Temperature dependence of spin resonance in cobalt substituted NiZnCu ferrites

Cobalt substitutions were investigated in Ni0.4Zn0.4Cu0.2Fe2O4 ferrites, initial complex permeability was then measured from 1 MHz to 1 GHz. It appears that cobalt substitution led to a decrease in the permeability and an increase in the \mus\timesfr factor. As well, it gave to the permeability spectrum a sharp resonance character. We also observed a spin reorientation occurring at a temperature depending on the cobalt content. Study of the complex permeability versus temperature highlighted that the most resonant character was obtained at this temperature. This shows that cobalt contribution to second order magnetocrystalline anisotropy plays a leading role at this temperature

Temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites

The temperature dependence of core loss in cobalt substituted Ni-Zn-Cu ferrites was investigated. Co2+ ions are known to lead to a compensation of the magneto-crystalline anisotropy in Ni-Zn ferrites, at a temperature depending on the cobalt content and the Ni/Zn ratio. We observed similar behaviour in Ni-Zn-Cu and it was found that the core loss goes through a minimum around this magneto-crystalline anisotropy compensation. Moreover, the anisotropy induced by the cobalt allowed a strong decrease of core loss, a ferrite having a core loss of 350 mW/cm3 at 80 ^\circ C was then developed (measured at 1.5 MHz and 25 mT). This result represents an improvement of a factor 4 compared to the state of art Ni-Zn ferrites

Effect of temperature and time on properties of Spark Plasma Sintered NiCuZn: Co ferrite

3 pagesInternational audienceSpark Plasma Sintering is a powerfal method to produce fine grain dense ferrite at low temperature. However, the process, usually conducted in neutral atmosphere in a carbon die, yields carbon surface deposition and reduction of Fe3+ into Fe2+. It's shown that subsequent annealing in air can remove carbon and, under some conditions, produce complete oxidation of Fe2+ ions. Regular values of the resistivity and permittivity (resp. 1 M­m, 13 "0) are recovered for most samples annealed not higher than 750±C. Relatively high value of the permeability (up to 240) and high merit factor (μs × fr > 5 GHz) have been achieved

Highly integrated power electronic converters using active devices embedded in printed-circuit board

International audienceIn this paper, we present a short overview of the power dies interconnects based on PCB technology, then we focus on embedding of power dies in the PCB material. In the second part of the article, we present in details the technology we developed to embed dies in PCB. Results show that the electrical performance of the die remains satisfying after embedding, but that dies with a copper topside metal layer are required for this process

Flexible serialized complementary coils for the detection of moving LF RFID tags

This paper focuses on bats detection, tagged at low frequency (134.2 kHz) with glasstags (typically : length 15 mm and radius 1 mm). The physical link is magnetic coupling. We propose the design of a reader antenna based on a multi-coil structure. The goal is to obtain the highest surface of detection, at a distance of 10-15 cm, i.e. defining a so called “volume of detection”. The cylindrical volume of the glasstags involves a high sensitivity to the magnetic field orientation. As the bats are flying, the tags equivalent surfaces are considered with a random orientation. Using complementary coils principle enables to detect fruitfully the glasstags in two perpendicular orientations named HM (horizontal mode) and VM (vertical mode). We propose the design of a flexible reader antenna structure by means of an adhesive copper tape fixed on a cloth. The prototype is designed after CST simulations and empirical formula evaluations. Measurements show a good agreement with the modelling and tests of detection are performed with the proposed reader antenna. By comparison with a commercial antenna, the prototype reaches the highest volume of detection in both HM and VM modes and fulfills the targeted distance of detection

Effet de la température et du temps de frittage sur les propriétés du ferrite NiCuZn :Co fritté avec le procédé Spark Plasma Sintering ( SPS ) et réalisation d'une inductance intégrès.

National audienceLe frittage du ferrite spinelle NiCuZn par le procédé Spark Plasma Sintering a été étudié pour une poudre nanométrique qui a été synthétisée préalablement par voie solide. Les propriétés structurales, diélectrique et magnétique pour ce ferrite ont été étudiées pour différentes valeurs de la température et du temps de frittage. Le matériau est bien densifié pour les différentes températures et temps de frittage. La résistivité du ferrite est assez élevée de l'ordre de 107 Ωm pour une température de frittage de 750 °C pendant 5 mn, la permittivité est proche de la littérature pour des températures inférieures à 750 °C et la perméabilité initiale est comprise entre 20 et 250. L'étude du cofrittage du ferrite avec le cuivre a montré que la diffusion à l'interface est très limitée, ce qui a permis de réaliser un composant intégré qui présente une inductance de 0,62 µH mais un facteur de qualité moyen dû au fait que le cuivre est directement noyé dans le ferrite

A nonlinear observer for DC Bus Voltage estimation and Sensor Diagnosis for a Battery Charger used in Automotive Systems

International audienc

Design of an Integrated Fast Battery Charger Controller on a FPGA Board

International audienceThis paper presents the implementation on a Field Programmable Gate Array (FPGA) of an integrated battery charger controller for Electrical Vehicle (EV) application. The control strategy is based on cascaded loops where the currents controllers of the inner loops are integrated on a FPGA and the voltage controller of the outer loop is implemented on a processor board. The aim is to take benefits from the two devices advantages. An advanced RST controller is used to control the sinusoidal currents. The FPGA simulation results are comparedto Matlab/Simulink simulations

Design of an Integrated Fast Battery Charger Controller on a FPGA Board

International audienceThis paper presents the implementation on a Field Programmable Gate Array (FPGA) of an integrated battery charger controller for Electrical Vehicle (EV) application. The control strategy is based on cascaded loops where the currents controllers of the inner loops are integrated on a FPGA and the voltage controller of the outer loop is implemented on a processor board. The aim is to take benefits from the two devices advantages. An advanced RST controller is used to control the sinusoidal currents. The FPGA simulation results are comparedto Matlab/Simulink simulations

Space Vector PWM Control Synthesis for a H-Bridge Drive in Electric Vehicles

International audienceThis paper deals with a synthesis of Space Vector PWM control methods applied for a H-bridge inverter feeding a 3-phase Permanent Magnet Synchronous Machine in Electric Vehicle application. First, a short survey of existing power converter architectures, especially those adapted to degraded operating modes, is presented. Standard SVPWM control methods are compared with three innovative ones using EV-drive specifications in the normal operating mode. Then, a rigorous analysis of the margins left in the control strategy is presented for a semiconductor switch failure to fulfill degraded operating modes. Finally, both classic and innovative strategies are implemented in numerical simulation; their results are analyzed and discussed