李泽元 教授
美国弗吉尼亚理工大学
美国工程院院士、中国工程院外籍院士、IEEE Fellow
报告题目：Powering the Next Generation of Processors

报告摘要：The advancement of microprocessors follows that of the Moore’s Law for more than 6 decades. Today’s graphic processor (GPU) is made of more than 60 billion transistors. GPUs are switching at a speed over GHz and consuming more than 1000 amperes with a current slew rate larger than 1000 A/μs. With such remarkable advancement, it also imposes a great challenge in the aspect of power delivery and management. Today’s processors are powered with scalable multi-phase buck converters, each buck is capable of delivering 40A current output. Therefore, over 25 such converters are required to deliver 1000A current to GPU. In addition, the switching speed of buck is limited to less than 1MHz, accompanying with transient responses several orders of magnitude lower than that of the processor. Consequently, a large amount of energy storage inductors and capacitors are utilized.
To overcome these issues, integrated magnetics with specific coupling arrangements are proposed to help accommodating the following desired features:1) Magnetic integration and field cancellation to reduce the volume, and 2) Inductors with such a nonlinear characteristic that they behave like large inductors so far as current ripple is concerned, while, during dynamic transients, they behave like small inductors thus enabling fast dynamic responses. This seemingly conflicting requirements are fulfilled establishing the “negative coupling” among them. This concept is further extended to large number of buck converters employed in a GPU.

报告人简介：Dr. Lee is a University Distinguished Professor Emeritus at Virginia Tech. He is a member of the U.S. National Academy of Engineering, U.S. National Academy of Inventors, an academician of Taiwan’s Academia Sinica, and a foreign member of the Chinese Academy of Engineering, China. Dr. Lee founded the Center for power electronics and led a program that encompasses research, technology development, educational outreach, industry collaboration, and technology transfer. To date, more than 230 companies worldwide have benefited from this industry partnership program. 
Dr. Lee has supervised to completion 92 Ph.D. and 93 M.S. students. He holds over 100 US patents, and has published over 330 journal articles and more than 760 refereed technical papers. His research interests include high-frequency power conversion, magnetics and EMI, distributed power systems, renewable energy, power quality, high-density electronics packaging and integration, and modeling and control. 
Dr. Lee is a recipient of the 2015 IEEE Medal in Power Engineering “for contributions to power electronics, especially high-frequency power conversion."