CPES
Center for Power Electronics Systems
A National Science Foundation Engineering Research Center
Virginia Polytechnic Institute and State University
674 Whittemore Hall (0179)
Blacksburg, VA 24061
INTRODUCTION
The switching-mode power electronics systems generate significant conducted electromagnetic interference (EMI) in a broad spectrum. This EMI can be detrimental to the normal operation of other electronics systems. The EMI must be suppressed to an acceptable level before it can propagate to other systems. EMI noise is traditionally categorized as either differential mode (DM) or common mode (CM) noise. DM noise is the noise current flowing within the power delivery paths, while CM noise is the noise current flowing between the ground and the power circuits. EMI study is a very extensive field, while most of the nuggets in this publication address the study of the generation, mitigation, propagation, and measurement of either DM or CM noise in front-end converters. The topics studied in this publication are defined in the following:
1. Generation and characterization of DM noise
2. Characterization, parasitic reduction and cancellation for EMI filters
3. EMI propagation, separation and measurement
4. Generation and characterization of CM noise
5. CM noise reduction with balance and parasitic cancellation techniques
6. Active EMI filters
7. Integrated EMI filters with planar structure
The first two nuggets discuss the generation of DM noise and the effects of boost inductors on DM noise in a boost power factor correction (PFC) converter. The characterization,extraction and cancellation of the parasitic parameters in EMI filters are discussed from third to fourteenth nuggets. Nuggets fifteenth and sixteenth address the propagation, separation and measurement of EMI noise. The next two nuggets talk about the parasitic cancellation to reduce EMI. Nugget nineteenth discusses the grounding of the filter. Nugget twenty addresses active EMI filter. Nuggets twenty-one to twenty-six address the concept, implementation and advantages of using balance concept to suppress CM noise. Nuggets twenty-seven to thirty-one address the implementation, and passive integration (including an EMI filter) of HID ballast.
Dr. Shuo Wang and Dr. Fred C. Lee
Center for Power Electronics Systems
Virginia Tech
April, 2008