author={Cong Wang and Naehyuck Chang and Younghyun Kim and Sangyoung Park and Yongpan Liu and Hyung Gyu Lee and Rong Luo and Huazhong Yang}, 

booktitle={Design Automation Conference (ASP-DAC), 2014 19th Asia and South Pacific}, 

title={Storage-less and converter-less maximum power point tracking of photovoltaic cells for a nonvolatile microprocessor}, 




abstract={This paper pioneers the maximum power point tracking (MPPT) of photovoltaic (PV) cells that directly supply power to a microprocessor without an energy storage element (a battery or a large-size capacitor) nor power converters. The maximum power point tracking is conventionally performed by an MPPT charger that stores in the energy storage element, and a voltage regulator (typically a DC-DC converter) produces a proper voltage level for the microprocessor. The energy storage element is an energy buffer and makes it possible to perform MPPT of the PV cells and power management of the microprocessor independently. However, the energy storage element, MPPT charger and DC-DC converter cause seriously limited lifetime (when a typical battery is adopted), significant energy loss (typically over 20%), increased weight/volume and high cost, etc. The proposed method enables extremely fine-grain dynamic power management (DPM) in every a few hundred microseconds and performs the MPPT without using an MPPT charger and a DC-DC converter as well as an energy storage element. We achieve 84.5% of energy harvesting efficiency using the proposed setup with huge reduction in cost, weight and volume, and extended lifetime, which is not even numerically comparable with conventional MPPT methods.}, 

keywords={maximum power point trackers;microprocessor chips;solar cells;voltage regulators;DC-DC converter;DPM;MPPT charger;PV cells;converter-less maximum power point tracking;dynamic power management;energy buffer;energy storage element;microprocessor power management;nonvolatile microprocessor;photovoltaic cells;storage-less maximum power point tracking;voltage regulator;Capacitors;Energy harvesting;Energy loss;Energy storage;Maximum power point trackers;Microprocessors;Switches},