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Title: Precision electronic speed controller for an alternating-current motor

Abstract

A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. The motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The speed error signal is generated by a novel vernier-logic circuit which is drift-free and highly sensitive to small speed changes. The phase error is also computed by digital logic, with adjustable sensitivity around a 0 mid-scale value. The drift error signal, generated by long-term counting of the phase error, is used to compensate for any slowmore » changes in the average friction drag on the motor. An auxillary drift-byte status sensor prevents any disruptive overflow or underflow of the drift-error counter. An adjustable clocked-delay unit is inserted between the controller and the source of the reference pulse train to permit phase alignment of the rotor to any desired offset angle. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of read-only memories, and a pair of digital-to-analog converters.« less

Inventors:
OSTI Identifier:
5302927
Application Number:
ON: DE84005997
Assignee:
EDB-84-030758
DOE Contract Number:  
W-7405-ENG-36
Resource Type:
Patent
Country of Publication:
United States
Language:
English
Subject:
42 ENGINEERING; 73 NUCLEAR PHYSICS AND RADIATION PHYSICS; ELECTRIC MOTORS; SPEED REGULATORS; DESIGN; LOGIC CIRCUITS; AMPLIFIERS; DIGITAL-TO-ANALOG CONVERTERS; MEMORY DEVICES; TIMING CIRCUITS; CONTROL EQUIPMENT; ELECTRONIC CIRCUITS; ELECTRONIC EQUIPMENT; EQUIPMENT; MOTORS; 420800* - Engineering- Electronic Circuits & Devices- (-1989); 651100 - Nuclear Physics- Experimental Techniques- (1980-)

Citation Formats

Bolie, V W. Precision electronic speed controller for an alternating-current motor. United States: N. p., Web.
Bolie, V W. Precision electronic speed controller for an alternating-current motor. United States.
Bolie, V W. . "Precision electronic speed controller for an alternating-current motor". United States.
@article{osti_5302927,
title = {Precision electronic speed controller for an alternating-current motor},
author = {Bolie, V W},
abstractNote = {A high precision controller for an alternating-current multi-phase electrical motor that is subject to a large inertial load. The controller was developed for controlling, in a neutron chopper system, a heavy spinning rotor that must be rotated in phase-locked synchronism with a reference pulse train that is representative of an ac power supply signal having a meandering line frequency. The controller includes a shaft revolution sensor which provides a feedback pulse train representative of the actual speed of the motor. An internal digital timing signal generator provides a reference signal which is compared with the feedback signal in a computing unit to provide a motor control signal. The motor control signal is a weighted linear sum of a speed error voltage, a phase error voltage, and a drift error voltage, each of which is computed anew with each revolution of the motor shaft. The speed error signal is generated by a novel vernier-logic circuit which is drift-free and highly sensitive to small speed changes. The phase error is also computed by digital logic, with adjustable sensitivity around a 0 mid-scale value. The drift error signal, generated by long-term counting of the phase error, is used to compensate for any slow changes in the average friction drag on the motor. An auxillary drift-byte status sensor prevents any disruptive overflow or underflow of the drift-error counter. An adjustable clocked-delay unit is inserted between the controller and the source of the reference pulse train to permit phase alignment of the rotor to any desired offset angle. The stator windings of the motor are driven by two amplifiers which are provided with input signals having the proper quadrature relationship by an exciter unit consisting of a voltage controlled oscillator, a binary counter, a pair of read-only memories, and a pair of digital-to-analog converters.},
doi = {},
journal = {},
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place = {United States},
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}