Penuaian Tenaga (EH) adalah penyelesaian untuk masalah pembekalan tenaga untuk sistem Internet pelbagai benda (IoT) yang dibina di persekitaran yang tidak menyokong bekalan kuasa elektrik. Penuaian tenaga yang dikumpul dari persekitaran alam dan mengisikan tenaga yang telah dikumpul ke dalam bateri yang boleh dicas semula telah mengatasi masalah berkaitan dengan hayat sistem yang terhad sebelum ini. Oleh sebab dimensi nod sensor yang kecil, bekalan kuasa yang dipasang pada nod sensor juga harus sangat terhad. Untuk meningkatkan kecekapan dan keteguhan sistem, sistem penuaian tenaga solar diguna dan direka dengan menggunakan litar pemilihan cawangan automatik dan kawalan pengecasan bateri litium. Pengisian bateri litium juga digunakan untuk membekalkan bekalan kuasa yang stabil dengan voltan 5V melalui Universal Series Bus (USB) standard. Bateri akan dicas apabila voltan bateri litium turun ke bawah paras yang telah ditetapkan dengan pencahayaan matahari yang mencukupi. Sistem berasaskan IOT yang direka akan disambungkan pada sensor hujan dan XBee, oleh itu jumlah arus yang diperlukan oleh sistem telah dikira dan diukur untuk mencapai objektif projek ini. Kemudian litar tersebut dibina dan diuji dengan mengunakan beberapa siri percubaan untuk permerhatian prestasi dan sifatnya. Ini termasuk ujian mengunakan pelbagai nilai beban, sudut panel solar ke arah eksperimen matahari, analisis masa nyata dan keseluruhan analisis prestasi sistem tersebut. Jumlah kuasa yang digunakan oleh sistem berasaskan IoT telah dikira dan adalah berada pada 0.25W. Mekanisme penuaian tenaga yang dicadangkan boleh beroperasi secara berterusan, seolar-olar sistem tersebut terdedah di bawah cahaya matahari yang mencukupi sekurang-kurangnya dalam masa 5 hingga 6 jam sehari. Solar panel yang digunakan juga telah diuji dan didapati bahawa panel tersebut boleh beroperasi dalam keadaan yang paling baik di antara 8V hingga 11V, di mana dapat membekalkan kuasa melebihi 1.465W. Apabila matahari bersinar berserenjang pada panel solar, panel dapat membekalkan kuasa keluaran yang tinggi iaitu pada 4.219W.
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Energy harvesting (EH) is an attractive and green solution to the problem in powering internet of things (IoT) in a rural environment which do not support power supply. Energy harvesting harvest energy from the ambient environment and replenishes its rechargeable battery had overcome the pitfalls associated with defining lifetime, which arise because EH never stops but can occasionally run out of energy. Due to the small dimension of a sensor node and explosion of system in the outdoor environment, the power supply attached to the sensor node has to be very limited in size and not able to produce enough power continuously. The proposed solar powered energy-harvesting system is the key technology for solving finite power problem. This scheme works on the principle of photo-voltaic effect. In order to enhance the efficiency and robustness of the system, the solar energy-harvesting system is designed by using an automatic branch selecting circuit and charging control of lithium battery. Lithium battery-charging is also used to afford a stable power supply with 5-V output voltage through a standard Universal Series Bus (USB) interface. The battery is charged once the voltage of lithium battery drops below the predetermined level with sufficient illumination of sun. The developed IoT based system is connected to a rain sensor and an XBee, hence the total current required by the system were calculated and measured in order to achieve the objective of this project. Then the circuit was built and tested by a several series of experiment to investigate its performance and characteristic. This includes various load test, angle of solar panel towards the sun experiment, real-time analysis and performance analysis. The total power consumed by the IoT based system was calculated and measured which is at 0.25W. It is demonstrated that the proposed energy harvesting mechanism could operate perpetually, given that the system is exposed to voltage more than 5V for at least 5 to 6 hours in a day. It is tested that the solar panel implemented operates best in between 8V to 11V, in which providing a power of more than 1.465W. When the sun shines perpendicularly to the solar panel, the solar panel will also provide a relatively high output power which is at 4.219W.
Hybrid energy harvesting development for internet of things (iot) / Shum Kar Yen