Transverse Flux Permanent Magnet Machine Research Articles

Multiobjective Sequential Optimization Method for the Design of Industrial Electromagnetic Devices

A multiobjective sequential optimization method (MSOM) is presented to deal with practical design problems of industrial electromagnetic devices. MSOM consists of a sequential optimization strategy of multiobjective optimization model and a modified central composite design (CCD) sampling method. To improve the optimization efficiency, Kriging model is employed to construct the approximate multiobjective optimization models. Then a modified CCD sampling method is presented to update the sample sets with the obtained Pareto optimal points and Kriging models. Thereafter, by investigating a test function and a three-dimensional permanent magnet transverse flux machine, it can be found that the proposed method is efficient, and the computation cost of finite element analysis can be saved remarkably.

Unbalanced Magnetic Forces in Rotational Unsymmetrical Transverse Flux Machine

The torque and unbalanced magnetic forces in permanent magnet machines are resultants of the tangential, axial and normal magnetic forces, respectively. Those are in general influenced by pole-teeth-winding configuration. A study of the torque and unbalanced magnetic forces of a small flux concentrating permanent magnet transverse flux machine (FCPM-TFM) in segmented compact structure is presented in this paper. By using FLUX3D software from Cedrat, Maxwell stress tensor has been solved. Finite element (FE-) magneto static study followed by transient analysis has been conducted to investigate the influence of unsymmetrical winding pattern, in respect to the rotor, on the performance of the FCPM-TFM. Calculating the magnetic field components in the air gap has required an introduction of a 2D grid in the middle of the air gap, whereby good estimations of the forces are obtained. In this machine, the axial magnetic forces reveal relatively higher amplitudes compared to the normal forces. Practical results of a prototype motor are demonstrated through the analysis.

Performance Comparison of Longitudinal Flux and Transverse Flux Permanent Magnet Machines for Turret Applications With Large Diameter

The aim of this paper is to provide performance comparisons between conventional longitudinal flux and transverse flux permanent-magnet machines using three-dimensional finite element analysis considering both electro-magnetic and mechanical fields. For a turret application with 2 meters in diameter size, not only electro-magnetic performance but also mechanical structural strength is important. Therefore, the comparison is focused on the torque density, machine efficiency, time constant, magnetic forces, and mechanical equivalent stresses occurred by the magnetic forces. For a specific turret application without an external cooling system, the obtained results provide an indication on which type of the machines is best suited regarding performance and size.

System Level Six Sigma Robust Optimization of a Drive System With PM Transverse Flux Machine

From our previous study, permanent magnet (PM) transverse flux machine with soft magnetic composite material core is very promising. However, from the point of view of engineering application, at least two more aspects have to be considered. First, not only the machine but also its control system has to be investigated and optimized simultaneously. Second, robust design requirements must be included in the system level optimization, which is a very important issue in modern quality design. Therefore, to improve the applications of this type of machine, we present a system level six sigma robust optimization method to design a drive system with this motor and field-oriented control scheme. The optimal robust solutions obtained are compared with those from deterministic optimization method and initial design scheme. From the comparison, we can see that the system's reliabilities and robust levels are improved significantly by the proposed method, and the probability of system failure can be reduced a lot.

Structural analysis and optimisation of transverse flux permanent magnet machines for 5 and 10 MW direct drive wind turbines

ABSTRACTThe transverse flux permanent magnet generator offers high power density in terms of active mass. Two configurations of this machine topology (referred to as TFPM‐1 and TFPM‐2) are described, and optimised electromagnetic designs are presented. Direct drive generators require a significant support structure, which is designed to minimise the deflection into the air gap due to inherent electromagnetic attraction forces. The design of these structures is also dependant upon the generator topology. Structural design tools, which can be used in a design office environment, have been developed for the transverse flux machine and verified using commercial numerical modelling packages. Generic disc and arm structures are used. Only static analysis has been performed, but this does provide the designer with an estimate for more detailed design. A comparison of mass is made between the two transverse flux machines and a more conventional iron‐cored permanent magnet generator. The comparison shows that TFPM‐2 has the lowest total mass at 5 and 10 MW, but the conventional iron‐cored machine is lighter than TFPM‐1. Copyright © 2012 John Wiley & Sons, Ltd.

Design Considerations of Permanent Magnet Transverse Flux Machines

Permanent magnet transverse flux machine (PMTFM) is well known for its high torque density and is interested in various direct-drive applications. Due to its complicated 3-D flux components, design and design optimization of a PMTFM is more difficult and time consuming than for radial flux electrical machines. This paper addresses two important design considerations for PMTFM - the influence of permanent magnet leakage flux, which plays an important role in the determination of machine output torque, and the leakage inductance. A new simple method to provide a quick estimation of the armature leakage inductance is proposed, avoiding use of complicated 3-D equivalent reluctance network model to estimate the circumferential armature leakage flux component, and the pole face fringing flux component. Analysis results are supported by 2-D, and 3-D finite element (FE) analysis results, and measurement results on a prototype surface-mounted PMTFM.

Dynamic modeling of transverse flux permanent magnet generator for wind turbines

The transverse flux permanent magnet machines have become an interesting possibility for offshore wind turbines. These machines have the highest relation between electrical torque and weight of active materials. The pole pair modular construction could eliminate or lower the gear ratio used in conventional wind turbines. This paper presents a dynamic model of a wind turbine equipped with a transverse flux permanent magnet generator connected to a direct-current power system using a combination of 3D finite element generator model and an aerodynamic model. The results indicate that the model can give accurate response for steady-state operation and for wind speed variations.

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...

Performance Comparisons Among Radial-Flux, Multistage Axial-Flux, and Three-Phase Transverse-Flux PM Machines for Downhole Applications

The aim of this paper is to provide performance comparisons among conventional radial-flux, multistage axial-flux, and three-phase transverse-flux permanent-magnet machines for downhole applications where the outer diameters are limited by well sizes, but the axial lengths can be relatively long. The comparison procedure is based on a high ambient temperature of 150°C, a small outer diameter of 100 mm, a current density of 4 A/mm2 , an electrical loading of 20 kA/m, and a constant speed of 1000 r/min, with their output torques being from several newton meters to 105 N·m and power up to 18 kVA. Three machine prototypes are chosen and optimized individually in terms of maximum torque density on the basis of some common constraints. The comparisons are focused on the torque density, machine efficiency, and power factor with respect to different pole numbers and axial lengths. For a specific downhole application without an external cooling system, the obtained results provide an indication of machines best suited with respect to performance and size.

Stationary-frame current control strategy for transverse flux permanent-magnet machine

A new stationary-frame AC current control strategy that can eliminate steady-state errors is discussed and applied to the control of transverse flux permanent-magnet machine (TFPM). Based on the principle of modulation and demodulation, this AC controller can achieve the same frequency response characteristic as the equivalent DC controller. Validity of the TFPM control system using this current control strategy is confirmed with simulation results.

On the attempts to optimize the performance and cost‐effectiveness of TFPM drives: a crucial challenge for the automotive industry

AbstractMuch attention is currently focused upon transverse flux permanent magnet machines (TFPMs), especially in automotive applications, in so far as, to date, they exhibit the highest power production capability. Different automotive manufacturers are currently involved in R&D programs dealing with TFPM concepts and the possibilities of their integration in electric and hybrid propulsion systems. This paper is devoted to the analysis of two R&D projects developed within the design of TFPMs intended for hybrid propulsion systems of heavy‐duty vehicles. In spite of the increasing interest in TFPMs and the significant improvements brought to their earlier topologies, we can firmly state that further investigations remain to be carried out before the TFPM concepts could be regarded as a mature technology for the automotive industry. Copyright © 2005 John Wiley & Sons, Ltd.

On the analysis and reduction of the cogging torque of a claw pole transverse flux permanent magnet machine

AbstractThe transverse flux permanent magnet machine (TFPM) is currently given an increasing attention, especially in electric and hybrid propulsion applications. Although significant improvements have been carried out on the earlier topologies, much work is still required before the TFPM can be regarded as a mature concept. Of particular interest is the cogging torque reduction which is a vital requirement in propulsion applications, as far as passenger comfort is concerned. The present paper deals with, in a first step, a three‐dimensional (3D) finite element analysis (FEA)‐based investigation of the cogging torque of a claw pole TFPM. Then, an approach to the cogging torque reduction based on skewing is proposed. This is done considering a single‐phase TFPM concept. Then, the study is extended to the three‐phase claw pole TFPM, considering different combinations of the axially‐arranged phases. Copyright © 2005 John Wiley & Sons, Ltd.

Modeling and output tracking of transverse flux permanent magnet machines using high gain observer and RBF Neural network

This paper deals with modeling and adaptive output tracking of a transverse flux permanent magnet machine as a nonlinear system with unknown nonlinearities by utilizing high gain observer and radial basis function networks. The proposed model is developed based on computing the permeance between rotor and stator using quasiflux tubes. Based on this model, the techniques of feedback linearization and H ∞ control are used to design an adaptive control law for compensating the unknown nonlinear parts, such as the effect of cogging torque, as a disturbance is decreased onto the rotor angle and angular velocity tracking performances. Finally, the capability of the proposed method in tracking both the angle and the angular velocity is shown in the simulation results.

ROBUST ADAPTIVE CONTROL OF TRANSVERSE FLUX PERMANENT MAGNET MACHINES USING NEURAL NETWORKS

This paper deals with modelling and adaptive output tracking of a Transverse Flux Permanent Magnet Machine (TFPM) as a non-linear system with unknown nonlinearities by utilizing High Gain Observer (HGO) and Radial Basis Function (RBF) networks. The technique of feedback linearization and H∞ control are used to design an adaptive control law for compensating the unknown nonlinearity parts, such the effect of cogging torque, as a disturbance is decreased onto the rotor angle and angular velocity tracking performances. Finally, the capability of the proposed method is shown in the simulation results.

Optimizing the Overlap Between the Stator Teeth of a Claw Pole Transverse-Flux Permanent-Magnet Machine

The paper presents a three-dimensional finite-element analysis-based optimization of the overlap between adjacent stator teeth of a claw pole transverse flux permanent magnet machine (TFPM). Two major optimization criteria are considered: 1) the maximization of the output torque and 2) the minimization of the cogging torque. The paper shows that an overlap of almost 30% fulfills both optimization criteria.

An Approach to Sizing High Power Density TFPM Intended for Hybrid Bus Electric Propulsion

New developments in electric machine topologies have highlighted the possibilities to make great improvements in propulsion applications. Of particular interest are hybrid buses which are expected to be introduced in the near future with a large scale, in city transportation networks, in an attempt to reduce air pollution and noise. For such application, transverse flux permanent magnet machine (TFPM)-based electric propulsion system is presently considered to be the most suitable design in so far as it exhibits the higher power production potential. This paper presents a sizing approach of two major TFPM topologies intended for hybrid bus electric propulsion. At first glance, it is quite commonly believed that an optimal design could be reached through a 3D finite element analysis. Nevertheless, and given the large number of degrees of freedom in design, finite element analysis would take a very long computation time and would not necessarily lead to optimal solutions. It has been found that analytical developments combined with numerical optimizations represent an interesting approach which offers an effective basis to TFPM sizing.