Micro-power non-inductive voltage boost converter for pyro energy harvestors at MOS sub-threshold voltage

Date
2014
Authors
Hasan, Md Qumrul
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Abstract

Introducing this thesis is a Non-Inductive Voltage Boost-Converter (NVBC) for a micro-power energy harvesting system applications in energy storage and delivery purposes. As we know, pyro-electric materials can act as an energy converter when they are heated or cooled based on pyro-electric effects. These materials, for example LiTaO3 crystals, can deliver a wide-range of micro-power ∼0.8V (thickness reduced for each degree of changing temperature) peak-voltage, or nominally 0.45V in a designated lab test setup. This voltage is not adequate in charge storage cells such as rechargeable batteries and also driving electronic circuits. Technology is in demand where a boost-converter must operate at MOS sub-threshold voltage (Sub-VTH) limits. Many designs have been proposed in the recent past that mostly used inductive voltage converter circuits, but they perform better at above MOS threshold voltages. Recently, just a few low-voltage CMOS-based micro-controller chips have been introduced to the IC markets, which also have an internal equivalent reactance similar to those inductive circuits. These voltage booster ICs lags in power efficiency, because they also require the internally switching clock-pulse generating circuits, thus increasing their design complexity. Therefore, proposed here is a novel concept of the NVBC that has eliminated the need of an inductor coil and associated high-speed switching circuits, thus achieving higher efficiency. This concept applies a simple self-synchronizing technique that adapts the NVBC automatically to the low-frequency energy signal of the pyro-electric devices. In this project, we proposed two designs, a novel NVBC considered to be designed for stabilizing the output of NVBC for running electronics devices. Initial prototypes of the electronic designs were tested and found that this stabilized NVBC had 86% efficiency. Another design and testing of the trickle charging system of a non-inductive voltage boost converter are built-in auto-dummy-load (ADL) for a battery charging system. We tested our designed circuit and found the trickle charging system of the non-inductive voltage boost converter is above 98.5% power efficient.

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Keywords
Boost Converter, Energy Harvesting, Micro power, Non-Inductive, Pyro-electric, Sub Threshold Voltage
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Department
Electrical and Computer Engineering