Low power stepper motor drive system and method
First Claim
1. A stepper motor drive system, comprising:
- a stepper motor having a rotor, and a plurality of windings corresponding to a plurality of motor phases;
first means for providing a drive power and applying said drive power to said windings to step said rotor, said first means maintaining a different one of said windings deenergized during each step;
second means comprising a stepping detector means for detecting a pulse induced into said deenergized winding by stepping said rotor, and comparing an amplitude and polarity of each said detected pulse to a reference amplitude and polarity resulting from stepping said motor in a desired direction of rotation, said stepping detector means being coupled to provide an output signal of a first logic level when said amplitude and polarity of said received pulse both correspond to said reference, and an output signal of a second logic level when at least one of said amplitude and polarity does not correspond to said reference; and
third means for receiving said output signal and applying a first control signal to said first means for decreasing said drive power provided by said first means in response to a said first logic level, and for increasing said drive power in response to said second logic level.
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Accused Products
Abstract
A system and method for driving a stepper motor utilizing a near minimum amount of driving power is described. A stepping detector is utilized to determine whether the motor has actually stepped in response to a driving power applied thereto. When it is determined that the motor has stepped, the magnitude of the driving power is decreased. When the stepping detector indicates a stall condition, the driving power is increased. As a result, the motor operates near stall condition and power consumption is minimized. In the preferred embodiment during each consecutive step a different phase of the motor is deenergized to conserve power. By stepping the motor a voltage pulse is induced into the deenergized phase. The polarity and magnitude of that voltage pulse are examined after each step to determine whether the motor has actually stepped. The use of the deenergized phase to ascertain motor status eliminates the need for an external stepping detector.
77 Citations
16 Claims
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1. A stepper motor drive system, comprising:
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a stepper motor having a rotor, and a plurality of windings corresponding to a plurality of motor phases; first means for providing a drive power and applying said drive power to said windings to step said rotor, said first means maintaining a different one of said windings deenergized during each step; second means comprising a stepping detector means for detecting a pulse induced into said deenergized winding by stepping said rotor, and comparing an amplitude and polarity of each said detected pulse to a reference amplitude and polarity resulting from stepping said motor in a desired direction of rotation, said stepping detector means being coupled to provide an output signal of a first logic level when said amplitude and polarity of said received pulse both correspond to said reference, and an output signal of a second logic level when at least one of said amplitude and polarity does not correspond to said reference; and third means for receiving said output signal and applying a first control signal to said first means for decreasing said drive power provided by said first means in response to a said first logic level, and for increasing said drive power in response to said second logic level. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A stepper motor drive system, comprising;
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a stepper motor having a rotor, and a plurality of windings corresponding to a plurality of motor phases; means for providing a drive power and applying said drive power to said windings to step said rotor, said means maintaining a different one of said windings deenergized during each step; an amplitude and polarity detector and pulse discriminator and selection logic means for detecting a pulse induced into said deenergized winding, and comparing an amplitude and polarity of said detected pulse to a reference amplitude and polarity resulting from stepping said motor in a desired direction of rotation, and for responsively providing an output signal of a first logic level when said amplitude and polarity of said received pulse both correspond to said reference, and an output pulse of a second logic level when at least one of said amplitude and polarity does not correspond to said reference; an up/down signal ramping means coupled to receive said output signal and to provide a substantially linearly decreasing ramp signal in response to an output signal of said first logic level, and a substantially linearly increasing ramp signal in response to an output signal of said second logic level, and to apply said ramp signal to said means for providing said drive power.
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16. A stepper motor drive system, comprising:
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a stepper motor having a rotor, and a plurality of windings corresponding to a plurality of motor phases; means for providing a drive power and applying said drive power to said windings to step said rotor, said means maintaining a different one of said windings deenergized during each step; an amplitude and polarity detector and pulse discriminator and selection logic means for detecting a pulse induced into said deenergized winding, and comparing an amplitude and polarity of said detected pulse to a reference amplitude and polarity resulting from stepping said motor in a desired direction of rotation, and for responsively providing an output signal of a first logic level when said amplitude and polarity of said received pulse both correspond to said reference, and an output pulse of a second logic level when at least one of said amplitude and polarity does not correspond to said reference; a history register means for receiving and storing a predetermined number of consecutive output signals of said first and second level and providing an output signal of a first logic level when all the stored signal levels indicate stepping in a desired direction, and an output signal of a second logic level, when at least one of said stored logic levels does not indicate stepping in a desired direction; and an up/down signal ramping means coupled to receive said output signal from said history register means and to provide a substantially linearly decreasing ramp signal in response to said received first logic level signal, and a substantially linearly increasing ramp signal in response to said received second logic level and to apply said ramp signal to said means for providing said drive power.
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Specification