Magnetic Properties in Finemet-Type Soft Magnetic Toroidal Cores Annealed under Radial Stresses

Applying tensile stresses on straight soft magnetic ribbons before core fabrication is a routine method of inducing magnetic anisotropy, while methods of stress annealing of ribbons after core winding are seldom explored. In this study, we utilize a novel approach to induce magnetic anisotropy by applying radial stresses on tape-wound cores of Fe73.5Si13.5B9Cu3Nb1 (at. %) ribbon during crystallization heat treatment. The results show that while stress annealing does not change the structural characteristics of annealed samples, the magnetic anisotropies induced can increase to values ~3–5 times larger than the sample annealed in the absence of external stress. This increase in magnetic anisotropy energy is associated with ~25–50% decrease of magnetic inductance in the treated cores. These results suggest that the magnetic properties of nanocrystalline soft magnetic alloys can be effectively tuned by applying radial stresses.

Influence of Parasitic Parameters on DC–DC Converters and Their Method of Suppression in High Frequency Link 35 kV PV Systems

Photovoltaic (PV) power generation has shown a trend towards large-scale medium- or high-voltage integration in recent years. The development of high-frequency link PV systems is necessary for the further improvement of system efficiency and the reduction of system cost. In the system, high-frequency high-step-up ratio LLC converters are one of the most important parts. However, the parasitic parameters of devices lead to a loss of zero-voltage switching (ZVS) in the LLC converter, greatly reducing the efficiency of the system, especially in such a high-frequency application. In this paper, a high-frequency link 35 kV PV system is presented. To suppress the influences of parasitic parameters in the LLC converter in the 35 kV PV system, the influence of parasitic parameters on ZVS is analyzed and expounded. Then, a suppression method is proposed to promote the realization of ZVS. This method adds a saturable inductor on the secondary side to achieve ZVS. The saturable inductor can effectively prevent the parasitic elements of the secondary side from participating in the resonance of the primary side. The experimental results show that this method achieves a higher efficiency than the traditional method by reducing the magnetic inductance.

The Important Thermal and Kinetic Properties of Crystals and Their Calculations with the Use of the Gibbs Potentials

In this work, the important thermal and kinetic characteristics of crystals are calculated. It was shown that in a state of thermodynamic equilibrium, the thermal properties of crystals are additive, and their value for an entire crystal is calculated by summing the values of thermal properties of the crystal lattice and the properties of the gas of free charge carriers in a crystal. These properties are fully characterized by the appropriate Gibbs potentials. In this work it was also shown that when the electric field E and temperature gradient ΔrT are created in a crystal, and this crystal is placed in the magnetic field with the magnetic inductance vector B, then there the electric charge and heat transport processes begin to exist in the crystal. These processes are described by the generalized electric and heat conduction equations. The tensors and the scalar coefficients in these equations – these are the kinetic properties of the crystals. They describe the nature of their actual properties and they have widespread and pragmatic applications in modern solid-state electronics

Stink or swim: techniques to meet the challenges for the study and conservation of small critters that hide, swim, or climb, and may otherwise make themselves unpleasant

The study of musteloids requires different perspectives and techniques than those needed for most mammals. Musteloids are generally small yet travel long distances and many live or forage underground or under water, limiting the use of telemetry and direct observation. Some are arboreal and nocturnal, facilitating telemetry but limiting observation, trapping, and many non-invasive techniques. Large sexual size dimorphism arguably doubles sample sizes for many research questions. Many musteloids defend themselves by expelling noxious chemicals. This obscure group does not attract funding, even when endangered, further reducing rate of knowledge gain. Nonetheless, passive and active radio frequency identification tags, magnetic-inductance tracking, accelerometers, mini-biologgers and some GPS tags are tiny enough for use with small musteloids. Environmental DNA can document presence of animals rarely seen. These technologies, coupled with creative research design that is well-grounded on the scientific method, form a multi-dimensional approach for advancing our understanding of these charismatic minifauna.

nanoSQUID operation using kinetic rather than magnetic induction

We report on a method of nanoSQUID modulation which uses kinetic inductance rather than magnetic inductance to manip-ulate the internal fluxoid state. We produced modulation using injected current rather than an applied magnetic field. Using this injected current, we were able to observe the triangle-wave shaped modulation of the device critical current which was periodic according to the London fluxoid quantization condition. The measurement results also confirmed that the fluxoid state inside a superconducting loop can be manipulated using primarily kinetic inductance. By using primarily kinetic inductance rather than magnetic inductance, the size of the coupling inductor was reduced by a factor of 10. As a result, this approach may provide a means to reduce the size of SQUID-based superconducting electronics. Additionally, this method provides a convenient way to perform kinetic inductance characterizations of superconducting thin films.

An Accurate Mathematic Model for PMSM by Taking Total Losses and Saturation into Account

An accurate mathematic model of permanent magnet synchronous motor (PMSM) is necessary for precise torque control and/or high efficiency drive control. This paper discusses the development model of PMSM by taking all losses and saturation into account. In the proposed model, all losses composing of the copper loss, core loss, mechanical loss and stray loss were analyzed to improve the torque equation. In addition, considering the influence of saturation level, the variations of the core loss resistance, direct-quadrature axis magnetic inductance and permanent magnet flux were discussed on support of the data analyzed by Ansoft. In order to verify the developed model, a start up simulation is performed in the mode of open-loop and the results confirm the validity of the model.

Electric vehicle wireless charging technology: a state-of-the-art review of magnetic coupling systems

Electric vehicles (EVs) are becoming more popular due to concerns about the environment and rising gasoline prices. However, the charging infrastructure is lacking, and most people can only charge their EVs at home if they remember to plug in their cars. Using the principles of magnetic inductance and magnetic resonance, wireless charging (WC) could help significantly with these infrastructure problems by making charging secure and convenient. WC systems also have the potential to provide dynamic charging, making long road trips with EVs feasible and eliminating range anxiety. In this paper, we review the companies available in the literature that have developed electric vehicle wireless charging systems, automobile manufacturers interested in such technology, and research from universities and laboratories on the topic. While the field is still very young, there are many promising technologies available today. Some systems have already been in use for years, recharging public transit buses at bus stops. Safety and regulations are also discussed.