3-D Analytical Magnetic Field Analysis of the Electro-magnetic Eddy Current Coupling
College of Energy and Electrical Engineering, Hohai University, Nanjing, P. R. China
This paper presents a 3-D analytical magnetic field analysis of an electro-magnetic eddy current coupling. Analytical magnetic distributions are predicted by employing a group of H-formulations in the conductor region and Laplacian equations with magnetic scalar potential in other regions in the Cartesian coordinate. Analytical results of magnetic field distributions and the electromagnetic force are derived and verified by the numerical computational by 3D finite element models in both Cartesian and cylindrical coordinate.
A Non-Taguchi Approach for Electromagnetic Devices Robust Design
Harbin Institute of Technology, China, People's Republic of
Electromagnetic devices containing permanent magnet are common and typical electromagnetic devices that have advantages of low power consumption, small size, high sensitivity, and its robustness optimization problem has aroused widespread concern. The effective consideration of the factors affecting the robustness of electromagnetic devices and the optimal combination of parameters are two important factors that affect the optimization effect of electromagnetic devices. A universal method based on the working point shift and uncertainty of output characteristics was proposed in this study that aimed at the drawbacks of traditional robustness design methods, such as ineffective consideration of the working point shift, ignorance of the interaction between parameters, choice of the optimal combination only from the existing level values, and inability to get the global optimal solution. A two-dimensional noise design scheme comprehensively consider the working point shift and manufacturing noise was built, the high-order dual response surface model for output characteristic mean and variance is built by analyzing the correlative interaction between design parameters. Simultaneously, a robustness assessment measure suitable for different optimization types is designed. On these bases, the robust optimal solution is sought using the multi-objective particle swarm optimization algorithm. Effectiveness of the method proposed in this paper was veriﬁed by the case study of a specific type of electromagnetic devices with permanent magnet.
Design of Coaxial Magnetic Gear Considering Space Harmonics in High Speed Applications
1Dong-A University, Korea, Republic of (South Korea); 2Electric Motor Research Center, Korea Electrotechnology Research Institute, Korea, Republic of (South Korea)
The coaxial magnetic gear can be applied in the various applications including wind power generation, electric propulsion system thanks to non-contact power transmission mechanism. But, there are space harmonics of the magnetic flux by the magnetic field modulation principle, and these space harmonics cause the considerable magnetic loss. Especially, in the high speed applications, the magnetic loss at the permanent magnet is severe. Thus, in this paper, the coaxial magnetic gear with the surface mounted PM for the high speed applications with 40,000rpm and 40kW is presented, and its design considering the space harmonic characteristics is conducted. At first, using the 2D-FEM, the characteristics of the space harmonics, which cause the eddy current losses of PM in each rotor, are analyzed. Secondly, to consider the trade-off between the increase of the pull-out torque and the decrease of operating torque by the magnetic loss, the optimum design with both of maximization of pull-out torque and minimization of eddy current loss of PM as the objective functions is performed. Finally, by 3D-FEM analysis for the optimum model, the characteristics of the eddy current loss of PM in each rotor are analyzed, and the appropriate topology design including the effective segmentation of PM in the each rotor to reduce the eddy current loss of PM is presented.
Characteristics Analysis of Iron Loss Caused by Space Harmonics and Efficiency Improvement Strategy in Doubly Fed Magnetic Geared Motor
Dong-A University, Korea, Republic of (South Korea)
The doubly fed magnetic geared motor, which has dual AC windings, can be operated with the different frequency each other in the inner and outer windings. Hence, the iron loss and resultant efficiency are varied by the space harmonics of the magnetic flux which are depending on the frequency condition in each winding. Thus, in this paper, firstly, the effect of the space harmonic components of the air-gap flux density on the inner stator, outer stator, and the modulating pieces is separately investigated. In addition to this, the iron loss characteristics at each ferromagnetic material are presented according to the frequency variations in the inner and outer windings. Secondly, the iron loss maps and the efficiency maps according to the frequency conditions of the inner and outer windings are drawn, and the causes of the difference between the maps are analyzed. Finally, the efficiency improvement for the whole operating region by the individual frequency control and the iron loss mapping is presented.
Analysis of Radial Force Wave of Permanent Magnet Synchronous Hub Motors with Fractional Slot Concentrated Windings
1Jiangsu University, China, People's Republic of; 2University of Technology Sydney, Australia; 3The University of Sydney, Australia; 4Huaiyin Institute of Technology, Huai'an 223003, China, People's Republic of
This paper presents the analysis and optimization of radial force of permanent magnet synchronous hub motor (PMSHM) with fraction-slots concentrated windings. As the hub motors are directly installed on the wheels, its radial force will directly affect the ride comfort of the vehicle. Therefore, the study on radial force of hub motor will be of great value. A 50-poles PMSHM which is preliminary designed for a distributed electric vehicle (EV) is taken as the basis for the analysis and optimization. Different slot number selections are given for 50-poles PMSHM, and the radial force of the motor under different slot numbers are analyzed and compared, and an appropriate slot number combination is selected for the PMSHM.
Wireless Charging Coil Design for Electric Vehicles Using Taguchi-Genetic Algorithm and Finite Element Method
National Cheng Kung University, Taiwan
This paper applies the Taguchi method-based genetic algorithm (GA) and finite element method (FEM) for the performance improvement of wireless charging, where the misalignment between coils is taken into consideration in anticipation of increasing the efficiency of power transmission. In the study, the effect of misalignment tolerance of coils is investigated. By employing the Taguchi method to determine the appropriate parameters, the GA is subsequently applied to the coil design so as to allow a larger misalignment tolerance during the charging process. To verify the method proposed, both numerical simulations and hardware realization of a wireless power transfer system are made under different scenarios. Experimental results indicate that the misalignment tolerance of coupling coil is improved, while the satisfactory power transmission efficiency can be well maintained. These outcomes serve as beneficial references for wireless charging of electric vehicles.
Hole Sensitivity Analysis for Topology Optimization of DC Conductor System
Sungkyunkwan University, Korea, Republic of (South Korea)
This paper proposes a hole sensitivity analysis for the topology optimization of a DC conductor system. A hole sensitivity analysis can be used to generate holes in the design region to optimize the topology. The generated hole, of which the positions are determined by evaluating the hole sensitivity in the region, changes the system topology and widens the design space. In the DC conductor system, the homogeneous Neumann boundary condition, one of the outer boundary conditions, is imposed on the surface of a generated air hole. Thus, by using the shape sensitivity formula for the outer boundary, the two-dimensional hole sensitivity formula for an air hole in a conductive material is derived. The electric field near the hole, which is analytically obtained, is also used during the derivation. To show the feasibility of the derived hole sensitivity formula, a numerical example with a known optimal design is tested.
Shape Sensitivity Analysis and Optimization of Electrodes in DC Conductor System
Sungkyunkwan University, Korea, Republic of (South Korea)
This paper proposes a sensitivity analysis for the shape optimization of electrodes in DC conductor system. The sensitivity formula for the boundary variation is derived by using the material derivative concept and the adjoint variable technique. The shape deformation is determined by the design velocity obtained from the derived sensitivity formula. The shape variation is expressed by using the level set method. Two numerical examples are tested to show the feasibility and usefulness of the proposed method.
Examination of High-Q-factor Conductor-embedded Planar Transformer with Magnetic Flux-Path Control Technology
Shinshu University, Japan
To improve the power density of switching power supply, transformers need to be smaller and suffer fewer losses. Increasing the drive frequency is an effective strategy to miniaturize a transformer. However, losses increase as the driving frequencies increases. In this paper, we investigate strategies to reduce the losses from conductor-embedded planar transformers, using magnetic flux path control technology. The AC resistance of a conductor-embedded planar transformer with magnetic flux path control technology is less than that of a conventional conductor-embedded transformer, and the Q value is improved.
Enhanced Genetic Algorithm for Topology Optimization of an Electromagnetic Actuator
Friedrich Alexander Universität Erlangen-Nürenberg, Germany
Topological optimization is a common tool in the field of mechanical engineering, but in the design of electrical machines and electromagnetic devices there is an open space for its application. In conventional design optimization, geometric optimization with changing the boundaries of the shape is common, but topological optimization is applied to give the designer more freedom to achieve a machine design, which can be closer to the customer goals. Gaining the design of an electrical machine with high torque or force and low weight is one of the desired goals, which is investigated in this study. To overcome the generation of intermediate material characteristics in the cells of the discretised design area, a binary genetic algorithm (GA) as a metaheuristic method is used. To enhance the low convergence rate of the GA, as a novelty, several chromosomes for each subarea of the design space are suggested, which are independent of each other and operate at the same time. This leads to a significant reduction of the computational time. After the automatic optimization process some manual changes are made to improve the manufacturability. The given design goals on the highly nonlinear E-core actuator, which is used as a first and simple case study, have been successfully achieved using the enhanced GA method to gain the best material distribution. It is possible to extend this method to other active parts of an electrical machine.
Determination of the Crack’s Parameters on the Basis of Non-Destructive Testing Using Different Metaheuristics
University of Maribor, Faculty of Electrical Enginering and Computer Science, Slovenia
This paper introduces a procedure for finding the position, length, depth, and width of a crack within a material, based on eddy current non-destructive testing. The measured values of the magnetic flux density are used for the crack parameters’ identification. The crack’s position and length are found by considering the differences in the measured magnetic flux densities between neighboring measurement points. The crack’s depth and width are found by using a stochastic optimization method connected with a finite element model. Three different metaheuristics are tested, which are Differential Evolution (DE), Artificial Bee Colony (ABC) and Teaching-Learning Based Optimization (TLBO).
Parameters Optimization Design of Double-D Coils Based on Minimum Loss for Electric Vehicle Wireless Charging System
1Nanjing Normal University, China; 2Nanjing Institute of Intelligent High-end Equipment Industry Co., Ltd.,China; 3The Jiangsu Engineering Laboratory of Gas-Electricity Integrated Energy,China
Compare with circular coils, Double-D coils are widely used in the wireless charging system of electric vehicles owing to its high coupling coefficient and excellent lateral offset tolerance. In order to obtain a higher coupling coefficient and reduce the leakage magnetic flux in the central part of the coils, this paper proposes a method that optimizing stray parameters, which can achieve more than 95% of transmitting efficiency and 11 kW output power simultaneously. The test results show that the optimization method can economize about 32% of the core material when the indexes are satisfied.
Optimum Design of Sensorless-oriented IPMSM Considering Torque Characteristics
1Yeungnam University, Korea, Republic of (South Korea); 2Hanyang University, Korea, Republic of (South Korea)
This paper presents the design process of a sensorless-oriented interior permanent magnet synchronous motor (IPMSM) with concentrated winding, based on spatial saliency for traction in electric vehicles. The purpose of the design method is to ultimately achieve both stable rotor position detection and acceptable torque characteristics such as cogging torque and torque ripple. After describing the evaluating procedure of sensorless controllability, the effects of the stator chamfer and notch are analyzed to figure out their effectiveness on sensorless drive. Focusing on the analysis results of the geometric parameters, the improved model is designed through optimization, considering both sensorless controllability and torque characteristics. Response surface methodology (RSM) is used for optimization. Then, the machine characteristics including the sensorless controllability as the simulation results of the prototype and improved model are compared. It is founded that the accuracy of the rotor position estimation and torque characteristics is improved simultaneously by means of the optimum design. Finally, the validity of the simulation results is verified by comparison with the test results of the prototype.
Resolving Eddy Current Phenomena in Turbogenerator End Regions during Open-Circuit using Magnetic Sub-Modelling Techniques
1Siemens AG, Germany; 2Helmut Schmidt University,Germany
The novel simulation technique of creating magnetic sub models, allows resolving phenomena such as local eddy currents in electric machine components while incorporating effects due to magnetic fields arising from larger machine parts. This procedure applied to turbogenerators gives opportunity to investigate effects of a rotor’s magnetic fields approaching and penetrating individual copper strands of stator Roebel-bars at core ends. It should be noted that the magnetically relevant end region of examined non-salient pole synchronous machines extends to several meters, whereas the complex geometry of the Roebel-bar is four to five orders of magnitude smaller. This cutting-edge method enables for the first time to resolve and directly compare resulting heat generation rates due to the described phenomenon with high resolution for different end zone designs.
Optimal Efficiency of Transverse Flux Permanent Magnet Synchronous Generator
1Universidad de Santiago de Chile, Chile; 2Universidade Federal de Santa Catarina, Brasil; 3Pontifícia Universidade Católica do Paraná, Brasil; 4Universidade Federal do Paraná, Brasil
In this work, a Transverse Flux Permanent Magnet Synchronous Generator (TFPMSG) with a U- and I- core toroidal coil in the stator is sized. Its rotor is calculated with buried permanent magnets and the consequent pole is established by flux concentration. The contribution of this paper is an efficiency optimization approach based on adaptive differential evolution approach of the TFPMSG, this topology has not been optimized in previous works. Additionally, two constraints are proposed in relation to the fractional pole pitch of the stator pieces, which have not been presented in previous research. The sizing of the TFPMSG with optimal efficiency will be validated with a finite element method.
Analytical Eddy Current Loss Model Unifying the Effects of Reaction Field and Non-Homogeneous 3-Dimensional Magnetic Field
1Purdue University, West Lafayette, IN USA; 2Tesla Motors Inc, Palo Alto, CA USA
In this paper, a new analytical model is proposed to estimate eddy currents inside linear conductive materials. The closed form formulation takes into account the effects of both the reaction field that dominates at high frequencies as well as the spatially non-homogeneous nature of the magnetic field penetrating the material. Although the model is suitable for most kinds of permanent magnet machines, it is particularly useful for surface permanent magnet machines where both of these phenomena are prominent. The numerical implementation of the model, which consists of a combination of the method of images and of 4-dimensional Fourier transform, is briefly discussed and the validation, using 2-D and 3-D FEM, is presented showing good agreement.