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The purpose of this paper is to present an optimal sizing methodology. It is applied to a foil-coil powder core power inductor used in new generation inverters designed for hybrid and full-electric vehicles. The methodology includes a preliminary analytical calculation and a numerical optimization aimed at minimizing the component size.

Unlike bulk magnetic alloys or ferrites, the magnetic non-linearity of powder materials cannot be neglected in the analytical calculation. This non-linearity requires the use of an iterative calculation to search the set of parameters for which the target inductance value and the minimum volume are simultaneously reached. The numerical optimization process is based on 2D Finite Element (FE) analysis carried out with FEMM software tool and a simplex-type algorithm run in Scilab software. These two freewares are coupled using the scifemm.sci script which is included in the FEMM distribution.

The association of analytical and FE approaches provides a relevant and quick sizing methodology. It was successfully applied to size a new power inductor.

The strong non-linearity of the powder material is correctly taken into account in the analytical model thanks to an iterative calculation process. Thus, the preliminary analytical solution is quite relevant. Consequently, a local FE-based optimization is enough to find the optimal solution close by the analytical one. No global optimization is required. A local optimum is sufficient.

The starting hesitation of a switched reluctance motor (SRM) is an issue which must be considered in the early motor design. It is mostly handled as a control concern. The starting procedure of a SRM using a single Hall-effect position sensor is analysed in this paper. This low cost position measurement solution requires a specific control strategy. That has been developed for a three-phase 6/4 SRM. The paper aims to discuss these issues.

The starting procedure begins with a rotor alignment step intending to bring the rotor to a known position. Afterward, only one phase is supplied on a periodic basis, to drive the rotor in the desired direction and accelerate up to a predefined speed threshold. Thus, the proposed procedure drastically simplifies the control strategy and permits a low cost sensor based control. 2D finite elements simulations are performed to analyse the starting performances in terms of response time and power efficiency. Both electrical and mechanical transients are considered in the simulation model thanks to simplifying assumption which consists in applying a time averaged voltages instead of instantaneous switching. Finally, the entire starting procedure with a one phase supply procedure is tested experimentally.

A starting procedure of a three-phase SRM is implemented. The control effectiveness is validated by complementary FE calculations and measurements.

The starting hesitation issue of a three-phase SRM is solved with an easy control strategy. During the acceleration phase, only one phase is self-controlled.