Search

The calculation of the temperature fields in solid state transformers is a critical step of the design process in order to ensure the stable and efficient operation of the device. Transformers operating in high frequencies can develop increased temperatures that potentially may result in the failure of the components due to the associated thermal stresses. This paper investigates the heat transfer mechanisms of a novel inductive power transfer (IPT) system submerged in a dielectric oil and operating at 50 kHz, in the context of SSTAR, a Horizon Europe project. The commercial software ANSYS is employed to implement a one-way coupled electromagnetic-thermal finite element simulation model in order to calculate the temperature field of the IPT components based on the electromagnetic losses. To cross-validate the model, the results obtained from ANSYS are benchmarked against the COMSOL software, revealing accepted temperature deviations between the two software. A comprehensive parametric analysis explores the impact of rated power, operating frequency, and dielectric gap on generated heat, highlighting their direct correlation with temperature increase. The findings underscore increased temperature levels, approximately reaching 224 °C under nominal operating conditions, with the temperature distribution concentrated around the transformer's windings. • Design of a novel high frequency 50 kHz Inductive Power Transfer system. • Assessment of the heat transfer mechanism of an Inductive Power Transfer system. • Development of a comprehensive coupled electromagnetic-thermal simulation model and validation. • Parametric analysis on the effect of rated power, frequency and dielectric gap on power loss and temperature. [ABSTRACT FROM AUTHOR]

In this paper, a novel numerical simulation approach based on the finite element method for dynamically modeling the excavation process of shield tunneling is proposed, with the shield-ground interactions well captured. This method is capable of mimicking the alternating modes of advancing and stopping of a shield boring machine during underground construction, with the important effects of the cutterhead rotation and slurry support pressure considered. Under the cutting action, the soil at the excavation face would experience irreversible deformation and damage, such that additional support needs to be provided by the cutterhead blades and slurry to maintain stability. The impacts of key construction parameters are examined, including cutterhead rotary speed, advance rate, and slurry support pressure, on shield tunneling operations and ground responses. The numerical model is rigorously validated against physical model experiments. This work provides useful insights into the mechanistic processes in the stratum during shield tunneling, including the spatiotemporal evolution of ground deformation patterns and stress redistributions. The results offer valuable guidance for optimizing shield tunneling operations and enhancing tunneling safety and efficiency. [ABSTRACT FROM AUTHOR]

In this paper, we study a weak Galerkin (WG) finite element method for semiconductor device simulations. We consider the one-dimensional drift–diffusion (DD) and high-field (HF) models, which involves not only first derivative convection terms but also second derivative diffusion terms, as well as a coupled Poisson potential equation. The main difficulties in the analysis include the treatment of the nonlinearity and coupling of the models. The weak Galerkin finite element method adopts piecewise polynomials of degree k for the approximations of electron concentration and electric potential in the interior of elements, and piecewise polynomials of degree k + 1 for the discrete weak derivative space. The optimal order error estimates in a discrete H 1 norm and the standard L 2 norm are derived. Numerical experiments are presented to illustrate our theoretical analysis. Moreover, numerical schemes also work out for the discontinuous diffusion coefficient problems. [ABSTRACT FROM AUTHOR]