INTERNATIONAL CONFERENCE ON CURRENT INNOVATIONS IN ENGINEERING AND TECHNOLOGY
ISBN: 378 - 26 - 138420 - 5
Electric power generation using piezoelectric crystal P.BALAJI NAGA YASHWANTH, GAUTHAM KUMAR MOKA, DONEPUDI JASHWANTH
ANIL NEERUKONDA INSTITUTE OF TECHNOLOGY AND SCIENCES
ABSTRACT
Key words: energy generation ,piezoelectric crystals
The usefulness of most high technology devices such as cell phones, computers, and sensors is limited by the storage capacity of batteries. In the future, these limitations will become more pronounced as the demand for wireless power outpaces battery development which is already nearly optimized. Thus, new power generation techniques are required for the next generation of wearable computers, wireless sensors, and autonomous systems to be feasible. Piezoelectric materials are excellent power generation devices because of their ability to couple mechanical and electrical properties. For example, when an electric field is applied to piezoelectric a strain is generated and the material is deformed. Consequently, when a piezoelectric is strained it produces an electric field; therefore, piezoelectric materials can convert ambient vibration into electrical power. Piezoelectric materials have long been used as sensors and actuators; however their use as electrical generators is less established. A piezoelectric power generator has great potential for some remote applications such as in vivo sensors,embedded MEMS devices, and distributed networking. Developing piezoelectric generators is challenging because of their poor source characteristics (high voltage, low current, high impedance) and relatively low power output. This paper presents a theoretical analysis to increase the piezoelectric power generation that is verified with experimental results.
INTRODUCTION Mechanical stresses applied to piezoelectric materials distort internal dipole moments and generate electrical potentials (voltages) in direct proportion to the applied forces. These same crystalline materials also lengthen or shorten in direct proportion to the magnitude and polarity of applied electric fields. Because of these properties, these materials have long been used as sensors and actuators. One of the earliest practical applications of piezoelectric materials was the development of the first SONAR system in 1917 by Langevin who used quartz to transmit and receive ultrasonic waves. In 1921, Cady first proposed the use of quartz to control the resonant frequency of oscillators. Today, piezoelectric sensors (e.g., force, pressure, acceleration) and actuators (e.g., ultrasonic, micro positioning) are widely available. The same properties that make these materials useful for sensors can also be utilized to generate electricity. Such materials are capable of converting the mechanical energy of compression into electrical energy, but developing piezoelectric generators is challenging because of their poor source characteristics (high voltage, low current, high impedance). This is especially true at low frequencies and relatively low power output.
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INTERNATIONAL CONFERENCE ON CURRENT INNOVATIONS IN ENGINEERING AND TECHNOLOGY
ISBN: 378 - 26 - 138420 - 5
PIEZOELECTRIC CRYSTAL? The phenomenon of generation of a voltage under mechanical stress is referred to as the direct piezoelectric effect, and the mechanical strain produced in the crystal under electric stress is called the converse piezoelectric effect.
The effect is explained by the displacement of ions in crystals that have a nonsymmetrical unit cell When the crystal is compressed, the ions in each unit cell are displaced, causing the electric polarization of the unit cell. Because of the regularity of crystalline structure, these effects accumulate, causing the appearance of an electric potential difference between certain faces of the crystal. When an external electric field is applied to the crystal, the ions in each unit cell are displaced by electrostatic forces, resulting in the mechanical deformation of the whole crystal.
P = d x stress and E = strain/d Piezoelectricity, discovered by Curie brothers in 1880, originated from the Greek word “ piezenin ”, meaning, to press. MAKING •
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The piezoelectric axis is then the axis of polarization. If the polycrystalline material is poled as it is cooled through its curie point, the domains in the crystals are aligned in the direction of the strong electric field. In this way, a piezoelectric material of required size, shape and piezoelectric qualities can be made within limits. In a given crystal, the axis of polarization depends upon the type of stress. There is no crystal class in which the piezoelectric polarization is confined to a single axis. In several crystal classes, however, it is confined to a plane. Hydrostatic pressure produces a piezoelectric polarization in the crystals of those ten classes that show piezoelectricity, in addition to piezoelectricity.
displacement of electrical charge due to the deflection of the lattice in a naturally piezoelectric quartz crystal The larger circles represent silicon atoms, while the smaller ones represent oxygen. Quartz crystals is one of the most stable piezoelectric materials.
ARTIFICIAL MATERIALS polycrystalline, piezoceramics are man made materials which are forced to become piezoelectric by applying large electric field. high charge sensitivity
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materials available which operate at 1000 F (540 C) characteristics vary with temperature
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ISBN: 378 - 26 - 138420 - 5
This help in reducing ripple in the output waveform. Here the output voltage produced is 2 to 3 volts.
CONFIGURATION:
Red indicates the crystal Arrows indicate the direction of applied force the compression design features high rigidity, making it useful for implementation in high frequency pressure and force sensors. •
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FOOT STEP GENERATION:
The inverter circuit converts 12 v DC to 12 v AC . Now the obtained 12 v AC is connected to a step up transformer. Commercially available transformer to reach is 12 v AC to 220 v AC. Transformer step up 12 v AC to 220-230v AC. The obtained voltage can be used for many applications.
POWER
When a piezoelectric material is put under pressure it generates potential across the other end. This basic principal us used to produced electrical supply. •
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By the ouput obtained a 12v battery is charged . Now the output of 12 v battery is given to a inverter circuit.
The output obtained is a AC voltage. This is the passed through a rectifying circuit which converts AC to DC voltage. The output is connected to a rectifying circuit , which produce a pulsating dc.
APPLICATIONS: The above method can be employed in many ways like… 1.railway station. 2. malls in cities. 3. escalators. Etc
To obtain pure DC we connect a capacitor parallel to the load.
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The other applications where pressure can be employed are: 1. In vehicles tire 2. In runway 3. Industries 4. Ships 5. In drilling machines.
ISBN: 378 - 26 - 138420 - 5
[4]-Gaur and Gupta “Engineering Physics”crystal structure.[58.8]
CONCLUSION: As the results shows that by using double actuators in parallel we can reduce the charging time of the battery and increase the power generated by the piezoelectric device. In second research where a piezoelectric generator was put to the test and generated some 2,000 watt-hours of electricity. The setup consists of a ten-meter strip of asphalt, with generators lying underneath, and batteries in the road’s proximity. So that it is clear by using parallel combination we can overcome the problems like of impedance matching and low power generation. The results clearly show that piezoelectric materials are the future of electric power generation.
Reference: [1]- “Piezoelectric Plate’s and Buzzers”, Oct. 17, 2009. [Online]. Available: http://jingfengele.en.alibaba.com/product/50 91700650159415/Piezoelectric_Buzzer_Plates.html [Accessed: Oct.17, 2009]. [2]- Anil Kumar(2011) „Electrical Power Generation Using Piezoelectric Crystal‟International Journal of Scientific & Engineering Research- Volume 2, Issue 5, May-2011. [3]- www.BEProjectReport.com
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