Amina Ibala

Accounting for the Armature Magnetic Reaction and Saturation Effects in the Reluctance Model of a New Concept of Claw-Pole Alternator

We describe the development and the experimental validation of a magnetic equivalent circuit (MEC) of a new claw pole alternator where the DC-excitation winding is located in the stator (CPAES), rather than in the rotor in conventional claw pole alternator. Thus, we discarded the brush-ring system and achieved crucial cost, compactness, and reliability benefits. The proposed MEC treats both no-load and loaded armature operations. It also accounts for the saturation of the magnetic circuit. We numerically solve the established MEC using the Newton-Raphson algorithm. We validated the established MEC by considering experimental tests carried out on a prototype of the CPAES. We found that the results yielded by the proposed MEC and those given by the experimental tests are in good agreement.

MEC-Based Sizing of a Hybrid-Excited Claw Pole Alternator

The paper is aimed at a magnetic equivalent circuit (MEC)-based sizing of a novel hybrid-excited claw pole alternator. It consists in a claw pole concept with a NdFeB permanent magnet (PM) excitation in the rotor and a dc one in the stator, with the homopolar flux eradicated owing to a magnetic barrier inserted between the stator yoke and lamination. The proposed MEC considers both linear and saturated magnetic circuit, with a focus on the modeling of the leakage fluxes. The developed model is applied for the prediction of the no-load characteristic which is validated by 3-D finite-element analysis (FEA). Then, a dual FEA-experimental validation is carried out considering the case of a dc excitation. Moreover, the proposed MEC makes the investigation of the influent sizing parameters on the machine back-electromotive force (EMF) production capability easy. This latter is enhanced owing to the integration of two ring ferrite PMs linked to the stator, along with a reduction of the volume of the NdFeB PM in the rotor. It has been found that the gained improvement is better than the benefit yielded by as many pole number ferrite PMs inserted between the claws.

Lumped Circuit Accounting for the Rotor Motion Dedicated to the Investigation of the Time-Varying Features of Claw Pole Topologies

This paper is aimed at the derivation and the resolution of a new lumped circuit-also called magnetic equivalent circuit (MEC)-based model of claw pole alternators (CPAs). Incorporating the rotor motion, the proposed MEC is intended to the investigation of the time-varying features of CPAs. Furthermore, it considers the saturation and the armature magnetic reaction. For the sake of simplicity, the MEC is derived assuming that the stator teeth and yoke are independent of the rotor position. Moreover, a specific hypothesis considering that the claws have the same shape along the axial direction with an opening equal to the one of the median plane is adopted. A dedicated numerical procedure based on the Newton-Raphson algorithm is developed in order to solve the proposed MEC. Hence, the prediction of selected time-varying features, considering both no-load and load operations, turns to be feasible. The comparison between the MEC results and those yielded by experiments carried out on a test bench, has led to good agreement.

On the Comparison Between the Stator- and Rotor-excited Claw Pole Alternators

Abstract This article compares the electromagnetic features of rotor-excited claw pole alternators and stator-excited claw pole alternators, which share the same rotor active length. Accounting for the 3D flux path characterizing both machines, the comparison study is based on a 3D finite-element analysis. Following a description of the flux linkage in these machines, special attention is paid to the investigation of their magnetic features, including the air gap spatial repartition of the flux density, torque-angle characteristics, and no-load characteristics. It has been found that the rotor-excited claw pole alternator exhibits a higher back-electromotive force production capability than the stator-excited claw pole alternator, which is penalized by (i) the additional lateral air gaps located in between the collectors and the magnetic rings, and (ii) the homopolar flux. The torque production capability of the stator-excited claw pole alternator is also affected by these drawbacks at low values of the field current. Increasing this leads to a saturation of the rotor-excited claw pole alternator, whose torque production is similar to that of the stator-excited claw pole alternator.

An attempt to improve the generating capabilities of an hybrid claw pole machine

Hybrid excited AC machines are presently given an increasing attention. Within this trend, the paper deals with a novel hybrid excited brushless claw pole machine. It consists in a claw pole machine excited by a PM in the rotor and by a field winding in the stator. In order to eradicate the claw-to-claw leakage flux and then improve the machine features, ferrite PMs are inserted in between the claws. An increase of the air gap flux density has been gained, so that the machine turns to be equipped by three excitation sources.

3D FEA based feature investigation of a claw pole alternator with DC excitation in the stator

This paper deals with finite element analysis (FEA) modeling and features investigation of a claw pole alternator with its DC-excitation winding is located in the stator rather than in the rotor in conventional machines. The proposed model takes into account for the saturation of the magnetic circuit. A special attention is paid to the distribution of the air gap flux density and the back-EMF. A validation of the results yielded by FEA is achieved considering both measurements carried out on a prototype of the studied machine and analytical results obtained by a reluctance model developed in a previous work.

On the modeling of a TFPM by reluctance network including the saturation effect with emphasis on the leakage fluxes

Purpose – This paper aims at the derivation of an accurate reluctance model of a transverse flux permanent magnet machine (TFPM) and its validation by finite element analysis (FEA).Design/methodology/approach – Analytical prediction of the different reluctances in the core, the permanent magnets, and the air. These reluctances characterize the paths of both main and leakage fluxes. Then, a validation of the proposed reluctance model is carried out using FEA. An interesting application of the proposed reluctance consists in the assessment of the TFPM torque production capability.Findings – The torque yielded by the reluctance model of the TFPM and the one computed using 3D‐FEA are in good agreement. This result is of great importance in so far as the CPU time required for 3D‐FEA computation is much more higher than the one consumed in the resolution of the reluctance model.Research limitations/implications – Further validation of the results yielded by the proposed reluctance model through their comparison...

3D MEC modeling of a hybrid-excited claw pole alternator incorporating the rotor motion

The paper is devoted to the modeling of a hybrid-excited claw pole alternator (HECPA) by means of a variable position 3D magnetic equivalent circuit (MEC). The study is initiated by the derivation of a MEC with the rotor position kept at the maximum flux linkage between the rotor and stator, enabling the investigation of the steady-state features. The incorporation of the rotor position in the MEC is then considered. A dedicated numerical procedure based on the Newton-Raphson algorithm is developed for the resolution of the proposed variable position MEC. The obtained fluxes, for the different considered positions, allow the prediction of the HECPA time-varying features under no-load operation. A comparison between the results predicted by the variable position MEC and those computed by finite element analysis reveals a good agreement.

Hybrid excited claw pole alternators: Attempt to satisfy the increasing power need on board

This paper is devoted to the topological and functional descriptions as well as a 3D FEA-based optimization of a hybrid-excited claw pole alternator, with a focus on its back-EMF production capability. The proposed claw pole concept is equipped by PM excitations in both stator and rotor and a field one in the stator. A special attention is paid to the cancelation of the homopolar flux which represents a specific leakage one associated to the field excitation. To do so, the effects of two (complete and partial) Aluminium-made magnetic barriers, inserted in between the stator yoke and lamination along the active length, on the back-EMF production capability are investigated. It has been found that the partial magnetic barrier is a compromise regarding the homopolar flux cancelation and the 3D-flux enhancement. Compared to the complete magnetic barrier, the partial one allowed an increase of the amplitude of the fundamental back-EMF; those of its harmonics remain almost unchangeable.

On the sizing of the PM excitation of a hybrid claw pole alternator

The paper is devoted to a 3D-finite element analysis (FEA) of a hybrid-excited claw pole alternator (HECPA) with emphasis on the sizing of the permanent magnet (PM) excitation and it effect on the back-EMF production capability and eddy current loss. The HECPA is equipped by three sources of excitation : (i) a toroidal field in the stator, (ii) a NdFeB PM in the rotor and (iii) two lateral ferrite PMs mounted on the magnetic collector. The study is initiated by the description of the topology of the HECPA. Then, an analysis of the flux paths through the magnetic circuit is carried out, prior an investigating by 3D FEA of the effects on the PMs widths on the back-EMF production capability as well as on the eddy current loss. The study is achieved by the a 3D FEA-based computation of the features of the HECPA with optimized PM excitation.