High-efficiency voltage regulation stage in energy harvesting systems

A high-efficiency voltage regulation stage in an energy harvesting system is presented. In an energy harvesting system, the availability of energy is uncertain. If energy is harvested from energy resources, the system operates; if not, the system does not work. Therefore, the energy harvesting system starts and stops repeatedly according to the presence or absence of energy. The repeated on and off state in the energy harvesting system decreases operating efficiency which is an important factor in such a system with the limited amount of harvested energy. To improve the efficiency of the system that repeatedly switch between on and off states, the energy dissipated in the transitional state should be minimized. In this work, a voltage regulation stage is implemented with two additional switches, two low power comparators and digital control logic in addition to the conventional regulation stage. The first switch determines the input voltage level of the regulation stage, and the second switch prevents undesired energy dissipation in the boosting state. When the regulation stage supplies power to a 100 ohm load resistor with a 100 uF load capacitor for 50 ms, the efficiency is improved up to 38%, and boosting time is reduced by 42% in comparison with the conventional regulation structure.