Title :
A Closed-Loop Maximum Power Point Tracker for Subwatt Photovoltaic Panels
Author :
López-Lapeña, Oscar ; Penella, Maria Teresa ; Gasulla, Manel
Author_Institution :
Sensors & Interfaces Group, Univ. Politec. de Catalunya, Castelldefels, Spain
fDate :
3/1/2012 12:00:00 AM
Abstract :
This paper proposes a closed-loop maximum power point tracker (MPPT) for subwatt photovoltaic (PV) panels used in wireless sensor networks. Both high power efficiency and low circuit complexity are achieved. A microcontroller (μC) driven by a fast clock was used to implement an MPPT algorithm with a low processing time. This leads to a maximum central-processing-unit duty cycle of 6% and frees the μC to be used in the remaining tasks of the autonomous sensor, such as sensing, processing, and transmitting data. In order to reduce power consumption, dynamic power management techniques were applied, which implied the use of predictive algorithms. In addition, the measurement and acquisition of the output current and voltage of the PV panel, which increase circuit complexity, was avoided. Experimental measurements showed power consumptions of the MPPT controller as low as 52 μW for a 2.7-mW PV power and up to 388 μW for a 94.4-mW PV power. Tracking efficiency was higher than 99.4%. The overall efficiency was higher than 90% for a PV panel power higher than 20 mW. Field measurements showed an energy gain 15.7% higher than that of a direct-coupled solution.
Keywords :
circuit complexity; maximum power point trackers; microcontrollers; power consumption; solar cells; wireless sensor networks; MPPT algorithm; PV panel; autonomous sensor; circuit complexity; closed-loop maximum power point tracker; direct-coupled solution; dynamic power management techniques; maximum central-processing-unit; microcontroller; power 2.7 mW; power 388 muW; power 52 muW; power 94.4 mW; power consumption; predictive algorithms; subwatt photovoltaic panels; wireless sensor networks; Complexity theory; Current measurement; Hysteresis; Power demand; Switches; Voltage control; Voltage measurement; Dynamic power management (DPM); energy harvesting; maximum power point (MPP) tracking; solar cells; wireless sensor networks;
Journal_Title :
Industrial Electronics, IEEE Transactions on
DOI :
10.1109/TIE.2011.2161254