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Ultra-fast charging of electric vehicles will soon be available to charge the batteries in less than 15 minutes to 80% state of charge. However, very few studies of batteries under these conditions exist. To design a battery pack with ultra-fast charging in mind, more information about batteries is needed, both electrically and thermally. In this thesis, the performance of three specific commercial lithium-ion batteries during ultra-fast charging is investigated and their thermal behaviour is simulated for use in the battery pack design process. The cells are charged at 1C to 6C current rates, or as high as 10C, and the surface temperature of each cell is measured. The loss calculated from the charging tests are used in a thermal analysis of the three batteries using finite element analysis. The batteries are modeled in a simple cooling apparatus to determine their thermal management requirements in a pack, i.e., how effectively must the heat be removed from the cells to obtain a specific temperature in a pack. Test results show that ultra-fast charging is possible with very little loss; but, it is dependent on the battery. The analysis illustrates important trade-offs between the battery type, charge rate, and the thermal management system. This thesis presents a holistic view to the study of the batteries for eventual use in the design of a battery pack. The thermal performance of the batteries is equally important as their electrical (charge) performance. It also attempts to justify the observed behaviour of the batteries by their underlying chemical behaviour. The work here can be used as a jumping-off point for further work on the ultra-fast charging of batteries or the design of a battery pack. / Thesis / Master of Applied Science (MASc) / Ultra-fast charging of electric vehicles, i.e., fully charging the vehicle in less than 15 minutes, will soon be more available. However, literature on the ultra-fast charging of the batteries used in these vehicles is limited. It is not widely known whether the batteries can effectively achieve ultra-fast charging or how the batteries behave under these conditions. Charging batteries this fast means that the battery cells will heat up. The temperature of the cell greatly impacts its longevity and safety. The thesis attempts to address these questions by studying three commercial lithium-ion batteries, selected for specific characteristics, that show potential for ultra-fast charging. The batteries are charged at different rates to ultra-fast charging levels and the charge performance at each rate is determined. The temperature of the batteries is simulated with different cooling systems to determine how effectively must heat be removed from the batteries to maintain the cells at a specific temperature.

Yes / In this study, the thermal performance analysis of porous fin with temperature-dependent thermal conductivity and internal heat generation is carried out using Haar wavelet collocation method. The effects of various parameters on the thermal characteristics of the porous fin are investigated. It is found that as the porosity increases, the rate of heat transfer from the fin increases and the thermal performance of the porous fin increases. The numerical solutions by the Haar wavelet collocation method are in good agreement with the standard numerical solutions.

Yes / In this paper, the Chebychev spectral collocation method is applied for the thermal analysis of convective-radiative straight fins with the temperature-dependent thermal conductivity. The developed heat transfer model was used to analyse the thermal performance, establish the optimum thermal design parameters, and also, investigate the effects of thermo-geometric parameters and thermal conductivity (nonlinear) parameters on the thermal performance of the fin. The results of this study reveal that the rate of heat transfer from the fin increases as the convective, radioactive, and magnetic parameters increase. This study establishes good agreement between the obtained results using Chebychev spectral collocation method and the results obtained using Runge-Kutta method along with shooting, homotopy perturbation, and adomian decomposition methods.

The goal of this dissertation is to present a systematic approach to integrating the multidisciplinary design process in power electronics through the integration of existing CAD tools, multidisciplinary modeling and system optimization. Two major benefits are expected from the utilization of the proposed integrated design methodology. Firstly, it will significantly speed up the design process and will eliminate errors resulting from repeated manual data entry and information exchange. Secondly, the integrated design optimization will result in better utilization of materials and components. In order to understand the basic relationship between electrical and thermal phenomena, the self-heating effect of a simple copper conductor is modeled analytically. Based on these models, a guideline for copper trace design is proposed. The next step towards developing an integrated design methodology is to create threedimensional solid-body-based models that characterize the electrical, thermal and mechanical properties. The electrical model of an integrated power electronics module (IPEM), including parasitic parameters, is developed and experimentally verified with impedance measurements. Together with the thermal model, it lays the foundation for the integrated electrical and thermal analysis and design. The software integration framework is presented along with the software tools chosen for this study, which include Saber for electrical circuit simulation, Maxwell Q3D Extractor for parameter extraction, and I-DEAS for geometry and thermal modeling. Each of these software tools is controlled via its own macro language files. iSIGHT is then used to interface with these tools in order to achieve software integration. The DC-DC IPEM layout design is investigated and improved upon by using the integrated design methodology. Several examples of parametric study are presented. The first example shows the tradeoff between electrical and thermal performance for different ceramic layer thicknesses of module substrate. The next example looks at the commonmode noise problem that exists in different direct-bonded copper (DBC) layouts. / Ph. D.

With the increase dependency on electricity to provide correct form of electricity for lightning, machines, and home and office appliances, the need for the introduction of high reliability power electronics in converting the raw form of electricity into efficient electricity for these applications is uprising. One of the most common failures in power electronics is temperature related failure such as overheating. To address the issue of overheating, thermal management becomes an important mission in the design of the power electronics to ensure the functional power electronics. Different approaches are taken by academia and industry researchers to provide efficient power electronics. In particular, the Center for Power Electronics System (CPES) at Virginia Tech and four other universities presented the IPEM approach by introducing integrated power electronics modules (IPEM) as standardized units that will enable greater integration within power electronics systems and their end-use application. The IPEM approach increases the integration in the components that make up a power electronics system through novel a packaging technique known as Embedded Power technology. While the thermal behavior of commonly used packages such as pin grid arrays (PGA), ball grid array (BGA), or quad flat pack (QFP) are well-studied, the influence of the Embedded Power packaging architecture on the overall thermal performance of the IPEMs is not well known. This motivates the presentation of this dissertation in developing an in-depth understanding on the thermal behavior of the Embedded Power modules. In addition, this dissertation outlines some general guidelines for the thermal modeling and thermal testing for the Embedded Power modules. Finally, this dissertation summarizes a few thermal design guidelines for the Embedded Power modules. Hence, this dissertation aims to present significant and generalized scientific findings for the Embedded Power packaging from the thermal perspective. Both numerical and experimental approaches were used in the studies. Three-dimensional mathematical modeling and computational fluid dynamics (CFD) thermal analyses were performed using commercial numerical software, I-DEAS. Experiments were conducted to validate the numerical models, characterize the thermal performance of the Embedded Power modules, and investigate various cooling strategies for the Embedded Power modules. Validated thermal models were used for various thermal analyses including identifying potential thermal problems, recognizing critical thermal design parameters, and exploring different integrated cooling strategies. This research quantifies various thermal design parameters such as the geometrical effect and the material properties on the thermal performance of the Embedded Power modules. These parameters include the chip-to-chip distance, the copper trace area, the polyimide thickness, and the ceramic materials. Since the Embedded Power technology utilizes metallization bonding as interconnection, specific design parameters such as the interconnect via holes pattern and size, the metallization thickness, as well as the metallization materials were also explored to achieve best results based on thermal and stress analyses. With identified potential thermal problems and critical thermal design parameters, different integrated cooling strategies were studied. The concept of integrated cooling is to incorporate the cooling mechanisms into the structure of Embedded Power modules. The results showed that simple structural modifications to the current Embedded Power modules can reduce the maximum temperature of the module by as much as 24%. Further improvement can be achieved by employing double-sided cooling to the Embedded Power modules. Based on the findings from the thermal analyses, general design guidelines were developed for future design of such Embedded Power modules. In addition, thermal modeling and testing guidelines for the Embedded Power modules were also outlined in this dissertation. / Ph. D.