Axial Flux Permanent Magnet Motor Research Articles

New Single-Phase Flux Switching Axial Flux Permanent Magnet Motor

In this paper, a new topology of a single-phase flux switching permanent magnet motor (FSPM) is presented. Unlike conventional FSPMs, the air-gap flux flows in the axial direction, and therefore, it is named the flux switching axial flux permanent magnet motor (FS AFPM). The proposed single-phase FS AFPM has a compact disc-type structure, four stator pole teeth, and two rotor pole teeth (4/2 combination). However, a number of the stator poles as well as the rotor poles can be easily increased, due to an enlarged circumferential length. It has two discs, one for the stator and other for the rotor. Like conventional FSPMs, this machine has a simple salient rotor pole structure. Along with the armature windings, the PMs are also embedded in the stator. A 3-D finite-element analysis is carried out for the characteristic analysis of the proposed single-phase FS AFPM. For the enhancement of the self-starting torque capability and unidirectional rotation, the rotor pole is tapered.

Analyzing distinctive rotor poles of the axial flux PM motors by using 3D-FEA in view of the magnetic equivalent circuit

Higher efficiency is always a desire for the electric machines researchers. One serious candidate is the axial flux permanent magnet motor to achieve that. These machines have advantages on power and torque density profile. This study aims to analyse the performances of the different rotor poles’ characteristics of the axial flux permanent magnet machines. The magnetic equivalent circuit designed and placed into the single gap axial flux permanent magnet machine to fathom the machine characteristic. The proposed rotors magnet poles are investigated in the view of the torque ripple reduction, back EMF waveforms and flux density distribution by using finite element analysis. Four different designs are compared. 3D analysis is used for FEA simulations. Torque ripple, back emf and magnetic flux distribution waveforms are obtained from the 3D FEA analysis. As a result, the proposed rotors are practicable and situated for higher performance.

An Extended Analytical Algorithm for Optimal Designing of a TORUS-type Non-slotted Axial-Flux Permanent Magnet Motor

This paper presents an analytical algorithm for optimal designing of double-sided TORUS-type non-slotted axial-flux permanent magnet motors with surface mounted magnets. For this purpose, the machine design process is treated here as a procedure that receives the machine rated parameters and design constraints and yields the optimal values of various design parameters. The design optimization problem is established here on categorizing the design parameters into several groups. The decision variables are specified as selective parameters. The constraints are imposed through the developed equations for sizing and performance prediction of the machine, yielding the calculable parameters analytically and independently from finite element analysis (FEA). The objectives are the machine efficiency and power density, which are finally maximized based on PSO algorithm. The design algorithm was implemented in MATLAB, and the solution was then employed for validation through simulating by FEA and fabricating an experimental prototype. The fabricated machine has a compact size and appropriate performances under various loading conditions. The program solution is also compatible with the results of FEA and experiment on the fabricated prototype. These all demonstrate the accuracy and efficiency of the proposed machine design algorithm.

Analytical Model for Predicting Vibration Due to Magnetostriction in Axial Flux Permanent Magnet Machines With Amorphous Metal Cores

This paper analyzes the vibration due to magnetostriction in axial flux (AF) permanent magnet (PM) machines with amorphous metal cores (AMCs). First, an analytical model is developed to predict the vibration due to magnetostriction. The solution regions of the analytical model are divided into yoke and teeth subdomains. Then, the effect of processing technics on the vibration of AMCs which is unable to consider in the analytical model was examined using measurements of vibration of AMCs. Through comparing the analytical results and experimental results, the correction factors of vibration acceleration are obtained. Finally, the vibration analysis of a 7 kW AF PM motor with AMCs is carried out by the analytical model.

Field Reconstruction Method in Axial Flux Permanent Magnet Motor With Overhang Structure

This paper employs an overhang structure for axial flux permanent magnet motor to enhance the torque density. However, the overhang structure requires a computationally expensive 3-D finite-element method (FEM) for analysis, because a quasi-3-D FEM cannot be applied to such a geometry. Thus, in order to reduce the computational cost of above-mentioned topology, this paper adopts a field reconstruction method (FRM). The conventional FRM is applicable only in the case, where the slot pitch to teeth length ratio is the same along radial direction. To address this problem, we introduce a virtual air gap concept so that it can take into account parallel slot effect as well as overhang effect. In this paper, the effectiveness of the proposed method is verified by the 3-D FEM and experimental results.

Characteristics Analysis Method of Axial Flux Permanent Magnet Motor Based on 2-D Finite Element Analysis

Three-dimensional (3-D) finite element analysis is generally required to analyze the performance of an axial flux permanent magnet (AFPM) motor because it has asymmetrical characteristics along the z-axis. Although the computing performance of CPU is enhanced owing to technological development, a large amount of analysis time is required for 3-D finite element analysis (FEA). This paper presents a method of AFPM motor to an equivariant linear synchronous permanent magnet (ELSPM) motor, both of which have identical output performance. The output performance of the proposed ELSPM motor becomes identical to that of the AFPM under the mandatory condition that the PM magnetic energy of both the models must be identical. The validity of the proposed ELSPM motor in terms of the accuracy and computation time is verified by comparing its results with the results of the AFPM motor based on the FEA.

Investigation of vibration and noise characteristics in axial flux permanent magnet synchronous motor with different magnet shapes

This paper investigates the vibration and noise characteristics of axial flux permanent magnet (AFPM) motor with different magnet shapes. A multiphysics model is developed to predict electromagnetic vibration and noise of AFPM motor which contains three steps. In the first step, nodal force exerted on the surface of stator tooth is calculated using 3D finite element method (FEM). Then, structural analysis is performed to investigate the structure natural characteristics and the nodal force calculated is mapped into structural model as the excitation in the second step. In the third step, the vibration and noise of AFPM motor are calculated through modal superposition method (MSM) and boundary element method (BEM) respectively. Vibration and noise characteristics of AFPM motor with different magnet shapes are investigated based on the multiphysics model. The results reveal that AFPM motor with sine-shaped magnet demonstrates lower noise level compared to AFPM motor with sector- or cylinder-shaped magnet.

Comparative study and performance evaluation of analytical methods for surface mounted permanent magnet brushless motors

Analysis and determination of magnetic field distribution of surface mounted permanent magnet (SMPM) motors has always been a topic of research. Though a number of methods like two-dimensional numerical and analytical methods have been proposed to evaluate the magnetic field and parameters of radial flux SMPM motors, the methods developed for axial flux permanent magnet motors are mainly three dimensional. Numerical methods provide accurate results but are not suitable for initial design analysis. The analytical methods are known for their accuracy, convenience, as well as are less time consuming than numerical methods. The analytical methods like conventional design method, magnetic equivalent circuit, generalised machine theory and Fourier analysis present in the literature for SMPM motor have been investigated in this study and the results obtained are compared and evaluated for radial flux SMPM and axial flux SMPM. Experimental results are included to demonstrate the percentage error obtained from different methods and denote the accuracy. From the comparison of different results, it can be concluded that the Fourier transform method is more realistic approach and is capable of computing the performance as well as field distribution simultaneously.

Investigation of a New Ironless-Stator Self-Bearing Axial Flux Permanent Magnet Motor

In this paper, a new type of self-bearing axial flux permanent magnet (SBAFPM) motor with ironless stator is proposed. The torque windings and the suspension windings are integrated into a cohesive whole with the same pole number for both torque and radial force generation. The fundamental structure and the working principle of the presented ironless-stator SBAFPM motor with ironless stator are illustrated. The control method and the implementation for the integrated windings system to produce force and torque independently are presented, as well as an FEA model for calculating the achievable drive torque and suspension force. Results indicate that the bearing force and the drive torque depend linearly on the respective current. The presented ironless-stator SBAFPM motor is free from tradeoff between force and torque, which will simplify the control of the torque and the levitation force.

A New Coreless Axial Flux Interior Permanent Magnet Synchronous Motor With Sinusoidal Rotor Segments

Axial flux permanent magnet (AFPM) motors are frequently used in many applications. Axial gap coreless motors with surface-mounted magnets are the most noteworthy ones due to their potentially higher efficiency and smaller axial length. In this paper, a new spoke-type AFPM coreless disk motor with dual rotor and single stator is proposed with sinusoidal rotor segments. This new disk-type motor is an interior PM (IPM) motor with spoke-type rotor and variable air gap to obtain sinusoidal back Electro-Motive Force waveform. It is shown that it is possible to increase the air-gap flux density in the proposed new coreless AF-IPM motor and increase the torque output compared with the conventional surface-mounted AFPM motors.

Driving-Scenario Oriented Optimal Design of an Axial- Flux Permanent-Magnet Motor for an Electric Vehicle

This paper proposes a driving-scenario oriented optimal design of an axial-flux permanent-magnet (AFPM) motor for an electric vehicle. The target torque and speed (TN) curve is defined as three operation zones— constant torque, maximum direct current, and maximum voltage—based on the driving scenario. The AFPM motor is designed to minimize energy consumption based on the motor weight and the frequent operating points of a driving cycle. The final result shows that the electric vehicle driven by the proposed AFPM motor consumes about 15% less energy than motors designed using traditional methods.

AFPM 전동기의 오버행 효과에 관한 연구

In this paper, the overhang structure was applied to the axial flux permanent magnet (AFPM) motor. This paper describes the overhang effect in the AFPM motor. Moreover, the overhang effect was analyzed according to the different overhang length and an optimal overhang structure was proposed. Finally, the proposed structure was applied to design, analysis and experiment of prototype motors. Through the comparison between 3D finite element analysis results and experimental ones, the validity of proposed structure is clarified.

개선된 Quasi-3D FEM을 통한 AFPM 전동기의 해석

In the quasi-3D finite element(FE) anlysis, the overall characteristics of axial flux permanent magnet(AFPM) motor could be composed of each computation region. However, A drawback of quasi-3D FEM is not to consider the end effect on the stack end. To address this problem, an improved quasi-3D FE analysis which considers the end effect of the AFPM motor was proposed. From results the 3D FE analysis, the validity of the proposed method is verified.

Optimal Design of an Axial-Flux Permanent-Magnet Motor for an Electric Vehicle Based on Driving Scenarios

This paper proposes a driving-scenario oriented optimal design of an axial-flux permanent-magnet (AFPM) motor for an electric vehicle. The target torque and speed (TN) curve is defined as three operation zones-constant torque, maximum direct current, and maximum voltage—based on the driving scenario. The AFPM motor is designed to minimize energy consumption based on the motor weight and the frequent operating points of a driving cycle. The final result shows that the electric vehicle driven by the proposed AFPM motor consumes about 15% less energy than motors designed using traditional methods.

Multi-objective approach of design optimisation of axial flux permanent magnet motor

Multi-objective approach of design optimisation of axial flux permanent magnet motor

Investigation of mechanical field weakening of axial flux permanent magnet motor

An investigation of axial flux permanent magnet motor (AFPM) characteristics was conducted with a proposed mechanical field weakening control mechanisms (by means of stator-rotor force manipulation) on the motor through modeling and experimentation. By varying the air gap between at least two bistable positions, the peak torque and top speed of the motor can be extended. The motor high efficiency region can also be extended to cover greater part of the motor operating points. An analytical model of the motor had been developed to study the correlation between the total attraction force (between the rotor and the stator) and the operating parameters of the motor. The test results shows that the motor output complies with the prediction of the research hypothesis and it is likely that a spring locking mechanism can be built to dynamically adjust the air gap of the motor to increase the operating range and could be applied in electric drivetrain applications to improve overall efficiency of electric and hybrid electric vehicles.

Investigation of Mechanical Loss Components and Heat Transfer in an Axial-Flux PM Machine

This paper investigates components of mechanical loss together with heat transfer effects in an axial-flux permanent-magnet motor. The mechanical loss components generated within electrical machines are well known; however, their prediction or derivation has not been widely reported in the literature. These, together with the electromagnetic loss sources and heat transfer effects, are crucial and must be accounted for when considering high-power-density, high-speed, and/or compact machine designs.

A NEW ANALYTICAL DESCRIPTION AND FEA VALIDATION OF AN EFFECTIVE METHOD TO REDUCE THE COGGING TORQUE IN SM-AFPM MOTORS

So far, several methods to reduce the cogging torque of permanent magnet motors have been introduced. Implementation and evaluation of these methods have usually been done on radial flux types of motors. Nowadays, as axial flux permanent magnet motors have more advantages over radial ones, they are more attractive. Therefore, in this paper analytical modeling and calculation of the most effective method impact in reducing the cogging torque in axial flux permanent magnet motors will be studied. In fact, in this method the radial edges of the magnets will be curved to have a significant impact on reducing this unwanted component. This paper introduces a new concept to model this method. Finally, the accuracy of the proposed method will be verified by finite element analysis.

Comparative Study between the Synchronous Motor to Permanent Magnets and Axial Flux (MSAP) and its Equivalent to Coiled Rotor (MSRB)

This work consists in conceiving of a coiled rotor synchronous motor equivalent to a permanent magnet axial-flux motor for electric vehicle by the joint method analytical / finite elements. An analytical model sizing motor is developed by the finite element method. A comparison between a 4 pairs of poles 6 teeth structure of a permanent magnet axial-flux motor and the studied motor is made in the goal to select the most effective structure for the same strength and same electric constant.

Magnetic modeling of radial-flux and axial-flux permanent-magnet motors for direct drive automotive. Specifications and comparison

Magnetic modeling of radial-flux and axial-flux permanent-magnet motors for direct drive automotive. Specifications and comparison