Browsing by Author "Kalingamudali, S. R. D."

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Design and implementation of automated heat shrink cutting process for industrial usage
(proceedings of the 4th International Research Symposium on Pure and Applied Sciences 2019, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Rajapaksha, R. M. D. M.; Dhananjaya, S.S.; Wijesuriya, M. W. A. S. H.; Fernando, K. M. S.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
An automated heat shrink cutting process for industrial usage has been designed and a prototype model implemented. The designed system consists of a microcontroller, a keypad, a stepper motor, and an ac synchronous motor. The inputs such as the length of the heat shrink and number of pieces required to be cut are given to the system through a keypad and entries are displayed in an LCD panel. That information is fed into the microcontroller, which is the main controller of the designed system. Roller pack of heat shrink is inserted into a socket formed by a rubber shaft attached to the stepper motor. Length measurement of the inserted heat shrink is done by the stepper motor using a simple calculation and heat shrink is pulled into the system for the calculated length. Then a cutting blade powered by the synchronous ac motor connected to the microcontroller cuts the heat shrink at the required length. The process will be repeated until it cuts the required number of pieces. The operation of the process is verified by cutting different number of pieces with different lengths. The designed system can measure a 0.2 mm least count and is better than required accuracy of 1 mm for normal industrial wire harness based product lines. The speed of the designed process is between 25-30 pieces per minute and is well above the speed of a trained human in the same task. It is expected that the cost effectiveness of this designed heat shrink cutting process will be found very useful in the automation of industrial wire harness production lines.
Design of an auto disconnecting regulator and a safety switch to prevent domestic gas leakages
(IEEE, 2020) Rajapaksha, R. M. I. U.; Perera, P. S. H.; Nandasena, P. K. D. M.; Gunarathna, P. S. T. K.; Gihan Kanishka, P. P. D.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
There is a growing demand for research in various aspects of smart homes. Automated security systems are an integral part of smart homes. Liquid Petroleum Gas (LPG) is one of the popular fuels used in domestic cooking. Therefore, there is a very high demand for LPG fire security systems. In this study, an automated LPG fire security system for domestic gas leakages has been designed and a prototype model is constructed. The designed system automatically takes preventive measures in case of gas leakage. It includes a newly designed automatically disconnecting regulator from the cylinder which shuts OFF gas supply from commercially available gas cylinders, a control circuit for switching OFF the power supply of nearby area of gas leakage and transceiver unit for sending SMS to the corresponding people. It has been designed to operate automatically when LPG concentration reaches to 200 PPM, a value well below the LPG gas inflammable concentration. LPG concentration is sensed by the MQ-5 gas sensor and fed into the microcontroller. The commercially available gas regulator is modified by attaching a spring and solenoid valve. The spring is compressed when the regulator is ON. Once an LPG leakage of appropriate PPM is detected, a pulse is sent to the solenoid valve such that the attached spring gets rest by removing the regulator from the cylinder. At the same time, a warning message will automatically send to the corresponding users and security personnel through a GSM module attached to the circuit. The circuit is embedded with a rechargeable battery to work even in power outage. Additional gas sensors are installed in electrical switches located near to the gas cylinder and kept in connection with the microcontroller through the Bluetooth module to cutoff electrical power to prevent any spark.
Designing a high-performance parametric speaker system: simulation and Optimization
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Gurusinghe, T. N.; Seneviratne, J. A.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
The parametric speaker is designed to direct omnidirectional sound waves towards a specific target. Over the past two decades, numerous research studies have been conducted to optimize parametric speaker systems, with a focus on enhancing audio quality and extending the range of sound propagation. The objectives of this research include the enhancement of the audio quality, the reduction of total harmonic distortion through modulation techniques, and the amplification of the modulated output to increase the effective hearing distance. These goals were pursued alongside the development of a properly designed ultrasonic transducer array circuit, a critical component of a parametric speaker system. Prior to the conception of the novel parametric speaker system, a comprehensive simulation study was conducted using the commercially available COMSOL Multiphysics software. For this study, the Pressure Acoustics, Frequency Domain (acpr) interface, the Solid Mechanics (solid) interface, and the Electrostatics interface were utilized. The principal aim of this simulation study was to analyse the minimal electric potential required for an ultrasonic transducer element to generate a directional sound wave capable of propagating over a one-metre distance. To achieve this, a PZT-5H piezoelectric element with a stacked aluminium metal diaphragm was constructed. The electric potential across the piezoelectric plate was step by step varied from 5 V to 100 V. Polar plots illustrating the sound pressure level of ultrasound propagation in the air domain at a distance of one-thousand-fourhundred millimetres from the source were generated for each simulation. The simulation model of the piezoelectric element was meticulously constructed after a thorough examination of a crosssectional cut of an ultrasonic transducer and the arrangement of layers within the metal cover. This model adopted a two-dimensional (2D) axially symmetric space dimension. This approach leveraged the rotational symmetry of the elements to simulate in 3D, thereby reducing simulation complexity. The analysis revealed that when the electric potential was below 10 V, the sound pressure remained below 60 dB. However, upon increasing the electric potential to above 60 V, although the expected directionality was achieved, distortions adversely affected the output signal. Such sound propagation characteristics were deemed unsuitable for a parametric speaker system. Upon analysing the polar graphs generated for a 30 V electric potential, it was evident that directionalized sound pressure levels in the air were achieved with minimal distortions compared to other simulated systems. Consequently, a 30 V electric potential was selected as the amplified signal voltage peak-to-peak for application to the designed ultrasound speaker. This approach was undertaken to ensure optimal performance and minimize distortion in the parametric speaker system.
Development of an off-grid solar PV system with battery-supercapacitor hybrid energy storage
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Pitigala, P. A. S. P.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
In off-grid photovoltaic (PV) systems, the charge controller is a significant device since the system's end-to-end efficiency depends on its efficiency. Currently, the commercially available MPPT charge controllers have an average efficiency of 90%. Supercapacitors' (SCs’) high energy density compared to traditional capacitors makes them used as energy storage devices. But theoretically, 50% of energy loss will occur in the capacitor charging loop if we charge it directly connecting to a power supply. According to the supercapacitor-assisted loss management (SCALoM) theory, inserting a useful resistive load into the capacitor charging loop, a portion of the above wasted 50% of energy can be utilised for beneficial work. This paper proposes a novel off-grid PV system with a battery-SC hybrid energy storage. This system utilises the SCALoM theory using the combination of a charge controller and battery as the useful load in the capacitor charging loop, while PV panels are used as the external power source. To achieve maximum use of the SCALoM theory, the SC must be kept under partially charged condition. An electronic switching network consisting of nine electronic switches was designed to realise this. Two SC banks, SC-1 and SC-2 were embedded in the prototype system. The proposed system operates in four different modes: SC-1 charging mode, SC-2 charging mode, SC bypass mode, and night mode. These modes are defined by the state of each switch in the switching network and the voltage of both SC banks. In SC-1 and SC-2 charging modes, the relevant SC bank is connected in series with the PV panels and charge controller while a DC load is connected in parallel to the SC bank. In this mode, the remaining SC bank is discharged through another DC load. In SC bypass mode, the operation of the system is the same as the typical off-grid PV system because both SC-1 and SC-2 are disconnected from the system so that the PV panels are connected in parallel with the charge controller. In this mode, DC loads are connected to the battery. In night mode, an SC bank is connected in series to the PV array and the charge controller and DC loads are connected to the battery again. For maximum utilisation, this system must be operated in SC- 1 and SC-2 charging modes as much as possible throughout the day. The overall operation of the system is controlled by microcontroller-based control circuitry. This system achieved end-to-end efficiencies of 87.36%, 87.50%, 75.68%, and 93.28%, respectively, for SC-1 charging, SC-2 charging, SC bypass, and night modes, respectively. Therefore, it can be concluded that the endto- end efficiency of an off-grid PV system can be increased by implementing a supercapacitor in a series configuration to the solar panel and to the charge controller.
Enhancing UPS battery life through C-rate control with a supercapacitor-assisted battery management system
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Ramesh, J. M. D. A.; Gunawardana, K. D. B. H.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
Battery management systems (BMS) are essential for optimizing the efficiency and dependability of batteries. BMS employs various methodologies and techniques for state of health (SOH) determination, state of charge (SOC) estimation, cell balancing, voltage regulation, current regulation, and overload prevention. This study aims to create a Supercapacitor Assisted Battery Management System (SCABMS) to enhance battery performance and lifespan using a C-rate controlled system by analyzing battery dynamics and load demands. The suggested Battery Management System (BMS) incorporates supercapacitors (SCs) to effectively handle sudden increases in power demand, thereby lessening stress on the main battery and improving its overall lifespan. Previous research indicates that reducing the Crate extends battery lifespan. The C-rate control method is used to manage battery discharge, with the system functioning in two modes depending on the load current. The first is when the load is drawing less than the set current where the load current is completely drawn from the battery without the SC assistant. When the load current exceeds the set current value, the current control circuit begins to limit the battery current for the selected value. In this scenario, the load voltage drops, and the parallel connected buck-boost converter is used to fix the load voltage into the rated value by supplying the rest of the load current. The buck-boost converter output voltage is fixed for the load voltage. The implemented prototype incorporates supplementary functionalities encompassing cell balancing, voltage regulation, current regulation, and overload protection within its BMS. The real-time current and voltage monitoring system was integrated into BMS to ensure a constant C-rate in charging/discharging cycles. Also, the battery's operating periods with and without the Battery Management System (BMS) under the same load circumstances should be compared. This technology successfully reduces power fluctuations and guarantees safe equipment shutdown in case of a power outage. The results indicate a well-maintained c-rate and show the potential of integrating SCABMS in high-power-demanding situations, subject to improvements in efficiency and practicality.
Fabrication and characterization of electrodeposited nano structured copper oxide-based supercapacitors
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Anjalika, B. R. L.; Jayathilaka, K. M. D. C.; Ranaweera, A. L. A. K.; Wijesundera, L. B. D. R. P.; Kalingamudali, S. R. D.
The increasing consumption of limited energy sources, primarily based on fossil fuels, and the resulting environmental issues, such as global warming and climate change, drive researchers to develop environmentally friendly and renewable energy conversions and storage systems. Supercapacitors (SCs) have emerged as a promising solution to meet the increasing global demand for efficient energy storage. The performance and efficiency of a supercapacitor depend directly on the electrode materials used. Nanostructured materials provide new and exciting approaches to developing supercapacitor electrodes for high-performance electrochemical energy storage applications. Interest in pseudocapacitive materials, particularly copper oxide, has grown due to its advantageous properties and application as electrode materials in energy storage devices. In this research, nano cuprous oxide thin films were used as supercapacitor electrodes, and Polyvinyl Alcohol-Potassium Hydroxide (PVA-KOH) gel polymer was used as both the electrolyte and separator for supercapacitors. The nano cuprous oxide films were synthesized on Ti substrates using the electrodeposition technique by controlling the pH of the deposition bath. For comparison, microstructured cuprous oxide thin films were also deposited on Ti substrates as electrodes using the electrodeposition technique. Structural and surface morphological properties of the fabricated electrodes were investigated using high-energy X-ray diffraction (HEXRD) and scanning electron microscopy (SEM). The HEXRD analysis showed the formation of a singlephase polycrystalline cuprous oxide film on the Ti substrate. The SEM revealed that the morphology of the electrodeposited cuprous oxide thin films strongly depends on the pH value of the deposition bath. The performance of cuprous oxide as an electrochemical supercapacitor electrode was analysed using cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS) techniques. In comparison to microstructured electrodes, the nano cuprous oxide electrodes demonstrate better electrochemical performance in terms of specific capacitance, energy density, and power density. The Cu2O//Cu2O supercapacitor with nano-Cu2O electrodes, prepared at pH 7.9, exhibited the highest specific capacitance of 176.02 mF/g, energy density of 61.4 mWh/kg, and power density of 44.23 W/kg. In contrast, the supercapacitor with microstructured electrodes, prepared at pH 6.3, exhibited a specific capacitance of 7.37 mF/g, energy density of 2 mWh/kg, and power density of 1.4 W/kg. The significant improvement is mainly attributed to the increased film surface area associated with cuprous oxide nanostructures. Therefore, nano copper oxide-based supercapacitor electrodes show great potential for supercapacitor applications.
Fabrication and characterization of sulfur-treated cuprous oxide-based supercapacitors
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Wijesinghe, W. A. N. D.; Jayathilaka, K. M. D. C.; Ranaweera, A. L. A. K.; Wijesundara, L. B. D. R. P.; Kalingamudali, S. R. D.
Supercapacitors are crucial for modern energy storage, offering high power density, fast charging, and life spans. They are widely used in various applications, meeting the need for lightweight, flexible, and eco-friendly energy solutions. Cuprous oxide (Cu2O) holds significant promise as an electrode material for supercapacitors owing to its distinctive properties. However, electrodeposited Cu2O films often have high resistivity and surface defects, hampering their electrochemical performance. To address this issue, sulfur treatment was employed to modify the surface properties of Cu2O electrodes, aiming to enhance their electrochemical performance. In this research, sulfur-treated Cuprous-oxide thin films were used as the supercapacitor electrodes, and PVA-KOH gel polymer was employed as the supercapacitor separator and electrolyte. The Cu2O films were synthesised on a Ti substrate via electrodeposition, followed by Ammonium Sulfide (NH4)2S vapour treatment for surface modification, with varying exposure times. Untreated Cu2O thin films were analysed for comparison. X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) were used to examine their structural and surface morphological characteristics. The XRD analysis showed that the Cu2O deposited on the Ti substrate treated with (NH4)2S vapour did not yield distinct CuxS peaks, indicating the formation of a very thin or amorphous CuxS layer on the film surface. SEM revealed an altered morphology of the electrodeposited Cu2O thin films after the (NH4)2S vapour treatment, with the development of a non-uniform additional layer on the surface. The electrochemical performance of sulfur-treated Cu2O electrodes for supercapacitors was studied using Cyclic Voltammetry (CV), Galvanostatic Charge/Discharge (GCD), and Electrochemical Impedance Spectroscopy (EIS). Sulfur-treated electrodes exhibited enhanced performance, showing higher specific capacitance, energy density, and power density compared to untreated electrodes. The supercapacitor utilising sulfur-treated Cu2O deposited on the Ti electrodes, treated for 10 s, demonstrated superior performance with a specific capacitance of 773.81 mF/g, energy density of 154.76 mWh/kg, and power density of 111.43 W/kg. Conversely, the untreated electrode-based supercapacitor exhibited lower values, with a specific capacitance of 23.34 mF/g, energy density of 4.67 mWh/kg, and power density of 3.38 W/kg. In summary, this study explored the impact of sulfur treatment on the electrochemical performance of electrodeposited Cu2O. CV, GCD, and EIS analyses revealed improved electrochemical performance due to the reduction of surface defects with (NH4)2S surface treatment. The results indicated that the best performance can be obtained in Cu2O with a 10 s (NH4)2S exposure duration for application in supercapacitors.
Investigation of MPPT in photovoltaic systems with step-down DC-DC converter and supercapacitor energy storage
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Premasiri, R. H. M. D.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
This study explores the implementation of Maximum Power Point Tracking (MPPT) in photovoltaic (PV) systems integrated with a step-down DC-DC converter and supercapacitor (SC) based energy storage. The integration of renewable energy sources, particularly solar power, necessitates highly efficient energy conversion and storage mechanisms to maximise the utility of the harvested energy. MPPT techniques play a pivotal role in optimising the power output of PV systems by dynamically adjusting the operating point to extract the maximum possible power under varying environmental conditions. SCs, with their high charge and discharge rates and high power density, emerge as a promising storage solution to manage the intermittent and variable energy output characteristic of PV systems. A Constant Voltage (CV) MPPT algorithm is employed to fine-tune the power output and ensure maximum energy efficiency. The experimental setup comprises a Solar Array Simulator simulating the PV array, interfaced with a step-down DC-DC converter, and an SC configured as the load. The system's performance is analysed by observing the available, actual and output power using a power analyser and evaluated to ascertain the robustness and effectiveness of the MPPT algorithm. The research distinguishes itself by utilising SCs as the primary load, an approach not commonly adopted in previous studies. Few studies have investigated the use of SCs exclusively as the load, and those that have indicated that MPPT is not efficiently achieved under such conditions. However, the analysed results affirm that the system proficiently tracks the maximum power point, attaining an average MPPT efficiency of 94.88% when the system is integrated with the CV MPPT algorithm. The average conversion efficiency attained was 75.62% with a basic DC-DC step-down converter constructed on a solderless board. It is anticipated that this MPPT efficiency will further improve with the application of more sophisticated MPPT algorithms such as Perturb and Observe (P&O), Incremental Conductance (IncCond), and Hill Climbing (HC). The average conversion efficiency can be increased by fine-tuning the converter and implementing more advanced topologies of DC-DC stepdown converters. This research makes a substantial contribution to advancing high-efficiency and dependable PV energy storage systems, underscoring the practical viability of SCs as an energy storage device. Furthermore, these findings have significant implications for SC-assisted Heating, Ventilation, and Air Conditioning (HVAC) systems integrated with PV systems, where efficient MPPT can enhance overall system performance as MPPT can be tracked when using the SC as the storage. Prospective studies will examine the long-term stability and scalability of this innovative approach in larger-scale PV installations, paving the way for more resilient and efficient renewable energy systems.
Maximum Power Point Tracking of an Off-grid Photovoltaic System Consisting of a Series Connected Supercapacitor with a Step-down Converter
(The Electrochemical Society, 2022) Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.; Kularatna, N.
An off-grid photovoltaic (PV) system's PV array is connected with a charge controller as the first power conversion stage. The average efficiency of the power stage of charge controllers is around 90%. Supercapacitor (SC) - battery hybrid PV system is a novel PV system that utilizes some of the wasted energy of a typical system and enhances the system's efficiency up to 98%. However, the feasibility of maximum power point tracking (MPPT) for this system is yet to be validated. This paper presents a comparative study to adapt MPPT for the proposed system consisting of a series- connected SC bank with PV array and step-down DC-DC converter. The step-down converter is used as the impedance matching network. Different solar irradiance profiles were emulated to check the feasibility and efficiency of MPPT. Experimentally, it was shown that the typical MPPT could be adapted to the proposed PV system with very high MPPT efficiency.
Novel slow switching technique for efficient solar energy harnessing for off grid photovoltaic systems
(proceedings of the 4th International Research Symposium on Pure and Applied Sciences 2019, Faculty of Science, University of Kelaniya, Sri Lanka, 2019) Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.; Kularatna, N.
Electricity consumers in remote areas where the grid connection is not available rely on diesel generators or off grid photovoltaic (P V) systems. These PV systems uses battery banks as backup energy storage. Those battery banks are charged by using a battery charge controller connected to a PV array. Because of the recent advances in solar charge controllers, they can reach maximum of 90% charging efficiency, where 10% will be unutilized. Since the efficiency of conventional solar panels lies around 20-25% which is relatively low as compared to other energy generation methods, it is important to utilize as much energy as possible produced by the solar panels. Also, when driving loads, energy stored in the battery bank again goes through a converter or inverter by wasting considerable amount of useful energy. Hence, the purpose of this study is to minimize the energy loss of the charging process of the battery bank while using the energy produced by the PV array in an effective manner. In previous publications, it was introduced a novel way of using supercapacitors (SCs) in an off grid PV system. When charging an empty capacitor in parallel with a source, 50% of energy is wasted irrespective of the value of total loop resistance. In contrast, by connecting a SC bank in series with a typical solar charge controller, it was shown that the energy loss of the combined system is less than the energy loss of parallelly connected SC bank and the battery bank in their individual systems. Experimentally, it has been shown that a 9% increment in overall charging efficiency of the combined system when a charge controller having 80% of efficiency is used to charge the battery bank in typical off grid PV system. The present study introduces a possible method of utilizing the energy stored in SC bank in an effective manner using an intelligent electronic switching scheme. The proposed method uses a second SC bank along with the existing one along with a smart electronic switching circuitry which is able to switch each SC bank between charging or discharging stages when necessary. When one SC bank is in its charging state, the other SC bank will be in its discharging state through a proper load. After that, when the first SC bank is fully charged or the second SC bank is fully discharged, positions of each SC bank is swapped so that the second SC bank will start its charging process while the first SC bank is now discharging through the load. This way both charging and discharging of SC bank can be done efficiently while charging the battery bank in the system by the same manner.
The role of ascorbic acid in optimizing optoelectronic performances of CdS thin films
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Danansuriya, D. B. U. I.; Hetti Arachchige, K. A.; Manilgama, T. T. D.; Kalingamudali, S. R. D.; Premaratne, W. A. P. J.; Jayathilaka, K. M. D. C.; Wijesundara, L. B. D. R. P.; Kumarage, W. G. C.
Cadmium sulfide (CdS), a widely studied (II-VI) group semiconductor, has long captivated the scientific community due to its potential applications in photovoltaic (PV) devices. However, optoelectrical properties of n-CdS, such as flat band potential, and optical band gap, are crucial for enhancing solar cell efficiency. This study explores the tunability of these properties in CdS thin films through chemical bath deposition (CBD) with a mild reducing agent ascorbic acid (C6H8O6). A series of CdS thin films were deposited on fluorine-doped tin oxide (FTO) glass substrates by using various concentrations of ascorbic acid (0, 0.1, 0.01, and 0.001 mol.dm-3). The deposition chemical bath consisted of 0.1 mol.dm-3 cadmium sulfate (CdSO4) and 0.2 mol.dm-3 thiourea (CS(NH2)2) as cadmium and sulfur sources, respectively. The deposition process was conducted at 80 °C for one hour at a pH of 11. Post-deposition, the CdS films were etched in the non-conductive side of the FTO with diluted hydrochloric acid (HCl), followed by annealing at 300 °C for one hour in air. All the electrical measurements were performed in a photoelectrochemical cell comprising a CdS/0.1 mol.dm-3 Na2S2O3/Pt half-cell with an active area of 1 cm². An Ag/AgCl electrode served as the reference for all characterizations. The short-circuit current density (JSC) has shown a significant increase with decreasing ascorbic acid concentration, achieving a 155.6% enhancement with a concentration of 0.001 mol.dm-3 compared to untreated CdS. Conversely, with increasing ascorbic acid concentration the opencircuit voltage (VOC) and the flat band potential (VFB) decreased. The highest reported photocurrent power (VOC×ISC) was observed in films deposited with 0.001 mol.dm-3 ascorbic acid, showing a 150.2% improvement over untreated CdS. Scanning electron microscopy (SEM) analysis revealed that ascorbic acid-treated CdS films exhibited aggregated nanoscale particles, whereas untreated films displayed larger clusters. Consequently, the photocurrent enhancement is attributed to these morphological changes that cause higher effective surface area in the ascorbic-treated CdS thin films compared to the untreated CdS. Furthermore, Mott-Schottky analysis confirmed that all deposited films retained n-type characteristics. This study demonstrates that the electronic properties of n-CdS can be finely tuned through ascorbic acid treatment, making it a promising approach for fabricating thin film solar cells with high light-to-current conversion efficiency. The ability to control and enhance these properties is invaluable for advancing PV applications and achieving higher solar cell performances.
Supercapacitor assisted LED (SCALED) lighting system with grid connection
(Faculty of Science, University of Kelaniya Sri Lanka, 2024) Kumara, W. R.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.
Photovoltaic (PV) systems are increasingly popular as the world shifts to sustainable energy. Generally, there are three main types of PV systems. The SCALED system consists of a PV panel, a Supercapacitor (SC) bank, and an LED. Utilizing the Supercapacitor-Assisted Loss Management (SCALoM) theory, the SCALED system integrates an SC bank and LED bulb to reduce energy loss during charging. Solar energy is stored in the SC bank and released to ensure the LED remains powered. However, the current SCALED system, with oversized solar panels and SC banks, is inefficient if it can't power LEDs at night or in adverse weather. To address this, an innovative approach is proposed by integrating the SCALED system with the grid for reliable energy storage and continuous LED illumination. In this innovative method, the SC bank and LED are connected in series with PV panels or grid connection in the SC charging loop. The system has two identical loops connected in parallel with the PV panels or grid. One SC bank charges while the other discharges, ensuring the LED bulbs remain powered. An electronic switching network with two SC banks manages four operational modes to optimise energy utilisation. These modes include alternating charging and discharging loops. A microcontroller-based control circuitry operates the system, which connects to the grid via a Switch Mode Power Supply (SMPS). A current sensor measures the current of the solar panel output. During adverse weather, the system switches to the grid when the output current drops solar panels below a threshold, isolating the solar panel. In the Developed SCALED system, MOSFETs efficiently manage power flow between the SC bank and LEDs, minimizing losses. Microcontrollers optimize energy use by controlling MOSFETs and monitoring voltage, and current levels, ensuring reliable LED operation even in adverse conditions. This improves overall system efficiency and reliability. When the solar panel output current exceeds the threshold value, the system will connect the solar panels and isolate the SMPS from the system. The system achieves a high charging efficiency of around 95%. Operational in all weather conditions and at night, the system ensures consistent LED illumination, enabling normal user operation regardless of weather during day and night.
Supercapacitor based novel approach for efficient solar energy harnessing
(Research Symposium on Pure and Applied Sciences, 2018 Faculty of Science, University of Kelaniya, Sri Lanka, 2018) Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.; Kalingamudali, S. R. D.; Kularatna, N.
Finding greener solutions through renewable energy sources to provide energy demand in 21st century is an important task due to the shortage of world energy sources. From many types of renewable energy sources, photovoltaic cell is the most popular device that can be used to harvest solar energy and produce electricity. Currently, efficiency of conventional solar panels lies between 20-25%. In addition, part of energy is lost during the power conversion process in solar power converters. Standalone photovoltaic systems used in houses and other buildings in remote areas employ solar charge controllers to charge their battery banks in order to store energy. Efficiency of these systems relies mostly on the efficiency of in built DC-DC converter of the charge controller. With the advancement of modern semiconductor technologies and electronics, maximum of 90% efficiency can be achieved by a brand new solar charge controller. Usually this value will be decreased with the years of usage. Hence, the purpose of this work is to minimize the energy wasted during charging process of the battery bank of a standalone photovoltaic system. The initial approach was to connect DC-DC converter and battery bank in series with a capacitor charging loop. When an empty capacitor is charged by delivering Q charge using an external source, it can theoretically be shown that 50% of energy will be lost in the charging loop regardless of the resistance of the loop. If a useful resistive load is attached to the capacitor charging loop in series, this wasted energy can be effectively utilized by doing a treasured work while charging the capacitor too. In this work, this basic concept was used by replacing the conventional capacitor from a supercapacitor and attaching the DC-DC converter and the battery bank as the useful resistive load. Thereby, charging both supercapacitor and battery bank has been done. Theoretical analysis of this novel method shows promising outcomes on achieving high charging efficiency. Experimental results show this technique increases the overall charging efficiency of a standalone photovoltaic system by 9% when 80% efficient DC-DC converter is used to charge the battery bank. Therefore, it can be concluded that the overall charging efficiency of a typical standalone photovoltaic system can be enhanced by adding supercapacitor in series. The energy stored in both devices could be used to drive DC or AC loads using necessary electronics.
Unlocking the potential of convolutional neural networks for precise classification of finger pulse waves in diabetic patients and healthy individuals
(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Gunathilaka, P. A. D. H. J.; Kumarika, B. M. T.; Jayathilaka, K. M. D. C.; Perera, D.; Liyanage, J.A.; Kalingamudali, S. R. D.
Pulse wave analysis (PWA) is a valuable technique for assessing the cardiovascular health of diabetic patients. However, it encounters several challenges, including the complexity of pulse wave signals and the need for standardization and validation of measurement methods. Convolutional Neural Networks (CNNs) play a crucial role in addressing these challenges by offering a robust and accurate approach to classifying pulse wave images. Pulse wave analysis offers a cost-effective, time-efficient, highly accurate, and non-invasive method for diagnosing diabetes-related cardiovascular issues. This study aims to investigate the effectiveness of CNN in classifying finger pulse wave images to accurately distinguish between diabetic and non-diabetic subjects, thus enabling non-invasive diabetes diagnosis. The study's methodology comprises four main steps: data collection, data preprocessing, CNN model development, and model evaluation. Primary data, including finger pulse waves, blood pressure, mean arterial pressure, oxygen saturation, and pulse rate, were acquired from the multipara patient monitor. Subsequently, single pulse wave cycles from 50 healthy individuals and 50 diabetes patients were subjected to preprocessing. The CNN model was developed through data collection, preprocessing, and the creation of its architecture, followed by compilation, training, and evaluation, ultimately achieving a 92% accuracy in classifying pulse wave images for non-invasive diabetes diagnosis. Descriptive statistics were used to summarize participants' demographic and clinical data, revealing no significant differences in age, gender, or body mass index between the two groups. The model's ability to discriminate based on pulse wave images highlights its potential for noninvasive diabetes diagnosis. In order to improve accuracy in future work, increasing the dataset size and conducting hyperparameter tuning will be essential for optimizing the CNN model.