Motor control circuit including motor current limiting means
AssigneeGeneral Electric Company
InventorCarlton E. Graf
Life of this patent
Estimating the term…
Abstract
A motor control circuit of the type in which the effective power supplied to the motor is controlled to govern motor operation includes a fast acting current limit circuit responsive to the motor current and operative to limit the power supplied to the motor to thus prevent excessive motor current. The current limit circuit compares a signal indicative of the motor current with a reference signal having a value which varies with respect to time and which is reset in response to prescribed control circuit conditions.
Claims15
In an electric motor control system of the type including controllable means for varying the effective power supplied to the motor for varying the operation thereof, means for limiting motor current by limiting the effective power delivered to the motor comprising:
- a. means to sense the value of the motor current and to produce a feedback signal proportional thereto;
- b. means to generate a reference signal having a value which varies with respect to time;
- c. means to initiate a new generation of said reference signal with each occurrence of a prescribed condition within said system;
- d. comparator means to compare said feedback signal and said reference signal and to produce a control signal in response to a prescribed relationship therebetween;
- and,
- e. means responsive to said control signal to govern the operation of the controllable means to thereby vary the effective power supplied to the motor.
In an electric motor control system of the type employing at least one controlled rectifier for varying the amount of power delivered from a source to the motor, means for limiting the motor current by determining the point in time when the controlled rectifier is rendered conductive comprising:
- a. means to sense the value of the motor current and to produce a feedback signal proportional thereto;
- b. means to generate a reference signal having a value which varies with respect to time;
- c. means to initiate a new generation of said reference signals with each rendering of the controlled rectifier conductive;
- d. comparator means to compare said feedback signal and said reference signal and to produce an inhibit signal in response to a prescribed relationship therebetween;
- and,
- e. means responsive to said inhibit signal to prohibit the rendering of said controlled rectifier conductive.
A system for controlling an electric motor comprising:
- a. means including a controlled rectifier for controlling the amount of power supplied to the motor from a source by varying the point in time when the rectifier is rendered conductive;
- and,
- b. means for controlling the point in time said controlled rectifier is rendered conductive including a motor current limiting feedback loop comprising,
- 1. means to sense the value of the motor current and to produce a feedback signal proportional thereto;
- 2. means to generate a reference signal having a value which varies with respect to time;
- 3. means to initiate a new generation of said reference signals with each rendering of the controlled rectifier conductive;
- 4. comparator means to compare said feedback signal and said reference signal and to produce an inhibit signal in response to a prescribed relationship therebetween;
- and,
- 5. means responsive to said inhibit signal to prohibit the rendering of said controlled rectifier conductive.
Dependencies are inferred from the claim text.