Axial Flux Permanent Magnet Machine Research Articles

Ultra‐fast finite element analysis of coreless axial flux permanent magnet synchronous machines

AbstractLarge‐scale design optimisation techniques enable the design of high‐performance electric machines. Electromagnetic 3D finite element analysis (FEA) is typically employed in optimisation studies for accurate analysis of axial flux permanent magnet (AFPM) machines, which require extensive computational resources. To reduce the computational burden, a FEA‐based mathematical method relying on the geometric and magnetic symmetry of coreless AFPM machines is proposed to estimate the machine performance indicators using the least number of FEA solutions, thereby significantly lowering the running time. This method is generally applicable to AFPM machines with low saturation effects and cogging torque as exemplified for a printed circuit board (PCB) stator coreless AFPM machine. To further reduce the computation time, a systematically simplified equivalent 3D FEA model for planar PCB coils integrated with this machine is also proposed. The practical implementation of the introduced method is elaborated based on an example optimisation study, and an analytical method for fast design scaling is also discussed. The results of the proposed approach are compared with detailed transient FEA results, and a prototype 26‐pole PCB stator coreless AFPM machine was also used to validate the results experimentally.

Nonlinear Analytical Solution in Axial Flux Permanent Magnet Machines Using Scalar Potential

Analytical model (AM) has significant value on early design stage for electric machines, in terms of both time and accuracy. AM can be developed based on vector or scalar potential, but all AMs for armature reaction are using the vector potential, and it is a difficult matter to model armature reaction by scalar potential. This is the gap that the work here proposed aims to fill. We, for the first time, report the load magnetic field prediction by using magnetic scalar potential. Also, the proposed nonlinear AM is developed for the surface mounted permanent magnet machine. The proposed model is development based on the two-dimensional harmonic subdomain approach by solving the Maxwell's equations. The magnetic sources, viz., the armature reaction is regarded as line current and solved at the connection boundaries. The comprehensive derivations and calculation algorithm are explained in detail. Moreover, the analytical model is developed for an axial flux PM machine, both finite element model and experiment are verified the correctness of proposed model, and good agreement is achieved. Moreover, a slightly modification can also be applied to the radial flux PM machines.

Multi-Objective Optimization of Yokeless and Segmented Armature Machine for In-Wheel Traction Applications Based on the Taguchi Method

For electrical machines with complex structures, the design space of parameters can be large with high dimensions during optimization. Considering the calculation cost and time consumption, it is hard to optimize all the design parameters at the same time. Therefore, in that situation, sensitivity analysis of these design parameters is usually used to sort out crucial parameters. In this paper, the sensitivity analysis-based Taguchi method is applied to optimize the axial-flux permanent magnet (AFPM) machine with yokeless and segmented armature (YASA) topology for an in-wheel traction system. According to the key parameters and their sensitivity analysis, the optimal machine scheme to meet the performance requirements can be formed. In this case study, the machine performance is improved significantly after optimization. Lastly, the experimental results verify the accuracy of the model used in this study.

Analytical model of an ironless axial flux permanent magnet machine for electromagnetic force calculation and vibration analysis

Analytical model of an ironless axial flux permanent magnet machine for electromagnetic force calculation and vibration analysis

Prototype development of a fully coreless multi-stage axial-flux permanent-magnet machine (AFPM) through the performance comparison between single-stator double-rotor (SSDR) and double-stator single-rotor (DSSR) configurations

Cascading rotor and stator in axial flux permanent magnet (AFPM) machine is a beneficial concept to increase the power density without increasing the diameter of the machine. Multi-stage AFPM can provide higher torque capability in applications requiring high power density. In this regard single-stator double- rotor (SSDR) and double-stator single-rotor (DSSR) are efficient machines compared to single -stage AFPM. Since SSDR and DSSR are also considered modular units to make multi-stage AFPM, like single-stage AFPM, this paper makes a comparison with analysis between SSDR and DSSR AFPM machines. Based on 3-D finite element analysis (FEA), the air-gap magnetic flux, voltage, current, torque, torque ripple, power and power density, efficiency are comparatively investigated to evaluate their performance. Results show that fully coreless topology only be achieved in SSDR AFPM machine with a higher power density. Finally, a prototype multi-stage coreless generator has been developed using a single stator double rotor (SSDR) configuration to justify the fully coreless concept. This prototype coreless generator eliminates eddy current losses and reduces weight, making it a suitable option for certain portable applications.

Equivalent Analytical Model of Magnetic Field in Parallel Magnetic Circuit Axial Flux Permanent Magnet Machines

The axial flux permanent magnet (AFPM) machines with the parallel magnetic circuit (PMC) rotor can effectively improve its torque density. The PMC rotor consists of two sub‐rotors, radial Halbach array permanent magnet (PM) and tangential PM. The magnetic fields generated by two sub‐rotors are not in the same 2‐D analytical planes. In this paper, an equivalent analytical model of PMC‐AFPM machines is proposed to solve this problem. The radial Halbach array PM rotor is equated to the axial Halbach array PM rotor based on the equivalent transformation principle. The exact subdomain models of equivalent axial Halbach array PM rotor and tangential PM rotor are built respectively and then superimposed to obtain the magnetic field distribution. The electromagnetic characteristics of the PMC‐AFPM machine under no‐load and load conditions are calculated by the proposed analytical model and compared with calculations of the finite element model (FEM). The results verify the accuracy of the equivalent analytical model. The comparative analysis of the AFPM machines with PMC rotor and tangential PM rotor verifies the advantage of PMC rotor configuration to improve the torque density. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Study on the Influence of a Combined-Halbach Array for the Axial Flux Permanent Magnet Electrical Machine With Yokeless and Segmented Armature

To increase torque density, a combined-Halbach array for the axial flux permanent magnet machine (AFPMM) with yokeless and segmented armature (YASA) is presented in this paper. Firstly, the YASA machine models with conventional axial magnets and combined-Halbach array magnets are established by using 3-D finite-element method (FEM). Then, the torque, torque per magnet-volume and no-load back electromotive force (back-EMF) are calculated, and the performance of two machines are analyzed and compared. It is demonstrated that the combined-Halbach array can improve the torque density of the machine and the utilization rate of the magnets. Finally, the combined-Halbach array rotor is optimized, where the rotor with unequal-thickness magnets is established, and its torque density is calculated under different thickness. The results show that the combined-Halbach array with unequal-thickness magnets can decrease the amount of permanent magnet materials, thus improve the utilization of magnets and reduce the costs.

Additively Manufactured Winding Design for Thermal Improvement of an Oil-Cooled Axial Flux Permanent Magnet Machine

Additively Manufactured Winding Design for Thermal Improvement of an Oil-Cooled Axial Flux Permanent Magnet Machine

A Novel Counter-Rotating AFPM Machine Based on Magnetic-Field Modulation for Underwater Propulsion System

The underwater propulsion system (UPS) with two counter-rotating propellers is very popular now. In tradition, it needs two electric machines or additional gears, which greatly increases the volume and weight of the system. Therefore, a novel counter-rotating axial-flux permanent magnet (AFPM) machine based on magnetic-field modulation (MFM) for the UPS is proposed. It contains a more pole (MP) rotor and a less pole (LP) rotor on two sides. The MFM is achieved through the split teeth on the stator. Based on the MFM, the two rotors can rotate in opposite directions. The principle of MFM and the relationships of rotary speeds between two rotors are analyzed. Furthermore, the effects of split tooth shape and dimensions on the performances of the proposed machine are also evaluated. The triangular skew fan-shaped split teeth are adopted in the counter-rotating AFPM machine. Finally, the prototype is manufactured and an experiment is conducted to validate the performance. The results show the consistency of analysis and experiment.

Design of an Integrated Magnetorheological Fluid Brake Axial Flux Permanent Magnet Machine

This paper presents the design and performance of an integrated magnetorheological fluid brake axial flux permanent magnet (IMRFB-AFPM) machine with two switchable operation modes: rotation and brake modes while the machine has two kinds of windings: armature winding in axial stators and braking winding in radial stator. In rotation mode, this machine is equal to a conventional AFPM machine with high torque density. When switching to brake mode, MR fluid is excited by braking winding and applies large damping stress to the rotor to brake it. This paper illustrates the machine topology, operation principles, and design flow of the proposed machine. Then, this paper analyzes the torque generation mechanism in two modes and applies parameters optimization to improve the torque capability of each mode. Due to the independence of the magnetic flux path, the parameters optimization is divided into two parts: AFPM part and IMRFB part. After the optimization process, the electromagnetic performances of the optimal IMRFB-AFPM machine are analyzed by finite element (FE) analysis. Finally, a prototype machine with the optimal geometric parameters is manufactured and verified experimentally. The experiment results agree well with FE analysis results, validating the feasibility and practicability of the proposed design.

Cogging Torque Reduction Techniques in Axial Flux Permanent Magnet Machines: A Review

Axial flux permanent magnet machines have garnered significant attention in recent years due to their numerous advantages in various applications, including electric vehicles, wind turbines, and robotics. However, one of the critical challenges associated with these machines is the presence of cogging torque, which can hinder their efficiency and performance. This review article provides a comprehensive overview of the state-of-the-art techniques employed for cogging torque reduction in Axial Flux Permanent Magnet Machines. Different techniques are described, encompassing geometric optimization, magnet placement, and skewing methods. Firstly, the significance of Axial Flux Permanent Magnet Machines is described, as well as the issue of the cogging torque. In the methods section, a review of the strategies for the reduction of cogging torque is described from various articles, and finally, in the discussion section, a list of actions is presented for cogging torque reduction for different topologies. The novelty of the study is that it combines strategies for cogging torque reduction in a single article.

Analysis and Optimization of Winding Losses of Axial Flux Permanent Magnet Machine with Concentrated Winding Flat Wires

Analysis and Optimization of Winding Losses of Axial Flux Permanent Magnet Machine with Concentrated Winding Flat Wires

Computation and Design of Detailed Sizing of Stator Slot Types Utilized in Axial Flux Permanent Magnet Machines

Computation and Design of Detailed Sizing of Stator Slot Types Utilized in Axial Flux Permanent Magnet Machines

Design of a Printed Circuit Board Axial Flux Permanent Magnet Machine for High Speed Applications

Design of a Printed Circuit Board Axial Flux Permanent Magnet Machine for High Speed Applications

Design Optimization of a Spoke Type Axial-Flux PM Machine for In-wheel Drive Operation

Design Optimization of a Spoke Type Axial-Flux PM Machine for In-wheel Drive Operation

Hybrid Optimization and Comparative Analysis of A Novel Double-Side Asynchronous Rotor Axial-Flux Permanent Magnet Machine

Hybrid Optimization and Comparative Analysis of A Novel Double-Side Asynchronous Rotor Axial-Flux Permanent Magnet Machine

Research on the Axial Stability of Large-Capacity Magnetic Levitation Flywheel Driven by Axial-Flux Permanent Magnet Machine Based on Runge-Kutta Method

Research on the Axial Stability of Large-Capacity Magnetic Levitation Flywheel Driven by Axial-Flux Permanent Magnet Machine Based on Runge-Kutta Method

A New Concept of Direct Oil Cooling System for AFPM Machines, Numerical Analysis and Optimization

Given the strong growth of the electric drive industry, the automotive sector needs to increase the power density of its motors, leading to a size decrease and, consequently, to economic savings. The increase in power density brings with itself the consequence of increasing the Joule effect losses in the active conductors of the machine. For this reason, the problem of cooling turns out to be of utmost importance precisely because of its direct coupling with mechanical and electromagnetic design. This paper has the aim to perform a CFD analysis concerning the cooling system of a permanent magnet axial flux electric machine. The innovative cooling system studied is a direct one which takes advantage of oil to cool down the DC powered coils. The innovation brought by the present research lays in both the direct axial ejection and the use of oil as coolant. At the current state of art, the coolant flows tangentially and, moreover, water is usually employed instead of oil. The main aim of this analysis will be, after a validation of the numerical code by comparison of the literature data, to minimize the maximum temperature of the coil by means of the proper positioning of the nozzle.

Torque Improvement of Dual-Rotor Coreless Stator AFPM Machine With Non-Overlapping Concentrated Winding for Counter-Rotating Ducted Fan Application

Torque Improvement of Dual-Rotor Coreless Stator AFPM Machine With Non-Overlapping Concentrated Winding for Counter-Rotating Ducted Fan Application

Analyzing heat transfer in Axial Flux Permanent Magnet electrical machines: A literature review on the discretization methods-FVM and FDM

Axial Flux Permanent Magnet (AFPM) machines have gained significant attention due to their high power density, efficiency, and compact design. However, effective heat transfer analysis is critical for optimizing their performance and reliability. This paper presents a comprehensive literature review on the application of discretization methods, specifically the Finite Volume Method (FVM) and Finite Difference Method (FDM), in the thermal analysis of AFPM machines. The fundamentals of FVM and FDM are briefly explained, followed by an exploration of their applications in AFPM machine thermal analysis. The advantages and limitations of using these methods are discussed, and a comparison between FVM and FDM is provided. Advanced discretization techniques, such as the Finite Element Method (FEM), and coupled thermal-electromagnetic analyses are also examined. The paper highlights studies that have utilized FVM or FDM in developing optimized designs and effective thermal management strategies for AFPM machines. Lastly, potential future research directions are identified, including the development of more efficient discretization methods, the incorporation of advanced materials, and the investigation of novel cooling techniques. This review offers valuable insights into the current state of research and potential future directions in the thermal analysis of AFPM machines using discretization methods.