Renewable Energy Development Center

The advancement of power electronics in recent years is largely attributed to the development of semiconductor components and new architectures for energy conversion systems. Among these, multicellular converters — which use a series connection of elementary switching cells — have gained significant attention This connection enables higher power processing without increasing stress on the switches, while also improving the output signal quality. However, managing the voltages across floating capacitors in these systems requires precise control. This paper proposes a hybrid modeling and control approach for a multicellular converter with three cells. The hybrid automaton model integrates both continuous and discrete dynamics, making it an effective tool for modeling power electronic systems with Boolean control inputs. Simulation results highlight the effectiveness of the proposed hybrid approach in overcoming voltage control and operational complexities in multicellular converters. By providing a novel solution to voltage control challenges, this modeling framework paves the way for advanced control solutions in power electronics applications. The findings demonstrate notable improvements in efficiency and response times, reinforcing the potential of hybrid modeling in optimizing power electronic systems.

This study presents the structural analysis and optimization of an external hydraulic gear pump with the aim of improving mechanical performance while reducing material usage and overall mass. The work addresses two main aspects: optimization of the pump casing and optimization of the internal gears. The geometric model was constructed in SolidWorks with fully parameterized dimensions to enable an efficient optimization workflow. Finite Element Analysis (FEA) in ANSYS Workbench was used to evaluate stress and deformation under realistic operating conditions. For the pump casing, simulation results were integrated into a Response Surface Methodology (RSM) framework to assess the influence of geometric parameters on structural behavior. The optimized casing achieved a 9.5% weight reduction while ensuring structural integrity, with a maximum deformation of 0.031 mm, a maximum stress of 127 MPa, and a safety factor of 3. The efficiency-to-mass ratio improved from 7.9 to 8.8. In parallel, optimization of the gear pair focused on minimizing stress concentrations and improving stiffness. Using ANSYS simulations combined with RSM, the optimized gear design reduced von Mises stress from 239.4 MPa to 224 MPa, reflecting better load distribution and enhanced durability. Overall, the results demonstrate the effectiveness of integrating finite element simulation with response surface optimization to achieve structural and performance improvements in hydraulic gear pumps.

The main objective of this work is devoted to the microencapsulation process by the complex coacervation using two types of natural polymer namely sodium alginate and gelatin to encapsulate a pharmaceutical active ingredient of the “Diclofenac” family of analgesics and to prolong its release in vivo. In a first step, the influence of physicochemical parameters on the existing interactions between both polymers has been studied. The effects of pH, Pr : Ps (Protein: polysaccharide) ratio and the addition of salt concentration through the particle size and Zetametry by the dynamic light scattering technique, make it possible to experimentally limit the optimal domain of coacervate formation; which is used to formulate the Diclofenac-based microparticles. The results revealed a great influence of pH on the formation of the P r:Ps complex with an impact on the mean diameter (D42). The latter recorded a clear increase, with a decrease in the electro-kinetic potential reflecting the neutralization of the charges at pH 3.5-4. The results also showed a better coacervation (interaction between the polymers) for ratios of alginate / gelatin equal to 4/1 and 3/1. The formulation of microparticles based on Diclofenac by coacervation was subsequently characterized on the technical (size and texture) and biopharmaceutical levels, which revealed a prolonged type release of 8 h.