• Energy Research

Accurately calculating the losses of ferromagnetic materials is crucial for optimizing the design and ensuring the safe operation of electrical equipment such as motors and power transformers. Commonly used loss calculation models include the Bertotti empirical formula and hysteresis models. In this paper, a new hybrid hysteresis model method is proposed to calculate losses—namely, the combination of the Jiles–Atherton hysteresis model (J–A) and the Fourier hysteresis model. The traditional Jiles–Atherton hysteresis model is mainly suitable for fitting the saturation hysteresis loop, but the fitting error is relatively large for internal minor hysteresis loops. In contrast, the Fourier hysteresis model is suitable for fitting the minor hysteresis loops because the corresponding magnetic induction strength or magnetic field is lower and the waveform distortion is small. Moreover, Fourier series expansion can be expressed with fewer terms, which is convenient for parameter fitting. Through examples, the results show that the hybrid hysteresis model can take advantage of the strengths of each model, not only reducing computational complexity, but also ensuring high fitting accuracy and loss calculation accuracy.

This paper presents the finite element analysis of a magnetoelectric energy harvester using a laminate composite constituted of laminated piezoelectric and magnetostrictive layers. In this study, both the nonlinear characteristics of the material and the dependency on the load impedance are considered. The multiphysics problem involving different physics equations is solved through a strongly coupled model. The nonlinear magnetostrictive behavior is considered using the Newton-Raphson method for various magnetic biases. The electrical circuit equation is incorporated in the finite element equations for the analysis load effect. The obtained results show a good concordance with the measurements and with those obtained by other analytical methods.

Abstract This paper presents the multiphysics modeling of a Rosen-type device using a magnetoelectric (ME) composite, which has hybrid sensor and energy transducer functions. The modeling of such a multiphysics problem involves magnetic, mechanical and magnetic phenomena and is strongly coupled using the finite element method (FEM). To take into account the impact of the impedance connected to the device ports, the system equation is also coupled to the electrical circuit equation. A good concordance is obtained in harmonic regime between the simulation results and the experiment ones available in the literature. The simulation results put in evidence that the input impedance of the dynamic signal analyzer, when it is used to monitor the output voltage of the sensor part, implicates an alteration of the frequency resonance. The high output voltage coefficient of the sensor and the significant deliverable power of the energy transducer make the ME Rosen-type device an ideal candidate for hybrid magnetic sensing and energy harvesting or wireless powering applications.

In the context of wireless and autonomous sensors, this paper presents the multiphysics modeling of an energy transducer based on magnetoelectric (ME) composite for biomedical applications. The study considers the power requirement of an implanted sensor, the communication distance, the size limit of the device for minimal invasive insertion as well as the electromagnetic exposure restriction of the human body. To minimize the electromagnetic absorption by the human body, the energy source is provided by an external reader emitting low frequency magnetic field. The modeling is carried out with the finite element method by solving simultaneously the multiple physics problems including the electric load of the conditioning circuit. The simulation results show that with the T–L mode of a trilayer laminated ME composite, the transducer can deliver the required energy in respecting different constraints.

In this paper, a priori model reduction methods via low-rank tensor approximation are introduced for the parametric study of a piezoelectric energy harvester (EH). The EH, composed of a cantilevered piezoelectric bimorph connected with electrical loads, is modeled using 3-D finite elements (FEs). Solving the model for various excitation frequencies and electrical load using the conventional approach results in a large size problem that is costly in terms of CPU time. We propose an approach based on the proper generalized decomposition (PGD) that can effectively reduce the problem size with a good accuracy of the solutions. With the proposed approach, field variables of the coupled problem are decomposed into space, frequency, and electrical load associated components. To introduce PGD into the FE model, a method to model the electrodes and electrical charges in the EH is presented. Appropriate choices for stopping criterions in the method and accelerating the convergence through updating after each enrichment are investigated. The proposed method is validated through a representative numerical example.

In this study, we present the fabrication and characterization of Ni/LiNbO 3 /Ni trilayers using rf sputtering. These trilayers exhibit thick Ni layers (10 µm) and excellent adherence to the substrate, enabling high magnetoelectric coefficients. By engineering the magnetic anisotropy of nickel through anisotropic thermal residual stress induced during fabrication, and by selecting a carefully chosen cut angle for the LiNbO 3 substrate, we achieved self-biased behavior. We demonstrate that these trilayers can power medical implant devices remotely using excitation by a small ac magnetic field, thereby eliminating the need for a dc magnetic field and bulky magnetic field sources. The results highlight the potential of these trilayers for the wireless and noninvasive powering of medical implants. This work contributes to the advancement of magnetoelectric materials and their applications in healthcare technology.

Abstract This paper presents experiment results of an energy transducer based on the magnetoelectric composites. Various configurations of the layered structure composed of the Terfenol-D or/and the Metglas with the PZT-5H have been investigated. The impact of Metglas on the performance of the transducer is outlined. The high output voltage coefficient and the significant deliverable power of the combination Terfenol-D/Metglas/PZT-5H makes it as an ideal energy transducer candidate for wireless powering of embedded device in biomedical applications.