US3586948A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and an arrangement of controlling a dc motor on constant speed
Assignee: PER E C UDDEN
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Filing: 1968-10-25
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Granted: 1971-06-22
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Expires: 1988-10-25
Abstract
Abstract A speed control circuit, electrically in parallel with a controllable semiconductor, which is electrically in series with a DC motor, said control circuit including an RC circuit in which the capacitor, upon cutoff of said semiconductor, discharges through the resistor of said RC circuit with a discharge current which is proportional to the motor current just before cutoff until the voltage across the semiconductor has reached its stationary DC voltage value. The discharge current is caused to flow through the resistor of the RC circuit thereby causing a voltage drop, which is detected and stored in a capacitor. The difference between the maximum actual stored resistor voltage and a command voltage is applied to the controllable semiconductor means to govern the speed of the motor.
Inventors
- 👤 John Ingmar Broome
- 👤 Bert Hjalmar Engman
- 👤 Sven Nils Johannes Linnman
- 👤 Per E C Udden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 19:17
CPC Classifications
H; H02; H02P; H02P7/00; H02P7/06; H02P7/18; H02P7/24; H02P7/28; H02P7/285; H02P7/29; H02P7/2913; Y; Y10; Y10S; Y10S388/00; Y10S388/907; Y10S388/917
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
202 words
A control circuit for maintaining constant the speed of a DC motor which is subjected to varying loads by varying the time ratio between conducting and nonconducting periods of controllable semiconductor means in series with said motor comprising, detecting means to detect the motor current subsequent to said controllable semiconductor means being turned off, storage means to store a quantity related to the maximum value of said current detected by said detecting means, means for comparing said quantity with a command voltage corresponding to the desired speed of said motor and detecting the difference, and means for applying said difference to said controllable semiconductor means to vary the ratio between its conducting and nonconducting periods, wherein said detecting means includes RC circuit means electrically in parallel with said controllable semiconductor means, through which a current flows, when said controllable semiconductor means is turned off, which is proportional to motor current prior to the time said controllable semiconductOr means is turned off, and developing across resistance means included in said RC circuit means a voltage proportional thereto, and said storage means includes capacitance means connected to said resistance means to store the maximum instantaneous value of the voltage developed across said resistance means.
Claim 2
Dependent Claim
202 words
A control circuit for maintaining constant the speed of a DC motor which is subjected to varying loads by varying the time ratio between conducting and nonconducting periods of controllable semiconductor means in series with said motor comprising, detecting means to detect the motor current subsequent to said controllable semiconductor means being turned off, storage means to store a quantity related to the maximum value of said current detected by said detecting means, means for comparing said quantity with a command voltage corresponding to the desired speed of said motor and detecting the difference, and means for applying said difference to said controllable semiconductor means to vary the ratio between its conducting and nonconducting periods, wherein said detecting means includes RC circuit means electrically in parallel with said controllable semiconductor means, through which a current flows, when said controllable semiconductor means is turned off, which is proportional to motor current prior to the time said controllable semiconductOr means is turned off, and developing across resistance means included in said RC circuit means a voltage proportional thereto, and said storage means includes capacitance means connected to said resistance means to store the maximum instantaneous value of the voltage developed across said resistance means.
Claim 3
Dependent Claim
54 words
A circuit according to claim 1 which further includes second R circuit means, also electrically in parallel with said RC semiconductor means, with a time constant proportional to the time constant of said motor, capacitance means included in said second RC circuit means being connected to said means for comparing through said storage means.
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) | 1974-06-21 | 1974-12-21 | 1975-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-06-21 | 1978-12-21 | 1979-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-06-21 | 1982-12-21 | 1983-06-22 | $7700.00 | Window Closed / Lapsed |