Sunghoon Lim

Low Torque Ripple Rotor Design of the Interior Permanent Magnet Motor Using the Multi-Phase Level-Set and Phase-Field Concept

This paper proposes a new optimization method to design the rotor of interior permanent magnet (IPM) motor which consists of a permanent magnet (PM) and ferromagnetic material (FM) for reducing the torque ripple. To express three different material properties (PM, FM, and air), a multi-phase level-set model representing two level-set functions is introduced and the concept of a phase-field model is incorporated to distribute level-set functions for controlling the complexity of the structural boundaries. The optimization problem is formulated to minimize the torque ripple under the volume constraints of each material. Two level-set functions are updated with their respective design sensitivities. To verify the usefulness of the proposed method, the rotor design example of the IPM motor is performed and a novel configuration is obtained.

Topology Optimization of a Magnetic Actuator Based on a Level Set and Phase-Field Approach

This paper aims at the development of a topology optimization method for magnetic actuator design using a levelset model that incorporates a fictitious interface energy model based on concepts in the phase-field method. The optimization problem is formulated for maximizing performance of a magnetic actuator with the ferromagnetic material constraint. The update scheme for implicit moving boundaries is developed based on the time evolutional equations. The proposed method is applied to the structural design of magnetic actuator and confirmed the effectiveness for achieving optimal configurations that deliver enhanced performance.

Design Optimization of Permanent Magnet Actuator Using Multi-Phase Level-Set Model

In this paper, a new approach to achieve the optimal design of a permanent magnetic actuator for maximizing the magnetic performance is presented. To consider three different materials such as permanent magnet, ferromagnetic material and air in design domain, the multi-phase level-set model representing two level set functions is employed. Each materials property is calculated in terms of relative magnetic reluctivity and remanent flux density for magnetostatic analysis. The optimization problem is formulated by the objective function for satisfying all of actuating conditions and the volume constraints of each material. Two level-set functions are updated with the time evolutional equation and the respective design sensitivities until the convergence conditions are satisfied. The structural design example of a permanent magnet actuator for a vacuum circuit breaker is performed to demonstrate the effectiveness of the presented method and an optimal configuration is obtained.

Level-Set-Based Optimal Stator Design of Interior Permanent-Magnet Motor for Torque Ripple Reduction Using Phase-Field Model

The interior permanent-magnet (IPM) motor is widely used in industrial applications due to its high power density. Despite this efficiency, the average torque increase achieved by the reluctance torque leads to high torque ripple, the major cause of motor noise and vibration. Therefore, many studies related to the size optimization have been performed to reduce this ripple effect. This paper suggests an optimal stator shape design for the IPM motor satisfying both improved torque performance and geometrical simplification for manufacturing. To control the geometrical complexity, the concepts of the phase-field model and the level-set method are employed. The optimization problem is formulated to minimize two values: the first is the torque ripple done by adjusting the torque values at any rotor position to constant target torque, and the second is the fictitious interface energy of the phase-field model as it narrows the interfacial region. The proposed method is applied to the structural stator design of a 12-pole 18-slot IPM motor developed as a power source for hybrid electric vehicles.

Level-Set-Based Topology Optimization Using Remeshing Techniques for Magnetic Actuator Design

This paper proposes a new level-set-based topology optimization method for magnetic actuator design using remeshing techniques that can generate meshes on the exact structural boundaries to improve the accuracy of finite-element analysis. Two remeshing techniques, such as the modified adaptive mesh method and the extended finite-element method (XFEM), are introduced for the optimization process. To control the computational time with meshing that is economical and analysis that is accurate, a new resolution parameter that can manage the level of mesh density around the level-set boundaries is employed in the modified adaptive mesh method. In the XFEM, the enrichment term in the element shape function is employed to track the exact outer boundary of the actuator. The optimization problem is formulated to maximize the magnetic force between the core and an armature under the volume constraint of the ferromagnetic material. To verify the effectiveness of the proposed method, it is applied to an electromagnetic problem for an optimal C-core actuator design that is very sensitive to structural boundaries.

Optimal Rotor Design of IPM Motor for Improving Torque Performance Considering Thermal Demagnetization of Magnet

This paper proposes a new design technique for improving torque performance of interior permanent magnet (IPM) motors with consideration of the thermal characteristic of magnet. To verify the driving performance of IPM motor at operating temperature, a magnetic-thermal coupled analysis was performed with a heat source, such as iron loss and copper loss, and the thermal characteristics of permanent magnet (PM) is considered to define the magnetic property. The optimization problem is formulated to minimize the harmonics of magnetic flux, which cause iron loss, as well as to maximize the output torque for satisfying the design target. To obtain an optimal rotor shape of the IPM motor, which is composed of both PM and ferromagnetic material, a multi-phase level set model is employed for representing the precise boundaries of the magnetic materials. A design example of a motor with Nd-Fe-B magnet, which has a tendency to be demagnetized at high temperature, is provided to verify the effectiveness of the proposed method.

Multi-Component Layout Optimization Method for the Design of a Permanent Magnet Actuator

This paper presents a multi-component layout optimization method that incorporates a parametric and topology optimization method to determine the optimal configuration of a permanent magnet actuator (PMA). The optimal position and size of the rectangular-type PM are obtained by the design sensitivities of size parameters. The level set-based topology optimization method, which can guarantee a high degree of freedom in geometrical change, is employed to obtain the optimal distribution of the ferromagnetic material (FM) that can affect the path of the magnetic flux. The optimization problem is formulated to maximize the magnetic force of the PMA under the fixed volume fraction constraint of each material. The magnetic properties of the PM and FM, such as the magnetic relative reluctivity and the direction of the remanent magnetic flux, are calculated by the geometric parameters and the sign of the level set function. To confirm the effectiveness of the proposed method, a design example of a simple C-core actuator is provided.

Model-Driven Design Framework for Future Combat Vehicle Development based on Firepower and Mobility: (1) Integrated Performance Modeling

Received 15 September 2014; received in revised form 22 October 2014; accepted 24 October 2014ABSTRACTThis paper proposes the 3D modeling and simulation technique for predicting the integrated per-formance of combat vehicle. To consider the practical driving and firing condition of a combatvehicle, the full vehicle model, which can define the six degrees-of-freedom of vehicle motionand various firing angles, is developed. The critical design parameters such as the stiffness anddamping coefficient of suspension system are applied to construct the analysis model of vehi-cle. A simple ballistic model, which incorporates the empirical interior ballistic model and thepoint mass trajectory model, is built to estimate the firing range and the firing recoil force. Topredict the integrated performance and analyze the effect of system parameters, MATLAB/SIM-ULINK model of a combat vehicle for performing the real time simulation is also developed.Several simulation tests incorporating the road bump and the firing recoil force are presented toconfirm the effectiveness of the proposed vehicle model.Key Words: Combat vehicle, Firepower, Integrated performance, Mobility, Modeling andsimulation, 3D vehicle model

Design Optimization of Moving-Coil Type Linear Actuator Using Level Set Method and Phase-Field Model

액추에이터의 용이한 제어와 진동 및 소음의 저감을 위해서는 가동자의 모든 동작 범위에서 Key Words : Moving-Coil Type Linear Actuator(가동코일형 리니어 액추에이터), Design Optimization(최적설계), Phase-Field Model(페이즈 필드 모델), Level-Set Method(레벨셋법) 초록: 가동코일형 리니어 액추에이터는 다른 형식의 액추에이터에 비해 구조가 간단하고 제어가 용이하여 다양한 산업 분야에 활용되고 있다. 본 연구에서는 리니어 액추에이터의 가동 특성을 향상시키기 위해 가동자의 모든 동작점에서의 추력을 반영한 목적 함수를 구성하고 최적설계 문제를 정식화하였다. 명확한 형상표현을 위해 레벨셋 함수를 설계변수로 설정하여 최적설계를 진행하고 성능과 생산성을 동시에 만족하는 액추에이터를 설계하기 위해 페이즈 필드 모델의 개념을 최적설계에 적용하여 최종형상의 단순화를 고려하였다. 제안한 기법의 효용성을 확인하기 위해 액추에이터 진동과 소음의 원인인 추력의 변동폭을 최소화하기 위한 코어 설계를 수행하여 추력의 변동을 감소시킬 수 있는 최적 형상을 제시하였고 복잡도 계수에 의한 최종 형상의 단순화도 확인하였다. Abstract: A moving-coil type linear actuator has been widely used in the system reciprocating short stroke because of its several advantages, such as the structural simplicity, low weight and a fast control response speed. This paper presents a design approach for improving the actuating performance with a clear expression of optimal configuration represented by a level set function. The optimization problem is formulated to minimize the variation of magnetic force at every moving displacement of the mover for fast and easy control. To consider the manufacturability of actuator, the concept of phase-field model is incorporated to control the complexity of structural boundaries. To verify the usefulness of the proposed method, the core design example of cylindrical linear actuator is performed.

Design Optimization of a Magnetic Actuator Incorporating the Concept of the Hybrid Analysis Method

This paper proposes a new design optimization method for a magnetic actuator based on a hybrid analysis method. The equivalent circuit method and the finite analysis method are combined to create a design method that is both accurate and efficient. The driving performance of the magnetic actuator is predicted through the use of simple circuit parameters, and the specific flux distribution required to obtain a detailed design is calculated only in the design domain, where finite elements are located. The magnetic potential, obtained from lumped circuit parameters, is used to set the boundary conditions of the design domain and for calculating the topological design sensitivity. Since the objective function and design constraints are defined using circuit parameters and the topological variable in the hybrid analysis model, the optimization problem is separated into two phases, to deal with two types of field variable. A simple design example of a solenoid-type actuator is provided to verify the effectiveness of the proposed method.