3:00 PM on Friday, November 16, 2012
Location: Whittemore 457
Dr. Ha will be the speaker.
Vibration energy abundant in nature such as human motions, industry machines, and automobiles is wideband and is a viable choice to power wireless sensor nodes. The most popular transducers for vibration energy harvesting are Piezoelectric (PZT) (lead, zicronate, and titanate) cantilevers, which offer high energy density, good scalability, and are available in various shapes. Vibration energy harvesting based on PZT cantilevers needs maximum power point tracking (MPPT) to maximize the power transfer. We present our power management circuit (PMC), which implements an MPPT algorithm to match the source resistance dynamically. Our PMC is low power, but the efficiency drops sharply at off resonant frequencies and is not suitable for wideband vibration energy harvesting. To address the problem, we investigated a variation of complex conjugate matching, which is tailored for wide bandwidth vibration energy. We present the method and simulation results.
Dong Ha received a B.S. degree in electrical engineering from Seoul National University, Korea, and M.S. and Ph.D. degrees in electrical and computer engineering from the University of Iowa, in 1984 and 1986, respectively. Since fall 1986, he has been a faculty member of the Department of Electrical and Computer Engineering, Virginia Tech. Currently, he is Professor and Director of Multifunctional Integrated Circuits and Systems (MICS) group. His group conducts research in power management circuits for energy harvesting, wireless motion sensors, a transceiver for high speed fiber optic communications, and high temperature RF ICs. He is a Fellow of the IEEE.