Stator Flux Reversal Permanent Magnet Research Articles

Analysis of a New Linear Dual Stator Consequent Pole Halbach Array Flux Reversal Machine

The permanent magnet machine has attracted much attention due to its high torque density at low speed and simple configuration. This feature is due to many magnetic pole pairs that flux in the air gap can be significantly changed with the smallest motion of the moving. In this paper, a linear dual stator flux reversal permanent magnet machine (LDSFRPMM) with toroidal winding is presented, which magnets embedded with Halbach and simple array on the translator and stator, respectively. The innovation of this structure over a conventional machine is the addition of a magnet between the stator teeth with the appropriate magnetic orientation, and finding the best width of permanent magnet on the stator and a change of the type of winding from the concentrated to the toroidal. By implementing these changes on a conventional machine, the main parameters of the machine such as back electromotive force (EMF), thrust force, power factor and permanent magnetic (PM) flux are increased which improves the performance of the proposed machine.

A Novel Tubular Partitioned Stator Flux-Reversal Permanent Magnet Linear Machine for Direct-Drive Wave Energy Generation

A novel tubular partitioned stator flux-reversal permanent magnet linear machine (PS-FRPMLM) is proposed for direct-drive wave energy generation. It consists of four flat PS-FRPMLMs and a moving aluminum tube, which not only combines the merits of permanent magnet machines and flux-reversal machines but also overcomes the space constraint between the permanent magnets and electric loadings. First, the topology and the operation principle are presented. Then, the proposed machines with different slot/pole combinations, i.e., 6/4, 6/5, 6/7, and 6/8, are optimized to obtain the maximum no-load electromotive force (EMF). Furthermore, the performances of these proposed machines are compared with those of conventional tubular FRPMLMs in both no-load and on-load states. The results show that this novel structure possesses lower cogging force, better PM utilization, and higher efficiency in the on-load state, which proves it to be suitable for application in direct-drive wave energy generation. Finally, a prototype of a single flat PS-FRPMLM is tested to verify the predicted finite element (FE) results.

Investigation and Analysis of Force Production Mechanism for Partitioned Stator Flux Reversal Permanent Magnet Linear Machine

Investigation and Analysis of Force Production Mechanism for Partitioned Stator Flux Reversal Permanent Magnet Linear Machine

Comparative Analysis of Partitioned Stator Flux Reversal PM Machine and Magnetically Geared Machine Operating in Stator-PM and Rotor-PM Modes

In this paper, the partitioned stator flux reversal permanent magnet (PM) (PS-FRPM) machine and the conventional magnetically geared (MG) machine operating in both stator-PM (SPM) and rotor-PM (RPM) modes are comparatively analyzed in terms of electromagnetic performance to provide design guides for an MG machine regarding an SPM- or RPM-type machine and a higher or lower gear ratio machine. It is found that an SPM-type machine is recommended since both PS-FRPM and MG machines operating in SPM modes have a higher phase back-EMF and hence torque than their RPM counterparts, respectively, as a result of a similar phase flux linkage but a higher electric frequency since the iron piece number is larger than the PM pole-pair number. Moreover, a smaller gear ratio machine is preferred from the perspective of a higher power factor and hence a lower inverter power rating, as the conventional MG machines with higher gear ratios suffer from larger flux-leakage, higher synchronous reactance and hence lower power factors, as well as higher iron losses, than the PS-FRPM machines. However, higher gear ratio machines feature lower cogging torques and torque ripples due to the smaller difference between the PM pole-pair number and iron piece number. Both prototypes of PS-FRPM machine operating in SPM mode and MG machine operating in RPM mode are built and tested to verify the finite element predicted results.

Comparative Analysis of End Effect in Partitioned Stator Flux Reversal Machines Having Surface-Mounted and Consequent Pole Permanent Magnets

In this paper, the end effects of a partitioned stator flux reversal permanent magnet (PM) machine with a surface-mounted PM (SPM) inner stator and a consequent pole PM (CPM) inner stator are comparatively analyzed. It is found that due to higher saturated inner stator steel in a CPM machine, it suffers from larger end effect than the SPM machine. Influence of armature reaction on end effect is investigated by a finite-element (FE) analysis, together with that of aspect ratio, i.e., axial stack length to stator outer diameter. Furthermore, it is found that in the CPM machine, the optimal PM arcs for the highest average electromagnetic torque predicted by 2-D and 3-D FE are different due to the variation of end effect with PM arc. Prototypes with both SPM and CPM inner stators are built and tested to verify the FE analysis.

Comparative Analysis of Partitioned Stator Flux Reversal PM Machines Having Fractional-Slot Nonoverlapping and Integer-Slot Overlapping Windings

This paper proposes a new partitioned stator flux reversal permanent magnet (PM) (PS-FRPM) machine having integer-slot overlapping windings, i.e., the slot number per pole per phase q is an integer, based on the magnetic gearing effect in stator-PM machines. Compared with the existing PS-FRPM machine with fractional-slot nonoverlapping windings, a more sinusoidal armature reaction magnetomotive force can be achieved in the proposed PS-FRPM machine with integer-slot overlapping windings, resulting in lower iron loss and PM loss. Electromagnetic performance of the PS-FRPM machine, which has q = 1 overlapping windings is analyzed and compared with PS-FRPM machine, which has q = 0.5 nonoverlapping windings by finite element (FE) analysis. FE results show that the proposed 24/10/12-outer-stator/rotor/inner-stator-pole PS-FRPM machine with q = 1 overlapping winding exhibits higher fundamental phase back-electromotive force, higher average electromagnetic torque and lower torque ripple, lower loss and higher efficiency, higher self-inductance but lower mutual inductance, higher d -axis inductance, and potential infinite flux-weakening capability compared with the 12/10/12-outer-stator/rotor/inner-stator-pole PS-FRPM machine with q = 0.5 nonoverlapping windings. Both prototype machines with q = 1 overlapping winding and q = 0.5 nonoverlapping windings are built and tested to verify the FE analyzes.

Partitioned stator flux reversal machines having Halbach array PMs

Purpose – In this paper, the partitioned stator flux reversal permanent magnet (PM) (PS-FRPM) machines with Halbach array PMs are investigated to compare with the machine having the conventional parallel magnetized PMs, and conventional FRPM machine. This paper aims to discuss these issues. Design/methodology/approach – The Halbach array PM machines with 2-, 3-, and 4-segment and ideal Halbach array PMs have similar topology and designed based on the PS-FRPM with parallel magnetized PMs. The open circuit analysis and electromagnetic performance has been calculated and compares with the aid of finite element (FE) method, and validated by experiments. Findings – The PS-FRPMs with Halbach array PMs have higher back-EMF and torque performance, as well as lower cogging torque and torque ripple, all having significantly higher torque density than the FRPM machine with single stator. The experimental results and FE predicted results of the 2-segment Halbach PM prototype machine are compared and good agreement is achieved. Originality/value – This paper introduces the new concept and design of PS-FRPMs having Halbach array PMs with different PM segments and idea PM array. The comparison with conventional FRPM and PS-FRPM with parallel magnetized PMs shows the benefits with PS-FRPMs with Halbach array PMs.

Partitioned Stator Flux Reversal Machine With Consequent-Pole PM Stator

In this paper, partitioned stator flux reversal permanent magnet (PS-FRPM) machines having different stator/rotor pole combinations with consequent-pole PM (CPM) stator are proposed and analyzed. Compared with the conventional 12-stator-pole PS-FRPM machines having 10-, 11-, 13-, and 14-rotor-pole rotors and surface-mounted PM (SPM) stator, the PM volume in the proposed PS-FRPM machines with CPM stator can be saved by 28.33%, 30%, 30%, and 33.33%, respectively, while the torque density are similar, i.e., 98.59%, 96.69%, 95.50%, and 97.15%, respectively. Besides, the proposed PS-FRPM machines with CPM stator can exhibit only <1% smaller efficiency compared with the existing PS-FRPM machines with SPM inner stator.