Analysis, Design and implementation of Energy Harvesting Systems for Wireless Sensor Nodes.

Abstract

With the recent advances in wireless communication technologies, sensors and actuators and highly integrated microelectronics technologies, wireless sensor networks (WSNs) have gained worldwide attention to facilitate monitoring and controlling of physical environments from remote locations that could be difficult or dangerous-to-reach. WSNs represent a significant improvement over wired sensor networks with the elimination of the hard-wired communication cables and associated installation and maintenance costs. The possible use of WSNs for real-time information in all aspects of engineering systems are virtually endless, from intelligent building control to health-care systems, environmental control systems, etc. As electronic hardware circuitries become cheaper and smaller, more and more of these WSN applications are likely to emerge, particularly as these miniaturized wireless sensor nodes offer the opportunity for electronic systems to be embedded unobtrusively into everyday objects to attain a ?deploy and forget? scenario.

The major hindrances of the "deploy and forget? nature of the WSNs are the limited energy capacity and unpredictable lifetime performance of the battery. In order to overcome these problems, energy harvesting/scavenging, which harvests/scavenges energy from a variety of ambient energy sources and converts into electrical energy to recharge the batteries, has emerged as a promising technology. With the significant advancement in microelectronics, the energy and therefore the power requirement for sensor nodes continues to decrease from few mWs to few tens of ?W level. This thesis presents a paradigm shift from a battery-operated conventional wireless sensor network (WSN) towards a truly self-autonomous and sustainable energy harvesting wireless sensor network (EH-WSN). In the EH-WSN, various types of energy harvesting (EH) systems and their respective main components viz. energy harvester (source), power management circuit, energy storage device and wireless sensor node (load) have been investigated and analyzed. EH systems, based on wind energy harvesting, thermal energy harvesting, vibration energy harvesting, solar energy harvesting, hybrid energy harvesting and magnetic energy harvesting, are designed in this dissertation to suit the target applications viz. ambient conditions and event/task requirements and then implemented into hardware prototypes for proof of concept. To optimize these EH systems, several different types of power-electronic based management circuits such as AC-DC active rectifier, DC-DC converter with maximum power point tracking, energy storage and latching circuit, etc. have been introduced.