Electronic Interface for Hybrid Vibration Energy Harvester

Abstract

The utilization of energy from a low frequency vibrational source, as related to a walking human or a moving vehicle, for powering portable electronic devices is becoming a viable alternative to the conventional use of battery-powered devices. The Vibration Energy Harvester (VEH) has become a more intensely researched topic in the last two decades, as a means for effective conversion of vibrational energy into electrical energy. Increasing power output and power density reflect the achievements in the area of vibration energy harvesting. Further improvement in power density is feasible through an increase in harvester component efficiency. An alternative approach for achieving higher power density of harvesting systems is a combination of two different VEHs on one common platform (for example electromagnetic and piezoelectric). An issue with such hybrid systems, not yet addressed in the literature, is the collection of electrical energy output into a single load. At the moment, the current research in Hybrid Vibration Energy Harvesters (Hybrid VEH) involves two electrical loads, i.e., one load for the electromagnetic source and a separate load for the piezoelectric source. The research work of this dissertation is focused on impedance matching and voltage adjustment of coupled piezoelectric and electromagnetic harvesters delivering electrical power into a common load. Simulation results indicate that it is feasible to employ an impedance matching device such as a voltage multiplier circuit. The conducted experimental investigations verify the simulation study. The proposed use of the voltage multiplier may be applied for impedance matching and voltage adjustment of different transducers as reviewed in the dissertation.