Souad Harmand

Thermal Topology Optimization of a Three-Layer Laminated Busbar for Power Converters

This paper focuses on a topology optimization method for laminated busbars in power converters that minimizes the quantity of copper used while keeping the temperature under the allowed limits. Busbars are widely studied for adding their stray inductance to the commutation loop, which causes surge voltage across the power devices. However, the study of heat dissipation is essential to control hotspots in the busbar and preserve the converter components. Current density and temperature are sensitive to shape modifications; hence, topology optimization based on multiphysics simulations is an aspect to be considered when designing prototypes for a good cost performance ratio. The temperature is calculated by an electrothermal two-dimensional (2-D) finite element method (FEM) superposition approach. Busbar plates are modeled in 2-D since the thickness is constant. Furthermore, the different layers are related by the thermal equations reproducing the heat transfers regarding the overlap in the laminated busbar. Simulation results are validated by experimental tests. Comparison with 3-D FEM proves the 2-D approach to be faster while remaining accurate and a perfect method for topology optimization resolutions, which are very time consuming for three-dimensional (3-D) geometries. The busbar topology optimization is made by maximizing the energy transfer with the environment and by varying the electric and thermal conductivities of the mesh elements. Optimization leads to more than 50% volume reduction.

Two-Phase Flow and Heat Transfer in Micro-Channels and Their Applications in Micro-System Cooling

Heat management in high thermal-density systems is confronting rising challenges due to the extremely high heat dissipation capacity requirement in ever more miniaturized and intensified processes. Efforts have been made for heat transfer enhancement. A number of heat transfer technologies including natural convention and radiation, forced convection, pool boiling, micro-channel flow boiling, heat pipes and capillary pumps were introduced. However, the drastically increasing heat transfer requirements are still calling for extensive experimental investigations, especially on the phase change processes in micro-scale. A review of the experimental studies on two-phase flow boiling and heat transfer in small flow passages was presented. Some experimental results published in the year 1993–2010 were overviewed, revealing some controversial conclusions on micro-scale flow boiling heat transfer mechanisms. Besides, several existing heat transfer correlations were assessed. It should be admitted that the existing database is still limited, especially for flow boiling in passages with unique geometries such as high-aspect-ratio cross section. Extensive explorations on two-phase flow boiling and heat transfer in micro-channels are essential for heat transfer predictions and applications in micro-systems.

Multiphysics topology optimization for laminated busbars

Laminated busbars acquire significant importance even if they are a passive component in converters. Their flat and overlapped conducting layers allow good heat dissipation and reduced stray inductance. Topology optimization enables balancing the amount of copper used with the maximum temperature and stray inductance of the busbar.

Flow Structure and Heat Transfer Numerical Study in a Rotor-Stator System Air-Gap

This paper deals with flow structure and heat transfer modeling in a two coaxial disk air-gap. Numerical estimations for the local Nusselt number on the rotor, for the radial and tangential velocities are compared with experimental results obtained using PIV and infrared thermography. Models used for the numerical approach are then validated for a turbulent Reynolds Number.© 2005 ASME