What is Power Factor Correction and what are the tradeoffs in the various approaches to implementing it?
by Steve Mappus, Systems Engineer, Fairchild Semiconductor Corp, Planet Analog , Planet Analog, Aug 03 2009
Focus:
Different approaches to active power factor correction (PFC) are explained and compared,
helping engineers to understand which method suits a particular application. Article defines
basic concepts such as power factor and current harmonic distortion, and the relationship
between the two. Motivations for implementing PFC are described including regulations such as
EN61000-3-2, which imposes harmonic current limits for equipment sold in Europe, and IEEE 519,
a standard applicable in the U.S. A popular circuit for active PFC, the nonisolated boost
converter, is described along with its three modes of operation---continuous conduction mode
(CCM), discontinuous conduction mode (DCM) and boundary conduction mode (BCM) (also known as
critical conduction mode (CRM)). The pros and cons of CCM and BCM PFC are discussed with
respect to different power levels, and interleaved BCM is discussed as a means of extending BCM
benefits to higher power levels. Fairchild's various PFC controllers are presented.
What you’ll learn:
- How to understand the pros and cons of CCM versus BCM versus interleaved BCM operation for PFC boost converters
- How to understand the basic concepts regarding power factor correction
- How to select a control technique for implementing active PFC
Notes:
Article also has the title "Got PFC?: Understanding Power Factor Correction and the tradeoffs in
the various approaches to implementing it."
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