least one other winding stage is energized in the appropriate sense to cause relative rotation, comprising providing a variable output voltage suitable for variable speed or variable torque motor operation by means of an adjustable voltage and reduction means serially connecting said motor to said power source;
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generating a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate; providing an adjustable substantially smooth control voltage for motor speed or torque control comprising said repetitive voltage waveform to said adjustable control voltage in a modulator to produce output pulses when intersections occur between said inputs, said output pulses occurring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections; applying energy from said power source to said motor during the active on time of said modulator pulses; and selectively adjusting said variable output voltage or said adjustable control voltage for motor speed or torque control.
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25. The method of controlling the speed or torque of an electronically commutated motor energized from a power source, said motor having a multistage winding assembly, and a magnetic assembly, the two arranged for mutual relative rotation, said motor in a given state of a multistate energization sequence having an unenergized winding stage in which an inducted back emf is integrated over time to determine the instant at which the mutual relative angular position has been attained suitable for commutation to the next state, and wherein in said given state at least one other winding stage is energized in the appropriate sense to cause relative rotation, comprising
providing a variable output voltage suitable for variable speed or variable torque motor operation by means of an adjustable voltage reduction means serially connecting said motor to said power source generating a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence on said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope, and a repetition rate which is high in relation to the commutation rate; -
providing an adjustable substantially smooth control voltage for motor speed or torque control comparating said repetitive voltage waveform to said adjustable control voltage in a modulator to produce output pulses when intersections occur between said inputs, said output pulses occurring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections; and applying energy from said power source to said motor during the active on time of said modulator pulses and simultaneously adjusting said variable output voltage and said adjustable control voltage for motor speed or torque control.
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26. The method of controlling the speed or torque of an electronically commutated motor energized from a power source, said motor having a multistage winding assembly, and a magnetic assembly, the two arranged for mutual relative rotation, said motor in a given state of a multistate energization sequence having an unenergized winding stage in which an induced back emf is integrated over time to determine the instant at which the mutual relative angular position has been attained suitable for commutation to the next state, and wherein in said given state at least one other winding stage is energized in the appropriate sense to cause relative rotation, comprising
providing a variable output voltage suitable for variable speed or variable torque motor operation by means of an adjustable voltage reduction means serially connecting said motor to said power source; -
generating a repetitive low voltage waveform of substantially constant repetition rate, amplitude and configuration, said characteristics being substantially free of dependence of said motor, said waveform having a first slope of a first duration and a second slope of a second duration and of opposite sense to said first slope and a repetition rate which is high in relation to the commutation rate; providing an adjustable substantially smooth control voltage for motor speed or torque control comparing said repetitive voltage waveform to said adjustable control voltage in a modulator to produce output pulses when intersections occur between said inputs, said output pulses occuring at said constant repetition rate and having an "active" on time equal to the interval between alternate pairs of intersections; applying energy from said power source to said motor during the active on time of said modulator pulses; and adjusting only said variable output voltage for a small reduction in motor speed or torque, and for a further reduction simultaneously adjusting said variable output voltage and said control voltage for motor speed or torque control.
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Specification