This paper presents a new technique for optimized energy harvesting using piezoelectric microgenerators called double synchronized switch harvesting (DSSH). This technique consists of a nonlinear treatment of the output voltage of the piezoelectric element. It also integrates an intermediate switching stage that ensures an optimal harvested power whatever the load connected to the microgenerator. Theoretical developments are presented considering either constant vibration magnitude, constant driving force, or independent extraction. Then experimental measurements are carried out to validate the theoretical predictions. This technique exhibits a constant output power for a wide range of load connected to the microgenerator. In addition, the extracted power obtained using such a technique allows a gain up to 500% in terms of maximal power output compared with the standard energy harvesting method. It is also shown that such a technique allows a fine-tuning of the trade-off between vibration damping and energy harvesting.

Harvesting energy from ambient sources has become of great importance these last few years. This can be explained not only by advances in microlectronics and energy harvesting technologies, but also by a growing industrial demand in wireless autonomous devices. In this field, piezoelectric elements offer outstanding performances, thanks to their high power density that makes them suitable for integrated microgenerators. However, such a domain still offers challenges to the research community. Particularly, embedding piezoelectric inserts as MEMS components raises the issue of low voltage output. Classical energy harvesting interfaces that feature bridge rectifier suffer from threshold voltage introduced by such discrete components, therefore compromising their use in real-life applications. In this paper is presented a new energy harvesting circuit that operates with ultralow voltage output, by the use of a magnetic voltage rectifier that does not present significant voltage gap. Experimental measurements performed on a simple transducer confirm theoretical predictions, and show that the proposed architecture operates well even for low-level vibrations, outperforming all known energy interfaces. Particularly, it is theoretically and experimentally shown that such an interface provides a gain greater than 50 compared to classical energy harvesting structures.

This paper presents an integrated optimal Energy Management Strategy (EMS) and sizing of a high-speed Flywheel Energy Storage System (FESS) in a battery electric vehicle (EV). The methodology aims at extending the battery cycle life and drive range by relegating fast dynamics of the power demand to the FESS. For the EMS, the battery power and FESS energy are considered as weighted objectives of an optimization problem that are established using Pontryagin's Minimum Principle (PMP). In order to derive the optimal FESS size, the sizing algorithm is targeted to minimize the battery degradation level and increase the FESS energy interaction with the system. The performance of the proposed methodology is assessed using some driving cycles including ECE-15, UDDC, HWFET, and US06. Comparing the proposed battery/FESS to the battery-only topology, the battery SoH and life cycle are improved considerably for different driving cycles.