Transverse Flux Motor Research Articles

Modeling and Analysis of a Novel Step Skew Crossed Teeth Transverse Flux Motor for Distributed Electric Propulsion System

Modeling and Analysis of a Novel Step Skew Crossed Teeth Transverse Flux Motor for Distributed Electric Propulsion System

Design, Analysis, and Comparison of Permanent Magnet Claw Pole Motor with Concentrated Winding and Double Stator

Permanent magnet motors have become an important component of industrial production, transportation, and aerospace due to their advantages of high torque density, high power density, high reliability, low losses, and high efficiency. Permanent magnet claw pole motor (PMCPM) is a special type of transverse flux motor which has a higher torque density compared to traditional permanent magnet motors. Due to the absence of winding ends, its axial space utilization is high, and the usage of windings is greatly reduced, reducing the cost and weight of the motor. PMCPM has the advantages of small space, a light weight, a high torque density, a high efficiency, and simple production, which have potential for use in the field of electric vehicles. The double-stator structure design can improve the torque density, efficiency, and radial space utilization of PMCPM, which helps to expand their applications in the field of electric vehicles. This article designs two PMCPM with concentrated winding while different rotor structures (PMCPM1 and PMCPM2) and a three-dimensional finite element method is employed to compare and analyze the performance of PMCPM1 and PMCPM2 and the traditional PMCPM (TPMCPM). Multiphysics analysis is carried out for PMCPM1 and PMCPM2. The stress of the inner and outer stators during interference assembly are analyzed. In this paper, a hybrid material core design is proposed, in which the stator yoke is rolled by silicon steel material and the stator claw pole is pressed by the SMC die method. The multiphysics simulation performance of the PMCPM1 and PMCPM2 with hybrid cores is analyzed.

Investigation of a Transverse-Flux Flux-Reversal Motor with Consequent-Pole Configuration

The transverse-flux motor, which has the advantage of high torque density, has become one of the research focuses of direct-drive motors for low speed and high-torque industrial applications. This paper aimed to propose a transverse-flux flux-reversal motor with consequent-pole configuration (TF-CFRM), which has a robust rotor structure and provides high torque density by using fewer expensive NdFeB permanent magnets. Firstly, the basic structure and running work principle of the TF-CFRM are introduced. Secondly, the analytical expression of electromagnetic torque is derived from a simplified 3D-equivalent magnetic-circuit model. Then, the preliminary optimization of the basic dimension is accomplished by the finite element method to improve the torque density. At last, the electrical performances, e.g., the torque density, overload capability, and power factor of the proposed TF-CFRM are analyzed and compared with those of the transverse-flux flux-reversal motor (TF-FRM) and traditional flux-reversal motor (FRM).

Analytical Optimal Design of a Two-Phase Axial-Gap Transverse Flux Motor

Transverse flux motors (TFMs) are being investigated to be used in vehicle traction applications due to their high torque density. In this paper, a two-phase axial-gap transverse flux motor is designed for an electric scooter, proposing a novel analytical design method. First, the dimensioning equations of the motor are obtained based on the vehicle requirements, and the stationary dq model is calculated. Then, the motor is optimized using a multiobjective genetic algorithm, and finally a 3D-FEM verification is made. Both the motor structure and the design method aim to have a low complexity, in order to favor the sizing and manufacturing processes through a low computation time and simple core shapes. This approach has not yet been explored in axial-gap TFMs.

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.

Investigations on Cogging Torque Mitigation Techniques of Transverse Flux Motor for Direct Drive Low-Speed Spacecraft Applications

Investigations on Cogging Torque Mitigation Techniques of Transverse Flux Motor for Direct Drive Low-Speed Spacecraft Applications

A Novel Dual-Consequent-Pole Transverse Flux Motor and Its Analytical Modeling

In this article, a novel dual-consequent-pole transverse flux motor and its analytical model are proposed. Differ from existed transverse flux machines, the proposed motor owns core-tooth-to-magnet types of the consequent-pole configuration on both stator and rotor. This unique motor configuration improves the no-load permanent magnet flux linkage interlinking with armature winding, thus leading to an enhanced torque density. The structure and working principle of the proposed motor are introduced as the first half part. Then, based on the combination of equivalent magnetic circuit method and subdomain method, an analytical modeling method is proposed to estimate the electromagnetic performance of the proposed motor. The parameters of the equivalent magnetic circuit model, e.g., the magnetomotive force and reluctances are calculated based on the subdomain model technique, considering the influence of the cores’ saturation and the axial end effect during calculation. Based on the magnetic field distribution result, the electromagnetic performance is estimated. The analytical results are verified by both the finite-element method and the prototype experiment.

Electromagnetic Design of a Dual-Consequent-Pole Transverse Flux Motor

In this paper, a dual-consequent-pole transverse flux motor and its electromagnetic design method are proposed. Both the stator and rotor of the proposed motor are designed to own the consequent-pole configurations. The unique motor structure improves the space utilization and the torque density. Firstly, the detailed structure and principle are introduced, and the development of the torque density of the proposed motor is discussed. Secondly, the electromagnetic design method's theory, considerations and flow process are listed. Then, the selections of some main structure parameters are proposed (e.g., pole-pitch, thickness of PMs and pole-arc coefficients of PMs). The electromagnetic performances of the proposed motor are compared with the existed transverse flux machines. At last, a prototype is manufactured and some primary experiments are done to verify and evaluate the proposed motor topology.

A Comprehensive Study on Transverse Flux Motor for Direct Drive Low-Speed Spacecraft Applications

Transverse flux motor (TFM) has been proven to be the ideal choice for high-torque direct drive applications, thanks to its higher specific torque density than the conventional radial flux machine. This article investigates the suitability of using TFM as the drive motor for precise position control based spacecraft applications, where mass and power reduction are the everlasting demands. Comparative configuration studies have been carried out to find the suitable type of permanent magnet motor for this application. Surface mounted TFM (SM-TFM) outweighs its competitors with lower power requirement and higher average torque, but with increased ripple content. Parametric studies of SM-TFM have been carried out to arrive at an optimal design of variables. To further increase the torque density, flux concentrated (FC) configurations of TFM have been analyzed. Average electromagnetic torque of FC and claw pole type TFM is higher than SM-TFM, with corresponding increase in the cogging torque. Electromagnetic simulation is carried out using Maxwell 3-D simulation software. Two variants of SM-TFMs are realized and the design is evaluated. Effect of Number of poles, material annealing, and strength of permanent magnet on the developed torque of SM-TFM are experimentally validated in the realized motor.

Analysis of magnetic field distribution in a transverse-flux linear motor with superconducting windings

The influence of permanent magnet excitation on HTS coil in transverse-flux linear motor is analyzed. Numerical analysis using finite-element method is carried for two commonly used magnet arrays - alternating and Halbach. The influence of magnet arrangements on critical current density of HTS winding operating in temperature of liquid nitogen of 77 K is examined. The goal is to find optimal air gap size and magnet span to assure the best performance of the motor where anisotropy of superconductor is taken into account.

Cogging Torque Reduction on Transverse-Flux Motor With Multilevel Skew Configuration of Toothed Cores

Transverse-flux motors are suitable for generating large torque because they can be designed to have both large electric loading and number of poles owing to their simple coil structure. On the other hand, they also often have large cogging torque due to the difficulty of employing conventional skew structure and assembling problem on a large number of cores. Thus, this paper describes transverse-flux motors with less number of parts on their stator cores by tooth ring cores and multilevel skew configuration for effectively reducing the cogging torque of the motors. From magnetic analysis result, the cogging torque is reduced by 96%, and the ratio of the cogging torque to average torque is 0.036% with the proposed multilevel skew configuration.

Fundamental design and analysis of a novel bipolar transverse-flux motor with stator permanent-magnet excitation

In this paper, a novel bipolar transverse flux motor with stator permanent magnet excitation is proposed based on the summary and analysis of the transverse flux motor and stator permanent magnet motor research achievements in recent years. It has been shown that the motor realizes the bipolar winding flux through the detailed analysis. The motor can be used as an inwheel motor in electric vehicles because of its external rotor and permanent magnets mounted on the stator radial surface. Secondly the basic structure and working principle of the motor are introduced. Then the relationship between the motor power and its dimensions is deduced. Thirdly the 3 dimensional finite element method(3D FEM) is used to analyze the static and transient characteristics, including the no-load magnetic field distribution and winding back EMF. Finally a three-phase 600W prototype has been made and the experimental analysis is carried out.

Transverse-Flux Motor Design With Skewed and Unequally Distributed Armature Cores for Reducing Cogging Torque

Transverse-flux motors have an advantage on realizing high torque density owing to their compatible design of a large number of poles and large magnetomotive force. However, many permanent magnets are required with increasing number of the poles, and that results in a big exertion for building magnet arrays. Thus, we have studied transverse-flux motors with a consequent-pole rotor having almost half amount of magnets compared with conventional magnet rotors. However, the consequent poles cause large cogging torque due to their deformed flux-density distribution. This paper presents magnetic-pole configuration for effectively reducing the cogging torque and its verification by magnetic analysis even though axially skewed configuration, commonly used, is difficult to be applied to transverse-flux motors due to their axially non-uniform structure. In this paper, radially skewed and unequally distributed configurations are introduced to the armature cores for eliminating the two most dominant harmonic components of the cogging torque. Analysis result indicates each configuration can eliminate the harmonic components selectively and effectively, and magnitude of the cogging torque decreases by 97.6%. These configurations can be applied to a wide variety of transverse-flux motors for eliminating any harmonic order of cogging torque, and can be considered to be promising techniques for realizing high torque density.

Experimental study on cogging-torque reduction of transverse-flux motor with skewed armature cores

Experimental study on cogging-torque reduction of transverse-flux motor with skewed armature cores

Torque Characteristic Analysis of a Transverse Flux Motor Using a Combined-Type Stator Core

An external rotor transverse flux motor using a combined-type stator core is proposed for a direct drive application in this paper. The stator core is combined by two kinds of components that can both be manufactured conveniently by generic laminated silicon steel used in traditional motors. The motor benefits from the predominance of low manufacturing cost and low iron loss by using a silicon-steel sheet. Firstly, the basic structure and operation principles of the proposed motor are introduced. Secondly, the expressions of the electromagnetic torque and the cogging torque are deduced by theoretical analysis. Thirdly, the basic characteristics such as permanent magnet flux linkage, no-load back electromotive force, cogging torque and electromagnetic torque are analyzed by a three-dimensional finite element method (3D FEM). Then, the influence of structure parameters on the torque density is investigated, which provides a useful foundation for optimum design of the novel motor. Finally, the torque density of the proposed motor is calculated and discussed, and the result shows that the proposed motor in this paper can provide considerable torque density by using few permanent magnets.

Optimal Design of Tubular Transverse Flux Motors With Low Cogging Forces for Direct Drive Applications

Linear permanent magnet (PM) motors have increasingly been used in high-performance applications where high accuracy and fast dynamic response are required. However, the presence of cogging force in linear motors compromises position and speed control accuracy, which can be particularly troublesome at low speeds. This paper presents analysis and minimization of cogging force associated with a tubular PM motor with transverse flux configuration. An analytical criterion is brought forward, which allows the impact prediction of leading design parameters on the cogging force in an accurate way. And the validity and results are verified by extensive three-dimensional numerical computations and experimental measurements. It is shown that the cogging force increases along with the PM height. And it is highlighted that the cogging force amplitude is a sinusoidal function of the stator segment length, which is quite different from that in conventional PM machines. This work has provided a basis for cogging force reduction, and will aid the design process of the transverse flux motor, especially when targeting high-performance direct drive applications.

Cogging-Torque Reduction of Transverse-Flux Motor by Skewing Stator Poles

Transverse-flux motors basically have coils wound in the rotational direction and armature cores surrounding them. This configuration allows the motors to be designed for multipole structures with the simple coil geometry independent of the pole number. Therefore, they have an advantage on high-torque generation over most motors having windings wound around teeth and put in slots. However, transverse-flux motors still have a production problem for their multipole rotor due to the assembly of the small and numerous permanent magnets. Thus, we have designed a consequent-pole transverse-flux motor, having a half amount of magnets on the rotor compared with the conventional surface-mounted magnet rotors, and capable of generating almost the same torque under the same size and excitation conditions. However, this motor also has large cogging torque due to the consequent poles, having deformed magnetomotive-force distribution. Thus, we propose a new skewed core structure for reducing the cogging torque, compatible to axially non-uniform structure of this motor. The Finite Element Method analysis result indicates the peak-to-peak value of the cogging torque that can reduce by 82% with this proposed skewed structure.

Research and development of in-wheel motor driving technology for electric vehicles

The structural form of a driving motor is arranged in the inner wheel hub, which is beneficial to electrification, integration and rationalisation of structure layout. The in-wheel motor is the key part of the electric vehicle driving system, and hence it has significant theoretical values and application values to analyse. Firstly, the development process and the main advantages of in-wheel motor as driving device of the electric vehicles are expounded. Then movement mode and driving method of in-wheel motor are comparatively analysed. Qualitative comparisons and analysis are carried out for induction motor, permanent magnet brushless direct current motor, switched reluctance motor (SRM) and transverse flux motor (TFM), which are regarded as the main electric vehicle driving motors. Finally, the present situation of application and research of in-wheel motor drive electric vehicles in China and abroad is analysed, and the breakthrough directions of in-wheel motor drive technology are proposed.

Research and development of in-wheel motor driving technology for electric vehicles

The structural form of a driving motor is arranged in the inner wheel hub, which is beneficial to electrification, integration and rationalisation of structure layout. The in-wheel motor is the key part of the electric vehicle driving system, and hence it has significant theoretical values and application values to analyse. Firstly, the development process and the main advantages of in-wheel motor as driving device of the electric vehicles are expounded. Then movement mode and driving method of in-wheel motor are comparatively analysed. Qualitative comparisons and analysis are carried out for induction motor, permanent magnet brushless direct current motor, switched reluctance motor (SRM) and transverse flux motor (TFM), which are regarded as the main electric vehicle driving motors. Finally, the present situation of application and research of in-wheel motor drive electric vehicles in China and abroad is analysed, and the breakthrough directions of in-wheel motor drive technology are proposed.

Enhanced Transverse-Flux Motor with Torus Coils

Two of the most important characteristics of electric vehicle motors are low cost and high reliability. Armature windings are difficult to manufacture with automated techniques and are not very reliable. Thus, to obtain a motor with low cost and high reliability, we have investigated a transverse-flux motor (TFM) containing a torus coil. In this study, we propose an enhanced TFM and discuss its principles and basic characteristics. The rotor has circumferential permanent magnets, and the stator has torus coils and axial 9-shaped cores. The stator core is arranged alternately in the circumferential direction, and has a radial and axial air gap. Our analysis confirms that the enhanced TFM produces a high torque per motor volume of 4.74 kN·m/m 3 .