Implementation of alternative-source battery charger for automated embedded measurement system

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Supervisor:
Krébesz Tamás István
Department of Measurement and Information Systems

There is a directive in the European Union, when a new dump is being built, a protective layer is needed to construct in the reservoir for the waste. The protective layer prevents the leechate from entering the ground. This layer is made from High Density Poli-Ethilen (HDPE) foil. The main profile of Geoelectro Ltd. is the installation of a sensor network, witch can detect and show the exact location of the damages of the HDPE foil layer. An automatic measurement instrument is under development, witch can initiate a measurement at a preprogrammed time. There is an important requirement toward the units of the embedded system. The requirement is that the units must work properly without line power. It is also important, to extend the time period of maintenance from a month to couple months, or a half year. We planning to build the instrument with a charging circuit witch monitors the instrument's battery, and refills it with the power needed by the instrument.

There are different ways for recharging the battery. The measurement system has a lot of sensors witch are inserted into the ground. I would like to perform experiment measurements with this sensor network, investigating the possibilities of harvesting telluric currents for battery charging. The other way to get the energy for battery charging is using solar cells. In this case it is important for the charger to be able to service the battery with enough amount of charging power considering the changing of the light conditions and the battery's voltage. The Maximum Power Point Tracking (MPPT) is a method developed for answer these problems. It gains 10-45% more charging power from a solar cell.

In my study, I will review the system design of the automated measurement system, considering the roles and specialties of each subunits. After the examination of the measuring unit I will give an estimation of power usage. Knowing that information I will lay down the requirements for the charger and make the exact specifications for the charging system.

I will run experiment measures for determining the possibility of using telluric currents for battery charging. The measurements will contain the investigation of stainless steel electrodes applicability, and the amount of power witch can be harvested with the measurement system's sensor network.

In the possession of the results, I will select the proper energy harvesting method for the charger device. I create the system and modular design of the charger, based on the V designing model. Based on the specifications I select the components for building the device. I create the hardware and software design of the charger. According to the plans, I build the device, and make it's firmware. After building and programming, I test the device, both it's hardware and software, and I analyse the operation of the whole automated measurement system.

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