This paper presents an analytical model of a common-mode choke suitable for accurate calculation of the choke impedance over a wide frequency range. The model consists of lumped parameters (resistances, inductances, and capacitances) related to individual turns of the coils wound on the core. It takes into account the mutual interactions between the turns and the core with respect to their inductive and capacitive links. The variation of the core permeability and losses with frequency up to 100 MHz is also included. The open-mode impedance characteristic calculated analytically for a VAC 6123x425 single-phase common-mode choke shows very good agreement with the 3-D finite-element model and the measured characteristic from 150 kHz up to 30 MHz, thus confirming the accuracy of the model over a wide frequency range.

A new measurement method for infrared (IR) surface temperature measurement of excitation winding in rotation is presented. The method is experimentally verified on a 400-kVA salient pole synchronous generator. This method uses an industrial IR thermometer which represents an alternative to expensive fast IR thermometers or cameras. The target application of this method is the determination of the dynamic limit in the P-Q diagram of a synchronous generator due to excitation winding overheating. The measurement error model which shows the way how to minimize measurement error has also been derived. The effect of the interpolar surface can be cancelled if the IR thermometer is positioned at a certain angle with respect to the machine's main axis. Digital temperature sensors have been mounted on the rotor to measure the excitation winding surface temperature for comparison.

Scaling laws are used when the size of a certain machine design with known performance needs to be adjusted for a new application with known requirements, or when a machine design is geometrically scaled and one needs to determine its performance. Scaling laws derived in this study allow one to quickly and accurately recalculate parameters of a geometrically scaled permanent magnet machine. They basically consist of two separate important scaling procedures: axial scaling and radial scaling. The third and inevitable scaling procedure is rewinding, which is used to adjust the winding for a required voltage level. Exact but simple analytical equations for the various parameters (torque, power, losses, mass, resistance, inductance, efficiency etc.) of the machine are derived using three independent scaling factors, one for each scaling procedure. Special attention is given to the inclusion of end‐winding influence and three‐dimensional permanent magnet loss effects. Algorithms for fast determination of winding parameters for a given voltage and fast determination of scaling factors for scaling based on the torque requirement with stack length limitation are presented. All derived scaling equations are numerically validated using two state‐of‐the‐art motor design software packages with automated extraction of parameters based on finite‐element calculations.

This paper proposes the novel scalable model of synchronous permanent magnet and synchronous reluctance machines which combines ultra-fast scaling laws with saturated flux-linkage and loss model. The scalable model is used for fast and accurate calculation of efficiency/loss maps and can also be used for drive cycle analysis including calculation of energy consumption. It is verified by comparison with an existing state-of-the-art efficiency map and drive cycle analysis software. Additionally, an experimental verification of a saturated flux-linkage and loss model is presented. The additional possible usage of the scalable model is to find the optimal size of a scaled machine in order to meet the drive cycle performance and requirements of a traction motor.

This paper presents an overview of methodology for usage of mathematical optimization procedures e.g. optimization algorithms to achieve optimal design of an electrical machine. A special care must be taken in order to handle parameter definition, boundary constraints, constraint functions, model feasibility and computationally expensive calculation such as finite element analysis. Variants of workflows using different approaches to optimization are presented.

This paper presents a method for reducing computational time in constrained single objective optimization problems related to permanent magnet motors modeled using computationally intensive finite element method. The method is based on differential evolution algorithm. The principal approach is to interrupt the evaluation of inequality constraints after encountering the constraint which is violated and continue their evaluation only if better solutions are obtained in comparison with the candidate vector from the previous generation both in terms of inequality constraints and the cost function. This approach avoids unnecessary time consuming finite element calculations required for solving the inequality constraints and saves the overall optimization time without affecting the convergence rate. The main features of this approach and how it complements the existing method for handling inequality constraints in Differential Evolution algorithm is demonstrated on design optimization of an interior permanent magnet motor for the low-floor tram TMK 2200. The motor geometry is optimized for maximum torque density.