Conference Agenda

Partial discharges have recently become an issue for electrical machines longevity. Thus, there is an interest in studying the phenomenon through numerical simulation. This task is rather complex since it requires to couple Finite Element Method (FEM) for the electrostatic field with a numerical simulation of the charge density flow using hydrodynamics model, which is known to be unstable with FEM. Thus, this communication proposes to compare the main stabilization methods with an analytical case dedicated to space charge context. It suggests that a logarithmic formulation of the problem can accurately ensure the positivity of the density as opposed to the common stabilizations methods. However, the conditions of convergence remain to be established and it comes with a significant additional computational cost.

Ultrahigh magnetic field generation is one of hot topics in the field of applied superconductivity. It is strongly desired for some applications such as compact fusion, magnetic resonance imaging, nuclear magnetic resonance (NMR), and particle accelerator for medical use. Although a world-record DC magnetic field of 45.5 T was successfully generated, the high-temperature superconducting magnet had the deterioration of its specification due to plastic deformation. Thereafter, investigation of the cause of specification deterioration has begun using simulations.

In this paper, an electromagnetic and mechanical simulation method coupling with the partial element equivalent circuit (PEEC) method and the two-dimensional linear elastic finite element method (FEM) are proposed. The current distributions of an insert HTS coil under background field of 31 T were simulated with/without consideration of coil shape deformation. These distributions differ due to the coil shape deformation, and the coil voltages are also different.

Evaluating the acoustic noise performance of an electric motor can be a computationally intensive process due to the coupling of several subsystems such as the electromagnetic, structural, and acoustic models. Where skewed poles are considered in the design, the problem becomes a purely 3D multiphysics problem which could increase the computational burden astronomically. This work, therefore, seeks to introduce surrogate models in the design process to reduce the computational cost associated with solving such 3D coupled multiphysics problems. Briefly, the procedure involves using the finite element method to generate a database of several skewed rotor pole surface-mounted permanent magnet synchronous motors and their corresponding electromagnetic, structural, and acoustic performances. Then, a surrogate model is fitted to the data to generate mapping functions that could be used in place of the time-consuming finite element simulations.

This paper proposes a mathematical model for 3D nonlinear magnetoelectric effects in heterogeneous composite structures. Through the coupling of the Finite Element Method (FEM) with the Boundary Element Method (BEM), only the active material is explicitly considered, and thus a single mesh is used to support all phenomena. A mixed formulation is used to model the magnetic phenomena, a vector potential formulation in the volume and a scalar potential formulation in the free space domain. Material laws for the magnetostrictive composite phase are derived from partial derivatives of a scalar invariant's formulation of the Helmholtz free energy. The coupled problem is solved by iteratively solving single-physics problems, and the full algorithm is applied to the modeling of a test case.

Quadrupole resonators (QPRs) used to characterize superconducting samples suffer from eigenfrequency shifts caused not only by multi-physical phenomena such as electromagnetic radiation pressure (Lorentz detuning) and microphoning but also due to the fabrication tolerances. As a result, they may affect the so-called RF-DC compensation calorimetric characterization method. A multi-physics problem with random input parameters is addressed to study a significant measurement bias of the surface resistance, observed mainly for the third operating mode of the given QPR. We use the pseudo-spectral method for uncertainty quantification (UQ) in the QPR model. The simulation results and their implication for the operational conditions of the QPR are discussed.

In this digest, an improved coupled field–circuit model for a stator interturn short-circuit (ITSC) fault inside a doubly fed induction generator (DFIG) is presented, in which the bidirectional interaction between the field domain and the circuit domain during a stator ITSC fault is captured. The control system of the DFIG is directly integrated into the calculated model. Meanwhile, the Cassie arc model is used to simulate the time-varying arc conductance in the circuit domain. As a study case, a 1.5 MW wound-rotor three-phase DFIG was modeled and subjected to a stator ITSC fault. The results indicate that such a stator ITSC fault can give rise to a short-circuit current of 0.21 kA, and stator currents are introduced into the control system as input variables, which affect the rotor voltage by changing the modulating signal. In addition, as the stator current amplitude increases in the fault phase, a small distortion appears in the rotor currents.