Transverse-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.

Development and Analysis of Novel Flux-Switching Transverse-Flux Permanent Magnet Linear Machine

The flux-switching transverse-flux permanent magnet linear machine (FSTFPMLM) is proposed in this paper, combining the advantages of the transverse-flux linear machine and the flux-switching linear machine. First, the structure and operating principle of the FSTFPMLM is presented. Second, the magnetic field of a simplified FSTFPMLM is numerically computed by the three-dimensional (3-D) finite-element method (FEM). Third, the thrust characteristics of the machine, including the thrust force, cogging force, and force ripple, are numerically analyzed. The influence of structure parameters on the thrust characteristics has been analyzed by the 3-D FEM. The law of thrust, cogging force, and force ripple as the pole pitch ratio between primary and secondary, and the ratio between the tooth width and pole pitch of the secondary variable provides the guidance to design FSTFPMLM, which aims to achieve a larger thrust, smaller cogging and force ripple using less permanent magnet materials. The thrust force capabilities of FSTFPMLM are compared with other topologies of linear machines. Finally, the prototype and experimental setup have been developed, and the calculated results and the measured results are in good agreement.

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.

Thermal Analysis of a Novel Cylindrical Transverse-Flux Permanent-Magnet Linear Machine

This paper presents a novel staggered-teeth cylindrical transverse-flux permanent-magnet linear machine (TFPMLM), which aims to improve the power factor and force density. Due to the compact structure and high performance requirement, thermal problems should be seriously considered. The three-dimensional (3-D) temperature field model is established. The determination of convection heat transfer coefficients is discussed. Equivalent thermal conductivities of stator core and winding are given to simplify the analysis. With the thermal effect of the adhesive coatings among permanent magnets (PMs) and mover yoke taken into account, the temperature field distribution and variation rules of the TFPMLM are obtained using the finite volume method (FVM). The influences of slot filling factor and air flow velocity on the temperature field distribution are analyzed. It is found that the hottest spot of the TFPMLM appears in the middle of the end winding; and there is no risk of demagnetization for PMs.

Research on the Magnetic Characteristic of a Novel Transverse-Flux PM Linear Machine Used for Free-Piston Energy Converter

Free-piston energy converter, composed of a free-piston engine and a permanent-magnet (PM) linear machine, is a promising generator concept for series hybrid electric vehicles (HEVs). In this paper, a novel transverse-flux PM linear machine is investigated for such applications. Unlike conventional transverse-flux machines, the proposed machine features simple mechanical structure. Flux leakage of the proposed machine is analyzed, and parameters of the machine are optimized by finite-element method (FEM). Compared with conventional flux configurations, such as radial flux, axial flux and Halbach, the proposed transverse-flux topology showed advantages in low cogging force, low thrust fluctuation, and high efficiency. A prototype was designed and manufactured. Further experiments indicated satisfactory load characteristic of the machine.

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.