This paper is a pre-print. This is an author-created, un-copyedited version of an article accepted by IEEE for NEWCAS'2015 conference. IEEE is not responsible for any errors or omissions in this version of the manuscript or any version derived from it. © 2015 IEEE. Personal use of this material is permitted. Permission from IEEE must be obtained for all other users, including reprinting/ republishing this material for advertising or promotional purposes, creating new collective works for resale or redistribution to servers or lists, or reuse of any copyrighted components of this work in other works. Please cite as: S Boisseau et al., Synchronous Electric Charge Extraction for Multiple Piezoelectric Energy Harvesters, Proc. NEWCAS, 2015. Synchronous Electric Charge Extraction for Multiple Piezoelectric Energy Harvesters S. Boisseau, P. Gasnier, M. Perez, C. Bouvard, M. Geisler, A.B. Duret, G. Despesse, J. Willemin CEA, LETI, Minatec Campus 17, rue des Martyrs - F-38054 Grenoble Cedex 9, France sebastien.boisseau@cea.fr Abstract—This paper presents a power management circuit implementing a Synchronous Electric Charge Extraction on piezoelectric energy harvesters based on a flyback architecture. The novelty of this circuit lies in its ability to handle multiple energy harvesters operating at different frequencies and different output voltages with a single and standard flyback coupled inductor. The power harvested by the various scavengers is stored in a single and mutual storage capacitor. By construction, the power management circuit is capable of dealing with high input voltages (>100V). Its power consumption is about 1.15μA@3V per energy harvester and its conversion efficiency reaches 83%; its good operation has been validated by simulations and experiments on two vibration energy harvesters. Keywords—Energy Harvesting; Power Management; Piezoelectric Energy Harvesters; Synchronous Electric Charge Extraction (SECE) I. INTRODUCTION Mechanical Energy Harvesting is a relevant candidate to supply Wireless Sensor Nodes (WSN) and especially in dark or dusty environments. Various concepts have been proposed to turn the power of vibrations, shocks, strains or movements of rotations into electricity to make sensor nodes fully autonomous for years. The three main electromechanical conversion principles have been implemented: electrostatic [1], piezoelectricity [2] and electromagnetism [3]; this paper is focused on the piezoelectric conversion. The output power of piezoelectric energy harvesters is generally in the 10μW- 100μW range and it has already been proven that this is enough to supply basic WSN. Yet, it is interesting to harvest more power to supply more complex WSN or to increase their operating frequency. One solution to increase the harvested power consists in multiplying the number of energy harvesters. Although the parallelization of energy harvesters has been proposed in various papers [4], only few efficient power management circuits have been proposed until now to handle multiple piezoelectric energy harvesters [5, 6]. This paper presents a power management circuit, based on a flyback topology, and implementing Synchronous Electric Charge Extraction (SECE) for multiple piezoelectric energy harvesters. SECE has already proven its benefits for single piezoelectric energy harvesters. Here, SECE is adapted to multiple energy harvesters with the aim of mutualizing the inductive circuit. The circuit is based on discrete components and able to deal with high input voltages by construction (>100V). Only basic electronic functions are employed to limit the power consumption of the circuit. Section 2 reminds SECE and the flyback topology which has been chosen. Section 3 introduces the power management circuit able to manage multiple piezoelectric energy harvesters. Simulation and experiments results are finally presented in Section 4. II. SYNCHRONOUS ELECTRIC CHARGE EXTRACTION AND FLYBACK TOPOLOGY A. Synchronous Electric Charge Extraction (SECE) Synchronous Electric Charge Extraction (SECE) [7] is a Synchronized Switch Harvesting (SSH) technique consisting in entirely extracting the energy stored in the piezoelectric energy harvester as soon as its output voltage (V p ) has reached its maximum (corresponding to an extremum of displacement of the energy harvester). This energy is then transferred to a storage capacitor through a coil (buck or buck-boost topology) or a coupled-inductor (flyback topology). The rest of the time, the energy harvester is let in open circuit. The typical waveforms of SECE applied to a piezoelectric energy harvester