Electricity: motive power systems – Induction motor systems – Power-factor control
Patent
1989-12-26
1991-04-16
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Power-factor control
318805, 318812, H02P 540
Patent
active
050086081
ABSTRACT:
A three-phase motor is operated by a controller having sets of thyristors which trigger electricity from each phase of a supply to the motor. The controller measures the interval .phi. between the voltage and the current when one phase of the motor makes a zero crossing and measures the interval .gamma. when the thyristors are non-conductive during a half-cycle of the voltage for one phase. A control angle .theta. is calculated according to the equation .theta.=.phi.+K.gamma., where K is a positive number. The control angle .theta. is compared to a reference value to derive an error value. The times at which the thyristors are triggered is controlled in response to the error value. To start the motor, the reference value is gradually decreased to trigger the thyristors progressively earlier during each half cycle of the supply voltage. To stop the motor, the reference value is gradually increased to trigger the thyristors progressively later during each half cycle of the supply voltage.
REFERENCES:
patent: 4052648 (1977-10-01), Nola
patent: 4259845 (1981-04-01), Norbeck
patent: 4355274 (1982-10-01), Bourbeau
patent: 4417190 (1983-11-01), Nola
patent: 4439718 (1984-03-01), Nola
patent: 4447788 (1984-05-01), Mundt et al.
patent: 4459529 (1984-06-01), Johnson
patent: 4469998 (1984-09-01), Nola
patent: 4482853 (1984-11-01), Bhavsar
patent: 4489264 (1984-12-01), Dabney
patent: 4581568 (1986-04-01), Fitzpatrick et al.
patent: 4628241 (1986-12-01), Bristow et al.
patent: 4704570 (1987-11-01), Hopkins
patent: 4823066 (1989-04-01), Fujika et al.
Merrison John C.
Rowan Timothy M.
Unsworth Peter J.
Allen-Bradley Company Inc.
Cabeca John W.
Shoop Jr. William M.
LandOfFree
Controller for starting and stopping electric motors does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Controller for starting and stopping electric motors, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Controller for starting and stopping electric motors will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-423507