Patent US3896356A successfully refreshed from Google Patents.
US3896356A
Expired / Lapsed
US
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Method and control system for improved stability of an induction motor via independent voltage, synchronous frequency, and slip frequency control at an operating point
Assignee: General Electric Co
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Filing: 1974-06-05
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Granted: 1975-07-22
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Expires: 1994-06-05
Abstract
Abstract The invention relates to a method and control system to improve stability of an induction motor by means of regulating, independently, the voltage, the synchronous frequency applied to the motor and the slip frequency of the motor. The system applies a voltage to the motor at a synchronous frequency and at a magnitude derived from an error signal indicative of the differences between a desired rotor speed or position and the true rotor speed or position. The synchronous frequency as determined by this control system is the sum of a desired slip frequency and a desired rotor frequency.
Inventors
- 👤 Robert E Hoffman
- 👤 John A Cline
- 👤 Christopher S Fuselier
- 👤 Atre John D D
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:51
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/08; H02P27/045; H02P27/048; H02P2207/00; H02P2207/01; H02P27/047
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
173 words
In a system for controlling a motor having a stator and a rotor for stable operation over a wide range of rotor speeds wherein motor control is effected by control of the amplitude and frequency components of the drive voltage applied to the motor, apparatus for control of the motor slip freqUency comprising the combination of independent: a. means for variation of the voltage amplitude responsive to a function of the algebraic sum of the commanded and actual rotor speeds; and b. means for variation of the frequency of the said voltage applied to said motor responsive to a function of the algebraic sum of said commanded rotor speed and the desired slip frequency; said means for variation being independent of each other and said means for variation of the frequency being independent of rotor speed whereby variation of said voltage amplitude will not cause a reactionary change in motor frequency and whereby the actual slip frequency of said motor is free to vary until true rotor speed approaches the desired rotor speed.
Claim 2
Dependent Claim
173 words
In a system for controlling a motor having a stator and a rotor for stable operation over a wide range of rotor speeds wherein motor control is effected by control of the amplitude and frequency components of the drive voltage applied to the motor, apparatus for control of the motor slip freqUency comprising the combination of independent: a. means for variation of the voltage amplitude responsive to a function of the algebraic sum of the commanded and actual rotor speeds; and b. means for variation of the frequency of the said voltage applied to said motor responsive to a function of the algebraic sum of said commanded rotor speed and the desired slip frequency; said means for variation being independent of each other and said means for variation of the frequency being independent of rotor speed whereby variation of said voltage amplitude will not cause a reactionary change in motor frequency and whereby the actual slip frequency of said motor is free to vary until true rotor speed approaches the desired rotor speed.
Claim 3
Dependent Claim
177 words
Apparatus for controlling the voltage applied to a motor having a stator and a rotor comprising: a. first electrical signal summing means for producing a rate error signal proportional to the difference between the true rotor speed and the desired rotor speed of the motor to be controlled; b. a second electrical signal summing means for producing a synchronous frequency signal proportional to the sum of the desired rotor speed and a desired slip frequency of the motor to be controlled; c. amplifier circuitry responsive to said first summing means for producing a magnitude signal proportional to a function of said error signal; and d. motor drive circuitry means responsive to said second electrical signal summing means and to said amplifier circuitry for applying an alternating voltage to said stator whose magnitude is proportional to the said magnitude signal and whose frequency is said synchronous frequency multiplied by the number of pole pairs of said rotor; whereby the actual slip frequency of said motor is free to vary until true rotor speed approaches the desired rotor speed.
Claim 4
Dependent Claim
177 words
Apparatus for controlling the voltage applied to a motor having a stator and a rotor comprising: a. first electrical signal summing means for producing a rate error signal proportional to the difference between the true rotor speed and the desired rotor speed of the motor to be controlled; b. a second electrical signal summing means for producing a synchronous frequency signal proportional to the sum of the desired rotor speed and a desired slip frequency of the motor to be controlled; c. amplifier circuitry responsive to said first summing means for producing a magnitude signal proportional to a function of said error signal; and d. motor drive circuitry means responsive to said second electrical signal summing means and to said amplifier circuitry for applying an alternating voltage to said stator whose magnitude is proportional to the said magnitude signal and whose frequency is said synchronous frequency multiplied by the number of pole pairs of said rotor; whereby the actual slip frequency of said motor is free to vary until true rotor speed approaches the desired rotor speed.
Claim 5
Dependent Claim
44 words
amplifier means responsive to said rate error signal for producing said voltage amplitude signal as a signal proportional to a function of the rate error; whereby the actual slip frequency of said motor is permitted to fluctuate until said motor approaches its commanded rate.
Claim 6
Dependent Claim
44 words
amplifier means responsive to said rate error signal for producing said voltage amplitude signal as a signal proportional to a function of the rate error; whereby the actual slip frequency of said motor is permitted to fluctuate until said motor approaches its commanded rate.
Claim 7
Dependent Claim
6 words
a command slip frequency signal, and
Claim 8
Dependent Claim
6 words
a command slip frequency signal, and
Claim 9
Dependent Claim
51 words
second electronic amplifier means responsive to said first electronic amplifier means for amplifying said rate error signal for producing said magnitude signal; said frequency and voltage magnitude channel circuits being independent whereby the magnitude of the voltage applied to said stator can vary independently of the alternating frequency of that voltage.
Claim 10
Dependent Claim
51 words
second electronic amplifier means responsive to said first electronic amplifier means for amplifying said rate error signal for producing said magnitude signal; said frequency and voltage magnitude channel circuits being independent whereby the magnitude of the voltage applied to said stator can vary independently of the alternating frequency of that voltage.
Claim 11
Dependent Claim
67 words
second electronic amplifier means for receiving and amplifying said rate error signal according to a predetermined function; c. motor drive circuitry responsive to both said frequency and voltage magnitude channel circuits and to a source of electrical power for applying an alternating voltage to said stator, said alternating voltage having a magnitude proportional to said voltage magnitude signal and a frequency proportional to said synchronous frequency signal.
Claim 12
Dependent Claim
67 words
second electronic amplifier means for receiving and amplifying said rate error signal according to a predetermined function; c. motor drive circuitry responsive to both said frequency and voltage magnitude channel circuits and to a source of electrical power for applying an alternating voltage to said stator, said alternating voltage having a magnitude proportional to said voltage magnitude signal and a frequency proportional to said synchronous frequency signal.
Claim 13
Dependent Claim
82 words
an actual rate signal proportional to the rate of the rotor of said motor; b. a frequency control channel responsive to said command rate signal and to said command slip frequency for producing said frequency control signal, said frequency channel including means for summing said command signals to form said frequency control signal; and c. a voltage amplitude channel responsive to said command rate signal and to said actual rate signal for producing said voltage amplitude signal, said voltage amplitude channel including:
Claim 14
Dependent Claim
82 words
an actual rate signal proportional to the rate of the rotor of said motor; b. a frequency control channel responsive to said command rate signal and to said command slip frequency for producing said frequency control signal, said frequency channel including means for summing said command signals to form said frequency control signal; and c. a voltage amplitude channel responsive to said command rate signal and to said actual rate signal for producing said voltage amplitude signal, said voltage amplitude channel including:
Claim 15
Dependent Claim
33 words
The apparatus of claim 1 wherein said function of said error signal to which said magnitude signal is proportional is a function of said error signal and the integral of said error signal.
Claim 16
Dependent Claim
42 words
Apparatus for controlling the voltage of a motor having a stator and a rotor comprising: a. a frequency channel circuit for producing a synchronous frequency signal which is a function of the desired rotor rate and the desired motor slip frequency including:
Claim 17
Dependent Claim
42 words
Apparatus for controlling the voltage of a motor having a stator and a rotor comprising: a. a frequency channel circuit for producing a synchronous frequency signal which is a function of the desired rotor rate and the desired motor slip frequency including:
Claim 18
Dependent Claim
37 words
The apparatus of claim 4 wherein the predetermined function according to which the said second electronic amplifier means amplifies said rate error signal is a function of said error signal and the integral of said error signal.
Claim 19
Dependent Claim
83 words
In a motor control system having an induction motor, motor drive circuits producing a stator voltage of the type E sin N omega st and having means for producing a signal measuring the actual speed of the rotor of said motor, the combination comprising: a. a frequency channel circuit for producing and applying to said motor drive circuits a synchronous frequency signal which is proportionAl to the sum of the desired rotor rate and the desired slip frequency, said frequency channel circuit including:
Claim 20
Dependent Claim
83 words
In a motor control system having an induction motor, motor drive circuits producing a stator voltage of the type E sin N omega st and having means for producing a signal measuring the actual speed of the rotor of said motor, the combination comprising: a. a frequency channel circuit for producing and applying to said motor drive circuits a synchronous frequency signal which is proportionAl to the sum of the desired rotor rate and the desired slip frequency, said frequency channel circuit including:
Claim 21
Dependent Claim
55 words
The motor control system combination of claim 6 wherein said second electronic amplifier means for amplifying said rate error signal further comprises integrating and summing amplifier means responsive to said rate error signal for producing as an outupt the sum of the weighted rate error signal and the weighted integral of the rate error signal.
Claim 22
Dependent Claim
76 words
In a system for controlling a motor having a stator and a rotor including drive circuitry for applying a power voltage to said stator, said power voltage being controlled as to amplitude and frequency in response to voltage amplitude and frequency control signals, and including control circuitry responsive to motor performance and to command signals for producing said voltage amplitude and frequency control signals, the improvement wherein said control circuitry comprises: a. electronic means for supplying
Claim 23
Dependent Claim
76 words
In a system for controlling a motor having a stator and a rotor including drive circuitry for applying a power voltage to said stator, said power voltage being controlled as to amplitude and frequency in response to voltage amplitude and frequency control signals, and including control circuitry responsive to motor performance and to command signals for producing said voltage amplitude and frequency control signals, the improvement wherein said control circuitry comprises: a. electronic means for supplying
Claim 24
Dependent Claim
43 words
The improved motor control system of claim 8 wherein said amplifier means of said voltage amplitude channel further comprises integrating and summing amplifier means whereby said function is the sum of the weighted rate error and the weighted integral of the rate error.
References Cited (Backward Citations)
US3512067A
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US3372323A
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US3593083A
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US3700986A
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US3671831A
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US3675099A
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-07-21 | 1979-01-20 | 1979-07-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-07-21 | 1983-01-20 | 1983-07-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-07-21 | 1987-01-20 | 1987-07-22 | $7700.00 | Window Closed / Lapsed |