Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1989-02-06
1990-04-17
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Primary circuit control
318809, H02P 700
Patent
active
049183672
ABSTRACT:
The present invention relates to a method for controlling an ac motor supplied by an inverter having several switches. In order that the torque can be adjusted to be as desired as rapidly as possible both with maximum voltage and in the vicinity thereof, one proceeds in accordance with the invention in such a way that a value (.DELTA..gamma.) representing the difference between the reference value and actual value of the angle between the stator flux and rotor flux of the motor is determined on the basis of a value representing the requirement for torque change of the motor, e.g. by means of the difference (.DELTA.T) between the reference valve (T*) and actual valve (T) of the torque, and a quantity representing the magnetic state of the motor, the next switching moment of the switches of the inverter, i.e. the so called limit between flux sectors (.DELTA..phi.), is shifted with a first quantity (k.sub.1 .DELTA..gamma.) proportional to the determined differential value to change the angle (.gamma.) between the stator flux and the rotor flux, i.e. the torque of the motor, in a stepwise manner to be as desired, and that switching moment of the switches of the inverter which is next in turn is shifted with second quantity (k.sub.2 .DELTA..gamma.) proportional to the determined differential value and reverse to the first quantity (k.sub.1 .DELTA..gamma.) to change the rotating speed of the stator flux.
REFERENCES:
patent: 4078191 (1978-03-01), Morters et al.
patent: 4280085 (1981-07-01), Cutler et al.
patent: 4400655 (1983-08-01), Curtiss et al.
patent: 4453116 (1984-06-01), Bose
patent: 4511835 (1985-04-01), Studtmann
patent: 4678248 (1987-07-01), Depenbrock
Takahashi et al; "Quick Torque Control of an Induction Motor by Means of Instantaneous Slip Frequency Control"; Electrical Eng. in Japan; vol. 106, No. 2, 1986.
ABB Stromberg Drives OY
Martin David
Shoop Jr. William M.
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