A Constant-Energy-Packet-Extraction-Based MPPT Technique With 98% Average Extraction Efficiency for Wide Range Generic Ambient Energy Scavenging Supporting 1000 × Source Resistance Range

Abstract

An energy harvesting system, featuring a novel generic maximum power point (MPP) tracking technique, compatible with a wide range of transducers is presented in this work. In conventional harvesting systems, the MPP tracking requires frequent open circuiting or prior knowledge about the transducer parameters. The proposed constant-energy-packet-extraction (CEPE) technique uses the technique of increasing the rate of energy extraction by frequency modulation to reach MPP and hence eliminates the need to open circuit, as well as the need for prior knowledge about the transducer parameters. The prototype system achieves an average extraction efficiency of 98% for a wide input voltage range from 50 to 500 mV and transducers with internal impedance ranging from <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$3~\Omega $ </tex-math></inline-formula> to 3.5 k <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\Omega $ </tex-math></inline-formula> . The converter has a peak end-to-end efficiency of 81.8%. A shared inductor-based startup technique is also integrated with the system, which can start operation from a minimum input voltage of 150 mV with minimal external components. It reuses the boost converter inductor, and hence, the system requires only one inductor and three capacitors as external components. The prototype chip is fabricated in 180-nm CMOS technology and occupies an on-chip area of 1.65 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , including startup.