Design Of Electrical Machines Research Articles

Outer rotor wound field flux switching machine for In‐wheel direct drive application

Nowadays the flux switching machines offer pivotal role in high speed applications. The flux sources (field excitation coil and armature winding or permanent magnet) are confined to the stator leaving rotor completely passive, and thus making the flux switching machine (FSM) more suitable for industrial applications. This paper emphasizes salient rotor pole and non-overlapping windings embedded in electrical machine design possess some pertinent features such as reduced copper losses, low-cost, and usage in high speed applications. The proposed design is analyzed for coil test analysis and flux linkage and torque. On the basis of the analysis performed, it is clear that 12-slot/13-pole has low cogging torque, high flux linkage, and maximum torque, compared with other topologies of outer rotor field excitation FSM. A deterministic optimization technique is adopted to enhance the performance of 12-slot/13-pole design. Further, finite element analysis (FEA) results are verified through Global Reluctance Network (GRN) methodology, which show close resemblance with error less than 1.2%. Hence, it validates the proposed design for outer rotor field excitation FSM direct drive application. The proposed design for hybrid electric vehicle torque characteristic is compared with existing interior permanent magnet synchronous machine (IPMSM) and 6-slot/7-pole wound field flux switching machine (WFFSM).

Design and optimisation of transverse flux machine with passive rotor and flux‐concentrating structure

This paper proposes a transverse flux machine which has the topology of flux-concentrating and passive rotor, and also conducts a design and optimisation for machine. With working process of the machine introduced, its topology structure and composition are introduced. The optimisation objectives and design parameters are obtained with analysis. Furthermore, the performance equations are deduced to determine the parameters which affect performance. Ten free parameters should be optimised and the number of pole pair is first optimised with preliminary simulation. Subsequently, Taguchi method is applied to reduce the number of free parameters, and four parameters are selected to be further optimised. Three approximation models are created, and the Kriging model is better to predict the simulation results, thereby substitute the simulation to be used to algorithm. Accordingly, NSGA-II and MOPSO are used to acquire the optimal design for the machine, and the best solution of algorithm is determined by the simulation based on the results from the two algorithms. Finally, the prototype experiment is conducted to verify the optimisation method and simulation. The whole optimisation process for design and optimisation of electrical machine which is timesaving in comparison with optimisation with only simulation can provide the reference for electrical machine's design.

Free-Form Design of Electrical Machine Rotor Cores for Production Using Additive Manufacturing

This work presents a finite element analysis-based, topology optimization (TO) methodology for the combined magnetostatic and structural design of electrical machine cores. Our methodology uses the Bi-directional Evolutionary Structural Optimization (BESO) heuristics to remove inefficient elements from a meshed model based on elemental energies. The algorithm improves the average torque density while maintaining structural integrity. To the best of our knowledge, this work represents the first effort to address the structural-magnetostatic problem of electrical machine design using a free-form approach. Using a surface-mounted permanent magnet motor (PMM) as a case study, the methodology is first tested on linear and nonlinear two-dimensional problems whereby it is shown that the rapid convergence achieved makes the algorithm suitable for real-world applications. The proposed optimization scheme can be easily extended to three dimensions, and we propose that the resulting designs are suitable for manufacturing using selective laser melting, a 3D printing technology capable of producing fully dense high-silicon steel components with good soft magnetic properties. Three-dimensional TO results show that the weight of a PMM rotor can be slashed by 50% without affecting its rated torque profile when the actual magnetic permeability of the 3D-printed material is considered.

Core Loss Estimation in Electric Machines With Flux-Controlled Core Loss Tester

The complexity of core loss estimation is a serious challenge in the design of high-efficiency electric machines. Current estimation methods based on the Steinmetz equation and loss separation are not accurate enough, even at the rated conditions. This paper describes a loss estimation technique combining finite-element analysis (FEA) and actual core loss measurements. First, flux density waveforms in various parts of the electric machine are determined using FEA. Second, the same waveforms are generated in a wound toroidal core made of the same material as used in the machine. The loss is measured per unit mass, and then the total motor core loss is calculated by integrating the measured W/kg loss values for predefined sections of the motor. These estimation results are compared with those of the Bertotti method. The proposed procedure is shown to improve the accuracy of loss estimation.

Reluctance Electric Machines: Design and Control [Book News

This book is an overview of various types of reluctance electrical machines and elements of their modeling, design, and control. It describes reluctance electrical machines by classification. The following types of machines are covered: reluctance synchronous machines; brushless dc multiphase reluctance machines; claw pole–synchronous motors; switched reluctance machines; Vernier permanent-magnet machine drives; flux- switched (stator permanent magnet) reluctance electric machines; flux-reversal reluctance electric machines; transverse flux-reluctance electric machines; dual stator winding (doubly fed brushless) reluctance electric machines; magnetically geared reluctance electric-machine drives; and dc plus ac doubly salient electric machines. The authors describe the construction of these machines and include mathematical models. They also compare electrical machines, underscoring their advantages and disadvantages. The book lists, in addition to the operational features, the costs of machine elements and how those elements affect machine construction. Also, modern control strategies, including motion sensorless operation, are thoroughly discussed. The inclusion of many examples and simulations makes this otherwise difficult material easy to understand. The book is very useful for students of electrical, mechanical, and mechatronics as well as for practicing engineers interested in the design and optimization of electrical machines and drive systems.

How Electrical Steel Optimizes Traction Electric Machine Design: A Serviceable Contribution to Electric Vehicles

Vehicle energy consumption and carbon dioxide (CO2) emission can be reduced by vehicle mass reduction and powertrain efficiency improvement; this has been the traditional approach for many past decades. However, because of recent stricter CO2 and fuel economy mandates across the globe, the conventional approach is no longer adequate. As a result, vehicle electrification is gaining traction.

Core-Loss Analysis of High-Speed Doubly Salient Electromagnetic Machine for Aeronautic Starter/Generator Application

Core-loss calculation is an important issue in the design and analysis of electric machines, especially in high-speed applications. However, because of the severe uneven distribution and local supersaturation of the flux density, in combination with the evident dc magnetic bias and the skin effect of the eddy current at a high frequency, it is difficult to estimate the core loss in a high-speed doubly salient electromagnetic machine. In this paper, two improved core-loss calculation methods are proposed. Additionally, an approach is established to determine the core-loss coefficients, which considers the influence of the frequency and amplitude of the flux density by adopting the function-fitting method. The change pattern of the core-loss coefficients is also investigated, together with the influence of the dc magnetic bias on the eddy-current loss. Finally, rotor-lock experiments and high-speed rotating experiments are both conducted. Additionally, two improved methods are used and compared for core-loss calculation.

A New Surrogate-assisted Robust Multi-objective Optimization Algorithm for an Electrical Machine Design

For a multi-objective optimization problem applied to the electric machine design, a new surrogate-assisted robust algorithm is proposed in this research. The proposed algorithm can find a robust and well-distributed Pareto front set rapidly and precisely for robust nondominated solutions using a surrogate model and an uncertainty consideration with a worst-case scenario. The outstanding performances of the proposed algorithm are verified by test functions. Furthermore, through the application of the optimal design process of a surface-mounted permanent magnet synchronous motor for an electric bicycle, the feasibility of this algorithm is verified.

Optimal Control and Design of Electrical Machines

This paper presents a global optimization approach aiming to improve the energy efficiency of electrical machines. The process is made on a hybrid stepper motor allowing to simultaneously optimize design and command. This approach is axed around Pontryagin's maximum principle, which is applied to a magnetodynamic model based on permeances network model. The originality of the proposed approach is to obtain in the same process, the minimization of the energy by optimal control and the minimization of the energy by optimal sizing.

Electrical and Electronic Technologies in More-Electric Aircraft: A Review

This paper presents a review of the electrical and electronic technologies investigated in more-electric aircraft (MEA). In order to change the current situation of low power efficiency, serious pollution, and high operating cost in conventional aircraft, the concept of MEA is proposed. By converting some hydraulic, mechanical, and pneumatic power sources into electrical ones, the overall power efficiency is greatly increased, and more flexible power regulation is achieved. The main components in an MEA power system are electrical machines and power electronics devices. The design and control methods for electrical machines and various topologies and control strategies for power electronic converters have been widely researched. Besides, several studies are carried out regarding energy management strategies that intend to optimize the operation of MEA power distribution systems. Furthermore, it is necessary to investigate the system stability and reliability issues in an MEA, since they are directly related to the safety of passengers. In terms of machine technologies, power electronics techniques, energy management strategies, and the system stability and reliability, a review is carried out for the contributions in the literature to MEA.

An Improved Core-Loss Calculation Method With Variable Coefficients Based on Equivalent Frequency

Core-loss calculation is an important issue in design and analysis of electric machine, especially in high-speed applications. However, because of the diverse structure, flux distribution, and rotational variation of flux density, it is difficult to predict core loss in electric machines exactly. In this paper, a concept of equivalent frequency is proposed for arbitrary waveforms. An improved core-loss calculation method with variable coefficients based on equivalent frequency is established for electric machines. Finally, the improved core-loss calculation method is verified by experiments on doubly salient electromagnetic motor. The conclusions are also applicable to many other kinds of electric machines.

Advanced Soft- and Hard-Magnetic Material Models for the Numerical Simulation of Electrical Machines

Accurate modeling of soft- and hard-magnetic materials for the numerical simulation of rotating electrical machines is required to allow predictions on the operational characteristics along the torque-speed map, already in the design stage. The full potential of most appropriate material selection and concurrent geometry adaption can only be utilized if models can represent actual material behavior. The accurate prediction of iron losses of soft-magnetic materials for various frequencies and magnetic flux densities, as well as the degradation due to manufacturing is eminent for the design of electrical machines. Therefore, advanced material models need to be adapted and their accuracy examined to further improve the modeling and enable progression. This paper will give an overview of the current modeling approaches applied at the Institute of Electrical Machines for soft- and hard-magnetic materials in the simulation of rotating electrical machines. A case example in the form of a traction drive is presented to which the models are applied. For the machine modeling, the inhouse solver pyMOOSE is utilized. In order to determine the losses with regard to manufacturing processes, the iron-loss model with material degradation is used in combination with a machine simulation scheme of the entire operating range of the machine. Here, various simulation approaches are combined to form the entire computational toolchain to obtain accurate results in the entire operational range.

Development of Differing Extent Mesh Adaptive Direct Search Applied for Optimal Design of Spoke-Type PMSM

Optimal design of electric machines using finite-element analysis (FEA) necessitates too much computation time to maintain high accuracy. To reduce the computation time and obtain a global optimum in multi-modal problems, this paper presents differing extent mesh adaptive direct search (DEMADS). The proposed algorithm is classified into three groups according to the poll searching frame and mesh size for assigning a global and local searching. In particular, DEMADS shares information among solutions based on a parallel multi-start strategy for earlier stopping by deviation and checking revisits. The effectiveness of DEMADS has been validated and evaluated as the function call number and the convergence number at a global optimum using benchmarking function. Finally, it is applied to an optimization problem that minimize torque ripple of a spoke-type permanent magnet synchronous machine via FEA.

Robust Optimization with Static Analysis Assisted Technique for Design of Electric Machine

Robust Optimization with Static Analysis Assisted Technique for Design of Electric Machine

Two-Level Surrogate-Assisted Differential Evolution Multi-Objective Optimization of Electric Machines Using 3-D FEA

A two-level surrogate-assisted optimization algorithm is proposed for electric machine design using 3-D finite-element analysis (FEA). The algorithm achieves the optima with much fewer FEA evaluations than conventional methods. It is composed of interior and exterior levels. The exploration is performed mainly in the interior level, which evaluates hundreds of designs employing affordable kriging models. Then, the most promising designs are evaluated in the exterior loop with expensive 3-D FEA models. The sample pool is constructed in a self-adjustable and dynamic way. A hybrid stopping criterion is used to avoid unnecessary expensive function evaluations.

Neutron grating interferometry investigation of punching-related local magnetic property deteriorations in electrical steels

Abstract Mechanical residual stress induced by manufacturing influences the magnetic behavior of non-grain oriented electrical steels, which are used for producing rotors and stators of electrical machines. The impairment occurs mainly along the cutting line of stator and rotor laminations. A locally resolved assessment of the magnetic material behavior of punched electrical steels is possible by using the neutron grating interferometry. In addition to this in situ measurement method, additional ex-situ measurements allow correlating local domain wall mobility and global magnetic polarization. Four different non-grain oriented electrical steels are investigated in this paper. This includes two sheet thicknesses of 0.35 mm and 0.65 mm both available having silicon contents of 2.30 wt-% as well as 2.74 wt-%. The specimens are produced by wire cutting and by punching using different process parameters, i.e., two relative cutting clearances of 5% and 10% plus a sharp and worn cutting edge wear state. The cutting method’s influence on the four different electrical steel’s magnetic behavior is discussed with respect to the local polarization distributions at varying magnetic field strengths next to the cutting lines. This novel approach for the first time allows an in situ investigation of altered magnetic properties with respect to the punching induced residual stress along the cutting line. Not only the maximum deterioration of the polarization next to the cutting line but also the extent of the magnetic property deterioration is pointed out. The effect of punching parameter variations is further verified using global magnetic measurements. The knowledge about the local polarization distribution next to the cutting line is critical for an improved development and design of electrical machines.

Modern Electrical Machine Design Optimization: Techniques, Trends, and Best Practices

Disruptive innovations in electrical machine design optimization are observed in this paper, motivated by emerging trends. Improvements in mathematics and computer science enable more detailed optimization scenarios that cover evermore aspects of physics. In the past, electrical machine design was equivalent to investigating the electromagnetic performance. Nowadays, thermal, rotor dynamics, power electronics, and control aspects are included. The material and engineering science have introduced new dimensions on the optimization process and impact of manufacturing, and unavoidable tolerances should be considered. Consequently, multifaceted scenarios are analyzed and improvements in numerous fields take effect. This paper is a reference for both academics and practicing engineers regarding recent developments and future trends. It comprises the definition of optimization scenarios regarding geometry specification and goal setting. Moreover, a materials-based perspective and techniques for solving optimization problems are included. Finally, a collection of examples from the literature is presented and two particular scenarios are illustrated in detail.

Real-Time FEM Computation of Nonlinear Magnetodynamics of Moving Structures on FPGA for HIL Emulation

Finite-element method (FEM) based hardware-in-the-loop emulation provides the most accurate and fast prototype platform for real-time design and testing of electric machines in a nondestructive environment. The application of transmission line modeling (TLM) can expeditiously reduce the FEM execution time by decoupling the nonlinear elements of the FEM equivalent network using transmission lines to keep the stiffness matrix unchanged through the simulation for static cases. However, in electric machines the TLM method suffers from the change of stiffness matrix in the time-stepped procedure due to movement. Furthermore, time consumption for the solution of numerous decoupled nonlinear equations for a fairly large number of TLM iterations in comparison with the conventional Newton–Raphson method remains a challenge. This paper proposes a novel real-time TLM method based on finite precalculated lower and upper triangular decompositions and field programmable gate array hardware implementation to exploit TLM parallelism for real-time simulation of magnetodynamics in electric machines. A two-dimensional FEM simulation of a single-sided linear induction machine is emulated in hardware and the results are validated experimentally and with Jmag-Designer software to show the effectiveness of the proposed method.

Experimental characterization and modeling of thermal resistance of electric machine lamination stacks

There is lack of information in the open literature on thermal properties of electric machine lamination stacks such as contact resistance and effective thermal conductivity, yet this information is critical for researchers and engineers in electric machine design and development. The thermal conductivity of electromagnetic steel lamination materials was measured, and the thermal contact resistance between laminations in a stack, as well as factors affecting contact resistance between laminations - such as the contact pressure and surface finish – were investigated. A model was also developed to estimate the through-stack thermal conductivity for materials beyond those that were directly tested in this work. Four lamination materials were investigated, including the commonly-used 26-gauge and 29-gauge M19 materials, the HF10, and Arnon 7 materials. Although this paper focuses on electric machines for automotive applications, the information is potentially applicable to any component utilizing electromagnetic steel laminations.

Electric Machines and Energy Storage: Over a Century of Technologies in Electric and Hybrid Electric Vehicles

Electric vehicles (EVs) were among the first automobiles ever built. In fact, in 1900, over 30% of the 2,370 cars in New York, Chicago, and Boston were EVs (Sulzberger 2004). Efficiency, cost-effectiveness, and lightweight energy storage and conversion capabilities have been the main developmental barriers since the first EV circa 1884 (Chan 2002). The development and production of EVs and hybrid EVs (HEVs) has been extensively revisited in the last few decades due to recent developments in electric machine material and design, power electronic semiconductors and packaging, energy storage, thermal management, and microprocessors. Additionally, the rising need for more efficient and environment-friendly transportation has further contributed to this new surge of interest.