US4288729A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Control system for D.C. electric motor
Assignee: Mitsubishi Electric Corp
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Filing: 1980-03-17
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Granted: 1981-09-08
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Expires: 2000-03-17
Abstract
Abstract A control system for a D.C. electric motor utilizing a Ward-Leonard rotation speed control system in which noise components in the input power to the motor are substantially eliminated. Switching means in the form of gate turning-off thyristors couples a delta-connected capacitance circuit to the input line to the motor between inductors coupled in series with each phase of the input line. Switching means is provided which is opened after a predetermined time delay from the firing time of the thyristor converter. The time delay is preferably approximately one-fourth of the system natural oscillation period.
Inventors
- 👤 Nobuo Anzai
- 👤 Eiki Watanabe
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 17:48
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/292; H02P7/293; Y; Y10; Y10S; Y10S388/00; Y10S388/907; Y10S388/917; Y10S388/921
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
66 words
A control system for D.C. electric motors comprising: a thyristor converter; a gate control circuit for controlling a firing point of said thyristor converter; capacitor means connected through resistor means to an input side of said thyristor converter; and switching means connected in parallel with said resistor means, said switching means being opened after a predetermined time delay from said firing point of said thyristor converter.
Claim 2
Dependent Claim
66 words
A control system for D.C. electric motors comprising: a thyristor converter; a gate control circuit for controlling a firing point of said thyristor converter; capacitor means connected through resistor means to an input side of said thyristor converter; and switching means connected in parallel with said resistor means, said switching means being opened after a predetermined time delay from said firing point of said thyristor converter.
Claim 3
Dependent Claim
38 words
The control system as defined in claim 1 wherein said predetermined time delay is approximately one-fourth of a system free oscillation period dependent on a reactance in the input side of said thyristor converter and said capacitance means.
Claim 4
Dependent Claim
19 words
The control system as defined in claim 1 or 2 wherein said switching means comprises a gate turning-off thyristor.
Claim 5
Dependent Claim
82 words
The control system as defined in either claim 1 or 2 wherein said thyristor converter is coupled to a three-phase power source, wherein said capacitor means comprises three-capacitors coupled in a delta configuration, and wherein said resistor means comprises three resistors, a first terminal of each of said resistors being connected to a corresponding junction point between said capacitors connected in said delta configuration a second terminal of each of said resistors being connected to a corresponding phase of the power source.
Claim 6
Dependent Claim
24 words
The control system as defined in either claim 1 or 2 wherein said switching means comprises a plurality of switching devices coupled in series.
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) | 1984-09-07 | 1985-03-09 | 1985-09-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-09-07 | 1989-03-09 | 1989-09-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-09-07 | 1993-03-09 | 1993-09-08 | $7700.00 | Window Closed / Lapsed |