Literature review about piezoelectric electronic circuit Research Paper

Literature review about piezoelectric electronic circuit (Rectification with an inductor and Buck DC-DC converter cuircuit) - Research Paper Example (Diamond, 2009) Much of its role in alternative energy and applications but first, what is piezoelectricity or, the piezoelectric effect? Wayne Tomasi (2004) defines the piezoelectric effect as generating electrical oscillations as varying mechanical stresses—either as, compression, tension, torsion or shearing, is applied across a crystal lattice structure (i.e. quartz, Rochelle salts, tourmaline, etc.) and vice versa. With this, ambient vibrations in and around systems which typically, are lost energy, can be captured and converted to usable energy, available for consumption—the primary goal of power harvesting; but since, as shown in research, the energy generated by piezoelectricity is insufficient to power most electronics, power harvesting technology has, mostly, focused on accumulation and storage techniques that would enable technology to collect enough energy for a variety of applications. (Sodano et al., 2005) In this premise, the researcher came up with a pro ject, entitled â€Å"Integrated Circuits for Energy Harvesting Application†, aiming to design and build a prototype circuit that utilizes piezoelectricity—via the PFCB-W14 piezoelectric device, for energizing small electronic systems, which in this case, is the charging of a Lithium-ion rechargeable battery—which have become very popular today. Figure 1. Equivalent Circuit and Power Generation of PFCB-W14 at 27Hz To better visualize the concept of piezoelectricity, illustrated above is an equivalent circuit of a piezoelectric generator—functioning as a capacitor and a resistor in series with the output terminals, as well as a bar chart of the power generation of Advanced Ceramics Incorporated PFCB-W14 at 27Hz, both obtained from PFCB-W14 Specifications Sheet. By closely looking into the chart, it can be seen that with load resistance in the range of 400k? to 600k?, at typical amounts of force applied, there is maximum power. And along the lines of impedan ce-matching, when the load and source impedances—in this case, the load and internal resistances, were equal, maximum power transfer occurs, an important point to consider in every circuit design. (Boylestad & Nashelsky, 1998) Also, note that the output of the generator is an ac voltage. Disregarding impedance-matching, rectifying the piezoelectric generator, and directly connecting the output to a capacitor or battery would have been a more straightforward approach for the project. Despite its simplicity and the fact that this circuit works, with the enormous mismatch between the resistances of the generator (in the order of millions) and the battery (merely in ohms, and at times even down to milliohms), basically all the power would be dissipated as heat in the generator itself. For a better implementation of the project, the circuit shown below was considered. Figure 2. Simple Charging Circuit using Inductor Illustrated above is a simple charging circuit that utilizes an i nductor, on top of piezoelectric generator, a rectifier bridge, a Zener diode and a Lithium battery that is being charged. Inductor Adding an inductor, as shown above, with sufficiently high reactance so as for the piezoelectric