Dual Storage Power Management for Energy Autonomous Microsystems

A major challenge towards enabling energy autonomous microsystems is cold-starting, especially in real use case environments which are often uncertain and involve long inactivity periods. In this article, a dual supercapacitor storage power management architecture is proposed, with the primary storage capacitor providing fast start-up and the secondary providing a large energy buffer. The circuit introduces a combination of a MOSFET switch and a buck converter that can handle efficient charge transport and eliminate leakage between the two storage capacitors, leading to faster cold starting. A start-up time reduction of more than two orders of magnitude over conventional solutions is experimentally demonstrated, for a 1.5 mF/470 mF supercapacitor combination, without a compromise in overall efficiency. The various functional modes of the system are experimentally analyzed, using an inductive power line energy harvester with currents that correspond to an industrially defined aircraft sensor use case. For example, 11 mW and 32 mW regulated output was measured from a 10 A and 15 A rms, 500 Hz power line, respectively. The architecture is configurable and can be dynamically parametrized and controlled to optimize power routing according to functional priorities by the microcontroller of the powered system.