ISSN Vol.08,Issue.16, October-2016, Pages:

Transcription

1 ISSN Vol.08,Issue.16, October-2016, Pages: A Self-Powered High-Efficiency Rectifier with Automatic Resetting of Transducer Capacitance in Piezoelectric Energy Harvesting Systems KARUMANCHI SREENU 1, P. MANOJ KUMAR 2, KOTHAPALLI SAIDULU 3 1 PG Scholar, Dept of ECE, Bomma Institute of Technology and Science, Khammam, TS, India, karumanchisreenu@gmail.com. 2 Assistant Professor, Dept of ECE, Bomma Institute of Technology and Science, Khammam, TS, India, manoj.punati@gmail.com. 3 Associate Professor & HOD, Dept of ECE, Bomma Institute of Technology and Science, Khammam, TS, India, ksaiduluece@gmail.com. Abstract: This paper introduces a self-controlled rectifier for piezoelectric vitality reaping applications, and the key thought of the proposed framework is to reset the transducer capacitor at ideal moments to boost the separated force. The proposed rectifier comprises of two switches and two dynamic diodes. The switches release the transducer capacitor at ideal moments two times for each cycle. The dynamic diodes depend on operation amps with a preset dc counterbalance, which decreases the voltage drop and the spillage current and maintains a strategic distance from flimsiness. What's more, the controller for the proposed rectifier is easy to lessen the circuit intricacy and the force dissemination. The proposed rectifier was composed and created in 0.18-μm CMOS innovation. Measured results show that it accomplishes power proficiency of 91.2%, and the measure of power extricated by the proposed rectifier is 3.5 times bigger when contrasted and the traditional rectifiers. The proposed rectifier does not require any off chip segments to empower full chip coordination, and the kick the bucket territory of the proposed circuit is mm2. Keywords: Active Rectifier, High Efficiency Rectifier, Op- Amp-Based Active-Diodes, Piezoelectric Cantilever, Piezoelectric Energy Harvesting, Synchronized Switch Harvesting On Inductor (SSHI). I. INTRODUCTION In Recent years, concentrated examination has been led on vitality collecting from surrounding sources. Disposal of batteries is exceptionally helpful for a few applications, for example, remote sensor systems, implantable medicinal gadgets, and tire-weight sensor frameworks, where substitution of a battery is excessive or unfeasible. Vitality gathering offers suitable arrangement for those applications. Piezoelectric(PE) vitality collecting frameworks offer a generally high vitality thickness extending from 10 to a few hundred μw/cm3 Fig1 demonstrates a customary PE vitality gathering circuit with a full-connect (FB) rectifier. The PE transducer is displayed as a sinusoidal current source, i P(t) = IP sin(2π fpt), in parallel with inside capacitor CP and resistor R P. Recurrence fp is the excitation recurrence. Capacitor CL and resistor RL model a capacity component, for example, a super capacitor or rechargeable battery and the heap, individually. A PE vitality gathering framework regularly embraces a customary FB rectifier, yet it causes low effectiveness due to the voltage drop of the diodes and the heap befuddle seen at the yield of the transducer. Fig.1. PE vitality gathering circuit with a traditional FB rectifier. Different rectifier plans to exchange greatest energy to the heap, where VC p signifies the voltage over the inside capacitor CP. The capacitor is charged contrarily amid the negative half cycle of the transducer current in Fig. 2(a). At the point when the current gets to be certain, the negative charge of CP is released first before it is charged to positive. The power from the transducer is conveyed to the heap, at the point when VC p achieves Vrect + Vdrop, where Vrect is the load voltage as appeared in Fig.1, and Vdrop the aggregate diode voltage drop. Note that, Vdrop is double the single diode voltage drop for a FB rectifier. It is critical to note that the transducer current to release the negative charge in Fig. 2(a) is squandered, along these lines prompting diminishment of the separated force IJATIR. All rights reserved.

2 KARUMANCHI SREENU, P. MANOJ KUMAR, KOTHAPALLI SAIDULU II. LITERATURE SURVEY We have studied that it contains a self-powered rectifier in piezoelectric energy harvesting applications, and the main idea of the proposed system is to reset the transducer capacitance at optimal instants of time to maximize the extracted output power. Here the rectifier contains two switches and two active diodes. The active diodes used here decreases the voltage drop, leakage current and also avoids instability because the diodes used here are based on opamps with a preset dc offset. And also in addition the controller used for the proposed rectifier is simple so reduces complexity and power dissipation.in order to decrease the power dissipation more and to obtain good skew rate here we replacing the Op-amp s with preset offset voltage with Class-AB Op-amp s. This rectifier is fabricated by 0.18μm technology of CMOS. In this, a rectifier with series Synchronized Switch Harvesting Inductor (Series SSHI) is proposed for piezoelectric (PE) energy harvesting system. The serial inductor helps to flip the voltage across the internal capacitor of the PE transducer instead of wasting the capacitor voltage by discharge. Active diodes are used for the switches to further improve the extraction efficiency. From measurements, the proposed rectifier shows a power extraction efficiency of 3.3 times that of the active full bridge (FB) rectifier, and more than 90% of the power conversion efficiency. two switches the two switches reset (discharge) transducer capacitor CP at the zero crossing point of the transducer current. A. Implementation of the Proposed Rectifier An implementation of the proposed rectifier and the corresponding timing diagram are shown in Fig. 3. Diode D1 is realized with a comparator-based active diode, COM1 and M1, and Diode D2 with COM2 +M2,. Diode D1 should be turned on: 1) when the transducer current flows into the load, or 2) when the reset loop is created. For both cases, the negative input of the COM1 is higher than the positive input. Then, output G1 of the comparator becomes low to conduct D1. Similarly, diode D2 conducts twice per cycle under the comparator output G2 at high. The digital control block uses the two signals G1 and G2 to detect the zero crossing point of the transducer current and generates the CLK. Fig.3. Implementation of the proposed rectifier with comparator-based active-diodes. (a) Proposed rectifier circuit. Fig.2. Circuit diagram of the proposed rectifier. This presents a high-efficiency inductor less self-controlled rectifier for piezoelectric energy harvesting. High efficiency is achieved by discharging the piezoelectric device (PD) capacitance each time the current produced by the PD changes polarity. This is achieved automatically without the use of delay lines, thereby making the proposed circuit compatible with any type of PD. In addition, the proposed rectifier alleviates the need for an inductor, making it suitable for on-chip integration. Reported experimental results show that the proposed rectifier can harvest up to 3.9 times more energy than a full wave bridge rectifier. To overcome the mismatch problem of comparators, op-amp-based active-diodes may use a preset offset voltage. Fig. 4 shows the proposed rectifier with a preset offset voltage for the op-amps. The op-amps functions as a comparator, but in contrast to comparator-based diodes, there is no leakage current or oscillation for the op-ampbased one. III. PROPOSED RECTIFIER WITH PROGRAMMED CAPACITOR RESET Fig2 shows the circuit diagram of the proposed rectifier, which consists of two active diodes, D1 and D2, and two switches, SW1 and SW2. The topology of the proposed rectifier is identical to the conventional FB rectifier shown in Fig. 1 except replacement of two diodes on the left branch by Fig.4. Proposed rectifier with op-amp-based active diodes.

3 A Self-Powered High-Efficiency Rectifier with Automatic Resetting of Transducer Capacitance in Piezoelectric Energy Harvesting Systems B. Implementation of the Digital Control Block The clock signal generator is the most critical part of the circuit, because it directly affects the operation of the rectifier. Several techniques were investigated for clock signal generation, but they are often complicate. Fig. 5 shows a circuit diagram of the proposed digital control block. The circuit consists of two sub blocks, a clock generator and a dead time control block. The CLK signal is generated using two D flip-flops from signals G1 and G2. To prevent from simultaneous turning on of the two switches, M3 and M4, during transition, a dead time control block in Fig. 5(b) generates two separate clocks, PCLK for M4 and NCLK for M3. The dead time control block ensures that M3, and M4 are never turned on at the same time. Fig.7.Output voltage V Cp waveforms for the conventional (top) and the proposed (bottom) rectifiers. Fig.5. Digital control circuit. (a) Clock generator. (b) Dead time control block. IV. MEASUREMENT RESULTS The proposed rectifier with op-amp-based active-diodes are designed and fabricated in 0.18-μm CMOS processing technology. The performance of the rectifier was measured under the following condition: current source I P = 94 μa in parallel with internal capacitor C P = 25 nf and internal resistor R P = 1 MΩ, excitation frequency f P = 200 Hz, and the load resistor variation from 15 to 200 kω with a 5-kΩ step. The equivalent circuit of the modeled PE transducer generates the open circuit voltage V OC = 3 V, Fig.8. Waveforms of the transducer capacitor voltage V Cp and the output voltage V rect for the proposed rectifier with comparator-based active-diodes. Fig.9. Die photos of the three rectifiers. Fig.6. (a) Theoretical, simulated, and measured output power of the proposed rectifier. (b) Theoretical and measured power efficiency. which was also considered in [2] [4]. The efficiency of the rectifier is obtained as the ratio of the output power of the rectifier to the maximum extracted power expressed. The theoretical value of the output power is given, and the measured output power is obtained as P out = V 2 rect/r L.

4 KARUMANCHI SREENU, P. MANOJ KUMAR, KOTHAPALLI SAIDULU TABLE I: Performance Comparison with Existing Fb Rectifiers for Pe Energy Harvesters Fig. 6(a) shows the three different output powers for the output resistance varying from 15 to 400 kω, one obtained from, the other one through simulation, and the last one through measurement. As can be observed in Fig. 6(a), the measured results are consistent with the theoretical values and simulation results. The maximum power of the proposed rectifier is obtained as P max = 2C p f p V 2 OC= 90 μw for R L = 100 kω under V rect = V OC = 3 V. The measured maximum power of 82.1 μw is obtained from Fig. 6(a) for the same load resistor value of R L = 100 kω. It was observed that measured V rect voltage is 2.9 V at the maximum power point. It is interesting to note that the theoretical maximum power of the conventional FB rectifier shown in Fig. 1 is obtained as only 24 μw. Fig. 6(b) shows the theoretical and measured power efficiency for varying load resistance. The efficiency increases rapidly as the resistance increases from 15 kω for both theoretical and measured cases, and achieves the maximum measured efficiency of 91.2% at the load resistance of 100 kω. As expected, the measured power efficiency is lower than the theoretical one, as the power dissipation of the rectifier circuit is ignored in derivation of P max. For comparison, the conventional rectifier with cross coupled op-amp-based active-diodes shown in Fig. 1 and the proposed rectifier with comparator-based active-diodes were also designed and fabricated on the same chip. Fig. 7 shows the measured transducer capacitor voltage V Cp (denoted as V BA in previous sections) waveforms of the conventional rectifier with cross-coupled op-amp-based active diodes (top graph) and the proposed rectifier with op-amp based activediodes (bottom graph) under same load resistor (R L = 155 kω). Fig. 7 shows that the proposed rectifier increases the peak voltage of V Cp by 1.63 times when compared with the conventional rectifier. Fig. 8 shows the measured waveforms for the transducer capacitor voltage V Cp and the output voltage V rect of the proposed rectifier with comparator-based active-diodes. A careful examination reveals that the capacitor resets even before the current becomes negative. It is due to a positive offset on the active diode, as explained. The positive offset reduces the maximum power to 74 μw to result in conversion efficiency of 82%, while the efficiency of the proposed rectifier with op-amp-based active-diodes is 91.2%. As noted in the earlier section, a positive offset voltage effectively increases the diode voltage drop of the corresponding active diode. The voltage drop across the two active diodes or V dsp + V dsn is about 10 mv, but it is still smaller than that of two typical passive diodes in series (2 VD ). The die photos of the three implementations of the rectifiers (conventional rectifier with cross-coupled op-amp based active-diodes and the proposed ones with op-amp and comparator-based active-diodes) are in Fig. 9. The area of the proposed rectifier based on op-amp occupies an active area of 0.08 mm 0.20 mm (= mm2). The rectifier consumes 240 μa, and each op-amp consumes 90 na, and the bias circuit consume 60 na. Table I compares the performance of the proposed rectifier with recent, state-ofthe-art rectifiers for PE energy harvesting applications. As a figure of metric, we compared the extracted power of each design with a FB rectifier. The comparison is provided in the last row. It is difficult to make a fair comparison due to differences in PE transducer, operation, and design environments such as the type and the model of PE transducers, processing technology, the input and output voltages, and the switching frequency. The proposed rectifier offers a few advantages over other designs. It does not require an inductor (external or internal) nor an external supply voltage, which enables full chip integration. The overall performance of the proposed rectifier performs better existing ones. V. CONCLUSION A rectifier for PE vitality collecting was displayed in this paper. Rectifiers assume a basic part for PE vitality collecting to boost the force exchange from the transducer to the heap. Two noteworthy wellsprings of misfortune for rectifiers for PE vitality collecting are the vitality waste amid the transducer capacitor charging/releasing and the diode voltage drop. A synchronized switch is a powerful plan to decrease the waste connected with the capacitor charging/releasing procedure. Existing strategies for synchronized switches have a few downsides, for example, complex control hardware, outside supply voltages, also, extensive size inductors. The proposed strategy for programmed resetting of the capacitor plans to address the downsides. The control hardware for the proposed strategy is basic, and it doesn't require an outer supply voltage nor an inductor. Dynamic diodes were seriously researched to lessen the diode voltage drop. Dynamic diodes are regularly taking into account comparators, yet, they confront counterbalance and wavering issues to bring about lower productivity. The proposed rectifier receives dynamic diodes in view of operation amps with an inherent balance cancelation, which address the deficiencies of comparatorbased dynamic diodes. The proposed rectifier was planned and manufactured in 0.18-μm CMOS handling innovation. Reproduction and estimation results are reliable with

5 A Self-Powered High-Efficiency Rectifier with Automatic Resetting of Transducer Capacitance in Piezoelectric Energy Harvesting Systems scientific results. The Estimation comes about demonstrate with low voltage output, Smart Mater. Struct., vol. 17, no. that the proposed rectifier can expand the separated force by 3, p , Mar up to 350% when contrasted and a routine FB rectifier, and accomplishes the most extreme productivity of 91.2%. In Author s Profile: spite of the fact that it is hard to make a reasonable Karumanchi.Sreenu, B.Tech in SRR examination, the proposed rectifier performs superior to Engineering Collage Karepally, Khammam, anything contending rectifiers in numerous perspectives. percentage is 64%, year of completed 2013 VI. REFERENCES [1] Xuan-Dien Do, Huy-Hieu Nguyen, Seok-Kyun Han, Dong Sam Ha, Fellow, IEEE, and Sang-Gug Lee, Member, IEEE, A Self-Powered High-Efficiency Rectifier With Automatic Resetting of Transducer Capacitance in Piezoelectric Energy Harvesting Systems, IEEE Transactions on Very Large Scale Integration (VLSI) Systems, Vol. 23, No. 3, March [2] X. D. Do, Y. H. Ko, H. H. Nguyen, H. B. Le, and S. G. Lee, An efficient parallel SSHI rectifier for piezoelectric energy scavenging systems, in Proc. IEEE Int. Conf. Adv. Commun. Technol., 2011, pp [3] Y. Ramadass and A. Chandrakasan, An efficient piezoelectric energy harvesting interface circuit using a biasflip rectifier and share inductor, IEEE J. Solid-State Circuit, vol. 45, no. 1, pp , Jan [4] Y. K. Ramadass, Energy processing circuit for lowpower applications, Ph.D. dissertation, Dept. Electr. Eng. Comput. Sci., Massachusetts Inst. Technology, Cambridge, MA, USA, Jun [5] Y. H. Lam,W. H. Ki, and C. Y. Tsui, Integrated lowloss CMOS active rectifier for wirelessly powered devices, IEEE Trans. Circuit Syst. II, vol. 53, no. 12, pp , Dec [6] S. Guo and H. Lee, An efficiency-enhanced CMOS rectifier with unbalanced-bias comparators for transcutaneous-power high-current implants, IEEE J. Solid- State Circuit, vol. 44, no. 6, pp , Jun [7] E. Dallage et al., Active self supplied AC-DC converter for piezoelectric energy scavenging systems with supply independent bias, in Proc. IEEE Int. Symp. Circuit Syst. Conf., May 2008, pp [8] N. J. Guilar, R. Amirtharajah, and P. J. Hurst, A fullywave rectifier for interfacing with multi-phase piezoelectric energy harvesters, in IEEE ISSCC Dig. Tech. Papers, Feb. 2008, pp [9] G. K. Ottman, H. F. Hofmann, A. C. Bhatt, and G. A. Lesieutre, Adaptive piezoelectric harvesting circuit for wireless remote power supply, IEEE Trans. Power Electron., vol. 17, no. 5, pp , Sep [10] Y. Sun, N. H. Hieu, C. J. Jeong, and S. G. Lee, An integrated high performance active rectifier for piezoelectric vibration energy harvesting systems, IEEE Trans. Power Electron. Lett., vol. 27, no. 2, pp , Feb [11] N. Krihely and S. B. Yaakov, Self-contained resonant rectifier for piezoelectric sources under variable mechanical excitation, IEEE Trans. Power Electron., vol. 26, no. 2, pp , Feb [12] M. Lallart and D. Guyomar, An optimized selfpowered switching circuit for non-linear energy harvesting April. M.Tech(Electronics & Communication Engineering College: Bomma Institute of Technology and Science (BITS), Khammam, TS, India, id: karumanchisreenu@gmail.com. Mr. P.Manoj Kumar, Qualification: M.Tech from Indur Institute of Technology(IIT), Sidhipet, Medak Dist, Designation: Associate Professor. Working: "P.MANOJ KUMAR received the B.Tech degree in Electronics and Communication Engineering from Srikavitha Engineering College, KMM,TS,INDIA in 2009 and M.Tech from Indur Institute of Technology (IIT), Sidhipet,Medak Dist in 2012.Presently,he is working as Asst.Prof in BITS,KMM, TS, India." -d: manoj.punati@gmail.com, Experience: 18 years. Mr. Kothapalli. Saidulu,received the B.Tech degree in Electronics and Communication Engineering from NCET, Vijayawada, AP, India, in 2001 and M.Tech In RADAR & Microwave from AUCE, VIZAG in Worked as Asst.Prof in Sri Kavitha Engineering College in , SRR Engineering College in Presently, he is working as Asso.Prof & as HOD in BITS,KMM,TS, India. And pursuing Ph.D from JNTUH in the field of Antennas in Bomma Institute of Technology and Science (BITS), Khammam, TS, India, -d: ksaiduluece@gmail.com, Experience: 12 years.