Efficient adaptive switch design for charge pumps in micro-scale energy harvesting

The performance of Micro-scale energy harvesting unit depends on the efficient design of charge-pump. Optimization of the dimension of MOSFET switches in charge pump is one of the techniques to improve the efficiency. In this work, a new optimization technique for transistor sizing and a concept of reconfigurable adaptive switches has been introduced to maximize the extracted power. A control unit is designed for adaptive reconfiguration of the switches. These proposed techniques are validated for linear charge-pump topology in UMC 180nm technology. Combined effect of size optimization of switch along with reconfigurable switch offers an improvement up to 23.5% in the net harvested power with 6% less silicon area

Mobile R-wave detection system powered by a thermoelectric generator

In modern medicine, monitoring devices for mobile application are using rechargeable power supplies. A new concept refers to energy scavenging techniques using heat emission from human body. This project deals with the development of a prototype and the feasibility study of a thermal harvester. A thermoelectric generator enables the device to work self-sufficient on temperature gradients between skin and ambient conditions. This developed energy harvesting system converts human body heat into electrical energy. In combination with ultra-lowpower components autonomous operation should be possible. The system should enable an R-wave detection circuitry. If the temperature gradient is high enough, there is supposed to be no lack of power as in case of ordinary battery systems. A system combining thermal energy harvesting and signal processing is developed. To show the functions of the energy harvester corresponding measurements are performed. The signal processing unit is set up but not evaluated in concrete measurements

Efficient Archietecture for Effective Utilization of Harvested Power in Microscale Energy Harvesting

Recent developments in combining sensors, microprocessors, and radio frequency (RF) communications holds the potential to revolutionize the way we monitor and maintain critical systems. In the future, literally billions of wireless sensors may become deeply embedded within machines, structures, and the environment. Sensed information will be automatically collected, compressed, and forwarded for condition based maintenance. Energy Harvesting comprises a promising solution to one of the key problems faced by battery-powered Wireless Sensor Networks, namely the limited nature of the energy supply (finite battery capacity). By harvesting energy from the surrounding environment, the sensors can have a continuous lifetime without any needs for battery recharge or replacement

Micro Scale Energy Harvesting For Ultra-Low Power Systems

Ultra-low power systems such as Wireless sensor network (WSN) nodes have emerged as an active research topic due to their vast application areas. Such WSNs would be able to perform their sensing functions and wireless communication without any supervision, configuration, or maintenance. These systems have to cope with severe power supply constraints. The need shared by most WSNs for long lifetimes and small form factors does not match up well with the power density of available battery technology. This could limit the use of WSNs due to the need for large batteries. It is not expected that better batteries for small devices will become available in the near future. Energy harvesting could therefore be a solution to making WSNs autonomous and could thus enable widespread use of these systems in many applications. Energy harvesting is becoming more and more popular for micro-power applications where the environmental energy is used to power up the systems. As sensors have become smaller, cheaper, and increasingly abundant, there have been commensurate reductions in the size and cost of computation and wireless communication. In context of micro scale solar energy harvesting systems, the design of ecient energy conversion unit and accurate maximum power point tracking(MPPT) unit becomes a tremendous challenge due to area constraint and very low (W) output power. This thesis presents a novel MPP tracking method including a charge pump based DC-DC converter for extracting energy from a tiny single PV cell (open circuit voltage 0.4V). We have used a feed-forward (FF) unit to track maximum power point. The design of FF MPP is derived from the operating point of solar cell under dierent solar intensity. This scheme consumes very little power and is faster when compared to other methods. This method eliminates the use of current sensor and other power hungry elements in the MPPT unit. The proposed method tracks the MPP with less than 2 % error and gives eciency of 63.50% through FF MPPT. The complete circuit has been simulated using 0.18 m CMOS process

Συλλογή ενέργειας απο το περιβάλλον για την αυτονόμηση ηλεκτρονικών διατάξεων

Στα πλαίσια αυτής της μεταπτυχιακής εργασίας πραγματοποιήθηκε μια πλήρη βιβλιογραφική μελέτη γύρω απο την τεχνολογία της συλλογής ενέργειας απο το περιβάλλον. Συγκεκριμένα πραγματοποιήθηκε θεωρητική προσέγγιση της αρχής λειτουργίας χρησιμοποιώντας έννοιες απο την κλασσική αλλά και την σύγχρονη φυσική. Περαιτέρω έγινε διαχωρισμός και πλήρη περιγραφή ως προς τον τρόπο σχεδίασης αλλά και τις τεχνολογίες κατασκευής τέτοιου είδους διατάξεων. Η περιγραφή για κάθε μορφή ενέργειας ολοκληρώνεται με εκτενή αναφορά πάνω στις διατάξεις που χρησιμοποιούνται και αποτελούν την τελευταία λέξη της τεχνολογίας. Ολοκληρώνοντας πραγματοποιείται μια οικονομοτεχνική μελέτη όσον αφορά τις προοπτικές ανάπτυξης της συγκεκριμένης τεχνολογίας καθώς και την επιρροή που ασκεί πάνω στο πεδίο των εφηρμοσμένων επιστημώνIn this master thesis we developed a full study around the technology of ambient energy harvesting. Specifically in the first part we have developed the theoritical operation considering laws and principles of classic and modern physics. Furthermore we described the design and manufacturing technology of each one of the devices. The description is completed with references of state of the art applications. Concluding we develop an economical and technical analysis corcerning the aspects of future development and the impact on the field of applied sciences