US3764872A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Stabilizing means for an a-c motor drive
Assignee: General Electric Co
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Filing: 1972-06-13
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Granted: 1973-10-09
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Expires: 1992-06-13
Abstract
Abstract An a-c adjustable speed motor drive system including an a-c motor and power conversion means for converting d-c electric power to adjustable frequency, adjustable voltage electric power for delivery to the motor is provided with stabilizing means for damping motor speed oscillations. The stabilizing means includes apparatus for generating a signal proportional to the component of actual motor current that is in phase with the motor voltage and feedback means responsive to the in-phase signal for generating a stabilizing signal proportional to and phase shifted with respect to oscillations in the in-phase signal related to motor speed oscillations. The stabilizing signal is supplied to and utilized by the control apparatus for the power conversion means to adjust either the output frequency or the output voltage of the power conversion means. The feedback means includes resistive and capacitive elements connected in series between the in-phase signal generating apparatus and the control apparatus.
Inventors
- 👤 Boice W Knight
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 06:58
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/08
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
311 words
A control signal generating apparatus for damping motor speed oscillations in an a-c adjustable speed motor drive system wherein said system includes a polyphase a-c motor, power conversion means for changing unidirectional electric power to polyphase power adjustabLe in frequency and voltage for application as drive current to said a-c motor, and control apparatus including frequency control means and voltage control means responsive to control signals generated by said control signal generating apparatus for respectively controlling the frequency and voltage of the polyphase power produced by said power conversion means, said control signal generating apparatus comprising: a. detector means, operative during delivery of polyphase power to said a-c motor by said power conversion means, for generating a phase signal proportional to the polyphase current applied to said a-c motor by said power conversion means which is in phase with the output voltage of said power conversion means; b. first feeback means coupled to said detector means and receiving therefrom said phase signal and further coupled to said voltage control means of said control apparatus for providing to said voltage control means an IR compensation signal proportional to said phase signal as a one of said control signals while said a-c motor is operating at a substantially steady speed; and c. second feedback means coupled to said detector means and receiving therefrom said phase signal, said second feedback means responsive to variations in said phase signal to produce a stabilizing signal, as another one of said control signals, and having variations therein proportional to and shifted in phase with respect to variations in said phase signal while the speed of said a-c motor is oscillating about a specified steady state speed, said second feedback means further being coupled to a selected one of said frequency control means and said voltage control means of said control apparatus for supplying said stabilizing signal thereto.
Claim 2
Dependent Claim
311 words
A control signal generating apparatus for damping motor speed oscillations in an a-c adjustable speed motor drive system wherein said system includes a polyphase a-c motor, power conversion means for changing unidirectional electric power to polyphase power adjustabLe in frequency and voltage for application as drive current to said a-c motor, and control apparatus including frequency control means and voltage control means responsive to control signals generated by said control signal generating apparatus for respectively controlling the frequency and voltage of the polyphase power produced by said power conversion means, said control signal generating apparatus comprising: a. detector means, operative during delivery of polyphase power to said a-c motor by said power conversion means, for generating a phase signal proportional to the polyphase current applied to said a-c motor by said power conversion means which is in phase with the output voltage of said power conversion means; b. first feeback means coupled to said detector means and receiving therefrom said phase signal and further coupled to said voltage control means of said control apparatus for providing to said voltage control means an IR compensation signal proportional to said phase signal as a one of said control signals while said a-c motor is operating at a substantially steady speed; and c. second feedback means coupled to said detector means and receiving therefrom said phase signal, said second feedback means responsive to variations in said phase signal to produce a stabilizing signal, as another one of said control signals, and having variations therein proportional to and shifted in phase with respect to variations in said phase signal while the speed of said a-c motor is oscillating about a specified steady state speed, said second feedback means further being coupled to a selected one of said frequency control means and said voltage control means of said control apparatus for supplying said stabilizing signal thereto.
Claim 3
Dependent Claim
44 words
A control signal generating apparatus as defined by claim 1 in which said second feedback means comprises capacitive and resistive elements connected in series whereby said stabilizing signal produced by said second feedback means in response to said phase signal, leads said phase signal.
Claim 4
Dependent Claim
68 words
A control signal generating apparatus as defined by claim 1 in which said stabilizing signal, produced by said second feedback means, is coupled to said voltage control means and in which said second feedback means provides a gain such that said stabilizing signal causes an increase in the voltage of the polyphase power produced by said power conversion means in response to an increase in said phase signal.
Claim 5
Dependent Claim
68 words
A control signal generating apparatus as defined by claim 1 in which said stabilizing signal, produced by said second feedback means, is coupled to said frequency control means and in which said second feedback means provides a gain such that said stabilizing signal causes a decrease in the frequency of the polyphase power produced by the power conversion means in response to an increase in said phase signal.
Claim 6
Dependent Claim
34 words
A control signal generating apparatus as defined by claim 1 further comprising means for attenuating operation of said first feedback means during the occurrence of motor speed oscillations about a steady state motor speed.
Claim 7
Dependent Claim
38 words
A control signal generating apparatus as defined by claim 1 in which said stabilizing signal, produced by said second feedback means, is coupled to only the selected one of said frequency control means and said voltage control means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-10-08 | 1977-04-09 | 1977-10-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-08 | 1981-04-09 | 1981-10-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-08 | 1985-04-09 | 1985-10-09 | $7700.00 | Window Closed / Lapsed |