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In the design of an electric machine, it is necessary for the designer to complete a robust design. The design parameters may be subjected to the uncertainty such as manufacturing tolerance, or deviation of the material characteristic. Any perturbation in a design parameter can lead to an unpredictable characteristic. This effect can be detected through a post process, such as a sensitivity analysis. In order to increase the numerical efficiency, this paper presents a new algorithm to evaluate the robustness in a candidate solution. It has a unique advantage in that the proposed algorithm can measure and control the extent of robustness according to the problem to be applied. The usefulness of the proposed algorithm is verified by means of the mathematical test function and the optimal overhang design of the surface permanent-magnet motor. The proposed method provides a new alternative as the decision maker of robustness in the robust optimization problem. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

The overhang structure is an effective solution to increase the performance of a surface-mounted permanent magnet (SPM) motor using a ferrite PM. If a ferrite PM, which can be demagnetized through a large armature reaction, is used for an SPM motor controlled by the field-weakening method, the ferrite PM can suffer from irreversible demagnetization. Moreover, if an SPM from the overhang structure is directly exposed to the armature reaction by the winding of the stator, a ferrite PM of an SPM motor could be partially demagnetized. Because of this, when the field-weakening method is used for the control of the SPM motor with the overhang structure, PMs are disadvantageous to the irreversible demagnetization. To solve these problems, a novel structure is proposed, which can increase the motor performance through the overhang structure without irreversible demagnetization in the overhang part. [ABSTRACT FROM AUTHOR]

To design electric machines, the motor performance, cost, and manufacturing have to be considered. Hence, researchers have called this the multi-objective optimization (MOO) problem in which the goal is to minimize or maximize several objective functions at the same time. In order to solve the MOO problem, various algorithms, such as nondominated sorting genetic algorithm II and multi-objective particle swarm optimization, have been widely used. When these algorithms are applied to the electric machine design, much time consumption is inevitable due to many times of function evaluations using a finite-element method. To solve this problem, a novel surrogate-assisted MOO algorithm is proposed. Its validity is confirmed by comparing the optimization results of test functions with conventional optimization methods. To verify the feasibility of its application to a practical electric machine, an interior permanent magnet synchronous motor is designed. [ABSTRACT FROM PUBLISHER]

An overhang structure is used to enhance the air-gap flux density and increase the torque density of a motor. In the preliminary design stage, consideration of the overhang effect is important for a precise prediction of the performance of a motor with overhang and for the selection of the proper overhang length. The 3-D finite-element method (FEM) is essential when analyzing a motor with an overhang structure due to the asymmetry in the axial direction caused by overhang. However, it is computationally expensive and time-consuming, especially during the initial design stage. In this paper, we propose a magnetic equivalent circuit model, which considers the overhang structure of a surface-mounted permanent-magnet motor. With the proposed analytical method, the computational time is significantly reduced in the preliminary design stage. The proposed analytical model is verified with a 3-D FEM analysis. [ABSTRACT FROM PUBLISHER]

The selection of optimal parameters during the design of an electric motor is a multivariable and multimodal optimization problem that requires a considerable amount of computational calculation time. To solve this type of problem, this paper proposes a novel multimodal optimization algorithm that is assisted by a surrogate model using the newly developed compressed sensing theory. Its effectiveness is confirmed by comparing the optimization results for test functions with the results of conventional optimization methods. These results show that the proposed method has more rapid and accurate convergence characteristics than conventional approaches. To verify the feasibility of its application to electric motors, an in-wheel motor is designed using the proposed algorithm. [ABSTRACT FROM PUBLISHER]

Although demand for the multi-segmented and multi-layered (MSML) interior permanent magnet (IPM) motor is high, the analytic method for this motor has not yet been proposed. The finite element method has been used in the analysis and design of the MSML IPM motor, even though it takes much time to perform. To solve this problem, the correct and rapid analytic analysis method for the MSML IPM motor is proposed in this paper. This method is called the MCC method because it is the combination of the Magnetic equivalent circuit, Conformal mapping to consider slotting effect, and Concentration flux of IPM. Furthermore, the feasibility of the optimization of the MSML motor by using the proposed MCC method is verified in this paper. [ABSTRACT FROM AUTHOR]

The Thomson coil actuator (TCA) is a useful switch due to its simple structure and rapid completion time. However, research on the TCA is not widely available. Research on the TCA has been focused on the basic working principles and the characteristic analysis of the TCA. To address these problems, an analysis method and a design method for the TCA are proposed in this paper. Concretely, the analysis and the design method using a numerical method and an analytical method are proposed in this paper. The critical design variables are inspected in detail in this research. The correctness of the proposed methods and the usefulness of the TCA for the high speed switch are verified through an experiment. [ABSTRACT FROM PUBLISHER]

The design of an electric machine is a multivariable and multimodal problem that requires much time to find the optimal design result. To address this problem, we propose a novel optimization algorithm using a kriging meta-model, a contour face climb method, a reinterpolation method in an expected region, an advanced pattern search method, and a uniform search method in the entire problem space. A rapid, exact, and reliable optimization process for a multivariable and multimodal design problem is possible using the proposed novel algorithm. Its validity was confirmed by comparing the optimization results of a test function with evolutionary optimization methods. For verification of the application to an electric machine, a dual-rotor axial flux permanent-magnet synchronous motor was designed using the proposed algorithm in this paper. [ABSTRACT FROM PUBLISHER]

In the two-dimensional (2-D) finite-element (FE) analysis, the overhang effect can be considered through an increase in the remanence flux density of the permanent magnet in order to reflect the increment of the air-gap flux density due to the overhang structure. However, a repetitive 2-D FE analysis was performed in order to match the air-gap flux density with it in the three-dimensional (3-D) FE analysis. The proposed method accurately accounts for the overhang effect without trial and error. From the results of the 3-D FE analysis, the validity of the proposed method is verified. [ABSTRACT FROM PUBLISHER]

When a motor is running under a load condition, it is difficult to analyze and measure the diverse types of loss occurring in the motor. To address this problem, the analysis and the measurement methods that assess the losses in a motor under a load condition are proposed in this paper. In high power density types of motors, eddy current loss is the major type of loss. A three-dimensional finite element method has been used for the analysis of the eddy current loss, which requires the much time and effort in the design process. To solve this problem, in this study we propose an analytic method that can be used for the analysis of the eddy current loss. The proposed loss analysis and measuring methods for a permanent magnet motor under a load condition are validated using a prototype. [ABSTRACT FROM AUTHOR]

The solenoid magnetic actuator has been widely used as an actuator for MS (magnetic switch). Thus, conventional MSs continuously consume electrical power to maintain a closed state. To address this problem, an innovative structure which uses a permanent magnet to generate holding force in the closed state without electrical power is suggested in this paper. Further, the permanent magnet is dedicated to the opening operation and the closing operation by means of its magnetic force. In other words, an eco-friendly MS is proposed in this research. However, this structure has a critical problem in that, if unexpected external force is applied to the MS when in the open state, the MS returns to the closed state by the force of the permanent magnet and remains in the closed state, causing an unintended operation of the load. To solve this problem, a novel inter-locking mechanism is proposed. Hence, we termed the proposed novel MS the MSPI (magnetic switch using a permanent magnet and an inter-locking system). In addition, analysis and design methods for the MSPI are proposed in this paper. The usefulness of the MSPI and the accuracy of the analysis and design methods are confirmed through an experiment. [ABSTRACT FROM AUTHOR]

The conventional climb method is difficult to apply for the multimodal and multi-dimensional optimization problem. To solve this problem, the improved climb method is proposed in this paper. The proposed algorithm can mitigate the time for the optimization and increase the reliability for the optimization. The proposed algorithm is verified through the optimization of an axial flux permanent magnet motor. [ABSTRACT FROM PUBLISHER]

The selection of optimum parameters in electromagnetic design usually requires optimization of multimodal, nonlinear functions. This leads to extensive calculations which pose a huge inconvenience in the design process. This paper proposes a novel algorithm for dealing efficiently with this issue. The proposed algorithm interprets the problem as an unexplored terrain for climbing. Through the use of contour line concept coupled with Kriging, the algorithm finds out all the peaks in the problem domain with as few function calls as possible. The efficiency of the proposed algorithm is demonstrated by application to conventional test functions. In this paper, the simulation results show that skewing does not necessarily reduce the cogging torque but may cause it to increase for certain pole-arc to pole-pitch ratio. The developed algorithm is applied to the magnet shape optimization of an axial flux permanent magnet synchronous machine and the cogging torque was reduced to 79.8% of the initial one. [ABSTRACT FROM AUTHOR]

The information in the published version of [1] contained incorrect information about the affiliation of the authors. The correct affiliations are listed above. [ABSTRACT FROM AUTHOR]