The most common method for the electrical steel sheet characterization uses the Epstein frame. However, in the case of high-temperature characterization, the standard Epstein frame is not adapted. This paper deals with the design of a frame adapted to high temperature, up to 600 °C. In a first step, the results at ambient temperature obtained between the normalized Epstein frame and the high-temperature device for different frequencies are compared in order to validate the new frame. The second step is dedicated to the characterization of soft ferromagnetic materials in high temperature, up to 600 °C and for different frequencies. Moreover, the effect of sheet thickness on their behavior has been studied at high temperatures. The obtained measurement results confirm the strong influence of both temperature and thickness on power losses.

In order to utilise PZT thin films for MEMS applications it is essential to optimise the d ₃₁ coefficient in order to maximise actuation efficiency. The d ₃₁ coefficient, which can be optimised by the poling process, should be different for films of different orientation. PZT thin films of , and have been deposited onto platinised silicon, their d ₃₁ coefficient measured and their effectiveness as microactuators compared and evaluated.

The increase of the operating temperature of electrical machines is a major challenge in the context of the large-scale use of electricity in many industrial or individual applications such as mobility. Indeed, working at higher temperatures makes it possible to place electrical actuators in critical areas – such as aircraft engines, for example – and/or to significantly improve the power-to-weight ratio of the machine. For several applications (deep pumping, ventilation, etc.), the use of the induction machine is still preferred due to cost, simplicity and robustness essentially. The objective of this study is to estimate the possibilities of making a high-temperature squirrel cage induction machine. A significant increase in the operating temperature of a machine would indirectly allow us to envisage an increase in the current density in the active conductors and thus a significant improvement in the power-to-weight ratio. However, this is at the sacrifice of efficiency. The aim of this study is to evaluate this decrease in efficiency correlated with the increase in the temperature to find the best compromise according to the relevant applications. An analytic sizing model has been proposed for the prediction of losses, which will be coupled with a thermal model to predict the temperature in different parts of the machine. This study presents essential information on the influence of temperature on the parameters important for the performance of an induction machine.

The requirement for electrical machines operating at extremely high temperatures has prompted researchers to focus on new materials. The use of nickel-coated copper (Cu/Ni) wires can be a promising alternative to copper wires because of their resistance to oxidation at high temperatures. In this paper, the characterization of Cu/Ni wires’ electrical resistance in the frequency domain as well as the measurement of pure nickel’s B(H) curve have been specified. The effect of nickel-coated on a copper wire is remarkable in terms of electrical resistance at high frequencies because of the skin effect and eddy currents. An original model has been proposed for the prediction of the electrical resistance. The originality is to consider the bimetallic conductor as a transformer in order to generate its model. Since the analytical calculation is not possible because of the non-linearity of nickel’s magnetic properties, a new numerical computational method for the determination of the impedances was proposed. The modeling results are correlated with the experimental tests made on 3 Cu/Ni wires: 0.3mm diameter with 27% of nickel in volume and 0.5mm diameter with 8 μm and 18 μm nickel thickness. The study thus provides essential information about the important parameters for the performance of electrical machines.

Electrical machines are commonly used in industries and transport and are manufactured with enameled wire coils with polymer insulation. In extreme conditions, as in aeronautics and aerospace, where temperatures exceed 280 °C, the organic insulation deteriorates and it is necessary to find another way to insulate winding wires, in order to ensure a longer life duration of the insulation system and a better operating reliability of electric motors in these environments. Ceramics are more resistant to high temperatures than polymers and the proposed study focuses on the temperature dependence of the dielectric properties of anodized aluminum strips for use in high-temperature electrical machine windings. Different dielectric parameters are measured during thermal constraint. The purpose is to determine the temperature index of the anodized strip and propose a thermal stress life model.

Piezoelectric thin films of PZT have been deposited using r.f. magnetron sputtering onto silicon substrates and cantilevers fabricated using chemical etching and photolithography. These micro-actuators are unobtrusive and are able to work over a wide bandwidth at low voltage. Results are presented for such a system.