Slotless PM machines with skewed winding shapes:3D electromagnetic modeling

The 3D modeling technique presented in this paper, predicts, with high accuracy, electromagnetic fields and corresponding dynamic effects in conducting regions for rotating machines with slotless windings, e.g. self-supporting windings. The presented modeling approach can be applied to a wide variety of slotless winding configurations, including skewing and/or different winding shapes. It is capable to account for induced eddy-currents in the conductive rotor parts, e.g. permanent magnet eddy-current losses, albeit not iron and winding AC losses. The specific focus of this paper is to provide the reader with the complete implementation and assumptions details of such a 3D semi-analytical approach, which allows model validations with relatively short calculation times. This model can be used to improve future design optimizations for machines with 3D slotless windings. It has been applied, in this paper, to calculate fixed parameter Faulhaber, Rhombic, and Diamond slotless PM machines to illustrate accuracy and applicability

Torque ripple reduction for 12-stator/10-rotor-pole variable flux reluctance machines by rotor skewing or rotor teeth non-uniformity

Variable flux reluctance machines (VFRMs) are interesting candidates to substitute permanent-magnet synchronous machines in many applications. However, they suffer from large torque ripple. In this paper two methods, stepped rotor skewing and rotor teeth non-uniformity, are researched to reduce the torque ripple of 12/10 (stator/rotor-pole ratio) VFRMs. Based on semi-analytic results and finite-element simulations, the effectiveness of these two methods is validated in both non-saturated and saturated machines.</p

Torque ripple reduction for 12-stator/10-rotor-pole variable flux reluctance machines by rotor skewing or rotor teeth non-uniformity

Variable flux reluctance machines (VFRMs) are interesting candidates to substitute permanent-magnet synchronous machines in many applications. However, they suffer from large torque ripple. In this paper two methods, stepped rotor skewing and rotor teeth non-uniformity, are researched to reduce the torque ripple of 12/10 (stator/rotor-pole ratio) VFRMs. Based on semi-analytic results and finite-element simulations, the effectiveness of these two methods is validated in both non-saturated and saturated machines.</p

Stray-field calculations on a shielded planar actuator using 3-D hybrid analytical modeling

ABSTRACT This paper applies a hybrid analytical modeling technique to calculate the magnetic stray-field of a shielded planar motor. The magnetic stray-field of the planar magnet array is accurately predicted by the presented modeling method. The inclusion of the magnetic shield is visible as a clear reduction of the magnetic field as will be confirmed by measurements

Analysis and design of a slotless tubular permanent magnet actuator for high acceleration applications

This paper presents the design of a linear actuator for high acceleration applications. In the analysis, a slotless tubular permanent magnet actuator is modeled by means of semianalytical field solutions. Several slotless topologies are modeled and compared to achieve the highest acceleration. A design has been proposed and built, and measurements are conducted to verify the model

Candidates of motor drives for 48V automotive applications

Abstract-In automotive systems, reliability and cost are paramount for the success of electrical drive systems. Considering the interior permanent magnet motor, the cost of the rareearth permanent magnet is becoming a big concern. In this paper, the switched reluctance motor, variable flux reluctance motor and synchronous reluctance motor are analyzed and compared as candidates for the 48V automotive applications. A recommendation is given for the selection of the motor drives

A comparison study of Modelling Techniques fo Permanent Magnet Machines

In this paper, four different modelling techniques for permanent magnet (PM) machines are compared for their accuracy and computational complexity. The considered techniques are primarily based on conformal mapping and harmonic modelling. In conformal mapping, the slotted air gap is mapped into a simpler canonical shape, where the field solution is calculated and then mapped back to the original domain. In harmonic modelling, the regions of the machine cross section are represented as Fourier series and coupled with each other by means of boundary conditions. The field solution is obtained by solving the boundary value problem. In order to quantify the accuracy of the field solutions, global parameters such as cogging torque and flux linkage are computed. The effectiveness of the modelling techniques are evaluated by comparing the global parameters and the simulation time with finite element analysis (FEA) result