Flux Permanent Magnet Linear Machine Research Articles

A novel tubular High-Power-Factor Transverse-Flux linear machine with Concentrated-Flux teeth

Due to principle constraints of the conventional transverse flux permanent magnet linear machine, its PM utilization is less than half. Besides, the complex structure and the serious magnetic leakage also lead to the limited thrust increase and the sharp decline of power factor. Therefore, the high-power-factor transverse-flux permanent-magnet linear machine (HPF-TFPMLM) using the concentrated-flux teeth is proposed in this paper. First, the topology and operation principle of the circumferentially distributed HPF-TFPMLM are investigated. The concentrated-flux teeth and multi-unit concentrated windings are introduced to improve power factor of the HPF-TFPMLM. To further study the proposed HPF-TFPMLM, its counterpart of the axial distributed topology is proposed for comparative analysis. Then, the key electromagnetic performance of power factor, thrust and thrust density of the HPF-TFPMLM are analyzed. Its performances including no-load EMF, magnetic field distribution and overload capacity are evaluated and compared with its counterpart. Finally, the feasibility and correctness of the investigated HPF-TFPMLM are verified.

Lumped Parameter Model and Electromagnetic Performance Analysis of a Single-Sided Variable Flux Permanent Magnet Linear Machine

A new Single-sided Variable Flux Permanent Magnet Linear Machine with flux bridge in mover core is proposed in this paper. The flux bridge prevents the leakage flux from the mover and converts it into flux linkage, which greatly influences the performance of the machine. First, a lumped parameter model is used to find the suitable coil combination and no-load flux linkage of the proposed machine, which greatly reduces the computational time and drive storage. Secondly, the proposed machine replaces the expensive rare earth permanent magnets with ferrite magnets and provides improved flux controlling capability under variable excitation currents. Multivariable geometric optimization is utilized to optimize the leading design parameters like split ratio, stator pole width, width and height of permanent magnet, flux bridge width, the width of mover’s tooth, and stator slot depth at constant electric and magnetic loading. The optimized design increases the flux linkage by 44.11%, average thrust force by 35%, thrust force density by 35.02%, minimizes ripples in thrust force by 23%, and detent force by 87.5%. Furthermore, the results obtained by 2D analysis are verified by 3D analysis. Thermal analysis is done to set the operating limit of the proposed machine.

Development of a consequent pole transverse flux permanent magnet linear machine with passive secondary structure

Transverse-flux machines have the advantage of high force density owing to the peculiarity of decoupling of electric loading and magnetic loading. In this paper, a novel consequent-pole transverse-flux permanent magnet linear machine (CP-TFPMLM) is proposed and investigated. The origination of the proposed machine is from an existing transverse-flux flux-reversal linear machine (TF-FRLM), by partially replacing permanent magnet poles with soft magnetic iron for further reducing the cost of magnets. The fundamental structure and operating principle are introduced at first. The electromagnetic performance, including back EMF, detent force, and thrust force, are investigated with the finite element method. The proposed machine can achieve similar performance as compared to the TF-FRLM but with half of the magnets are used.

Enhancement of a Thrust Force of a Tubular Electromagnetic Launcher With Transverse Flux Configuration by Leakage Flux Suppression

This paper presents an approach for enhancing the thrust force of a tubular transverse flux permanent magnet linear machine (TFPMLM) that has been developed for electromagnetic applications. It is shown that, by introducing auxiliary cores to suppress the leakage flux, the thrust force of the tubular TFPMLM can be significantly enhanced, by ~ 130%, under the same volumetric constraints. The effectiveness of the proposed technique is validated by extensive three-dimensional finite element computations.

Influence of the Permanent Magnet Magnetization Length on the Performance of a Tubular Transverse Flux Permanent Magnet Linear Machine Used for Electromagnetic Launch

This paper investigates the underlying influence of permanent magnet (PM) magnetization length on the performance of a tubular transverse flux PM linear machine working as the propeller of an electromagnetic launcher, including its main flux linkage, cogging force, and thrust force. The theoretical analysis is brought forward and verified with 3-D numerical computations. It is shown that the cogging force increases with the increase of the PM magnetization length, whereas the main flux linkage and thrust force do not follow this rule, which is quite different from that in conventional PM machines.

Analysis and Computer-Aided Simulation of Cogging Force Characteristic of a Linear Electromagnetic Launcher With Tubular Transverse Flux Machine

This paper investigates a linear electromagnetic launcher with tubular transverse flux permanent-magnet linear machine (TFPMLM). Special focus is given on its cogging force characteristic, including the theoretical analysis and computer-aided simulation. Both 3-D and equivalent 2-D finite-element analyses are performed to calculate the cogging force, and the results are compared. It is shown that the proposed 3-D to 2-D equivalence can predict the cogging force of the tubular TFPMLM in an accurate and fast way.