Peter Gangl, Michael Winkler. Topology optimisation of electric machines: quest for global optima.

It is well-known that real-world topology optimisation problems often exhibit multiple local minima and that derivative-based methods are prone to getting stuck in a possibly suboptimal local solution. We present a way of computing multiple locally optimal solutions to topology optimisation and illustrate the method for a two-pole synchronous reluctance machine.

Alessio Cesarano, Peter Gangl, Charles Dapogny. Space-time shape optimization of rotating electric machines.

In the present work we propose a different approach to simulate and optimize a rotating electric motor. We solve the eddy-current equation, with the use of the shape derivative and space-time finite element methods. We then also consider electro-thermal coupling.

Andreas Gschwentner, Manfred Kaltenbacher, Barbara Kaltenbacher, Klaus Roppert. Comparison of a quasi Newton method using Broyden's update formula and an adjoint method for determining local magnetic material properties of electrical steel sheets.

In this work, two different approaches for solving an inverse problem to determine the local magnetic material properties of electrical steel sheets are compared. The first approach involves a quasi Newton method approximating the Jacobian with Broyden's update formula and the second is an adjoint method. To handle the ill-posedness of the inverse problem, a Thikonov regularization is used for both methods and the regularization parameter is computed via Morozov's discrepancy principle.

Theodor Komann, Stefan Ulbrich. Robust Design Optimization of Electrical Machines with IGA.

In recent years, the usage of electric equipment has increased dramatically in society and has significantly impacted our daily lives. The production and usage of electrical machines leads to uncertainties that should be considered in the design process. Therefore we investigate a nonlinear constrained optimization problem with uncertain parameters for an electrical machine. By utilizing a robust worst-case formulation we obtain an optimization problem of bi-level structure. This type of problems are difficult to treat computationally and hence suitable approximations are required.

Our goal is twofold: Firstly, we aim to reduce the volume of the permanent magnet, a significant factor due to its composition of costly rare earth elements. Secondly, we want to minimize the variance of the torque by optimizing the shape of the air gap. Simultaneously, it is crucial to maintain a pre-determined performance standard which is given by the torque.

The quantities which are necessary for computing the torque are calculated from magnetic vector potential provided by the magnetostatic approximation of Maxwell's equation, an elliptic PDE. We employ Isogeometric Analysis (IGA) using the open-source GeoPDEs software for the discretization of the PDE. IGA uses Non-Uniform Rational B-Splines (NURBS) for precise geometric depiction, thereby eradicating the need for remeshing. This quality renders IGA suitable for design optimization and ensures its compatibility with CAD software, thus allowing the direct application of optimization results in the design process.

To conclude, we present numerical results for the proposed approach.