MICRO-POWER NON-INDUCTIVE VOLTAGE BOOST CONVERTER FOR PYRO-ENERGY HARVESTORS AT MOS SUB-THRESHOLD VOLTAGE

By

MD QUMRUL HASAN

Project Requirements for the Degree of

MASTER OF SCIENCE IN ELECTRICAL ENGINEERING

August 2012

ABSTRACT

 Introducing in this thesis is a Non-Inductive Voltage Boost-Converter (NVBC) for micro-power energy harvesting system applicable in energy storage and delivery purposes. As we know that, 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 designated lab test setup. This voltage is not adequate in charging 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. Very recently, just a few low-voltage CMOS-based micro-controller chips have been introduced to the IC markets which also have internal equivalent reactance similar to those inductive circuits. These voltage booster ICs lag 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 achieved 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 stabilized 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 non-inductive voltage boost converter with built-in auto-dummy-load (ADL) for battery charging system. We tested our designed circuit and found trickle charging system of non-inductive voltage boost converter is above 98.5% power efficient.

References:

[1] Sandeep Kumar Bompthapali, “Electronic Simulator Module for Pyroelectric Devices”, MSEE project report (December 2012).

 [2] S. B lang, “pyroelectricity: from ancient curiosity to modern imaging tool”, Physics today, (2005).

[3] http://homepages.which.net/~paul.hills/Batteries/BatteriesBody.html

[4] http://www.arxterra.com/battery-comparisons/

[5] http://faculty.wwu.edu/vawter/PhysicsNet/Topics/DC-Current/RCSeries.html