A Photovoltaic Power Management System using a Luminance-Controlled Oscillator for USN Applications

Abstract

Abstract-This paper presents a power management system of the dye-sensitized solar cell (DSSC) for ubiquitous sensor network (USN) applications. The charge pump with a luminance-controlled oscillator regulates the load impedance of the DSSC to track the maximum power point (MPP) under various light intensities. The low drop-out regulator with a hysteresis comparator supplies intermittent power pulses that are wide enough for USN to communicate with a host transponder even under dim light conditions. With MPP tracking, approximately 50% more power is harvested over a wide range of light intensity. The power management system fabricated using 0.13 µm CMOS technology works with DSSC to provide power pulses of 36 µA. The duration of pulses is almost constant around 80 µs (6.5 nJ/pulse), while the pulse spacing is inversely proportional to the light intensity.

Photovoltaic Cells for Micro-Scale Wireless Sensor Nodes

“…Prior PV cell modeling efforts ( [8], [18] amongst many others) have focussed on large panels with output powers greater than 1mW while, as will be presented later, the characteristics and system dynamics differ considerably when micro PV cells are considered. Previous works exploring PV cell based energy harvesting in the context of self-powered (WSN [4], [10]) use preliminary values from datasheets and iteratively compute remaining model parameters. This work utilizes data from continuous measurement of PV cell current-voltage (IV) characteristics to arrive at a simulation model.…”