5μW-to-10mW input power range inductive boost converter for indoor photovoltaic energy harvesting with integrated maximum power point tracking algorithm

摘要

Energy harvesting provides a means to supply wireless sensor networks in building environments with autonomous and sustainable power [1,2]. Indoor light can be converted into electricity by a solar cell and stored in a rechargeable battery or super-capacitor [3]. Depending on the indoor illumination level and the installed location as well as the orientation of the solar cell, the output power of an amorphous silicon solar cell can vary from less than a few μW/cm² up to hundreds of μW/cm² [3]. To manage the variation in both the illumination and panel size, a power-management circuit that is able to efficiently handle a wide range of input power is necessary. A solar cell can be modeled as a light-controlled current source in parallel with a diode. Its output current is determined by the output voltage in an exponential relation. At one point, the solar cell reaches its maximum power point (MPP). This MPP can be tracked by tuning either the output voltage or the load impedance [4].