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Permanent magnet synchronous motors (PMSMs) have a scale of applications linking to the industrial machines. As these machines often work in a wide temperature range, the PMSM quality consistency is threatened by the temperature fluctuate. In fact, at the start of the production of the PMSMs, the quality consistency distribution already exist due to the manufacturing dispersion. However, traditional experiment‐based consistency analysis method is inadequate for the PMSM, due to its inevitable destructive measurement for the magnetic properties. To deal with the problem, this paper proposed a model‐based quality consistency analysis method. In this paper, mechanism analysis of the temperature influence on PMSMs is carried out by the finite element analysis and the digital modeling method, so that the impact of dispersion can be depicted by model rather than destructive measurement. The relationship between the temperature and PMSM cogging torque as well as other features is quantitatively revealed. To obtain the NdFeB temperature coefficient, magnetic samples were prepared and measured. Then, the temperature characteristics of the sensitive components of PMSM are established, and the PMSM temperature characteristics can be simulated by integrating temperature coefficients into the PMSM digital model. The qualitative and quantitative temperature characteristics of cogging torque are verified by experiments with a batch of PMSMs. [ABSTRACT FROM AUTHOR]

A permanent magnet synchronous motor (PMSM) is a crucial device for power conversion in an energy system. The cogging torque of the PMSM is a crucial output characteristic, the robustness of which affects the operational reliability of the energy system. Therefore, the robust design optimization (RDO) of cogging torque has aroused widespread concern. There are several challenges in designing a robust cogging torque PMSM. In particular, some design parameters contain repetitive units, and the finite element analysis (FEA) method is time-consuming. State-of-the-art RDO methods usually treat these uncertainties from repetitive units as the same parameter, which neglects the fluctuation of the manufacturing process and cannot obtain a robust solution for the cogging torque of the motor efficiently and accurately. In order to solve this issue, an approximate modeling method based on manufacturing uncertainties analysis for RDO is proposed in this paper. First, the peak-to-peak value of cogging torque (Tcpp) is used to characterize the cogging torque, which is decoupled to an ideal component and fluctuation component produced by the center values and manufacturing tolerances of design parameters. The design of experiments (DoE) and simulation of the two components are carried out. Then, these two components are approximated separately, and the approximate model of Tcpp is obtained by adding the two components. Finally, the proposed approximate model is embedded into the RDO algorithm, and the PMSM design scheme for good Tcpp robustness is obtained. The effectiveness of the proposed method is verified through a case study of the PMSM. [ABSTRACT FROM AUTHOR]

Currently, the finite element method (FEM) and analytical calculation are widely employed for the modeling of electromagnetic acoustic transducers (EMATs). However, it takes long time for finite element calculation. Previous analytical models for bulk wave EMATs are generally considered separately and incompletely, and expressions of radiated wave fields contain infinite integrations and multiple singular points, which result in complex numerical computation. A complete model containing the Lorentz force and radiated wave field calculation for the EMAT with a spiral coil and a NdFeB permanent magnet is established. By introducing a current loop instead of the permanent magnet and adopting the truncated region eigenfunction expansion (TREE) method, the distributions of static and dynamic magnetic fields and their generated Lorentz forces are calculated. A series expansion method is proposed for the computation of radiated wave fields, which replaces the integration by series operation and avoids the solutions of singular points effectively. The Lorentz forces and radiated wave fields of a typical transducer are computed. The validity of the model is verified by FEM and experiments. Their good agreements verify the accuracy and validity of the model. [ABSTRACT FROM AUTHOR]

At present, finite element method (FEM) is still the mainstream tool in a range of complex science and engineering applications, including the analysis of structures, heat, fluid, and electromagnetics. However, FEM becomes computationally very intensive when the number of physics equations grows and the mesh is refined. In this paper, we investigated the parallel computing techniques in the nonlinear magnetostatic field solution of an axisymmetrical actuator with permanent magnet by proposing a generalized black-box transmission line method (BB-TLM). A novel black-box circuit model was built to represent complex FEM element data. By means of the transmission line model, each element is isolated and then a series of parallel procedures is considered during the solution stages. The magnetic field distribution and magnetic force of the studied actuator are calculated by the proposed method and the simulation results are compared with COMSOL. Compared with the conventional N-R method, the generalized BB-TLM algorithm greatly reduces the computation time. [ABSTRACT FROM AUTHOR]

The consistency problem caused by the uncertainties in manufacturing process is a significant factor influencing the quality of electromagnetic device (EMD). The foundation of quality analysis and consistency optimization is the substantial calculation for the input-output characteristics of the product. As for EMD, the interaction of electricity, magnetism (permanent magnetism), and dynamics make the calculation quite complicated. At present, finite-element method (FEM) is a common method for calculating the output characteristics of EMD. However, FEM takes too much time for calculating, it is difficult to be applied for the quality analysis and consistency design of EMD that requires substantial calculation. In this paper, a new approach for the quality analysis and consistency design of EMD based on the approximate model has been proposed. First, the approximate model for calculating the EMD output characteristics is established on the basis of FEM simulation results. Second, using the approximate model, the quality analysis of batch products is conducted with Monte Carlo method. Finally, the optimal design for consistency is carried out with robust tolerance design method. The effectiveness of the method proposed in this paper is verified by the case study of a certain type of electromagnetic relay with permanent magnet. [ABSTRACT FROM AUTHOR]

Electromagnetic acoustic transducers (EMATs) have low transduction efficiency and they are sensitive to the electromagnetic noise, which can result in low signal-to-noise ratio of the received signals. This article presents a multi-physical finite element (FE) model for meander-line (ML) coil EMATs, operating on the Lorentz force mechanism, and the influence of the surrounding electromagnetic fields is also taken into consideration. The generation and reception of Rayleigh waves by EMATs can be described by this model. The receiving performances of two kinds of ML coils have been simulated by the FE model and tested by experiments. The experimental results agree well with the simulation. [ABSTRACT FROM AUTHOR]

• Dynamic characteristics testing and evaluation of electromagnetic devices. • A digital modeling approach to evaluate dynamic characterization is proposed. • Multiphysics modeling approach for FEM description of the electromagnetic devices. • The nonlinear effects of temperature on the dynamic characteristics are considered. • Transmission line parallel algorithm improves the efficiency of solving FEM models. Electromagnetic systems of Electromagnetic devices involve multiphysics coupling of electromagnetic fields, electrical circuits, mechanical motion, and temperature fields. When the digital prototype model has a large number of meshes, the commercial finite element software also has the disadvantage of long computation time in the simulation of dynamic characteristics of electrical apparatus. This paper proposes a transmission line method (TLM) based digital modeling method for the electromagnetic-thermal-force coupling to test and evaluate the static and dynamic characteristics of electromagnetic devices more accurately and efficiently. The case study is developed on a direct current (DC) contactor, and the dynamic characteristics testing and modeling in the electromagnetic-thermal-force coupling of the contactor are investigated. The numerical results of the finite element method (FEM) model for the electromagnetic system of the contactor are compared with the commercial FEM software Altair Flux and the experimental results, which demonstrate the exceptional accuracy of the proposed digital modeling method for the multiphysics coupling of the DC contactor. Meanwhile, the dynamic characteristics of the DC contactor at different ambient temperatures are measured and evaluated, and the comparison with the experimental measurements shows the applicability of the proposed digital prototype model at different ambient temperatures. Compared with the conventional Newton-Raphson (NR) iteration, when dividing fine mesh and extremely fine mesh, the TLM parallel computing significantly improves the efficiency of solving the dynamic characteristics of multiphysics coupling by about 35 % and 44 % with the same computational accuracy, respectively. The dynamic characteristics evaluation method combined with digital modeling technology and experimental measurements proposed in this paper demonstrates high accuracy and solving efficiency, making a notable contribution to the field of design and optimization of electromagnetic devices. [ABSTRACT FROM AUTHOR]

• A finite-element (FE) model of electromagnetic transient of Sen transformer (ST) with field-circuit coupling is proposed, and the proposed model can characterize the effects of core and winding topology on the internal magnetic field distribution. • The proposed FE model can characterize the electromagnetic field changes of the ST device under different conditions, such as short-circuit fault, injected harmonics, and dynamic power flow control in the external power system. • The electromagnetic transient field-circuit co-simulation of the ST device and external power system is realized. The conventional electromagnetic transient model of Sen transformer (ST) is mainly established by the magnetic equivalent circuit method, which can be used for the fast calculation of transient characteristics for ST. Unfortunately, this approach may lead to oversimplification and missing significant information in the modeling process. To accurately calculate the transient electromagnetic field and reveal the internal magnetic field distribution of the ST under different operating conditions, an electromagnetic transient model and field-circuit coupling numerical calculation of ST based on finite-element (FE) method is proposed in this paper. The proposed model can characterize the effects of core and winding topology on the internal magnetic field distribution, as well as the complex nonlinear property of core materials, such as saturation, eddy current, and hysteresis. The field-circuit coupling method enables the FE model to establish a connection with external networks and realize the electromagnetic transient field-circuit co-simulation of the ST device and external power system. The case studies are performed on a FE model of the ST and a two-machine transmission system. The corresponding winding voltage and current variations of the ST in the presence of short-circuit fault, injected harmonics, and dynamic power flow control in the external networks are analyzed. The numerical calculation and co-simulation results of the proposed FE model of the ST and the external networks are compared with the commercial FE software, which demonstrates the effectiveness of the proposed FE model of the ST. Moreover, the co-simulation results of dynamic power flow control show that the ST can adjust the power flow distribution of two transmission lines through changing compensation voltage. [ABSTRACT FROM AUTHOR]

Abstract: Surface wave electromagnetic acoustic transducers (EMATs) are becoming preferred sensors of automatic inspection systems for the detection of surface-layer defects in hostile environments. Aiming at establishing a 3-D model for meander-line-coil surface wave EMATs operating on the Lorentz principle, a novel modeling method is proposed by combining numerical calculations and analytical solutions with special attention to the influence of the dynamic magnetic field. Simulation and analysis find that the frequency of the surface waves due to the dynamic magnetic field is twice that due to the static magnetic field; the excitation of surface waves with two frequencies can effectively improve the sensitivity of EMATs to flaws; and the force due to the dynamic magnetic field generates surface waves more efficiently than that due to the static one when the excitation current exceeds 528.9A. The accuracy of the established model is verified by experiment. [Copyright &y& Elsevier]