A framework of concurrent task scheduling and dynamic voltage and frequency scaling in real-time embedded systems with energy harvesting

Xue Lin, Yanzhi Wang, Siyu Yue, Naehyuck Chang, Massoud Pedram
2013 International Symposium on Low Power Electronics and Design (ISLPED)  
Energy harvesting is a promising technique to overcome the limitation imposed by the finite energy capacity of batteries in conventional battery-powered embedded systems. In particular, the question of how one can achieve full energy autonomy (i.e., perpetual, battery-free operation) of a real-time embedded system with an energy harvesting capability (RTES-EH) by applying a global control strategy is investigated. The energy harvesting module is comprised of a Photovoltaic (PV) panel for
more » ... ing energy and a supercapacitor for storing any excess energy. The global controller performs optimal operating point tracking for the PV panel, state-ofcharge management for the supercapacitor, and energy-harvestingaware real-time task scheduling with dynamic voltage and frequency scaling (DVFS) in the embedded load device. The controller, which accounts for dynamic V-I characteristics of the PV panel, terminal voltage variation and self-leakage of the supercapacitor, and power losses in voltage converters, employs a cascaded feedback control structure with an inner control loop determining the V-I operating point of the PV panel and an outer supervisory control loop performing real-time task scheduling and setting the voltage and frequency level in the embedded load device (to keep the state-ofcharge of the supercapacitor in a desirable range). Experimental results show that the proposed global controller lowers the task drop rate in a RTES-EH by up to 60% compared with baseline controller within the same service time.
doi:10.1109/islped.2013.6629269 dblp:conf/islped/LinWYCP13 fatcat:z3thxa6ckfamzic62dyu3mnsnu