In this paper, lumped parameters for a variable phase-pole induction machine with wound independently controlled stator coils are computed using finite-element simulations. Differently from finite-element simulations of conventional electrical machines, this solution uses a per-solenoid approach.

Batteries in energy storage systems are exposed to electrical noise, such as alternating current (AC) harmonics. While there have been many studies investigating whether Lithium-ion batteries are affected by AC harmonics, such studies on Nickel Metal Hydride (NiMH) batteries are scarce. In this study a 10 Ah, 12 V NiMH battery was tested with three different harmonic current frequency overlays during a single charge/discharge cycle: 50 Hz, 100 Hz, and 1000 Hz. No effect on battery internal temperature or gas pressure was found, indicating that NiMH battery aging is not affected by the tested harmonic AC frequencies. This can reduce the cost of energy storage systems, as no extra filters are needed to safeguard the batteries. Instead, the capacitive properties of the batteries give the possibility to use the battery bank itself as a high pass filter, further reducing system complexity and cost.

Today, multiphase electric machinery is considered in automotive traction applications. Some multiphase machine topologies also enable the possibility to change the pole and/or phase number during operation, an option which can be of benefit thanks to the large speed range that an electric machine for traction applications typically operates with. In this paper, an analytical model of the current dynamics for the wound independently-controlled stator coils (WICSC) and the intelligent stator cage drive (ISCAD) machines is presented. The model, based on setting up a permeance network in the stator and rotor and a rotor-angle dependent connection between the two networks, allows for predicting current transients during pole and phase changes. Thus, it is suitable for the design of control methods exploiting both the multiphase nature of the machine as well as performing pole-number changes during operation. The presented model is validated by comparing results from a corresponding finite-element based model of a WICSC machine during a pole change.

This study presents an analysis of the harmonic content on the dc-link (battery) side in electric drives with permanent-magnet synchronous machines (PMSMs) adopting fractional-slot concentrated windings (FSCWs) which can have a significant harmonic content. An analytical expression for predicting the ripple content in the dc-link (battery) current utilising data from a two-dimensional finite element method (2D-FEM) based model is presented and found to be in good agreement with corresponding experimental results. The FEM model is also used to demonstrate that the resulting harmonic content in the phase currents when operating at speeds well above the bandwidth of a conventional proportional + integral type controller can result in a substantial increase in magnet losses. Finally, a previously reported, experimentally evaluated model of an automotive traction battery and the associated battery cable is combined with an implemented model of the FSCW-PMSM (utilising data from the 2D-FEM model), converter and control to predict the resulting harmonic content in the battery current. The presented methods can be utilised when analysing the impact of harmonics on both the ac and dc sides of an automotive electric drive system.

This paper deals with the design and evaluation of a short-circuit rotor-ring for enhanced self-sensing capability in a 2-pole slotless permanent-magnet motor. High-frequency rotor anisotropy is enabled by adding as hort-circuited rotor-ring. Optimal ring-dimensions are determined by parametric numerical studies. An effective high-frequency saliency of up to 1.8 is demonstrated. The steady-state estimation error is within ±2◦, practically unaffected by current level (in contrast to slotted self-sensing electrical machinery) due to the large effective air-gap. The proposed observer performs properly also during dynamic load changes. Fall-times from 3000 to 0 rpm in less than 50 ms with negligible overshoot are demonstrated. Also parasitic effects such as power losses, heating and torque ripple are analyzed.

In this paper the harmonic plane decomposition from part I is completed. Multiphase electrical machines with independently controlled stator coils benefit from a fixed amount of current controllers and unified models. In part I, the foundation for such models was laid. This paper shows that the choice of the base case has to fulfill certain criteria to properly represent vector-space quantities. More specifically, phase-pole configurations with an even number of pole pairs need adapted base cases with reduced rank as compared to the odd base case. Continuous modeling and control requires retention of the dimensionality of Clarke matrices. A different number of stator and rotor slots can lead to aliasing in the transformation, when keeping the dimension consistent. Therefore, a specific Clarke transformation for rotor quantities based on the developed theory is elaborated. Finally, it is demonstrated how the harmonic plane decomposition can be used to model each harmonic plane of an arbitrary phase-pole configuration with conventional machine equivalent circuits, e.g. the T-equivalent or inverse-Γ models.

In this first paper of a two-part series, the harmonicplane decomposition is introduced, which is an extension of the vector-space decomposition. In multiphase electrical machines with variable phase-pole configurations, the vector-space decomposition leads to a varying numbers of vector spaces when changing the configuration. Consequently, the model and current control become discontinuous. The method in this paper is based on samples of each single slot currents, similarly to a discrete Fourier transformation in the space domain that accounts for the winding configuration. It unifies the Clarke transformation for all possible phase-pole configurations such that a fixed number of orthogonal harmonic planes are created, which facilitates the current control during reconfigurations. The presented method is not only limited to the modeling of multiphase electrical machines but all kinds of existing machines can be modeled. In the second part of this series, the harmonic plane decomposition will be completed for all types of machine configurations.

A high demand for electrification of the transportsector has resulted in a need to provide compact and reliableelectric power trains where the electric machine is a key element.The cooling system has a strong impact on the specific torqueand power capability of the machine. The selection of thecooling solution should not be based on the steady-state coolingperformance only but also on the transient characteristics owingto the typical operational load nature of the propulsion system,where the load is not continuous (as it usually is in industrialapplications), but it frequently varies in time depending on thevehicle type and the driving style. This paper investigates indetail the cooling capabilities of a direct winding liquid coolingsolution and compares it with a traditional frame liquid coolingarrangement in the transient condition. As a result of thecomparison, it was found that the location of heat removal closeto the heat source makes the temperature transient time faster,which allows to apply overload operating points more frequently.

In this paper, which is tutorial in nature, a description together with associated code samples is presented for predicting iron losses from a two-dimensional, finite-element model implemented using Comsol Multiphysics and Matlab. Two different conventional iron-loss models are presented and compared. The parameters for the adopted loss models are determined for an M250-35A-type steel and sample loss-density distributions are presented for different electric machine geometries.