POWER HARVESTING

HUMAN AS POWER GENERATOR K.R.Sasitharan, UG Scholar, L.Vijay anand, Assistant professor, Dept. of EEE, Dept. of EEE, Erode Sengunthar Engineering College, Email:[email protected]. Erode Sengunthar Engineering College, Email:[email protected]. ABSTRACT In this paper, some of the short comings in the existing systems has been rectified. The advances have allowed numerous ways for power harvesting systems in practical applications in order to meet the power demand. The use of piezoelectric crystal is to generate electric output from surrounding vibrations. Piezoelectric materials have a crystalline structure that they can convert vibrations into electrical energy and is vice-versa. These materials have the ability to absorb mechanical energy from their surroundings, usually ambient vibration, and transform it into electrical energy that can be used to power other devices. The produced electrical energy from the piezoelectric crystal is very low in the order of 2-3volts and is initially stored in a 2v rechargeable battery through a charge controller ,since it is not possible to charge a 12V battery through crystal output . In order to increase the voltage, the boost converter circuit is used. The use of boost converter is to increase the level of voltage ranges about 12V and is stored in a 12V battery. In order to supply power to the load an inverter circuit is required by which the generated voltage is fed to the CFL lamp load .This project can be implemented in dense populated areas like railway station, bus stands etc where more amount of vibration energy will be obtained. In this paper, we discuss about many researches that has been performed in the area of power harvesting. I .Introduction Man has needed and used energy at an increasing rate for his purpose. Due to this a lot of energy resources have been exhausted and wasted. The utilization of waste energy of foot power with human locomotion is very much relevant for highly populated countries where the roads, railway stations, bus stands, temples, etc. The human bio-energy being wasted if it can be made possible for utilization it will be very useful energy sources. Walking is the most common activity in day to day life. While walking, the person loses energy to the surface in the form of vibration.This energy can be tapped and converted to electrical form. In this paper, piezoelectric crystals were used as a medium. These piezoelectric crystals convert the mechanical vibrations into electrical energy. II. Piezoelectric crystals: One of the most suitable method for obtaining the energy surrounding a system is achieved by using piezoelectric crystals. Piezoelectric crystals is one of small scale energy sources. The piezoelectric crystals are subjected to vibration they generate a very small voltage, commonly known as piezoelectricity. It has a crystalline structure that converts an applied vibration into an electrical energy .The piezoelectric effect exists in two properties: The first is the direct piezoelectric effect that describes the material’s ability to transform mechanical strain into electrical charge. The second form is the converse effect, which is the ability to convert an applied electrical potential into KEYWORDS: Power harvesting, Energy generation, Piezo-electric crystal Mechanical strain energy.. B. Dis-Continuous mode: Due to the vibrations, piezo-electric crystals generates the electrical power. The produced output voltage is in the form of AC. Then it can be converted to DC by passing it through Rectifier circuit. The converted DC voltage can be fed into Boost converter. Then it is shown in the fig.3. III .Boost converter A boost converter (step-up converter) is a power converter with an output DC voltage greater than its input DC voltage. It is a class of switching-mode power supply (SMPS) containing at least two semiconductor switches (a diode and a transistor) and at least one energy storage element. Filters made of capacitors (sometimes in combination with inductors) are normally added to the output of the converter to reduce output voltage ripple. The schematic for boost converter is shown in the fig.4 In the Off-state, the switch is open and the only path offered to inductor current is through the flywheel diode D, the capacitor C and the load R. This results in transferring the energy accumulated during the On-state into the capacitor. In some cases, the amount of energy required by the load is small enough to be transferred in a time smaller than the whole commutation period. In this case, the current through the inductor falls to zero during part of the period. IV.PWM BASED CIRCUIT MOSFET DRIVER The basic principle of a Boost converter consists of two Modes of operations: A. Continuous mode: In the On-state, the switch S (see fig.4) is closed , resulting in an increase in the inductor current. When a boost converter operates in continuous mode, the current through the inductor (IL) never falls to zero. Figure 4.1shows the typical waveforms of currents and voltages in a converter operating in this mode. IV. 1. PWM: Pulse-width modulation (PWM) of a signal or power source involves the modulation of its duty cycle, to either convey information over a communications channel or control the amount of power sent to a load. IV.2 Power delivery: PWM can be used to reduce the total amount of power delivered to a load without losses normally incurred when a power source is limited by resistive means. This is because the average power delivered is proportional to the modulation duty cycle. With a sufficiently high modulation rate, passive electronic filters can be used to smooth the pulse train and recover an average analog waveform. High frequency PWM power control systems are easily realizable with semiconductor switches. The discrete on/off states of the modulation are used to control the state of the switch(es) which correspondingly control the voltage across or current through the load. The major advantage of this system is the switches are either off and not conducting any current, or on and have (ideally) no voltage drop across them. The product of the current and the voltage at any given time defines the power dissipated by the switch, thus (ideally) no power is dissipated by the switch. Realistically, semiconductor switches such as MOSFETs or BJTs are non-ideal switches, but high efficiency controllers can still be built. using an electronic switch such as a triac). In this case the PWM duty cycle is defined by the frequency of the AC line voltage (50 Hz or 60 Hz depending on the country). These rather simple types of dimmers can be effectively used with inert (or relatively slow reacting) light sources such as incandescent lamps, for example, for which the additional modulation in supplied electrical energy which is caused by the dimmer causes only negligible additional fluctuations in the emitted light. Some other types of light sources such as light-emitting diodes (LEDs), however, turn on and off extremely rapidly and would perceivably flicker if supplied with low frequency drive voltages. Perceivable flicker effects from such rapid response light sources can be reduced by increasing the PWM frequency. If the light fluctuations are sufficiently rapid, the human visual system can no longer resolve them and the eye perceives the time average intensity without flicker. IV.3 Voltage Regulation: PWM is also used in efficient voltage regulators. By switching voltage to the load with the appropriate duty cycle, the output will approximate a voltage at the desired level. The switching noise is usually filtered with an inductor and a capacitor. One method measures the output voltage. When it is lower than the desired voltage, it turns on the switch. When the output voltage is above the desired voltage, it turns off the switch. IV.4 PERIPHERAL CONTROLLER(PIC) : PWM is also often used to control the supply of electrical power to another device such as in speed control of electric motors, volume control of Class D audio amplifiers or brightness control of light sources and many other power electronics applications. For example, light dimmers for home use employ a specific type of PWM control. Home use light dimmers typically include electronic circuitry which suppresses current flow during defined portions of each cycle of the AC line voltage. Adjusting the brightness of light emitted by a light source is then merely a matter of setting at what voltage (or phase) in the AC cycle the dimmer begins to provide electrical current to the light source (e.g. by INTERFACE The microcontroller that has been used for this paper is from PIC series. PIC microcontroller is the first RISC based microcontroller fabricated in CMOS (complementary metal oxide semiconductor) that uses separate bus for instruction and data allowing simultaneous access of program and data memory. The main advantage of CMOS and RISC combination is low power consumption resulting in a very small chip size with a small pin count. The main advantage of CMOS is that it has immunity to noise than other fabrication techniques. IV.6 IC voltage regulators Various microcontrollers offer different kinds of memories. EEPROM, EPROM, FLASH etc. are some of the memories of which FLASH is the most recently developed. Technology that is used in pic16F877(shown in fig 4.5)is flash technology, so that data is retained even when the power is switched off. Easy Programming and Erasing are other features of PIC 16F877.The PIC microcontroller is used here in order to generate the PWM required for the MOSFET driver circuit. Voltage regulators comprise a class of widely used ICs. Regulator IC units contain the circuitry for reference source, comparator amplifier, control device, and overload protection all in a single IC. IC units provide regulation of either a fixed positive voltage, a fixed negative voltage, or an adjustably set voltage. The regulators can be selected for operation with load currents from hundreds of milli amperes to tens of amperes, corresponding to power ratings from milli watts to tens of watts .A fixed three-terminal voltage regulator has an unregulated dc input voltage, Vi, applied to one input terminal, a regulated dc output voltage, Vo, from a second terminal, with the third terminal connected to ground. The series 78 regulators provide fixed positive regulated voltages from 5 to 24 volts. Similarly, the series 79 regulators provide fixed negative regulated voltages from 5 to 24 volts. IV.7 Inverter: IV.5 POWER SUPPLY Circuit Diagram Description: The power supply required for the microcontroller is obtained from the source and is regulated to +5V (shown in fig4.6.1)for the proper functioning of the microcontroller. this is achieved by means of using a regulator IC 7805.Similarly another voltage regulator IC is also necessary in order to regulate the boosted voltage to +12V(shown in fig4.6.2) which is the appropriate battery voltage. An AC load can be powered from a DC source by using a converter to change DC to AC. This circuit is designed for taking 230V AC from the 12V DC input(shown in fig 4.7). An AC load can be powered from a DC source by using a converter to change DC to AC. This is efficiently done through above circuit with the use of two transistors Q1 & Q2 and one Transformer (T). The wattage of output depends on these three equipments. A DC-to-AC inverter energized from a 12-volt DC input signal uses a single stage inverter circuit to produce a quasi-sine wave output signal. When we are giving 12v DC input to the circuit, initially it goes to diode D1 which is used to product reverse voltage. Then Q1 will conduct first, at that time we can get the positive cycle of 230v output in the output transformer side. It will prolong some seconds and gets saturated then Q2 will conduct this time. This switching makes the reverse polarity in the output side with constant 230v output. Then Q2 will conduct some seconds and gets saturated and Q1 will conduct. Likewise this switching makes alternating 230v output in the transformer output side. This will continue up to the input given to the circuit, which makes constant 230V AC output in the transformer side. The output voltage of the inverter is decided only in the transformer. While saying in briefly, DC to AC converters a direct current voltage is applied to a socalled half bridge with two power transistors connected in series. The power transistors are gated alternatively conducting and generate at their connection point an alternating voltage for the load. DC-to-AC voltage converters have many uses, such as the supply of power to gas discharge lamps or, after rectifying and smoothing the AC voltage, supplying power to electronic circuits, motors, relays, magnetic valves, magnetic clutches, etc. DC-to-AC power converters are often used in uninterruptible power supplies. V. BATTERY Cylindrical 18650 lithium iron phosphate cell before closing The three primary functional components of a lithium-ion battery are the negative electrode, positive electrode, and the electrolyte. The negative electrode of a conventional lithium-ion cell is made from carbon. The positive electrode is a metal oxide, and the electrolyte is a lithium salt in an organic solvent.[8] The electrochemical roles of the electrodes change between anode and cathode, depending on the direction of current flow through the cell. The most commercially popular negative electrode material is graphite. The positive electrode is generally one of three materials: a layered oxide (such as lithium cobalt oxide), a polyanion (such as lithium iron phosphate), or a spinel (such as lithium manganese oxide). The electrolyte is typically a mixture of organic carbonates such as ethylene carbonate or diethyl carbonate containing complexes of lithium ions. These non-aqueous electrolytes generally use non-coordinating anion salts such as lithium hexafluorophosphate (LiPF6), lithium hexafluoroarsenate monohydrate (LiAsF6), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), and lithium triflate (LiCF3SO3).Depending on materials choices, the voltage, capacity, life, and safety of a lithium-ion battery can change dramatically. Recently, novel architectures using nanotechnology have improve performance. been employed to 4.8 Lithium- Ion Battery Pure lithium is very reactive. It reacts vigorously with water to form lithium hydroxide and hydrogen gas. Thus, a nonaqueous electrolyte is typically used, and a sealed container rigidly excludes water from the battery pack .Lithium ion batteries are more expensive than Ni Cd batteries but operate over a wider temperature range with higher energy densities, while being smaller and lighter. They are fragile and so need a protective circuit to limit peak voltages. V.CONCLUSION: It has been concluded that by continuously stressing the crystal for two hours the voltage developed is enough to charge a mobile battery. By introducing prieto battery , a rechargeable battery made of nanotechnology the efficiency of this system has been improved. The boost converter improves the voltage effectively and power has been improved by enhancing the current gain using the TTL logic. This can be implemented in dense populated areas like railway stations, bus stands etc. References: [1].Energy Harvesting from Piezo-electric Materials Fully Integrated in Footwear, IEEE transactions on industrial electronics, vol. 57, no. 3, march 2010 [2]. Efficiency of energy conversion for a piezoelectric power harvesting system Y C Shu and I C Lien Institute of Applied Mechanics, National Taiwan University, Taipei 106, Taiwan, Republic of China.