• 한국소음진동공학회논문집
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• 제22권3호
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• pp.208-213
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• 2012

With great advancement of the automobile functions, environmental factors become important performances, especially noise. This paper investigates noise sources of outer rotor type BLDC motor using in the air-conditioner of the automobiles. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. Structural analysis is conducted through modal test and analysis. For modal analysis, 3D finite element analysis is carried out using commercial program ansys. Electromagnetic causes are analyzed from local force that is computed by Maxwell stress tensor method. Local force excites structure of motor directly. Finally, correlation analysis is performed to determine effect between noise causes.

• 전기학회논문지
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• 제58권3호
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• pp.496-501
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• 2009

Interior Permanent Magnet Synchronous Motor (IPMSM) produces two kind of torque that Magnetic and Reluctance torque. The permanent magnet linkage flux ${\Psi}_a$ and d-axis and q-axis inductances have an important influence on the torque characteristic of IPMSM. Thus their accurate prediction is essential for predicting performance aspect such as the torque and flux-weakening capabilities. In this paper, the influence of barrier width on the ${\Psi}_a$ and $L_d$, $L_q$ is calculated by FEM analysis. Predictions are validated by comparison the average torques, using Maxwell Stress Tensor method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.709-710
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• 2008

In this paper, we calculated permanent magnetic linkage flux ${\psi}_{\alpha}$ and Ld, Lq parameters of IPMSM and compared two model which has different barrier width. IPMSM has two kinds of torque that reluctance torque and magnetic torque. In constant torque region, using the Maxwell stress tensor method, we calculated the torque and current phase angle ${\beta}$ which has appeared maximum torque. In weakening flux region, we calculated the current phase angle ${\beta}$ which flux ${\psi}_o$ lower than limited flux ${\psi}_{omax}$. From the current phase angle ${\beta}$, we calculated torque by torque equation and compared two model characteristic.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.742-743
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• 2015

Magnetic couplings are do not require any mechanical contact with the power transmitted to the secondary side according to the primary side. For this reason, well-suited for isolated systems such as vacuums or high pressure. So, this paper presents the force characteristic analysis of the permanent magnet (PM) linear coupling with vertical magnetized using an analytical magnetic field calculations. Based on the definition of governing equations and magnetic vector potential, we obtained the analytical solutions according to the boundary condition for each of the regions. Also, we derived from the force generated in the permanent magnet surface using the Maxwell stress tensor. The analytical results are proved the validity by comparing to the finite element method (FEM).

• Journal of Electrical Engineering and Technology
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• 제5권4호
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• pp.592-596
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• 2010

In a multi-layer interior permanent magnet synchronous motor, the d- and q-axis parameters vary nonlinearly according to different load conditions, consequently changing the level of saturation. The flux-linkage of d- and q-axis conveys ripple characteristics resulting from mechanical structure and degree of magnetic saturation. If the calculated flux-linkage is correct, the torque using the Maxwell stress tensor method is the same torque calculated by the flux-linkage. However, discrepancy between results exists. In this paper, the d- and q-axis flux-linkage, in consideration of the ripple characteristic, is calculated. Simulation results are then compared with experimental results.

• 대한기계학회논문집A
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• 제33권6호
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• pp.584-589
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• 2009

As the automobile energy efficiency stands out an important matter of interest, the magnetic engine valve system receives attention. It has an advantage of no engine power leakage in opening and closing the valve. Moreover, it generates much bigger force than the piezo actuator system, so it can be a good alternative system of the cam and camshaft system. However, since the valve system is not light enough, it is necessary to make its weight reduce. In this study, topology optimization is applied to find the optimal shape of the armature in a magnetic valve system combined with the finite element analysis for the magnetic field analysis. The result is used to obtain a concept design. The adjoint variable method is employed in order to calculate the design sensitivity of the magnetic driving force in the armature component mostly to reduce the computational time during the repeated sensitivity calculation. The sequential linear programming is employed for the optimization algorithm.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권5호
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• pp.305-312
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• 2000

This study deals with the dynamic response of a rotor in Switched Reluctance Motor(SRM) caused by the unbalance force such as the unbalanced mass and electromagnetic force. The method to analyze the mechanical response of the rotor supported on the bearing is based on an extension of the 3-dimensional Transfer Matrix Method(TMM) coupled with the electromagnetic force calculated by Maxwell stress tensor. The displacement of the rotor as a function of frequency according to the position of the unbalanced mass is evaluated from the frequency response function (FRF). The rotor behaviour with the electromagnetic force is compared with that without the electromagnetic force. In addition, the resonance speeds and the vibration modes are analyzed and demonstrated in this paper. These results are useful in designing the mechanical rotor and in balancing properly the rotor to reduce vibration and noise.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 A
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• pp.139-141
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• 1996

The switched reluctance motors(SRM) are simple and robust in structure. Because the wide range of power and speed, their application field is increasing. In order to design the motors and to evaluate the performance of them properly, an accurate study about the analysis of motor characteristics is required. In this paper, for the analysis of SRM characteristics, the finite element method which is based on the solution of combined equations both the electromagnetic field equations and the circuit equations of stator is adopted. The analysis model is to he assumed two-dimensional and the nonlinear property of magnetic materials is considered by Newton-Raphson method. To verify the usefulness of the proposed algorithm, commercial SRM is chosen and simulated. The computed torques obtained by Maxwell Stress Tensor are compared with the experimental data and it is found that they are in good agreement. By applying the proposed algorithm to two cases, currents of stator and torques at every angular positions of rotor are obtained step by step. Comparing them, one can recognize that torque ripple of SRM can he improved by controlling the switching sequences of driving circuits.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 B
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• pp.840-842
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• 2001

The cogging torque and torque ripple in motor which cause noise and vibration are an inevitable phenomenon and they give a bad effect to motor performance. So we are required to reduce the cogging torque and torque ripple not by electrical controlling but by changing the inner mechanical structure and we focused on the permanent magnet. In this research, we calculated current, torque, Back-EMF(electromotive force) and cogging torque according to the change of the magnet shape using two dimensional FEM(Finite Element Method). Maxwell stress tensor and time-stepping method. From the results, we present an appropriate model that can satisfy both low cogging torque, low torque ripple and high efficiency.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2007년도 추계학술대회논문집
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• pp.834-839
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• 2007

This paper investigates the distortion of magnetic field of a brushless DC (BLDC) motor due to deformed rubber magnet. Global or local deformation of rubber magnet in the BLDC motor is mathematically modeled by using the Fourier series. Distorted magnetic field is calculated by using the finite element method, and unbalanced magnetic force are calculated by using the Maxwell stress tensor. The first harmonic deformation in the global deformation of rubber magnet generates the first harmonic driving frequency of the unbalanced magnetic force, and the rest harmonic deformations of rubber magnet except the harmonic deformation with multiple of common divisor of pole and slot introduces the driving frequencies with multiple of slot number ${\pm}1$ to the unbalanced magnetic force. However, the harmonic deformation with multiple of common divisor of pole and slot does not generate unbalanced magnetic force due to the rotational symmetry. When the rubber magnet is locally deformed, the unbalanced magnetic force has the first harmonic driving frequency and the driving frequencies with multiples of slot number ${\pm}1$.