ICAPS 2023
Permanent URI for this collectionhttp://repository.kln.ac.lk/handle/123456789/26832
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Item Comparison of different methods for generating SPWM signal for the development of a pure Sine wave inverter(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Hemal, S. B. N. H.; Dilshan, G. K. D.; Karunarathna, M. A. D. D. S.; Morawakaarachchi, K. N.; Senanayake, S. V.; Premasiri, R. H. M. D.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.An inverter is an electronic device which is used for converting Direct Current (DC) to Alternating Current (AC) because AC is the predominant form of electrical power used in homes, businesses, and most electrical appliances. Inverters can be categorized based on the type of waveform that they produce, such as Pure Sine Wave Inverters, Modified Square Wave Inverters and Square Wave Inverters. This paper discusses the development of a Pure Sine Wave Inverter with an output voltage of 230 VRMS and a frequency of 50 Hz using the Sinusoidal Pulse Width Modulation (SPWM) technique. Three SPWM signal generation methods, including analogue comparator, microcontroller, and SPWM driver module methods, were tested. This study presents a method to obtain a 230 VRMS, 50 Hz output sine wave in three steps. The first step involves the generation of an SPWM signal with frequency control, utilizing the DC source supply. The analogue comparator method uses op-amps as the analogue comparator. Then, it compares a reference sinusoidal wave with a high-frequency (in kHz range) carrier triangular wave. The output of the op-amp comparator is SPWM. The frequency of this reference sinusoidal wave is chosen based on the required inverter output frequency (50 Hz). In that process, the comparator gives out a pulse when the voltage of the sine waveform is greater than the triangular voltage, and this pulse is used to trigger the respective inverter switches. When designing a circuit that involves op-amps, the slew rate of the op-amp is a critical consideration. To generate an SPWM signal using an ATmega328p microcontroller, the microcontroller was used to generate a series of PWM signals by digital high and digital low. The corresponding time of each pulse's delay is added using the microsecond function. Increasing and decreasing duty cycle, and then a series of PWM signals. As the pure sine wave inverter SPWM driver module EGS002 was used and, that method was the more accurate method, and a clean SPWM signal was generated with less harmonics. Although this type of inverter board has more features, the circuitry was not complex because of the module. Secondly, we employ the MOSFET H-bridge stage to obtain the desired sine wave output. Finally, the third step focuses on supplying a high DC voltage to the H-bridge circuit, which the DC-DC PWM boost converter generates. Several circuit protections were included to ensure the device's safety and reliability. In the process of SPWM generation, although in the analogue comparator method, op-amps offer a low-cost option, a microcontroller is favoured for its superior precision and ability to handle high-power applications effectively. However, the EGS002 module stands out as the preferred method due to its user-friendly nature, comprehensive protection features, and ability to provide valuable feedback, making it a more economically efficient choice in the overall design.Item Mosquito detection and repellent system using acoustics signals for household use.(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Senanayake, S. V.; Warnakulasooriya, C. B.; Ranaweera, A. L. A. K.; Jayathilaka, K. M. D. C.There are over 130 mosquito species in Sri Lanka, and this abundance may be the reason for the spread of several critical diseases. Therefore, an effective mosquito repellent system, including a mosquito detection mechanism, is essential for daily life. Using acoustic signals is a harmless and cost-effective method for detecting and repelling pests compared to other visual or thermal processes. Therefore, this research investigates a novel approach for detecting mosquitoes and creating an effective mosquito-repellent mechanism based on acoustic signals. A system capable of distinguishing mosquitoes from other sound sources based on their unique wing flapping frequency was built and repelling them using specific ultrasonic frequencies was realized. The system consists of several components, including microphones, amplifiers, and filters, tested in both simulations and experiments. The methodology involved in determining the wing flapping frequency of mosquitoes by concentrating mosquitoes in a soundproof container, which was found to be within the 800-900 Hz range, with slight differences between male and female mosquitoes. Additionally, the effect of ultrasound in repelling mosquitoes was explored, discovering an effective frequency range of 42 kHz to 44 kHz. The system was subjected to numerous iterations and improvements to enhance mosquito detection sensitivity and the band of repellent frequencies. The final design includes an instrumentation amplifier for cancelling the noises and a second order Sallen-Key bandpass filter for filtering the flapping frequency of mosquitoes. However, due to the limitations of conventional condenser microphones, the discrepancy between simulations and physical implementations appeared. Further, the interference from surrounding noise caused some complications. Despite these obstacles, the results showed the system's potential in detecting and repelling mosquitoes. The system can be improved further by incorporating more sensitive microphones and filter circuits. By providing power with rechargeable batteries, it can be made portable. The flexibility and adaptability of the system design offer exciting possibilities for future enhancements and optimizations. In conclusion, this research advances the field of mosquito detection and repellence, providing new insights into the potential of acoustic signal processing in pest detection and control. Future improvements to the system could significantly contribute to mitigating the risks associated with mosquito-borne diseases.Item 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.Item Optimising energy efficiency in a PV-enabled base transceiver station(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Jayasooriya, J. A. T. D.; Piyumal, P. L. A. K.; Ranaweera, A. L. A. K.The need for green energy sources has become paramount in the modern world due to the environmental hazards of non-green alternatives. Essential services, including the telecommunication industry, must also align with this goal. As foundational elements of the telecommunications network, base transceiver stations offer a ripe opportunity to integrate green energy solutions. However, the prevalent scenario reveals that many of these stations continue to rely on conventional grid-based power sources, with only a limited fraction equipped with standalone photovoltaic (PV) systems. This study addresses a pressing challenge in integrating standalone PV systems with base transceiver stations. Central to this challenge is the conundrum of power generation backups, specifically during the morning hours, when the battery reserves charged by the PV systems are frequently depleted. This operational gap necessitates the deployment of supplementary power generators, imposing substantial operational costs that diminish the cost-efficiency advantages anticipated with the introduction of PV systems. The methodology involved a detailed analysis of the selected base transceiver station's total DC power consumption patterns from 15th May 2023 to 21st May 2023. These insights guided the design of an efficient energy harvesting system enriched with a supercapacitor-battery hybrid energy storage arrangement. A Maximum Power Point Tracking (MPPT) controller was acquired to optimise system performance; its effectiveness was verified through efficiency calculations and PV array emulator Irradiance Profiles, and its efficiency exceeded 90%. An intelligent power management strategy was implemented, automatically switching to consume supercapacitor (SC) energy when the voltage level exceeds a threshold, conserving battery bank energy, ensuring uninterrupted operation, and extending battery lifespan. The prototype's operational modes, including neutral, SC charge recovery, and SC bypass, have been successfully demonstrated. Results indicate that the suggested photovoltaic system prototype effectively tracks the PV array's maximum power point (MPP), comparable to standard systems using traditional MPPT algorithms. This novel system promises to not only obviate the need for extensive generator backups but also potentially reduce their capacity compared to conventional configurations. Realising a green energy-powered telecom network is a vast and complex process, demanding guaranteed performance and cost-effectiveness for a period of at least about 15 years. This research marks a significant milestone in advancing green energy solutions and highlights the crucial role of base transceiver stations in establishing a sustainable telecommunication infrastructure. Embracing eco-friendly technologies is essential in safeguarding our planet and ensuring a brighter future for generations to come.Item 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.Item Investigation of multi-functional metamaterial unit cell operating at SHX-X Band Frequencies(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Saraph, A. K.; Ranaweera, A. L. A. K.; Jayathilaka, K. M. D. C; Senevirathne, J. A.Metamaterials are man-made materials having unique and distinct properties which are not available in natural materials. In this study, a metamaterial unit cell is fabricated with a squarecircular- hexagonal split ring resonator. The feasibility of the fabricated unit cell as a perfect absorber, sensor, and antenna is investigated. The proposed unit cell structure is initially simulated, numerically analysed, and optimized using High Frequency Structure Simulator (HFSS), a commercially available EM simulation software. First, the potential of the designed unit cell to be functioned as highly efficient metamaterial absorber in the Super High Frequency (SHF) – X band is verified. Simulations revealed that the reflection coefficient S11 is lower than 10 dB across the whole test frequency range around 9.2 GHz and the absorptivity is 99.8%. Unit cell has been fabricated with standard PCB fabrication process. The fabricated unit cell is composed of alternate layers of Cu and FR4 dielectric medium in which a Cu split ring absorbs all incident electric and magnetic fields within a single planar layer that is only 0.6 mm thick. Experimental characteristics of the designed unit cell were analysed using the Vector Network Analyzer (VNA). To observe the resonant behaviour a non-contact measurement was performed with home-made copper ring due to the increased accuracy. Experimental results showed relatively high Q-factor revealing that the designed unit cell has lower energy dissipation as compared to the energy stored. By replacing the FR4 layer in the metamaterial absorber (MMA) unit cell with a sensor layer made of air, a design for a metamaterial sensor is suggested liquid density sensing applications. The liquids with different densities were inserted to the air layer and the respective resonance frequencies were obtained. A change in the resonant frequency shifting of the metamaterial unit cell show that it can be used as a liquid density sensor. The proposed sensor can be employed in microwave frequency range for chemical, biological, agricultural, and medical applications. Finally, a design for a metamaterial patch antenna is proposed using the same unit cell. It is made of three layers consisting of the patch and the ground layer made of Cu and the substrate with FR4 dielectric material in between. The patch antenna was found to resonate at several frequencies between 0 and 15 GHz, with the lowest S11 reflection coefficient measured at 7.52 GHz and -21.2456 dB. We envision that this antenna will find application in the miniaturization and integration of various telecommunication equipment functions, particularly for items that are used frequently in daily life such as mobile communication systems, smart phones, portable tablets, GPS receivers, wireless Internet devices, etc.Item 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.Item Development of a cost-effective real-time commuter counting system for public transportation in Sri Lanka(Faculty of Science, University of Kelaniya Sri Lanka, 2023) Premasiri, R. H. M. D.; Koralage, K. G. S. D.; Hasaranga, J. P. K.; Alawaththa, A. K. N. A.; Seneviratne, J. A.; Ranaweera, A. L. A. K.The use of smart systems in public transportation is relatively new in the Sri Lankan context. This study introduces a cost-effective solution for accurately counting the number of bus passengers at any given time. Current passenger counting systems in Sri Lanka often suffer from inaccuracies and inefficiencies, hindering the effective management of public transportation and addressing problems including long bus queues, ticketing fraud, long waiting times, etc. Precise passenger count is essential for optimising services and resources, ultimately enhancing the efficiency of public transportation in the country. The proposed system is designed to be installed in buses and includes an online platform where users can enter the bus number and check the passenger occupancy in real-time. The proposed system comprises several key components: two input sensors, a microcontroller, a wireless connectivity module, an in-built display, an input panel, and an output display. The two sharp IR sensor modules employed as input sensors are connected to a microcontroller. An inbuilt display connected to the microcontroller provides output information, including passenger count, number of vacant seats, GPS signal strength, and data transmitting capability. Data is wirelessly sent to a cloud database for storage, retrieval, and processing, enabling users to access relevant information via a web application. The algorithm employed in this system ensures precise passenger count by detecting specific sequences of readings from the two IR sensors. To increment the passenger count, the system requires the following sequence: "0-0, 1-0, 1-1, 0-1, 0-0." This sequence corresponds to the detection of a passenger boarding the bus. Each step in the sequence represents the state of the two IR sensors, with "0" indicating no obstacle and "1" indicating an obstacle (i.e., the presence of a passenger). The algorithm recognizes this sequence as an entry event and increments the passenger count accordingly. Conversely, the algorithm relies on the following sequence to accurately decrease the passenger count when a passenger exits the bus: "0-0, 0-1, 1-1, 1-0, 0-0." This sequence represents a passenger leaving the bus. The algorithm reduces the passenger count by monitoring the sensor readings and identifying this sequence. These specific sequences in the algorithm ensure reliable and accurate passenger counting. By requiring a particular order of sensor readings, false positives or negatives caused by noise or temporary obstacles are minimised, leading to a more precise passenger count. The online platform allows users to access passenger occupancy in a particular bus, which aids in real-time service optimization for public transportation management. The system achieves precise real-time passenger occupancy tracking using two Sharp IR sensors and a finely tuned algorithm. Tested results of the pilot system show that data empowered public transportation management in Sri Lanka by optimising routes, efficiently allocating resources, and significantly improving the overall commuter experience. In conclusion, the combination of affordability, reliability, and user-friendliness makes this proposed solution suitable for efficiently managing public transportation systems.