Mar 7, 2011

APEC: Day 2

Day 2 of APEC was far more technical and involved then Day 1. In the morning session, I attended “The Dark Side of Flyback Converters” presented by Christophe Basso. Basso is a French power electronics engineer who has written at least one book. When I was doing my senior design project, I used his book on simulating switch-mode power supplies in PSPICE to generate my transient and frequency response curves. As luck would have it, I was designing a flyback converter supply for the Alienware MX11 gaming laptop which, at that time, had not yet come on the market. Flyback converters are the most common DC-DC topology on the commercial market. About 85% of the power supplies from consumer products use flyback converters because they use the fewest components and are therefore the cheapest solution.

Basso’s talk covered many of the subjects I had read about in his book so I was already familiar with most of it. His discussion of control loops took the basic concepts and went into the fine design and mathematic details. Overall, it was a very enjoyable talk with some dry moments.

After the morning session and lunch, the opening plenary session took place from 1:30 – 5:30 pm. The very first speaker was Slobadon Cuk, a legend in the power electronics community. Dr. Cuk was a student of Dr. Middlebrook, the “alpha” of power electronics. He unfortunately passed away this past year so there was a moment of silence to honor his memory before Cuk began his talk. Cuk himself received his PhD from Caltech and created his own converter topology, known as the Cuk converter. My power electronics professor in college, Dr. Khai Ngo, was once a student of Cuk’s at Caltech so his reach is pretty widespread.

Another notable presenter was Dr. Dushan Boroyevich, president of the IEEE Power Electronics Society and research professor at Virginia Tech’s Center for Power Electronics Systems (CPES). He discussed the implementation of “microgrids” in the United States. The idea is very intriguing because it means a complete revolution of the current power grid. This is actually a subject I will explore in depth in a future blog post, but basically each building in the United States could essentially be its own grid using high and low voltage DC rails. In the current grid design, high voltage AC gets transmitted across power lines to step-down transformers and is fed into the sockets in your house. For most consumer appliances and products, the AC is converted to DC to power the devices and power is lost in the translation. If you scale up these losses for nearly every device in your home, the losses add up. The CPES proposal is to set 1 high voltage and 1 low voltage bus through homes and building such that consumer products can be directly run off DC voltage or converted with DC-DC converters, which typically have higher efficiencies than AC-DC because the voltage does not need a rectification stage. Look for more details on this in future blogs.

I ended my day at the exhibition ballroom. Several companies dealing in power electronics showed up to hock their products to all the representatives. There wasn’t much for me to see since I am only a hobbyist engineer rather than a practicing engineer at the moment. One a sad note, the availability and quality of free stuff was lacking. I will make more trips back in the remaining days of the conference.

Tomorrow, some graduate student friends of mine in the CPES program at Virginia Tech are presenting their research papers so I am looking forward to hearing what they have to say.


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