Stepper motor control circuit and apparatus
First Claim
1. A motor control circuit and apparatus for controlling an electrical motor having a rotatable shaft adapted to rotate incrementally clockwise or counterclockwise in response to electrical currents applied to the motor comprising:
- (a) input means including command signal input means for receiving an electrical command signal and power input means for receiving a sufficient electrical current to energize the control circuit and motor;
(b) clock means for providing periodic electrical clock signal pulses to the control circuit;
(c) up/down counter means electrically connected to said clock means for counting clock pulses on each clock signal pulse and for providing an output signal in the form of a binary representation of total clock pulses;
(d) comparing circuit means electrically connected to the up/down counter means and to the command signal input means for determining an up/down direction of the up/down counter before each clock signal pulse so that the up/down counter counts in a single direction until the binary representation of total counts is equivalent to an incremental count nearest beyond the input command signal and thereafter oscillates between an incremental count at least one count nearest above and an incremental count at least one count nearest below said input command signal; and
(e) decoder means connected to the up/down counter and adapted to be connected to the motor for transmitting electrical currents to the motor to cause the shaft to rotate to and oscillate about a commanded average rotational position responsive to the binary representation of total counts of the up/down counter.
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Accused Products
Abstract
The present invention relates to a motor control circuit for a stepper motor which causes a motor shaft to oscillate between an incremental rotational position nearest above and nearest below a commanded average rotational position identified by an electrical command signal. A clock is provided for sending periodic clock signal pulses to the control circuit. An up/down counter is connected to the clock for counting clock pulses on each clock cycle and for providing an output signal in the form of a binary representation of total clock pulses. A comparing circuit electrically connected to the up/down counter is used to control an up/down direction of the up/down counter before each clock signal pulse so that the up/down counter causes the motor shaft to rotate to a position nearest beyond the commanded shaft position and to thereafter oscillate between an incremental count nearest above and an incremental count nearest below the commanded average rotational position. The invention provides the benefit of greater average shaft position resolution and, additionally, because oscillation is provided, the present invention is particularly useful in the electrical positioning of valve spools or variable displacement pumps in a manner which reduces the possibility of spool sticking.
20 Citations
26 Claims
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1. A motor control circuit and apparatus for controlling an electrical motor having a rotatable shaft adapted to rotate incrementally clockwise or counterclockwise in response to electrical currents applied to the motor comprising:
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(a) input means including command signal input means for receiving an electrical command signal and power input means for receiving a sufficient electrical current to energize the control circuit and motor; (b) clock means for providing periodic electrical clock signal pulses to the control circuit; (c) up/down counter means electrically connected to said clock means for counting clock pulses on each clock signal pulse and for providing an output signal in the form of a binary representation of total clock pulses; (d) comparing circuit means electrically connected to the up/down counter means and to the command signal input means for determining an up/down direction of the up/down counter before each clock signal pulse so that the up/down counter counts in a single direction until the binary representation of total counts is equivalent to an incremental count nearest beyond the input command signal and thereafter oscillates between an incremental count at least one count nearest above and an incremental count at least one count nearest below said input command signal; and (e) decoder means connected to the up/down counter and adapted to be connected to the motor for transmitting electrical currents to the motor to cause the shaft to rotate to and oscillate about a commanded average rotational position responsive to the binary representation of total counts of the up/down counter. - View Dependent Claims (2, 23)
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3. A motor control circuit and apparatus for controlling an electrical motor having a rotatable shaft adapted to rotate incrementally clockwise or counterclockwise in response to electrical currents applied to the motor comprising:
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(a) input means including command signal input means for receiving an electrical command signal and power input means for receiving a sufficient electrical current to energize the control circuit and motor; (b) clock means for providing periodic electrical clock signal pulses to the control circuit; (c) up/down counter means electrically connected to said clock means for counting clock pulses on each clock signal pulse and for providing an output signal in the form of a binary representation of total clock pulses wherein said up/down counter means includes a binary up/down counter having at least an 8-bit binary output; (d) comparing circuit means electrically connected to the up/down counter means and to the command signal input means for determining an up/down direction of the up/down counter before each clock signal pulse so that the up/down counter counts in a single direction until the binary representation of total counts is equivalent to an incremental count nearest beyond the input command signal and thereafter oscillates between an incremental count at least one count nearest above and an incremental count at least one count nearest below said input command signal; and (e) decoder means connected to the up/down counter and adapted to be connected to the motor for transmitting electrical currents to the motor to cause the shaft to rotate to and oscillate about a commanded average rotational position responsive to the binary representation of total counts of the up/down counter. - View Dependent Claims (4, 5, 6, 7, 8, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 24, 25, 26)
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9. A motor control circuit and apparatus for controlling an electrical motor having a rotatable shaft adapted to rotate incrementally clockwise or counterclockwise in response to electrical currents applied to the motor comprising:
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(a) input means including command signal input means for receiving an electrical command signal and power input means for receiving a sufficient electrical current to energize the control circuit and motor; (b) clock means for providing periodic electrical clock signal pulses to the control circuit; (c) up/down counter means electrically connected to said clock means for counting clock pulses on each clock signal pulse and for providing an output signal in the form of a binary representation of total clock pulses; (d) comparing circuit means electrically connected to the up/down counter means and to the command signal input means for determining an up/down direction of the up/down counter before each clock signal pulse so that the up/down counter counts in a single direction until the binary representation of total counts is equivalent to an incremental count nearest beyond the input command signal and thereafter oscillates between an incremental count at least one count nearest above and an incremental count at least one count nearest below said input command signal; (e) decoder means connected to the up/down counter and adapted to be connected to the motor for transmitting electrical currents to the motor to cause the shaft to rotate to and oscillate about a commanded average rotational position responsive to the binary representation of total counts of the up/down counter; and (f) short circuit protection means for turning off the electrical currents from the decoder means when such currents exceed a predetermined level. - View Dependent Claims (10)
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Specification