Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1980-11-10
1982-12-28
Smith, Jr., David
Electricity: motive power systems
Induction motor systems
Primary circuit control
318798, H02P 540
Patent
active
043664288
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD OF THE INVENTION
The present invention relates to asynchronous motor drives.
REVIEW OF THE PRIOR ART
The relatively low response of the existing types of asynchronous motor drives accounts for a limited travel accuracy of working members of NC machine tools.
There is known an asynchronous motor drive (cf.USSR Inventor's Certificate No 193,604, Cl. H 02p 5/28, published on Mar. 13, 1967 in the "Bulletin of Discoveries, Inventions, Industrial Designs and Trademarks", No. 7, 1967) comprising, in a series arrangement, active and reactive stator current setters, a rotor position transmitter, a rotor current frequency meter, a unit of phase-sensitive rectifiers, and a controlled current source connected to the stator windings of the asynchronous motor. In this drive, signals of the active and reactive stator current setters are applied to the control inputs of the phase-sensitive rectifiers unit via the exciting circuits of the rotor position transmitter and rotor current frequency meter.
The time constants of the rotor position transmitter and rotor current frequency meter are quite considerable, which accounts for a relatively slow response of the asynchronous motor drive and its inability to ensure accurate travel of working members of high-duty and high-accuracy NC machine tools.
There is further known an asynchronous motor drive comprising a rotor position transmitter. In this drive, the stator windings of the asynchronous motor are electrically connected through a controlled current source to outputs of a phase-sensitive rectifiers unit whose control inputs are electrically connected to setters of active and reactive stator currents. Other inputs of the phase-sensitive rectifiers unit are connected to outputs of a multiphase voltage source (cf. "Ustroystva i elementy system avtomaticheskogo regulirovaniya i upravleniya. Technicheskaya kibernetika", kniga 3, "Ispolnitelnye ustroystva i servomechanismy"/"Units and Components of Automatic Control Systems. Technical Cybernetics", Book 3, "Actuators and Servomechanisms"/, ed. by V. V. Solodovnikov, Machinostroyeniye Publishers, Moscow, 1976, pp. 266-271).
In this latter drive, signals of the active and reactive stator current setters are applied to the control inputs of the phase-sensitive rectifiers unit via the exciting circuit of the rotor position transmitter. However, this exciting circuit has a considerable time constant, which accounts for a relatively slow response of the drive and a low accuracy of controlling the torque of the output shaft. As a result, the drive under review is unable to ensure accurate travel of working members of machine tools.
It is an object of the present invention to provide an asynchronous motor drive with a reduced time lag of signals of the active and reactive stator current setters, wherefore, the drive would feature a faster response and a higher accuracy of controlling the torque, rotation speed and position of the output shaft.
SUMMARY OF THE INVENTION
The foregoing object is attained by providing an asynchronous motor drive comprising a transmitter of the rotor's position in the asynchronous motor whose stator windings are electrically connected via a controlled current source to outputs of a phase-sensitive rectifiers unit having its control inputs electrically connected to setters of active and reactive stator currents, other inputs of the phase-sensitive rectifiers unit being connected to outputs of a multiphase voltage source, the drive being characterized, according to the invention, in that it contains a phase converter connected to the output of the rotor position transmitter, two multipliers whose first inputs are connected to outputs of the phase converter, while their second inputs are connected to outputs of the active and reactive stator current setters, an adder connected with its inputs to outputs of the multipliers and with its output to the control inputs of the phase-sensitive rectifiers unit, a sinusoidal voltage former whose output is connected to the input of the rotor position
REFERENCES:
patent: 3465226 (1969-09-01), Sullivan
patent: 3593083 (1971-07-01), Blaschke
patent: 3805135 (1974-04-01), Blaschke
Russian-Engineering Cybernetics Ed. V. V. Solodovnikov.
Bai Roland D.
Brodovsky Vladimir N.
Chabanov Alim I.
Feldman Alexandr V.
Ivanov Evgeny S.
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