PROPORTIONAL MOTOR ACTUATOR CIRCUIT

• US 3,742,327 A
• Filed: 01/15/1971
• Issued: 06/26/1973
• Est. Priority Date: 01/15/1971
• Status: Expired due to Term

• Current Assignee: Johnson Controls International BV (Johnson Controls International plc)
• Original Assignee: Robert G. Nettles
• Inventors: Nettles, Robert G.
• Primary Examiner(s): Dobeck, B.
• Application Number:
  US05/106,650
• Time in Patent Office: 893 Days
• Field of Search: 318/678,683,615,624
• US Class Current: 318/678
• CPC Class Codes: G05D 3/1472 with potentiometer
• CPC Class Codes: G05D 3/18 delivering a series of pulses
• CPC Class Codes: H02P 23/24 Controlling the direction, e.g. clockwise or counterclockwise

Abstract

A motor actuator circuit for use in heating and air conditioning and process control systems to selectively rotate a motor shaft which positions a damper or valve. A command signal, such as a voltage, or a potentiometer controlled by a sensing element of the system provides a signal representing the desired position for the damper and a sense potentiometer provides a signal representing the actual shaft position; a signal comparator circuit including a differential amplifier having an output switching stage is responsive to a potential difference between the signals to effect energization of one of a pair of motor windings, the energized one of the pair being determined by the polarity of the difference signal; and detent circuits derive a detent signal from the voltage across the other one of the motor windings for coupling to the amplifier input to increase the potential difference, the sense potentiometer wiper being linked to the motor shaft so that the potential difference decreases as the shaft rotates to the desired position, and the motor is deenergized when the desired position is reached.

Claims

1. In a motor control circuit for effecting selective energization of first and second windings of a motor to rotate the motor shaft to a desired position, command means for providing a command input signal representing the desired position for said shaft, sense controller means for providing a sense signal representing the actual position of said shaft, comparator means having first and second inputs for receiving said command and sense signals, respectively, said comparator means being responsive to a change in said command signal relative to said sense signal to effect the energization of aid first and second windings selectively to cause rotation of said shaft in a direction toward said desired position, and detent means for extending first and second detent signals derived from said first and second windings to the first and second inputs, respectively, of said comparator means whenever said windings are energized to increase the difference between said command and sense signals supplied to the first and second inputs of said comparator means.

2. A motor control circuit as set forth in claim 1 wherein said sense controller means includes signal characterizing means operable when enabled to modify said sense signal whereby a linear change in said command input signal effects non-linear change in the shaft position.

3. A motor control circuit as set forth in claim 2 wherein said sense controller means includes first potentIometer means and said signal characterizing means includes adjustable resistor means and means for connecting said adjustable resistor means in parallel with said first potentiometer means.

4. In a motor control circuit for effecting selective energization of first and second windings of a motor to rotate the motor shaft to a desired position, command input means for providing a command input signal representing the desired position for said shaft, sense controller means for providing a sense signal representing the actual position of said shaft, comparator means responsive to a difference in the amplitudes of said signals to effect energization of said windings to rotate said shaft in a direction toward the desired position, and detent means including first circuit means connected between one of said motor windings and said command input means to provide a detent signal to said command input means whenever said windings are energized and second circuit means connected between the other of said motor windings and said sense controller means to provide a detent signal to said sense controller means whenever said windings are energized, to thereby increase the potential difference between said command and sense signals supplied to said comparator means.

5. A motor control circuit as set forth in claim 3 wherein said comparator means includes first output means enabled whenever said command signal increases a predetermined amount relative to said sense signal to energize said windings to effect rotation of the shaft in one direction, and second output means enabled whenever said command signal decreases a predetermined amount relative to said sense signal to energize said windings to effect rotation of said shaft in the opposite direction.

6. A motor control circuit as set forth in claim 3 including over-signal clamping means connected between said sense controller means and said command input means.

7. In a motor control circuit for effecting selective energization of first and second windings of a motor to rotate the motor shaft to a desired position, command controller means for providing a command signal representing the desired position for the shaft, sense controller means for providing a sense signal representing the actual position of the shaft, comparator means including switching means operable whenever said command and sense signals differ by a given amount to provide an output signal, the polarity of the output signal being different as the command signal increases or decreases relative to the sense signal, first drive means responsive to an output signal of one polarity to energize said windings to effect rotation of the shaft in one direction and second drive means responsive to an output signal of a second polarity to energize said windings to effect rotation of the shaft in the opposite direction , and detent means including first circuit means connected to provide a first detent signal derived from said first winding to said command controller means whenever said windings are energized, and second circuit means connected to provide a second detent signal derived from said second winding to said sense controller means whenever said windings are energized, said first and second detent signals being coupled to said command and sense controller means , respectively, to increase the difference between said command and sense signals, said sense controller means being controlled by said motor shaft such that as said shaft rotates towards said desired position, the amplitude of the sense signal approaches the amplitude of the command signal, to thereby decrease the difference between said command and sense signals below said given amount and effect deenergization of said windings.

8. A motor control circuit as set forth in claim 6 wherein said command controller means includes first potentiometer means connected across output terminals of a voltage source for providing said command signal at a wiper of said first potentiometer means and wherein said senSe controller means includes second potentiometer means connected across said source output terminals for providing said sense signal at a wiper of said second potentiometer means.

9. A motor control circuit as set forth in claim 8 wherein said first circuit means comprise resistance means connected between said first winding and said first potentiometer wiper to couple said detent signal to said first potentiometer wiper whenever said second winding is energized, and said second circuit means comprise second resistance means connected between said second winding and said second potentiometer wiper to couple said detent signal to said potentiometer wiper whenever said first winding is energized.

10. A motor control circuit as set forth in claim 8 including diode means connected between said resistance means of said first circuit means and a terminal of said second potentiometer means for assuring that a sense signal greater in amplitude than the command signal can always be obtained.

11. A motor control circuit as set forth in claim 6 wherein said command controller means includes first potentiometer means connected across a pair of output terminals of a voltage source which provide a first potential across said command controller means, and said sense controller means includes second potentiometer means and limit potentiometer means serially connected across a further pair of output terminals of said source which provide a second potential across said sense controller means, said limit potentiometer means being adjustable to vary the potential across said second potentiometer means between said first potential and said second potential.

12. In a motor control circuit for effecting selective energization of first and second windings of a motor to rotate the motor shaft to a desired position, command controller means for providing a command signal of an amplitude representing the desired position for the shaft, sense controller means for providing a sense signal of an amplitude representing the actual position of the shaft, comparator means including switching means operable whenever the amplitudes of the command and sense signals differ by a given amount to provide an output signal, the polarity of the output signal being different as the command signal increases or decreases relative to the sense signal, first drive means enabled responsive to an output signal of one polarity to effect energization of said windings to effect rotation of the shaft in one direction and second drive means enabled responsive to an output signal of a second polarity to effect energization of said windings to effect rotation of the shaft in the opposite direction and detent means including first circuit means connected between one of said windings and said command controller means to provide a first detent signal derived from said one winding whenever said windings are energized and second circuit means connected between the other of said windings and said sense controller means to provide a second detent signal derived from said other winding whenever said windings are energized, said first and second detent signals being coupled to said command and sense controller means, respectively to increase the difference between said command and sense signals, said sense controller means being controlled by said motor shaft such that as said shaft rotates towards said desired position, the amplitude of the sense signal approaches the amplitude of the command signal decreasing the difference between the amplitude of said command and sense signals below said given amount to thereby effect deenergization of said windings.

13. In a motor control circuit for effecting selective energization of first and second windings of a motor to rotate the motor shaft to a desired position, command controller means for providing a command signal representing the desired position for the shaft, sense controller means for providing a sense signal representing the actual position of the shaft, comparatoR means including a first input transistor having an input electrode connected to said sense controller means to receive said sense signal and a first control electrode, a second input transistor having an input electrode connected to said command controller means to receive said command signal and a second control electrode, a first switching transistor having a first input electrode connected to said first control electrode and a second input electrode connected to said second control electrode, and a second switching transistor having a first input electrode connected to said second control electrode and a second input electrode connected to said first control electrode, and means forward biasing said first switching transistor and reverse biasing said second switching transistor to provide an output signal of a first polarity whenever the amplitude of the command signal exceeds the amplitude of the sense signal by a predetermined amount of reverse biasing said first switching transistor and forward biasing said second switching transistor to provide an output signal of the opposite polarity whenever the amplitude of the sense signal exceeds the amplitude of the command signal by said predetermined amount, first drive means responsive to one of said output signals to energize said windings to effect rotation of said shaft in one direction, second drive means responsive to the other one of said output signals to energize said windings to effect rotation of said shaft in the opposite direction, and detent means including first circuit means connected to provide a first detent signal derived from one of said windings to said command controller means and second circuit means connected to provide a second detent signal derived from the other of said windings to said sense controller means, said first and second detent signals being coupled to said command and sense controller means, respectively to thereby increase the difference in amplitude between said command and sense signals.

14. A motor control circuit for effecting selective energization of first and second windings of a motor to rotate the shaft to a desired position, said motor control circuit comprising command input mans for providing a first signal representing the desired position for the shaft, sense controller means for providing a second signal representing the actual position of the shaft, signal comparator means including input means responsive to a difference in said first and second signals to provide a potential difference of a first or a second polarity between first and second output which indicates an increase or a decrease in the first signal relative to said second signal, and output means with first and second switching means having control circuits reversely connected between said first and second outputs such that when the potential difference between said outputs is one polarity, said first switching means is enabled and said second switching means is disabled to provide a first output signal, and when the potential difference between said outputs is of a second polarity, said second switching means is enabled and said first switching means is disabled to provide a second output signal, first drive means responsive to said first output signal to effect energization of one of said motor windings, and a second drive means responsive to said second output signal to effect energization of the other of said motor windings, and detent means including first circuit means connected between one of said motor windings and said sense controller means for coupling a detent signal derived from said one windings to said sense controller means whenever said windings are energized and second circuit means connected between the other one of said motor windings and said command input means for coupling a further detent signal derived from said other motor winding to said command input means whenever said windings are energized to thereby increase the difference between said command and sense signals.

15. In A motor control circuit for effecting selective energization of first and second windings of a motor to rotate the motor shaft to a desired position, signal comparator means, command means for supplying a command signal representing the desired position for said shaft to an input of said comparator means, sense controller means for supplying a sense signal representing the actual position of said shaft to a further input of said comparator means, said comparator means being responsive to a change in said command signal relative to said sense signal to selectively energize said windings to cause rotation of said shaft in a direction toward said desired position, and signal characterizing means connected to said sense controller means and operable when enabled to modify the sense signal provided by said sense controller means whereby a linear change in said command signal relative to said sense signal effects a non-linear change in the position of said motor shaft.