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CMOS circuits for electromagnetic vibration energy harvesters : system modeling, interface design and implementation
Energy harvesting enables making electrical use of available ambient energy. Different types of energy harvesters allow to scavenge different forms of ambient energy and to convert them into an electrically useable form. Several sources of ambient energy are widely available, e.g. temperature differences, light, vibrations, etc. This work is focused on harvesting energy from ambient vibrations via small-scaled electromagnetic energy transducers. The applied electromagnetic vibration energy harvesters typically allow harvesting of some microwatts to some milliwatts of power. These power levels are sufficient to supply an electronic application such as a wireless sensor node or an internet-of-things device. Thus, energy autonomous systems can be established that are exclusively self-supplied by environmental energy. In spite of well designed and highly efficient energy harvesters there is the need to condition the converted energy. A vibration energy harvester provides an AC output and as a consequence the AC voltage needs to be converted into a DC voltage because an electronic application typically requires a DC supply. Furthermore, in order to extract as much power as possible, the power output of the harvester has to be optimized and the power must be efficiently transferred to an energy buffer element. Hence, an interface circuit that is connected between the harvester and an energy buffer element is needed. This work presents two interface circuits, in which different types of active AC-DC conversion and maximum power point tracking are implemented. Theoretical studies of the interfacing techniques and of the harvester modeling are given first. Based on that, the implementations of the interface circuits, which are fabricated in a 0.35 μm CMOS technology, are described. Both systems operate energy autonomously and they optimize the energy harvesting performance of the system, e.g. power conversion efficiencies of up to 95% are achieved and up to 91% of the possible power can be harvested. In addition to the power conditioning, the interface circuits also comprise a voltage conditioning that enables over-voltage protection and output-voltage regulation in order to reliably power an application. Consequently, the use of a small-scaled electromagnetic vibration energy harvester in combination with a highly efficient interface circuit allows to realize a compact and energy autonomous unit.
CMOS circuits for electromagnetic vibration energy harvesters : system modeling, interface design and implementation
Energy harvesting enables making electrical use of available ambient energy. Different types of energy harvesters allow to scavenge different forms of ambient energy and to convert them into an electrically useable form. Several sources of ambient energy are widely available, e.g. temperature differences, light, vibrations, etc. This work is focused on harvesting energy from ambient vibrations via small-scaled electromagnetic energy transducers. The applied electromagnetic vibration energy harvesters typically allow harvesting of some microwatts to some milliwatts of power. These power levels are sufficient to supply an electronic application such as a wireless sensor node or an internet-of-things device. Thus, energy autonomous systems can be established that are exclusively self-supplied by environmental energy. In spite of well designed and highly efficient energy harvesters there is the need to condition the converted energy. A vibration energy harvester provides an AC output and as a consequence the AC voltage needs to be converted into a DC voltage because an electronic application typically requires a DC supply. Furthermore, in order to extract as much power as possible, the power output of the harvester has to be optimized and the power must be efficiently transferred to an energy buffer element. Hence, an interface circuit that is connected between the harvester and an energy buffer element is needed. This work presents two interface circuits, in which different types of active AC-DC conversion and maximum power point tracking are implemented. Theoretical studies of the interfacing techniques and of the harvester modeling are given first. Based on that, the implementations of the interface circuits, which are fabricated in a 0.35 μm CMOS technology, are described. Both systems operate energy autonomously and they optimize the energy harvesting performance of the system, e.g. power conversion efficiencies of up to 95% are achieved and up to 91% of the possible power can be harvested. In addition to the power conditioning, the interface circuits also comprise a voltage conditioning that enables over-voltage protection and output-voltage regulation in order to reliably power an application. Consequently, the use of a small-scaled electromagnetic vibration energy harvester in combination with a highly efficient interface circuit allows to realize a compact and energy autonomous unit.
CMOS circuits for electromagnetic vibration energy harvesters : system modeling, interface design and implementation
Leicht, Joachim (author)
2019-01-01
Theses
Electronic Resource
English
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