16-01-2012, 03:31 PM
Residential Piezoelectric Energy Sources
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Technical Overview
Piezoelectric materials exhibit the unique property known as the piezoelectric effect. When these materials are subjected to a compressive or tensile stress, an electric field is generated across the material, creating a voltage gradient and a subsequent current flow. This effect stems from the asymmetric nature of their unit cell when a stress is applied. As seen in Figure 1, the unit cell contains a small positively charges particle in the center. When a stress is applied this particle becomes shifted in one direction which creates a charge distribution, and subsequent electric field.
Application to Residential
There are several ways to incorporate piezoelectric technology into a residential setting. The first would be to use small piezoelectric sources in the place of batteries. These piezoelectric sources could be used to power sensors throughout the house so that the batteries would never need to be changed. Another application was one proposed by Dr. Rob Clark and Dr. Henri Gavin. Their idea was to use piezoelectric materials to cancel out vibrations in certain household appliances.
Simulation Results
In my physics 171L class for my final project I modeled a circuit I found in a book in the simulation program PSpice. The circuit used a piezoelectric transducer as the voltage source which than fed into an op amp. The purpose of the circuit was to provide a voltage gain of 100. Our simulation results proved that the op amp did in fact multiply the voltage from the piezo-transducer by a factor of 100. Unfortunately, in the program we could not find an actual piezo-transducer so we had to model it with an ideal voltage source with an estimated equivalent Thevenin resistance
Future Direction
The next step would be to team up with Dr. Gavin and work with the energy harvesting setup he has. Once you understood the fundamentals of it, you could model some of your own circuits on a simulation program. Right now the most likely simulation to use would be Ansys.
