PurposeA fundamental disadvantage of three‐dimensional finite element (FE) simulations is high computational cost when compared to two‐dimensional models. The purpose of this paper is to present an approach to minimize the computation time by achieving the same simulation accuracy.Design/methodology/approachThe applied approach for avoiding high computational cost is the multi‐slice method. This paper presents the adoption of this method to a tubular linear motor.FindingsIt is demonstrated that the multi‐slice method is applicable for tubular linear motors. Furthermore, the number of slices and thereby computation time is minimized at the same accuracy of the simulation results.Practical implicationsThe results of this paper offer a faster computation of skewed linear motors. At this juncture, the results are independent from the deployed FE solver.Originality/valueThe methods developed and proved permit a faster and more accurate design of tubular linear motors.
This paper presents non-conforming sliding interfaces for motion in 3-D finite element simulations. Sliding interfaces are favorable, especially for field circuit coupling in comparison to other approaches such as the Lockstep method because an arbitrary position of the rotor is possible. A previously presented approach by the authors is extended to take eddy-currents into account. The sliding interfaces approach utilizes specific Lagrange multiplier to handle the relative motion between stator and rotor which require a magnetic scalar potential formulation. The formulation is presented as well as methods to compute the mandatory cohomology basis functions.
This paper will describe current and ongoing developments of wire less-connected RFID reader systems for evaluation of a passive user localization system. A two-tier architecture of different wireless-connected RFID readers will be introduced. On the lower level, i.e. the first tier, several wireless technologies can co-exist using different kinds of communication technologies to connect different RFID readers. These technologies are connected through a fully meshed WiFi/WLAN network to bring them into the IP world. This IP infrastructure is the second tier, built up on IEEE 802.11
Purpose -Depending on the load the flux-density distribution inside power transformers core shows significant local variations due to stray fluxes which enter the transformer core. As saturation of the core has to be avoided the flux-density distribution has to be determined early in the design stage of the transformer. This paper seeks to address these issues. Design/methodology/approach -To determine the load dependent flux-density distribution the operating point of the transformer is calculated considering linear and non-linear material properties. The operating point is determined using a linearised lumped parameter model of the transformer under various load conditions. Considering non-linear material properties the inductance matrix depends on the operating point and will be extracted by means of the FEM whenever the magnetic energy within the transformer changes notably. Findings -This paper presents a numerical stable approach to calculate the operating point of a transformer by using the magnetic flux linkage as state variable for the coupled field problem.Research limitations/implications -The proposed approach uses a fixed time-step to update the lumped parameters by means of the FEM. This results in long simulation times. In further research it is planned to implement an adaptive time-step method based on the change of the magnetic energy. Originality/value -A numerical stable approach to calculate the operating point of a transformer by using the magnetic flux linkage as state variable for the coupled field problem is proposed. The methodology is applied to a 2D model of a three-phase transformer. However, it also can be applied to 3D FE models. Based on the calculated operating point, the flux-density distribution can be determined and several post-processing methods can be executed (e.g. determination of core losses, . . .).
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