US3819992A
Expired / Lapsed
US
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Method and apparatus for providing efficient and stable power inversion with voltage and frequency control
Assignee: POWER CONTROL CORP
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Filing: 1972-01-21
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Granted: 1974-06-25
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Expires: 1992-01-21
Abstract
Abstract Three-phase pulse width modulated inverters are operated to drive an alternating current motor under varying frequency and voltage conditions. The modulated pulse rate is varied to maintain smooth motor control at low frequencies. Provision is made for automatic switching to a current minimization operation after start-up for constant load conditions and automatic switching is provided to change the modulated pulse mode when predetermined voltage limits of the inverters are exceeded.
Inventors
- 👤 K Opal
- 👤 C Kelly
- 👤 C Newcamp
- 👤 R Pietkiewicz
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 04:12
CPC Classifications
H; H02; H02P; H02P27/00; H02P27/04; H02P27/06; H02P27/08; H02P27/047
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
138 words
A power control system comprising first means for translating a motor speed input reference into a ramp frequency output signal and a voltage reference, said first means including means for generating a switch signal when the ramped frequency reference corresponds to the motor speed reference; second means responsive to the switching signal and to a representation of motor current for varying the inital voltage reference to minimize the motor Current; third means responsive to a representation of desired output frequency produced by said first means for producing variable frequency mode control signal and a gating pulse series; fourth means for modulating the gating pulse series appropriate to the frequency mode control of said third means for producing modulated pulses; and fifth means coupled to said third and fourth means for producing three-phase modulated pulse signals for the motor.
Claim 2
Dependent Claim
138 words
A power control system comprising first means for translating a motor speed input reference into a ramp frequency output signal and a voltage reference, said first means including means for generating a switch signal when the ramped frequency reference corresponds to the motor speed reference; second means responsive to the switching signal and to a representation of motor current for varying the inital voltage reference to minimize the motor Current; third means responsive to a representation of desired output frequency produced by said first means for producing variable frequency mode control signal and a gating pulse series; fourth means for modulating the gating pulse series appropriate to the frequency mode control of said third means for producing modulated pulses; and fifth means coupled to said third and fourth means for producing three-phase modulated pulse signals for the motor.
Claim 3
Dependent Claim
27 words
The motor control system of claim 1 wherein said fifth means includes logic circuits for limiting the minimum and maximum pulse widths of the modulated pulse series.
Claim 4
Dependent Claim
36 words
The motor control system of claim 1 wherein said fifth means includes logic circuits for detecting a possible voltage overload condition and responds to this detection by reducing the pulse rate of the modulated pulses accordingly.
Claim 5
Independent Claim
77 words
A method of three-phase motor control comprising generating variable pulse rate series of gating pulses corresponding to different output frequencies, respectively; translating the lowest pulse rate into three-phase control signals; producing six-phase inverter gate signals in response to the three-phase control signal and to the variable pulse rate modulated pulses having widths corresponding to voltage output; and limiting the minimum and maximum widths of the modulated pulses to insure proper commutated inversion to produce motor drive signals.
Claim 6
Independent Claim
77 words
A method of three-phase motor control comprising generating variable pulse rate series of gating pulses corresponding to different output frequencies, respectively; translating the lowest pulse rate into three-phase control signals; producing six-phase inverter gate signals in response to the three-phase control signal and to the variable pulse rate modulated pulses having widths corresponding to voltage output; and limiting the minimum and maximum widths of the modulated pulses to insure proper commutated inversion to produce motor drive signals.
Claim 7
Dependent Claim
22 words
The method defined in claim 4 wherein the voltage output reference is produced by current minimization control sensitive to measured motor current.
Claim 8
Dependent Claim
23 words
The method defined in claim 4 wherein pulse width modulation is referenced to the effective center of the pulse rate variable gating pulses.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-06-24 | 1977-12-24 | 1978-06-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-06-24 | 1981-12-24 | 1982-06-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-06-24 | 1985-12-24 | 1986-06-25 | $7700.00 | Window Closed / Lapsed |