Wind Flutter Energy Converter for Wireless Sensor Networks

Methods for harvesting energy from the environment have been widely studied in recent years. Theoretically, these renewable environmental resources could provide endless energy to drive large batches of autonomous systems for applications. Renewable energy sources include solar radiation, wind or water flow, temperature differences, etc. Moreover, human motion, such as walking or arm-swinging, and machine/vehicle-induced vibrations can also provide adequate energy to power certain electronic devices.;"Flutter" is a phenomenon that describes the structural self-excited oscillation attributable to the positive feedback between elastic structures and aerodynamic forces. Flutter is always considered harmful in some engineering applications, such as bridge decks and airfoils, among others. However, flutter has also been proven effective for the extraction of energy from airflows, which is the focus of the current project.;In the present thesis, a novel energy converter using the aerodynamic principle known as flutter is discussed. The objective is to harvest energy from low-speed wind flows to power electronic applications, such as wireless sensor networks, outdoor lighting systems, etc. A systematic approach to optimize the efficiency of a low-speed wind energy conversion system, i.e., by providing a theoretical background to analyze and understand the entire energy transduction process, is presented.;Experimental results are also discussed to validate the theoretical formulation. The prototype device comprises four parts, namely, a) a wind-belt specifically designed to transform the wind flows into periodic mechanical vibrations; b) an electromagnetic resonant device with two coils fixed on a supportive housing and a permanent magnet inside a movable bolt acting as a piston; c) a power management circuit, which can store induced electrical energy into a super capacitor and provide an appropriate voltage level to support commercial electronic devices; and d) a wireless sensor node, which includes a microcontroller MSP430, a CC2500 wireless transceiver unit, and a temperature sensor. Typically ∼ 7 mW of electrical energy can be obtained at ∼3 m/s wind speed using a one-meter long belt. The capability of this generator as a driver for such a commercial wireless temperature sensor is demonstrated.