Power control circuit for induction motor
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorHidehiko Sugimoto
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Abstract
A control circuit 3 for an induction motor 2 detects the voltage applied across the motor winding and the current flowing therethrough. The supply power and the feedback power are determined from the detected voltage and current and are supplied to a computing unit whose output controls a voltage regulator such that the voltage applied across the motor winding results in a fixed, predetermined ratio between the effective and apparent powers to maximize the motor efficiency and to minimize the motor's power consumption regardless of variations in the line voltage and fluctuations in the motor load.
Claims4
A power control circuit for an induction motor, said power control circuit comprising:
- a detecting means connected between an alternating current power source and said induction motor for detecting the supply power and the feedback power flowing between said source and said motor;
- a voltage regulating means for controlling an input voltage applied to said induction motor such that the ratio between the supply power and the feedback power is maintained at a predetermined value;
- wherein said supply power is defined to be equal to the product of the instantaneous value of said voltage applied to said motor and a current flowing through said motor when said product is positive in value;
- and
- wherein said feedback power is defined to be equal to the product of the instantaneous value of said voltage applied to said motor and said current flowing through said motor when said product is negative in value.
Dependencies are inferred from the claim text.