This article presents a theoretical investigation into the thermal behavior of a pack of 18650 lithium-ion commercial batteries used for the propulsion of two-wheeled electric vehicles. In the first part, we highlight the theoretical aspects that describe the energy balance of a cylindrical lithium-ion battery based on the law of conservation of energy. The research aims to emphasize the effect of temperature on the technical performance of batteries. Next, using the COMSOL Multiphysics 6.2 software package, "heat transfer in solids and fluids", the thermal behavior was modeled for a single cylindrical battery cell, type 18650 lithium-ion, 3.7 V, 2200 mAh, respectively a battery pack with the same type of cells, 18650 lithium-ion. The battery pack was made in the structure of 3 cells in series and 7 cells in parallel (3S7P). The distribution of the temperature generated inside the battery cell, respectively in the structure of the 3S7P battery pack, was taken into account, at a charge/discharge rate considered extreme of 5.5C. In order to ensure a quality mesh in the process of simulating the geometry of the 3S7P battery pack, a mesh convergence study was also considered through progressively finer runs until the temperature of the battery pack did not change significantly with the subsequent refinement of the mesh. Simulations of thermal behavior were conducted while accounting for thermal conductivity, density, heat capacity, and heat source in the batteries. The battery pack was thermally loaded to measure temperatures inside the protective case, starting from an initial ambient temperature. The results obtained demonstrate several characteristics that can enhance the technical performance of battery packs used in electric two-wheeled vehicles.

The main scope of this research was to complete and validate the analysis of stator winding topologies of six-phase AC machines using the winding quality factor by determining fault tolerance and validating it through experimental tests. This paper proposes a unified and practical methodology for evaluating the performance of stator windings in six-phase induction machines, with emphasis on magnetic field quality and fault-tolerant operation. The approach combines analytical modeling of the magnetomotive force (MMF) with its graphical representation using the MMF polygon, enabling an efficient assessment of harmonic content through a global indicator, referred to as the winding quality factor. Several representative winding topologies are analyzed within a common framework, including single-layer and double-layer configurations with full-pitch and short-pitch coils, suitable for generating homologous series of six-phase machines. The study considers both normal operating conditions and post-fault regimes, particularly operation with a single three-phase set. The results reveal the strong influence of winding topology on harmonic distortion and overall machine performance, highlighting the trade-offs between magnetic field quality and fault tolerance. It is shown that appropriate winding design can reduce spatial harmonics and improve robustness under degraded operating conditions. The theoretical findings are validated through experimental investigations, demonstrating good agreement between analytical predictions and measured data. A parallel analysis was performed between the theoretical findings and experimental data, and the results conform to the authors’ expectations.