Title:
SYSTEM FOR DIGITALLY CONTROLLING AN INDUCTION MOTOR
Document Type and Number:
WIPO Patent Application WO/1986/001654
Kind Code:
A1
Abstract:
A system for digitally controlling an induction motor, which corrects the difference between the real speed of the induction motor and a specified speed in such a manner that the real speed follows the specified speed, and which has a current negative feedback loop. The system comprises means (9) for obtaining an exciting current from the real speed of the induction motor and a torque instruction of the difference; means (10) for obtaining a secondary current which is a load current from the torque instruction of the difference; means (12) for obtaining a primary current amplification and a current phase based upon the exciting current and the secondary current; means (11) for obtaining a slip frequency from the real speed and the torque instruction; means (13) for obtaining an exciting phase of the rotational magnetic field from the slip frequency and the real speed; means (15) for obtaining a current instruction of each of the phases relying upon the amplitude of the primary current and the current phase; means (16 - 21) for obtaining voltage instructions relying upon current deviation between the current instruction of each of the phases and the feedback current from the current negative feedback loop; means (29) for generating an electromotive force for correcting a counterelectromotive force based upon the exciting current; and means (22 - 24) for superposing the electromotive force on said voltage instruction to correct the counterelectromotive force based upon said exciting current. In a range on the upper side of the ground speed, the counterelectromotive force of the induction motor is maintained constant by signals formed by outputs from a means (9) which obtains an exciting current from the real speed of the induction motor and a torque instruction of the difference, from means (11) which obtains a slip frequency from the real speed and the torque instruction, and from means (29) which generates an electromotive force for correcting the counterelectromotive force based upon the exciting current.
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Inventors:
FUJIOKA YOSHIKI (JP)
KOUNO SHINICHI (JP)
KOUNO SHINICHI (JP)
Application Number:
PCT/JP1985/000477
Publication Date:
March 13, 1986
Filing Date:
August 30, 1985
Export Citation:
Assignee:
FANUC LTD (JP)
International Classes:
H02P21/08; (IPC1-7): H02P5/41
Foreign References:
| JPS57162986A | 1982-10-06 | |||
| JPS5628109B2 | 1981-06-29 | |||
| JPS5232523A | 1977-03-11 | |||
| JPS5879488A | 1983-05-13 | |||
| JPS5866593A | 1983-04-20 | |||
| JPS56125996A | 1981-10-02 |
Other References:
See also references of EP 0191870A1
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