Power and frequency bandwidth improvement of piezoelectric energy harvesting devices using phase-shifted synchronous electric charge extraction interface circuit

Lefeuvre, Elie,Badel, Adrien,Brenes, Alexis,Seok, Seonho,Yoo, Chan-Sei Sage Science Press (UK) 2017 Journal of intelligent material systems and struct Vol. No.

Analysis of piezoelectric energy harvesting system with tunable SECE interface

Lefeuvre, E,Badel, A,Brenes, A,Seok, S,Woytasik, M,Yoo, C-S Institute of Physics Publishing 2017 Smart materials & structures Vol.26 No.3

<P>Numerous interface circuits have been proposed over the past years to improve the performances of piezoelectric energy harvesting devices. The so-called synchronous electric charge extraction interface (SECE) brought the advantage of harvesting power independently of the load voltage. In counterpart, its performances exhibited sensitivity to the electromechanical coupling. It was shown, in particular, that harvested power was significantly decreased at high coupling. To overcome this drawback, the so-called tunable SECE interface has recently been proposed. Instead of the total charge extraction performed by the original SECE, the tuning method consists in extracting only a portion of the electric charge. This paper presents the analytical modeling of an energy harvesting system composed of a linear piezoelectric resonator associated to the tunable SECE interface. Contrary to previous model limited to describe the system behavior at resonance, this model enables to extend the analysis off-resonance. The presented theoretical analysis and experimental results clearly show the possibility to increase both the power and the frequency bandwidth by adequate control of the tunable SECE interface.</P>

Xanthomonas axonopodis pv. eucalyptorum pv. nov. Causing Bacterial Leaf Blight on Eucalypt in Brazil

Ferraz, Helvio Gledson Maciel,Badel, Jorge Luis,da Silva Guimaraes, Lucio Mauro,Reis, Bruna Paolinelli,Totola, Marcos Rogerio,Goncalves, Rivadalve Coelho,Alfenas, Acelino Couto The Korean Society of Plant Pathology 2018 Plant Pathology Journal Vol.34 No.4

Bacterial leaf blight is a major disease of eucalypt, especially under nursery conditions. Different bacterial species have been associated with the disease in several countries, and despite its importance worldwide, it is not clear to date whether similar disease symptoms are caused by the same or by different etiological agents. In this study, 43 bacterial strains were isolated from blighted eucalypt leaves collected in different geographic areas of Brazil and inoculated onto a susceptible eucalypt clone. Polyphasic taxonomy, including morphological, physiological, biochemical, molecular, and pathogenicity tests showed that only certain strains of Xanthomonas axonopodis caused symptoms of the disease. Strains varied in their aggressiveness, but no correlation with geographic origin was observed. MLSA-based phylogenetic analysis using concatenated dnaK, fyuA, gyrB and rpoD gene sequences allocated the strains in a well-defined clade, corresponding to Rademarker's group RG 9.6. Inoculation of nineteen plant species belonging to seven botanical families with representative strain LPF 602 showed it to be pathogenic only on Eucalyptus spp, and Corymbia spp. Based on distinct biochemical and pathogenic characteristics that differentiate the eucalypt strains from other pathovars of the X. axonopodis species, here we propose their allocation into the new pathovar X. axonopodis pv. eucalyptorum pv. nov.

Shunt-diode rectifier: a new scheme for efficient piezoelectric energy harvesting

Brenes, Alexis,Lefeuvre, Elie,Badel, Adrien,Seok, Seonho,Yoo, Chan-Sei Institute of Physics Publishing 2019 Smart materials & structures Vol.28 No.1

<P>This paper highlights the interest of shunt-diode rectifiers to optimize the performances of piezoelectric vibration energy harvesters based on linear load adaptation. It provides, for the first time, a full analytical study of the input power and frequency bandwidth of such a system. We show that this architecture is well-suited for piezoelectric energy harvesting. In the presented approach, a so-called shunt diode is connected across the electrodes of the piezoelectric transducer, which makes the piezoelectric voltage unidirectional instead of alternating. Thus, DC–DC converters usually used for power optimization can be directly connected to the transducer. We show that weakly-coupled linear inertial piezoelectric energy harvesters generate higher power when connected to a shunt-diode rectifier than to a bridge rectifier. Moreover, the frequency bandwidth is enlarged by the use of the single-diode shunt rectifier, especially for strongly-coupled piezoelectric generators. The proposed architecture is also interesting for low piezoelectric voltages, at which voltage drops across the diodes used for AC–DC conversion critically degrade the power efficiency. Experimental results validate the presented analytical study and highlight the higher efficiency of the shunt-diode rectifier circuit. Compared to a standard bridge rectifier architecture, we demonstrate an increase of +43% output power on a weakly-coupled generator and an increase of +5% bandwidth on a strongly-coupled generator.</P>

Unipolar synchronized electric charge extraction for piezoelectric energy harvesting

Brenes, Alexis,Lefeuvre, Elie,Badel, Adrien,Seok, Seonho,Yoo, Chan-Sei Institute of Physics Publishing 2018 Smart materials & structures Vol.27 No.7

<P>This paper highlights the interest of a shunt rectifier to improve the efficiency of the synchronized electric charge extraction (SECE) circuit formerly developed for piezoelectric energy harvesters. Compared to the classical SECE circuit, which requires a full-bridge rectifier, the proposed architecture is especially interesting for low-amplitude vibrations generating a low piezoelectric voltage, typically lower than 2 V RMS. We provide a full analytical study validated by experimental measurements to illustrate the high performance of the so-called unipolar SECE (USECE) as well as the impact of the resonator characteristics on the overall performance of the harvester. We also propose a model including the main causes of power dissipation, which is validated experimentally, showing that the power efficiency of the circuit is much less dependent on the vibration frequency and magnitude than classical SECE. The proposed architecture combines the high input power of SECE with the high power efficiency resulting from unipolar operation, reaching more than 75% power efficiency in situations where classical SECE is limited to an efficiency lower than 35%. Our experimental results show an increase of +200% output power obtained with USECE compared to classical SECE, which is due to the combination of a higher input power and a higher power efficiency of the proposed circuit.</P>

Xanthomonas axonopodis pv. eucalyptorum pv. nov. Causing Bacterial Leaf Blight on Eucalypt in Brazil

Hélvio Gledson Maciel Ferraz,Jorge Luis Badel,Lúcio Mauro da Silva Guimarães,Bruna Paolinelli Reis,Marcos Rogério Tótola,Rivadalve Coelho Gonçalves,Acelino Couto Alfenas 한국식물병리학회 2018 Plant Pathology Journal Vol.34 No.4

Bacterial leaf blight is a major disease of eucalypt, especially under nursery conditions. Different bacterial species have been associated with the disease in several countries, and despite its importance worldwide, it is not clear to date whether similar disease symptoms are caused by the same or by different etiological agents. In this study, 43 bacterial strains were isolated from blighted eucalypt leaves collected in different geographic areas of Brazil and inoculated onto a susceptible eucalypt clone. Polyphasic taxonomy, including morphological, physiological, biochemical, molecular, and pathogenicity tests showed that only certain strains of Xanthomonas axonopodis caused symptoms of the disease. Strains varied in their aggressiveness, but no correlation with geographic origin was observed. MLSA-based phylogenetic analysis using concatenated dnaK, fyuA, gyrB and rpoD gene sequences allocated the strains in a well-defined clade, corresponding to Rademarker’s group RG 9.6. Inoculation of nineteen plant species belonging to seven botanical families with representative strain LPF 602 showed it to be pathogenic only on Eucalyptus spp, and Corymbia spp. Based on distinct biochemical and pathogenic characteristics that differentiate the eucalypt strains from other pathovars of the X. axonopodis species, here we propose their allocation into the new pathovar X. axonopodis pv. eucalyptorum pv. nov.