Transverse Flux Permanent Magnet Research Articles

Research on a Novel Hybrid Axial Transverse Flux Permanent Magnet Motor With Compound Rotor

Research on a Novel Hybrid Axial Transverse Flux Permanent Magnet Motor With Compound Rotor

Analytical modelling of the linear transverse flux permanent magnet motor using magnetic equivalent circuit method

AbstractThe authors propose an analytical modelling approach for the linear transverse flux permanent magnet motor using the magnetic equivalent circuit method. The main focus of this study is to predict the phase flux‐linkage characteristic of the motor. Essential equations required for implementation of the model and how to solve it are described clearly so that someone can use it easily. A typical motor is selected to apply the proposed model and simulation results, including static characteristics of flux‐linkage and thrust, are presented. To validate the developed analytical model, the discussed motor is also analysed with 3D finite element method using MAXWELL software and the obtained simulation results are compared to each other.

Electromagnetic Vibration Analysis of Transverse Flux Permanent Magnet Linear Submersible Motor for Oil Production

A transverse flux linear motor is a special type of linear motor with a high thrust force density, and it has broad application prospects in the field of linear direct-drive systems. In the process of oil production, the vibration of the linear motor poses a significant amount of harm to the system due to its special slender structure. This paper focuses on the electromagnetic vibration of a transverse flux permanent magnet linear submersible motor (TFPMLSM). Firstly, the no-load air gap flux density is calculated based on the field modulation principle. Secondly, the radial electromagnetic force (REF) of the TFPMLSM is calculated, and the finite element method (FEM) is used to analyze the time-space and spectral characteristics of the REF. Then, the influence of secondary eccentricity on the frequency spectrum of the REF is further concluded. Finally, the natural frequencies of each vibration mode are calculated using the modal superposition method and the influence of the REF on the motor vibration is obtained through magnetic-structural coupling analysis. The research results found that the motor does not cause resonance at low speeds, and the fundamental frequency of REF has the greatest impact on electromagnetic vibration.

Analytical Calculation of Hybrid Excitation Transverse Flux Permanent Magnet Synchronous Linear Motor Based on Schwarz–Christoffel Mapping

An analytical calculation method of thrust and suspension force based on Schwarz–Christoffel (SC) mapping is presented for hybrid excitation transverse flux permanent magnet synchronous linear motor (HETFPMSLM) applied to a maglev train. The effectiveness of the analytical calculation is verified by three-dimensional finite element analysis. Firstly, the structure and principle of HETFPMSLM are analyzed, and its longitudinal two-dimensional SC mapping model is proposed. The magnetic field of HETFPMSLM is calculated by MATLAB’s SC Toolbox. Then the suspension force and thrust are calculated by the Maxwell stress tensor method, which is compared with the 3D finite element to verify the accuracy of the analytical calculation.

Design and Performance Analysis of Permanent Magnet Claw Pole Machine with Hybrid Cores

Permanent magnet claw pole machine (PMCPM) is a special kind of transverse flux permanent magnet machine. Compared with other electrical machines, it has the advantages of high torque density and high efficiency for high speed operation. However, because of its complex irregular structure, the manufacturing process using silicon sheets is complicated. Soft magnetic composite material (SMC) is manufactured by powder metallurgy technology, which can produce various shapes of stator core structures, so it is easier to produce various irregular shapes of the stator core. However, the raw SMC material is relatively expensive, and the mechanical strength of SMC is weak. In this paper, a PMCPM with hybrid cores is proposed. With the adoption of hybrid silicon sheet — SMC cores and amorphous alloy — SMC cores, the torque ability of PMCPM can be improved greatly and it can have higher efficiency for more wide operation frequency. Meanwhile, its mechanical strength has been improved and it can be designed for high torque direct drive applications as it is a modular machine. Furthermore, three methods are proposed to reduce the additional eddy current loss which resulted from the employment of hybrid cores in PMCPM.

A Generalized Per-Phase Equivalent Circuit Model of the PMSM With Predictable Core Loss

Equivalent circuit model (ECM) of the permanent magnet (PM) synchronous motor (PMSM) lays the foundation of the motor analysis, design, optimization, and control. However, the most widely used ECM of the PMSM ignores the core loss, which accounts for a considerable part of the electromagnetic loss and may exceed the copper loss in the medium and high-speed ranges. Previous researches of ECMs with predictable core loss are hard to satisfy the prediction precision over a broad range of speed and current. Therefore, a generalized per-phase ECM of the PMSM with predictable core loss is proposed. The proposed ECM topology and parameter identification method can effectively enhance the prediction accuracy of both the no-load and load core loss, and each component of the core loss in terms of the hysteresis, eddy current, and anomalous loss can be analyzed separately. Apart from the core loss, the proposed ECM has better precision in predicting the motor's output performance, such as mechanical characteristics, compared with traditional ECMs. The merits of the proposed ECM have been experimentally validated on the prototype of a PM transverse flux synchronous motor. This proposed ECM can be promotionally employed in other control strategies, such as model predictive control, to improve the PMSM performance.

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.

Analytical Performance Estimation of a Fall-Back Inner-Rotor Transverse-Flux Permanent Magnet Generator using Magnetic Equivalent Reluctance Circuit

The potential of wind energy resources is propelled fast and power extraction is increasing considerably due to the development of reliable and cost-effective wind turbine generators. Various permanent magnet (PM) wind generators have been implemented for wind power generation, among which, the conventional transverse-flux permanent magnet generator (TFPMG) is popular due to their higher torque density and simple coil design, but it has some disadvantages in comparison with radial flux PM generator, i.e., higher flux leakages and complex 3D flux pattern. In this article, a fall-back inner rotor transverse-flux PM wind generator FB-TFPMG has been investigated to override the disadvantages of conventional TFPMG. It employs half of the total PMs on the rotor and U-shaped stator cores. An analytical model of the proposed FB-TFPMG has derived using magnetic equivalent reluctance circuit (MERC) to predict the performance of the generator, i.e., flux densities in the air-gap, under aligned and unaligned conditions of rotor PMs with U-shaped stator cores. The results of the MERC model is verified with the results obtained through 3D finite element analysis.

Design and FEM analysis of high‐power density C‐core permanent magnet transverse flux generator with reduced PM volume

Design and FEM analysis of high‐power density C‐core permanent magnet transverse flux generator with reduced PM volume

Topologies comparison and rotor optimization of the hybrid axial transverse flux permanent magnet motor

With the advantages of high power density, the hybrid axial transverse flux permanent magnet motor (HATF-PMM) is investigated in this paper. Eight topologies of the novel HATF-PMM are proposed, analysed and compared. The applicable scopes of different topologies are summarized and the optimal topology is selected. Based on the characteristics of hybrid flux motor, an indirect optimization method through magnetic circuit decoupling and recombination is proposed. The rotor parameter optimization is performed by the proposed indirect optimization method. In the end, the HATF-PMM scheme with high power density is obtained, and the optimization law of HATF-PMM rotor parameters is revealed through the optimization process, which proves that the HATF-PMM has great potential in the application of more-electric aircraft.

Design optimization of a novel linear transverse flux switching permanent magnet generator for direct drive wave energy conversion

Linear transverse flux permanent magnet machines (LTFPMs) are categorized as high force density topologies, which are suitable candidates for direct drive and low-speed applications. This paper introduces a novel LTFPM topology, which also proposes advantages of the flux-switching machines. This proposed linear transverse flux switching PM machine (LTFSPM) has two long passive translators located at the armature's top and bottom sides. The topology offers a high value of force density, and also, it is a cost-effective topology due to its double-sided passive translator. Furthermore, the PMs are fully utilized in the magnetic circuit, the end winding length is negligible, and the iron cores can be laminated easily. In this paper, the operation principle of the topology is explained and its magnetic circuit is discussed. To reduce the computational time of optimization procedure, a double-layer method is adopted, which provides high robustness, low computational time, and high precision. Results of the finite element method indicate that the proposed machine can be considered a potential candidate for linear motion applications especially direct drive wave energy conversion systems, which require high force density values.

A New Type of Transverse Flux Permanent Magnet Rim Motor and Its Modeling Analysis

In this paper, a new type of transverse flux permanent magnet rim motor is obtained by combining transverse flux permanent magnet motor with shaftless rim motor. When a sinusoidal current is passed through the stator of the motor, a rotating magnetic field will be generated. The rotating magnetic field interacts with the constant magnetic field generated by the rotor magnet, and the interaction will drive the motor to rotate. The new motor has the advantages of high power, low noise, small vibration and small volume, and is suitable for marine propulsion and other fields. This paper introduces the special magnetic field distribution of the new motor, and uses the 3D finite element analysis method to analyze the electromagnetic field of the motor’s no-load and load conditions. The paper will verify the correctness and superiority of the model.

A Novel Structure of Tubular Staggered Transverse-Flux Permanent-Magnet Linear Generator for Wave Energy Conversion

This paper presents a novel linear generator structure of three-phase tubular staggered transverse flux permanent magnet linear generator (TSTF-PMLG) for wave energy conversion. Compared with conventional TF-PMLGs, the new structure has a simpler magnetic flux path, high mechanical strength, low cogging force and more suitable for low-speed direct driven situation. In the primary of TSTF-PMLG, a nonuniform teeth steel sheets structure is used and steel sheets of different phases are in different angel so that the groove can be separated by staggered steel sheets in the plane perpendicular to the direction of movement. By the analytical model, the operation principle of the proposed linear generator is explained. Then through the finite element analysis, the distribution of the main flux and leakage flux, the no-load characteristics and output power of TSTF-PMLG are analyzed in detail. And the influence of the lamination factor on the output characteristics of the TSTF-PMLG is obtained. Subsequently the appropriate design parameters of the TSTF-PMLG are selected. During the TSTF-PMLG processing, the method of mixing silicon steel sheets and fiberglass board is used to limiting the lamination factor. Finially, a prototype of 150 W rated power and 79% rated efficiency is presented. And the experimental results verify the theoretical analysis.

Two-Segment Magnet Transverse Flux Ferrite PM Generator for Direct-Drive Wind Turbine Applications: Nonlinear 3-D MEC Modeling and Experimental Validation

Transverse flux PM generator (TFPMG) is a capable option for direct-drive wind turbine (DDWT) applications due to its high-power characteristics at low speeds. NdFeB-based TFPMGs may suffer from a higher total cost and lower thermal capabilities compared to the ferrite-based TFPMGs. Not yet covered in the existing literature, in this paper a transverse flux ferrite PM generator (TFFPMG) is proposed, designed, and modeled, which can also resolve the unipolar flux generation and even-order harmonics in the flux linkage of the conventional TFPMGs that occurred in conventional TFPMGs through its innovative two-segment trapezoidal shape magnet structure. Due to the 3-D flux path nature in the proposed TFFPMG, either 3-D finite element analysis (FEA) or 3-D magnetic equivalent circuit (MEC) modeling should be used. As a computationally efficient modeling method, a nonlinear 3-D MEC is established to model the entire structure of the TFFPMG while the core saturation and nonlinear permeances are also fully considered to improve the modeling accuracy. The electromagnetic performance of the proposed TFFPMG modeled by 3-D MEC in various loading conditions is validated by both 3-D FEA and experimental results using a 2.5 kW TFFPMG. A close agreement between 3-D MEC modeling predictions, 3-D FEA, and test results confirms the reliability of the MEC modeling for the proposed TFFPMG.

Design and analysis of semi-closed stator core transverse flux permanent magnet generator

Purpose The purpose of this paper is to modernize the generator system of wind turbine concept that not only improves the efficiency and power density but also reduces the system cost making design simpler and less expensive, especially in large-scale production. Design/methodology/approach This paper presents a new permanent magnet transverse flux generator (PMTFG) for wind energy production. The key feature of its composition is the double armature coil in a semi-closed stator core. The main structural difference of the presented design is the use of double coil in the same space of semi-closed stator core and reduced number of stator pole pairs and rotor magnets from 12/24 to 10/20. 3D simulations are performed using finite element analysis (FEA) to measure induced voltage and magnetic field distribution at no load. The FEA is performed to quantify the change in flux linkage, induced voltage and output power as a function of different speeds and load current. Findings Results show that PMTFG with double coil configuration has improved electromagnetic performance in terms of flux linkage, induced voltage, output power and efficiency. The power density of 10/20 PMTFG with the double coil is 0.0524 KW/Kg, about an 18% increase compared to the conventional design. Research limitations/implications The proposed PMTFG is highly recommended for direct drive applications such as wind power. Originality/value Four models are simulated by FEA with single and double coil configuration, and load analysis is performed on all simulated models. Finally, results are compared with conventional PMTFG.

Design of a Novel Claw Pole Transverse Flux Permanent Magnet Motor Based on Hybrid Stator Core

Transverse flux permanent magnet motor (TFPM) benefits from the high power density and design freedom but traditional TFPM exhibits some disadvantages-high flux leakage, cogging torque, and low-power factor-which restrict its development. In order to overcome these disadvantages, claw pole TFPM (CTFPM) is developed, but it also be plagued by the demerits of soft magnetic composite (SMC) material. In this article, a novel CTFPM based on hybrid stator core (Hybrid-CTFPM) is proposed to improve the performance of CTFPM. The parameters of claw pole are investigated in this article and are optimized using a new optimization strategy eventually. This article provides a valuable reference for the design and optimization of CTFPM.

A Spiral Translator Permanent Magnet Transverse Flux Linear Generator Used in Direct-Drive Wave Energy Converter

Direct-drive wave energy converter (DD-WEC) simplifies the structure and improves the efficiency of wave energy conversion. Permanent magnet transverse flux linear generator (PMTFLG) combines the merits of transverse flux linear generator (TFLG) and permanent magnet linear generator (PMLG), and is suitable for low-speed high thrust density applications, like DD-WEC. However, it suffers from a significant demerit which is the high cost due to the rare earth permanent magnets (PMs). A stator-PM spiral translator PMTFLG (ST-PMTFLG) is proposed in this article. Armature winding and PMs are arranged in outer stator and inner stator, respectively while the translator is made of spiral steel blocks and nonmagnetic blocks. Similar to the magnetically geared machine, the proposed topology is suitable to be used in low-speed long-stroke application. Results show that ST-PMTFLG has advantages of low PM consumption and high thrust density. The thrust per PM volume of 12/11 ST-PMTFLG is 4.18 MN/m3.

Optimization Design of a Novel Flux-Switching Transverse-Flux Permanent Magnet Tube Linear Motor

A novel flux-switching transverse-flux permanent magnet tube linear motor (FSTFPMTLM) with oblique air-gap is proposed in this article, which combined the merits of the tube linear motor, the transverse-flux linear motor, and the switched-flux linear motor. The structure and operating principle of the FSTFPMTLM is presented first. Considering this motor has a 3-D magnetic circuit and designing the motor with high performance, this article proposes an optimization method for the FSTFPMTLM by decomposing the design of the motor into two steps to separate optimization using experimental design method. The first step is to optimize the cross-section part of the motor. After that the optimized motor is compared with the initial one by finite element method (FEM). The prototype is then manufactured and tested.

Diagnosis and detection of dynamic eccentricity fault for permanent magnet transverse flux generator

The authors analyse no-load and full-load performance of a permanent magnet transverse flux generators (PMTFGs) in fully aligned condition as well as under different types of mechanical faults including static eccentricity (SE), dynamic eccentricity (DE), inclined rotor (IR) and run-out (RO) faults. An analytical model is developed to calculate the air-gap permeance. This permeance is used to estimate the flux density and back-electromotive force in the healthy and faulty machine. Performance of the machine is predicted using the proposed analytical model and verified by comparing it with the results obtained using three-dimensional time stepping finite element method. Finally, the spectra of stator current in the PMTFG under SE, DE, IR and OR faults are determined through which the amplitude of side-band components with a specific frequency pattern is extracted. It can detect the eccentricity fault precisely, recognise its type and determines its severity.

Design of a Transverse Flux Permanent Magnet Generator Using a Reluctance Circuit

This work presents an analytical methodology to design a permanent magnet transverse flux generator using a reluctance circuit. Unlike other research, it fully indicates the details to design the rotor, stator, and the air gap of the machine, with all its geometry. In the design section, special considerations to determine the outer diameter of the rotor, and the accompanying pole pitch for the U-cores and I-cores are presented. The proposal of an iterative algorithm using a reluctance circuit to calculate the turns of the armature winding and curved trajectories of flux tubes to model the leakage flux that will allow the synchronous inductance calculation also is presented. The proposed methodology allows determining the performance and the lumped parameters of the generator. Furthermore, it provides evidence that with this design it is possible to select the values of standard voltage for electric generators of this topology. The analytical results of the magnetic flux densities, magnetic flux, lumped parameters, electromotive force, terminal voltage, armature current, power factor, and efficiency are compared with 3D finite element method. Analyzing these results, it is possible to verify the good agreement between them.