D.C. motor control
AssigneeGeneral Electric Company
InventorChandler A. Johnson, III
Life of this patent
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Abstract
A control circuit for a direct current motor having separately excited armature and field windings and operable in both the constant torque and constant horsepower modes includes a speed control circuit having a transfer characteristic providing an extremely high gain at lower frequencies and a low gain, for example unity, at higher frequencies and further includes means to reduce the low frequency gain when motor operation is switched from the constant torque to the constant horsepower mode.
Claims14
A control system for a direct current motor having separately excited armature and field windings comprising:
- (a) a controlled power supply for supplying variable voltage power to said armature windings;
- (b) means to provide a feedback signal proportional to motor speed;
- (c) a speed control circuit for developing a control signal operable to govern the operation of said power supply to thereby control the voltage furnished to said armature winding, said control circuit including,
- (1) means to provide a reference signal proportional to desired motor speed, and
- (2) comparison means to compare said speed reference signal with said feedback signal to produce said control signal, said comparison means having a transfer characteristic providing a relatively high gain in response to relatively low frequency input signal components and a relatively low gain in response to relatively high frequency input signal components;
- (d) means responsive to the counterelectromotive force of said motor to provide an output signal when said force exceeds a predetermined level;
- and,
- (e) means responsive to said output signal to reduce the low frequency gain of said comparison means.
A control system for a direct current motor having separately excited armature and field windings comprising:
- (a) selectively operable means for applying power to said armature and field windings;
- (b) means to develop a signal representing the counterelectromotive force of said motor;
- (c) means to determine when the counterelectromotive force of said motor exceeds a predetermined value and to provide an output signal proportional thereto;
- (d) means to develop a feedback signal proportional to motor speed;
- (e) control means responsive to said feedback signal to provide a control signal for controlling the power supplied to said armature winding, said control means having a gain which varies with frequency;
- and,
- (f) means responsive to said output signal to reduce the low frequency gain of said control means.
Dependencies are inferred from the claim text.