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

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

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

Usage of the inductive energy storage in the field winding for driving the variable reluctance motor

In automotive systems, reliability and cost are paramount for the success of electrical drive systems. Considering the switched reluctance motor (SRM), the power electronics cost dominates the total cost of the electrical drive. In this respect, especially the dc-link capacitor significantly contributes to the total bill of the material. This paper proposes the use of a dc-excited winding in an 8/6 SRM as a means of reducing the capacitor. The energy conversion of the motor is analyzed intensively. The control algorithm of the field winding is investigated and an active control algorithm is proposed to provide and absorb the energy in parallel with the dc-link capacitor. The effectiveness of this control method is confirmed by the cosimulation between the finite-element method and the Simulink

Field weakening capability of 12-stator/10-rotor-pole variable flux reluctance machines

Variable flux reluctance machines (VFRMs) are viable candidates for automotive applications. This paper investigates the field weakening capability of a 12/10 VFRM. Starting with voltage and toque equations, the paper reveals the relationship between torque-speed characteristics and the current arrangement (slot division) of both DC-field and armature windings. The method for expanding the working envelope by tuning DC or AC currents is discussed for different slot divisions. The results are validated by 2D finite element analysis

Comparative analysis of inductances of air-gap windings

Inductance value of an electrical machine is important for high-speed electrical drives. In this paper, a comparative analysis of inductances of toroidal, skewed and concentrated air-gap windings has been performed. Analytical approach of inductance calculation, using Biot-Savart’s law and method of images, is applied to toroidal and concentrated windings. The analytical method of inductance calculation is verified by FEM 3D. Additionally, comparison of the conductor length of the windings is performed

High-speed slotless permanent magnet machines: modelling and design frameworks

This paper presents a design framework for high-speed slotless permanent magnet machines based on extended harmonic modeling (HM) technique to predict various electromagnetic properties and torque distribution. The developed models for generic design framework are able to evaluate slotless PM machines' topologies with a wide range of 3D slotless windings, (including those with skewing), and can be also used for future design optimization routines