Power factor controller
AssigneeCynex Manufacturing Corporation
InventorsDan Green, Sandor Goldner
Life of this patent
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Abstract
A power factor controller for an AC induction motor which controls the input power to the motor commensurate with the loading on the motor so as to improve efficiency. The circuit provides a signal representative of the phase difference between the current through the motor and the voltage across it. The phase difference varies with motor loading and accordingly is utilized to control the input power to the motor. The improvement in efficiency is displayed in terms of the percent savings provided by the controller. The circuit provides an immediate response to initial energization of the motor to enable the motor to reach full speed in minimum time.
Claims19
A power factor controller for an AC induction motor comprising:
- a control means adapted to be electrically connected in series with each phase winding of the AC motor for controlling the power to said winding;
- circuit means coupled to said control means for providing an output which varies in accordance with the difference in phase between the current through said winding and the voltage across said winding, said phase difference varying with motor loading, and for providing said output to said control means for varying the duration of "on" time of each cycle of input power to said winding in accordance with said phase difference to thereby provide input power to the motor commensurate with the loading on the motor so as to improve efficiency,
- start-up means for producing an output signal to said circuit means whereby said circuit means maintains the "on" time of said control means at maximum for a predetermined duration to enable the motor to reach full speed in minimum time, and
- means coupled to said start-up means for causing said start-up means to produce its output signal when said motor is initially energized simultaneously with initial energization of said circuit means as well as for causing said start-up means to produce its output signal when said motor is initially energized after said circuit means have already been energized.
A power factor controller for an AC induction motor comprising:
- control means adapted to be electrically connected in series with each phase winding of the AC motor for controlling the power of said winding;
- circuit means including means for detecting the voltage across the winding, means for detecting the current through the winding, means for providing an output which varies in accordance with the difference in phase between the current through said winding and the voltage across said winding, said phase difference varying with motor loading, means for providing a ramp signal corresponding to the voltage sensed, and comparator means for combining the ramp signal with said output and for providing the result of the comparison to said control means for varying the duration of "on" time of each cycle of input power to said winding in accordance with said phase difference to thereby provide input power to the motor commensurate with the loading on the motor so as to improve efficiency,
- display means, and
- means coupling said display means to said output for causing said display means to provide a display of the amount by which energy consumption has been reduced at particular loads.
Dependencies are inferred from the claim text.