Electricity: motive power systems – Induction motor systems – Primary circuit control
Patent
1992-04-30
1994-03-15
Shoop, Jr., William M.
Electricity: motive power systems
Induction motor systems
Primary circuit control
318254, 318439, 318757, H02P 528
Patent
active
052948773
ABSTRACT:
A circuit for operating a polyphase dc motor includes first circuitry for determining when the back emf of the floating driving coils crosses zero. A first counter counts a time period between a first set of zero crossings, and a second counter is loaded with the count reached by the first counter. The second counter counts a time period between a subsequently occurring set of zero crossings. If the second counter reaches zero before the occurrence of a third zero crossing, a warning signal is generated. A method for determining if a deceleration rate of a polyphase dc motor exceeds a predetermined threshold includes measuring a first period between a first set of zero crossings of the back emf of the floating driving coils, and comparing the measurement of the first period with a subsequent period between a subsequent set of zero crossings. If the subsequent period is larger than the first period by a predetermined amount a warning signal is produced. The first period is measured by counting up from zero at a first predetermined rate from a first zero crossing until a second zero crossing occurs. The comparison of the measurement of the first period with a subsequent period is done by counting down at a second predetermined rate from the count reached in the up count when the second zero crossing occurred. And the warning signal is produced if the down count reaches a zero before a third zero crossing occurs.
REFERENCES:
patent: 4027215 (1977-05-01), Knight et al.
patent: 4104570 (1978-08-01), Hamby et al.
patent: 4642537 (1987-02-01), Young
patent: 5151642 (1992-08-01), Lombardi
Bachand Richard A.
Jorgenson Lisa K.
Martin David
Robinson Richard K.
SGS-Thomson Microelectronics Inc.
LandOfFree
Circuit and method for detecting deceleration rates of a polypha does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Circuit and method for detecting deceleration rates of a polypha, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Circuit and method for detecting deceleration rates of a polypha will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1538255