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Adaptive On-Time Control for PFC Light Load Efficiency Improvement
Case ID:
09-124
Web Published:
9/14/2012
Light load efficiency of a power factor correction circuit is improved by adaptive on-time control and providing for selection between a continuous conduction mode and a discontinuous conduction mode wherein the discontinuous conduction mode increases time between switching pulses controlling connection of a cyclically varying voltage to a filter/inductor that delivers a desired DC voltage and thus can greatly reduce the switching frequency at light loads where switching frequency related losses dominate efficiency. the mode for controlling switching is preferably selected for each switching pulse within a half cycle of the cyclically varying input voltage. A multi-phase embodiment allows cancellation of EMI noise at harmonics of the switching frequency and adaptive change of phase angle allows for cancellation of
dominant higher order harmonics as switching frequency is reduced.
Patent Information:
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Serial No.
Patent No.
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Category(s):
Electrical
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For Information, Contact:
Li Chen
Licensing Associate
Virginia Tech Intellectual Properties, Inc.
(540) 443-9217
lchen@vtip.org
Inventors:
Qian Li
Fred Lee
Ming Xu
Chuanyun Wang
Keywords:
Microelectronics