In this paper, a three-air-gapped structure of a ferrite core for a resonant inductor is proposed. The electromagnetic and thermal field models are built using a 3D finite element method. Compared with the conventional signal-air-gapped structure of a ferrite core, the simulation and analysis results show that the proposed three-air-gapped ferrite core resonant inductor can reduce eddy-current loss and decrease temperature rise. In addition, the optimal position of air-gapped is presented.

Gapped magnetic components are inherent to applications where conversion of power would force magnetic flux density beyond the saturation point of magnetic materials. A physical discontinuity in a magnetic path, which an air gap represents, signifies a drastic change in its reluctance to magnetic flux. This gives rise to a phenomenon referred to as the fringing effect, which impacts the performance of magnetic components. The fringing flux also affects the physical properties of magnetic components, such as magnetic reluctance and inductance. Since inductance of gapped magnetic components is a function of the size of the air gap, a relatively simple change to the configuration of the air gap or splitting a single gap into a plurality of gaps entails, frequently, a radical change to the magnetic circuit of the component. This paper examines the way the air-gap configuration affects the distribution of the fringing flux and, by extension, magnetic reluctance and inductance. A method to aid the design of multigap inductors is presented based on 3-D electromagnetic modelling as well as measurements. An analytic expression, which closely approximates the required length of quasi-distributed gaps substituting a single gap, is developed.

This paper presents a numerical model for the horizontal continuous casting of cast iron (HCCCI). A computational three-dimensional (3D) steady-state, coupled with fluid flow and heat transfer simulation model was developed and validated against experimental results to study the shell thickness and solidification of ductile cast iron. The study introduces the influence of an air gap at the melt-mould interface, which has long been known to have a detrimental effect on the efficiency of the process. The effect of the length and thickness of the melt-mould air gaps (also referred to as top air gaps) on solidification and remelting of the solid strand is studied. Parametric studies on top air gaps suggested a substantial effect on the solid and eutectic area at the top-outlet end of the die when the length of air gas was varied. This study serves to create a foundational and working model with the overall objective of process optimisation and analyzing the effect of operating process input parameters on the shell thickness of the strand.

The Halbach array structure rotor of the aero motor can satisfy the requirements of high power density and high air-gap flux for aeronautical motors. The size parameters of the rotor are determined by the power rating of the motor based on an analytic method. Producing a Halbach array structure is difficult. Comparison and analysis of the structure of the aero motor showthat the overall structure of the rotor adopts a three-axial-section classic Halbach-array hollow structure, and the rotor magnetic steel adopts a discrete structure of 4 blocks per pole and a single 45◦ magnetisation mode, which reduces the processing difficulty of the rotor magnetic steel. The finite element method was used to analyse the magnetic flux density distribution of the aeronautical motor under various working conditions. The results show that the motor can produce uniform air-gap flux density at various working conditions and present good sinusoidal periodicity. Furthermore, the axial segment did not produce obvious magnetic flux leakage. Finally, considering the eddy current loss of the stator under the rated power-generation condition with high-frequency magnetic field, we conducted coupling analysis of electromagnetic and heat flows to verify that the thermal characteristics of the rotor magnetic steel material could meet the requirements for the aero motor.

The concentrated winding (CW) is obviously different from the traditional distributed winding (DW) in the arrangement of windings and the calculation of winding factors, which will inevitably lead to different performances of the permanent magnet synchronous motor (PMSM). In order to analyze the differences between the CW and the DW in the performance, a 3 kW, 1500 r/min PMSM is taken as an example to establish a 2-D finite element model. The correctness of the model is verified by comparing experimental data and calculated data. Firstly, the finite element method (FEM) is used to calculate the electromagnetic field of the PMSM, and the performance parameters of the PMSM are obtained. On this basis, the influences of the two winding structures on the performance are quantitatively analyzed, and the differences between the two winding structures on the performance of the PMSM will be determined. Finally, the differences of efficiency between the two winding structures are obtained. In addition, the influences of the winding structures on eddy current loss are further studied, and the mechanism of eddy current loss is revealed by studying the eddy current density. The analysis of this paper provides reference and practical value for the optimization design of the PMSM.