Abstract. This paper deals with an electrical modelling and optimization of a thermal energy harvester dedicated to power autonomous systems. Such devices based on bimetal strips and piezoceramics turn thermal gradients into electricity by a two-step conversion mechanism. This work focuses first on a demonstration of a ST-WSN (GreenNet demonstration platform) supplied by the harvester to validate, for the first time, the harvesters viability. That demonstration focuses attention on the need for an optimized power management circuit for piezoelectric generators able to reach output voltages up to 20V. The work deals then with the proposal of an equivalent lumped element model of the piezoelectric transducer with its SPICE implementation to enable the optimization of a dedicated power management circuit based on the Pulsed Synchronous Charge Extractor (PSCE). Simulations using the SPICE model and the power management circuit lead to an increased extracted power by 144%. IntroductionThe field of energy harvesting has become a predominant research area, especially, with the development of wireless sensors and communication node networks. Industrial and health monitoring, smart buildings, internet of things, these are some domains where node networks can be widely used. However, the impractical aspect of wired systems and the problems related to the power supply by short-lifetime batteries are raised for those applications. This brought attention on ambient energy harvesters and explains the great interest in energy scavenging devices over the last years. In this paper, a thermal energy harvester previously presented in [1,2,3] is studied. The harvester is based on coupling a bimetal to a piezoelectric transducer where a two-step conversion mechanism occurs. The heat flowing through the bimetal strip is converted into mechanical oscillations insuring the thermo-mechanical conversion; the second step consists in the conversion of the bimetallic strip impacts into electricity by a piezoelectric transducer. A bimetal strip is characterized by two equilibrium positions as shown in Fig. 1(a). Due to the bimetal thermo-mechanical bi-stability explained in [4], the bimetal snaps up and hits the piezoelectric membrane once its temperature raises and reaches a threshold temperature called the snap-up temperature. At that point, the bimetal is at its upper-position and releases a part of its energy to the piezoelectric. While being in contact with the piezoelectric acting as a cold surface, the temperature of the bimetal decreases until it reaches a certain snapping-back temperature that makes it switch-back to its initial

For electromagnetic interaction analysis in power electronics, the study and the design of Near-Field integrated magnetic antennas are presented. An antenna model is developed and compared to experimental data. The modeling and the performances of the prototype is discussed in function of the source position and the antenna design.

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This study deals with near-field probes integration onto power electronic modules for the magnetic field measurement. In this paper, electromagnetic disturbances characterization is investigated. A loop-antenna-type, its design and its modeling are detailed. The measurement obtained on a buck power converter are presented. An analysis of conducted currents within the power module is developed. Based on them, it is shown that the probe measurements allow recovering the characteristics and the distribution of the electromagnetic disturbances.