Field weakening system for pulse-controlled three-terminal d.c. motor
Abstract
Abstract A pulse control circuit for a d.c. series motor having an armature and two oppositely-wound field windings, comprises two semiconductor static switching devices, such as thyristors, each connected in series with the armature and a respective one of the field windings, control means for varying the mark-to-space ratio of conduction of each switching device thereby to vary the mean voltage applied to the motor, one or other of the switching devices being brought into operation to energize the associated field winding in dependence on the desired direction of drive of the armature. The control means is adapted, when the mark-to-space ratio of one of the static switching devices has been brought to a predetermined maximum value, to cause simultaneous operation of the other static switching device at a lower mark-to-space ratio thereby to energize the associated field winding so as to reduce the net flux in the motor and further increase the motor speed.
Inventors
- 👤 Albert E. Sloan
Bibliographic Details
Claims Analysis
Total Claims: 6References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1986-05-23 | 1986-11-22 | 1987-05-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1990-05-23 | 1990-11-22 | 1991-05-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1994-05-23 | 1994-11-22 | 1995-05-24 | $7700.00 | Window Closed / Lapsed |