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International Journal of Industrial Engineering & Technology (IJIET) ISSN 2277-4769 Vol. 3, Issue 3, Aug 2013, 55-66 © TJPRC Pvt. Ltd.

GREEN ENERGY HARVESTER BASED ON FREQUENCY CONVERSION METHOD S. SIVAKUMAR, P. SIVARAJ, K. BHASKAR, G. R. KARTHI & K. SENTHILKUMAR Department of Electrical Science, Veltech Dr. RR & Dr. SR Technical University, Chennai, Tamil Nadu, India

ABSTRACT This paper presents a new generation of Green energy being renewable can be generated in many industries where there is continuous source of vibrations. The cantilever beam is used as a source of vibration for power generation. MEMS sensor placed on the beam will convert the mechanical energy generated from the movement of the beam into electrical energy. The output of MEMS is given to the ADC for analog to digital conversion and then to microcontroller in order to monitor the value of energy generated. The obtained energy is boosted up using a DC-DC booster. The output of the DCDC booster is stored in a storage device. The obtained energy is used to power the low power electronic devices and wireless sensor nodes in industries. The voltage control is provided by the microcontroller.

KEYWORDS: Green Energy Scavenging, Cantilever Beam, MEMS, DC-DC Conversion, Microcontroller & Keil Compiler

INTRODUCTION This paper presents a novel method for energy harvesting and converting it to a useful form. Scavenging energy from the environment, also known as “energy harvesting”, is defined as the conversion of ambient energy into a usable electrical form. The collected energy from the environment is either sufficient to power a remote sensor or at least is able to extend the rechargeable battery lifetime. The energy generated is used to vibrate the cantilever beam which is connected with MEMS. Among available energy-harvesting methodologies, MEMS based approach was chosen because of abundant vibration accessibility and energy harvesting productivity. The obtained energy is boosted up using a DC-DC converter. The output of the DC-DC converter is stored in a storage device. The stored energy is inverted to AC voltage and is given through the relay and utilized for other purposes for lighting lamps for example. The voltage control is provided by the microcontroller. The advantages of this paper is low cost, robust, sufficient output to power the wireless sensor node, reduces system operating cost, reduces labor cost in industries for maintenance and replacement, environmentally friendly design, highly sensitive, easy to implement.

Figure 1: Basic Block Diagram Henry A.Sodano et al (1) carried out with the recent advances in wireless and Microelectro-Mechanical Systems (MEMS) technology, the demand for portable electronics and wireless sensors is growing rapidly. Because these devices


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S. Sivakumar, P. Sivaraj, K. Bhaskar, G. R. Karthi & K. Senthilkumar

are portable, it becomes necessary that they carry their own power supply. In most cases this power supply is the conventional battery; however, problems can occur when using batteries because of their finite lifespan. For portable electronics, replacing the battery is problematic because the electronics could die at any time and replacement of the battery can become a tedious task. In the case of wireless sensors, these devices can be placed in very remote locations such as structural sensors on a bridge or Global Positioning System (GPS) tracking devices on animals in the wild. When the battery is extinguished of all its power, the sensor must be retrieved and the battery replaced. Because of the remote placement of these devices, obtaining the sensor simply to replace the battery can become a very expensive task or even impossible. For in-stance, in civil infrastructure applications it is often desirable to embed the sensor, making battery replacement unfeasible. If ambient energy in the surrounding medium could be obtained, then it could be used to replace or charge the battery.

FUNDAMENTALS OF ENERGY HARVESTING Cantilever Beam A cantilever is a beam anchored at only one end. The beam carries the load to the support where it is resisted by moment and shear stress. Cantilever construction allows for overhanging structures without external bracing. Cantilevers can also be constructed with trusses or slabs. This is in contrast to a simply supported beam such as those found in a post and lintel system. A simply supported beam is supported at both ends with loads applied between the supports from Ozge Zorlu et al (2).

Figure 2: A Cantilever Beam Descriptions of Cantilever Beam A projecting structure, such as a beam, that is supported at one end and carries a load at the other end or along its length. A member, such as a beam, that projects beyond a fulcrum and is supported by a balancing member or a downward force behind the fulcrum. A linear structural member supported both transversely and rotationally at one end only; the other end of the member is free to deflect and rotate. Cantilevers are common throughout nature and engineered structures; examples are a bird's wing, an airplane wing, a roof overhang, and a balcony. A horizontal cantilever must be counter balanced at its one support against rotation. This requirement is simply achieved in the design of a playground seesaw, with its double-balanced cantilever. This principle of counterbalancing the cantilever is part of the basic design of a crane, such as a tower crane. More commonly, horizontal cantilevers are resisted by being continuous with a backup span that is supported at both ends. This design is common for cantilever bridges; all swing bridges or drawbridges are cantilevers. The applications of cantilever beams are Aircraft, Micro electro mechanical system & Pre stresses cantilever beams are present in buildings & bridges. MEMS Structure and Operation Principle 

Three Axis Accelerometer The MMA7361L is a low power, low profile capacitive micro machined accelerometer featuring signal


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conditioning, a 1-pole low pass filter, temperature compensation, self-test, 0g-Detect which detects linear freefall, and gSelect which allows for the selection between 2 sensitivities. Zero-g offset and sensitivity are factory set and require no external devices. The MMA7361L includes a Sleep Mode that makes it ideal for handheld battery powered electronics.

Figure 3: Accelerometer Block Diagram 

Principle and Operation of MEMS The Free scale accelerometer is a surface-micro machined integrated circuit accelerometer. The device consists of

a surface micro machined capacitive sensing cell (g-cell) and a signal conditioning ASIC contained in a single package. The sensing element is sealed hermetically at the wafer level using a bulk micromachined cap wafer. The g-cell is a mechanical structure formed from semiconductor materials (polysilicon) using semiconductor processes (masking and etching). It can be modeled as a set of beams attached to a movable central mass that move between fixed beams. The movable beams can be deflected from their rest position by subjecting the system to acceleration. As the beams attached to the central mass move, the distance from them to the fixed beams on one side will increase by the same amount that the distance to the fixed beams on the other side decreases. The change in distance is a measure of acceleration. The g-cell beams form two back-to-back capacitors. Analog to Digital Converter The ADC0808, ADC0809 data acquisition component is a monolithic CMOS device with an 8-bit analog-todigital converter, 8-channel multiplexer and microprocessor compatible control logic. The ADC0809 data acquisition component is a monolithic CMOS device with an 8-bit analog-to-digital converter, 8-channel multiplexer and microprocessor compatible control logic. The 8-bit A/D converter uses Successive approximation as the conversion technique. The converter features a high impedance chopper stabilized comparator, a 256R voltage divider with analog switch tree and a successive approximation register. The 8-channel multiplexer can directly access any of 8-single-ended analog signals. The device eliminates the need for external zero and full-scale adjustments. Easy interfacing to microprocessors is provided by the latched and decoded multiplexer address inputs and latched TTL TRI-STATEÂŽ outputs. The design of the ADC0808, ADC0809 has been optimized by incorporating the most desirable aspects of several A/D conversion techniques. The ADC0808, ADC0809 offers high speed, high accuracy, minimal temperature dependence, excellent longterm accuracy and repeatability, and consumes minimal power.These features make this device ideally suited to applications from process and machine control to consumer and automotive applications. For 16-channel multiplexer with common output.


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S. Sivakumar, P. Sivaraj, K. Bhaskar, G. R. Karthi & K. Senthilkumar

Figure 4: ADC Block Diagram Multiplexor The device contains an 8-channel single-ended analog signal multiplexer. A particular input channel is selected by using the address decoder. The address is latched into the decoder on the low-to-high transition of the address latch enable signal. Microcontroller The AT89S52 is a low-power, high-performance CMOS 8-bit microcontroller with 8K bytes of in-system programmable Flash memory. The device is manufactured using Atmel’s high-density nonvolatile memory technology and is compatible with the Indus-try-standard 80C51 instruction set and pin out. The on-chip Flash allows the program memory to be reprogrammed in system or by a conventional non-volatile memory programmer. By combining a versatile 8-bit CPU with in-system programmable flash on a monolithic chip, the Atmel AT89S52 is a powerful microcontroller which provides a highly flexible and cost-effective solution to many embedded control applications.AT89S52 provides the following standard features: 8K bytes of Flash, 256 bytes of RAM, 32 I/O lines, Watchdog timer, two data pointers, three 22 16-bit timer/counters, a six-vector two-level interrupt architecture, a full duplex serial port, on-chip oscillator.

Figure 5: LDC Circuit Boost Converter A DC-to-DC converter is an electronic circuit which converts a source of direct current (DC) from one voltage level to another. It is a class of power converter. The LM358 series consists of two independent, high gain, internally frequency compensated operational amplifiers which were designed specifically to operate from a single power supply over a wide range of voltages. Operation from split power supplies is also possible and the low power supply current drain is independent of the magnitude of the power supply voltage. In the linear mode the input common-mode voltage range


Green Energy Harvester Based on Frequency Conversion Method

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includes ground and the output voltage can also swing to ground, even though operated from only a single power supply voltage. The unity gain cross frequency is temperature compensated. The input bias current is also temperature compensated. The LM358 series are op amps which operate with only a single power supply voltage, have true-differential inputs, and remain in the linear mode with an input common mode voltage of 0 VDC. Relay Relay is necessary with almost every electrical plant and no part of the system is left unprotected. The choice of protective depends upon several aspects such as type and rating of the protected equipment, its importance, locations, probable abnormal conditions; cost etc. protective relaying is one of the several features of the system design concerned with minimizing damage to the equipment and interruptions to service when electrical failures occur. When any abnormal conditions anywhere in an electrical power system, some action is necessary to isolate the abnormal condition instantaneously, in some cases, after a predetermined time delay. Such action must be automatic and selective (i.e.) it must segregate the faulty section or piece of apparatus leaving the healthy remainder in service. Electrical equipment failures would cause intolerable outages. There must be additional provisions to minimize damage to the equipment and interruptions to the service. The function of protective relaying is to cause the prompt removal from service of any element of the power system when it suffers a short circuit, or when it starts to operate in any abnormal manner that might cause damage or otherwise interface with the effective operation of the rest of the system. The relaying equipment is aided in this task by circuit breakers that are capable of disconnecting the faulty element when they are called upon to do so by the relaying equipment. The secondary function of the protective relaying is to provide indication of the location and type of failure. To disconnect abnormally the operating part so as to prevent subsequent faults. Inverter An inverter is an electrical device that converts direct current (DC) to alternating current (AC); the converted AC can be at any required voltage and frequency with the use of appropriate transformers, switching, and control circuits. Solid-state inverters have no moving parts and are used in a wide range of applications, from small switching power supplies in computers, to large electric utility high-voltage direct current applications that transport bulk power. Inverters are commonly used to supply AC power from DC sources such as solar panels or batteries. Three-phase inverters are used for variable-frequency drive applications and for high power applications such as HVDC power transmission. A basic three-phase inverter consists of three single-phase inverter switches each connected to one of the three load terminals. For the most basic control scheme, the operation of the three switches is coordinated so that one switch operates at each 60 degree point of the fundamental output waveform. This creates a line to-line output waveform that has six steps. The six-step waveform has a zero-voltage step between the positive and negative sections of the square-wave such that the harmonics that are multiples of three are eliminated as described above. When carrier-based PWM techniques are applied to six-step waveforms, the basic overall shape, or envelope, of the waveform is retained so that the 3rd harmonic and its multiples are cancelled. 3-phase inverter switching circuit showing 6-step switching sequence and waveform of voltage between terminals A and C (23-2 states)To construct inverters with higher power ratings, two six-step three-phase inverters can be connected in parallel for a higher current rating or in series for a higher voltage rating. In either case, the output waveforms are phase shifted to obtain a 12step waveform. If additional inverters are combined, an 18-step inverter is obtained with three inverters etc. Although inverters are usually combined for the purpose of achieving increased voltage or current ratings, the quality of the waveform is improved as well.


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S. Sivakumar, P. Sivaraj, K. Bhaskar, G. R. Karthi & K. Senthilkumar

PROTOTYPE TEST RESULTS AND DISCUSSIONS

Figure 6: Power Supply Circuit Diagram The AC voltage, typically 220V rms, is connected to a transformer, which steps that AC voltage down to the level of the desired DC output. A diode rectifier then provides a full-wave rectified voltage that is initially filtered by a simple capacitor filter to produce a DC voltage. This resulting DC voltage usually has some ripple or AC voltage variation. Regulator circuit removes the ripples and also remains the same DC value even if the input DC voltage varies or the load connected to the output dc voltage changes. A 230V, 50Hz Single phase AC power supply is given to a step down transformer to get 12v supply. This voltage is converted to DC voltage using a Bridge Rectifier. The converted pulsating DC voltage is filtered by a 2200 micro farad capacitor and then given to 7805 voltage regulator to obtain constant 5v supply. This 5v supply is given to all the components in the circuit. A RC time constant circuit is added to discharge all the capacitors quickly. To ensure the power supply a LED is connected for indication purpose. Transformer The potential transformer will step down the power supply voltage (0-230V) to (0-6V) level. Then the secondary of the potential transformer will be connected to the precision rectifier, which is constructed with the help of op amp. The advantages of using precision rectifier are it will give peak voltage output as DC; rest of the circuits will give only RMS output. Bridge Rectifier When four diodes are connected as shown in figure, the circuit is called as bridge rectifier. The input to the circuit is applied to the diagonally opposite corners of the network and the output is taken from the remaining two corners. Let us assume that the transformer is working properly and there is a positive potential, at point A and a negative potential at point B. The positive potential at point A will forward bias D3 and reverse bias D4.The negative potential at point B will forward bias D1 and reverse D2. At this time D3 and D1 are forward biased and will allow current flow to pass through them; D4 and D2 are reverse biased and will allow current flow. The path for current flow is from point B through D1, up through RL, through D3, through the secondary of the transformer back to point B, this path is indicated by the solid arrows. One-half cycle later the polarity across the secondary of the transformer reverse, forward biasing D2 and D4 ad reverse biasing D1 and D3.Current flow will now be from point A through D4, up through RL, through D2, through the secondary of T1, and back to point A. This path is indicated by the broken arrows. The current flow through RL is always in the same direction. In flowing through RL this current develops a voltage. Since current flows through the load (RL) during both half cycles of the applied voltage, the bridge rectifier is a full-wave rectifier. One advantage of a bridge rectifier over a conventional full-wave rectifier is that with a given transformer the bridge rectifier produces a voltage output that is nearly twice that of the conventional full-wave circuit. Voltage Regulator Voltage regulators comprise a class of widely used ICs. Regulator IC units contain the circuitry for reference


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source, comparator amplifier, control device and overload protection all in a single IC. IC units provide regulation of fixed positive voltage, a fixed negative voltage or an adjustably set voltage. 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.

Figure 7: Internal Block Diagram The KA78XX/KA78XXA series of three-terminal positive regulator are available in the TO-220/D-PAK package and with several fixed output voltages, making them useful in a wide range of applications. Each type employs internal current limiting, thermal shut down and safe operating area protection, making it essentially indestructible. If adequate heat sinking is provided, they can deliver over 1A output current. Although designed primarily as fixed voltage regulators, these devices can be used with external components to obtain adjustable voltages and currents. Keil C51Cross Compiler The Keil C51 C Compiler for the 8051 microcontroller is the most popular 8051 C compiler in the world. It provides more features than any other 8051 C compiler available today.The C51 Compiler allows you to write 8051 microcontroller applications in C that, once compiled, have the efficiency and speed of assembly language. Language extensions in the C51 Compiler give you full access to all resources of the 8051. Coding #include <REGX51.H> sbit rs=P3^2; sbit rw=P3^3; sbit en=P3^4; sfr datas=0xA0; #define MYDATA P0 sbit A1=P1^0; sbit A2=P1^1; sbit A3=P1^2; void lcdinit(void); void lcdcmd(unsigned char ); void delay(unsigned int del);


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S. Sivakumar, P. Sivaraj, K. Bhaskar, G. R. Karthi & K. Senthilkumar

void lcddata(unsigned char ldat); void lcdinit(void) { lcdcmd(0x38); lcdcmd(0x38); lcdcmd(0x38); lcdcmd(0x06); lcdcmd(0x0e); lcdcmd(0x01); lcdcmd(0x0C); lcdcmd(0x80); } void lcdcmd(unsigned char lcmd) { datas=lcmd; rs=0; rw=0; en=1; delay(100); en=0; } void delay(unsigned int del) { while(del--); } void lcddata(unsigned char ldat) { datas=ldat; rs=1; rw=0; en=1;


Green Energy Harvester Based on Frequency Conversion Method

delay(100); en=0; } void Delay(); void init() { SCON=0x50; TMOD=0X20; TH1=0XFD; TR1=1; } void lcddisp(unsigned char val[16]) { char i; for(i=0;i<16;i++) lcddata(val[i]); } void txs(unsigned char value) { TI=0; SBUF=value; while(TI==0); } unsigned char val1[6],val,sp,spt,spf; void main() { unsigned char i=0,oc=0; unsigned char hb=0; init(); lcdinit(); P3_5=0;

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S. Sivakumar, P. Sivaraj, K. Bhaskar, G. R. Karthi & K. Senthilkumar

P3_7=1; while(1) { while(RI==0) { A1=0; A2=0; A3=0; val1[0]=MYDATA; txs('A'); txs((val1[0]/100)+0x30); txs(((val1[0]%100)/10)+0x30); txs((val1[0]%10)+0x30); lcdcmd(0x80); lcddisp("Voltage= "); lcdcmd(0xC0); lcddata((val1[0]/100)+0x30); lcddata(((val1[0]%100)/10)+0x30); lcddata((val1[0]%10)+0x30); if(val1[0]>80) { P3_7=1; P3_5=1; lcdcmd(0xC8); lcddisp("High "); Delay(); } else { P3_7=0; P3_5=0;


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Green Energy Harvester Based on Frequency Conversion Method

lcdcmd(0xc8); lcddisp(" "); } } RI=0; val=SBUF; switch(val) { case 'A': P3_5=1;break; case 'B': P3_5=0;break; case 'C': P3_6=1;break; case 'D': P3_6=0;break; case 'E': P3_7=1;break; case 'F': P3_7=0;break; default : break; } } } void Delay() { int i; for(i=0;i<20000;i++) { } } Hardware Kit Prototype

Figure 8


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S. Sivakumar, P. Sivaraj, K. Bhaskar, G. R. Karthi & K. Senthilkumar

CONCLUSIONS A vibration based energy harvester using MEMS is presented. The prototype is able to work over a wide range of external vibration frequencies. In addition to this, higher external vibration frequency values naturally increases the performance of the proposed harvester. The obtained PD (Power Density) is the highest PD (50mW continuous) obtained for the vibration based energy harvester operating at low frequency values to the best of our knowledge. The generated power renders our design a very efficient energy harvester for daily application. Another important phase of our study is the investigation of scaling down the dimensions of the proposed structure and to see its feasibility to be used in very lowpower Microsystems. It is seen that the PD of the device increases as the device volume is scaled down. Thus it is clear that the proposed method is a good candidate to be used in powerless micro system applications operating at low-frequency vibrating medium.

REFERENCES 1.

Henry A.Sodano, Daniel J.Inman and Gyuhae Park, “A Review of Power Harvesting from Vibration using Piezoelectric Materials”, The Shock and Vibration Digest, Vol. 36, No. 3, May 2004 Pages (197–205) ©2004 Sage Publications

2.

Ozge Zorlu, Member, IEEE, Emre Tan Topal, and Haluk Külah, Member, IEEEA “Vibration-Based Electromagnetic Energy Harvester Using Mechanical Frequency Up-Conversion Method” IEEE SENSORS JOURNAL, VOL. 11, NO. 2, FEBRUARY 2011, Pages (481-488).

3.

Cx51 Compiler, Optimizing C Compiler and Library Reference for Classic and Extended 8051 Microcontrollers User’s Guide 11.2000.

4.

DC Motor with Speed and Current Closed Loops, Driven by eTPU on MCF523x Covers MCF523x and all eTPUequipped Devices by: Milan Brejl & Michal Prince System Application Engineers, Roznov Czech System Center, Freescale Semiconductor, Application Note, AN2955, and Rev. 0, 06/2005.

5.

Electric Power Generation Using Piezoelectric, Resonator for Power-free Tokyo, JAPAN, *Hitachi ULSI Systems, Co. Ltd., Kokubunji, Tokyo, JAPAN.

6.

Generation Rajeevan Amirtharajah and Anantha P. Chandrakasan, Member, IEEE, IEEE JOURNAL OF SOLIDSTATE CIRCUITS, VOL. 33, NO. 5, MAY 1998.

7.

Introduction to Vibration Energy Harvesting Francesco Cottone Marie Curie Research Fellow ESIEE Paris – University of Paris Est,f.cottone@esiee.fr, NiPS Energy Harvesting Summer School, August 1 -5,2011

8.

LM78XX/LM78XXA, 3-Terminal 1A Positive Voltage Regulator, FAIR CHILD SEMICONDUCTOR, MARCH 2008.

9.

Specifications of LCD Module, Part Number Gdm1602b Series Date JULY 28, 1998.

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