• Proceedings of the KIEE Conference
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• 2006.04b
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• pp.118-120
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• 2006

This paper proposes a new stator pole shape having non-uniform air-gap in order to minimize the undesirable torque ripple of switched reluctance motor(SRM). Through numerical analysis using finite element method(FEM) and optimization, the proposed pole-shape-optimized stator is proven to give reduced torque ripple.

• Journal of Magnetics
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• v.18 no.4
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• pp.380-385
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• 2013

We find a metastable vortex state of the perpendicular magnetic anisotropy free layer in spin transfer torque magnetic tunneling junctions by using micromagnetic simulations. The metastable vortex state does not exist in a single layer, and it is only found in the trilayer structure with the perpendicular magnetic anisotropy polarizer layer. It is revealed that the physical origin is the non-uniform stray field from the polarizer layer.

• Journal of Magnetics
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• v.19 no.4
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• pp.411-417
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• 2014

This paper presents the shape optimization of a permanent magnet synchronous motor to reduce the torque ripple and iron loss. Specifically, the harmonics of the electromotive force and cogging torque are decreased by adjusting the permanent magnet arrangement and non-uniform air gap length. In addition, an additional flux path along the q-axis is proposed with a unique rotor shape to increase the q-axis inductance and reluctance torque. The improvement in the performance of the proposed model is verified with simulated and experimental results.

• Journal of Electrical Engineering and Technology
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• v.13 no.5
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• pp.1996-2003
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• 2018

In this paper, the design and characteristic analysis of a novel single-phase hybrid switched reluctance motor (HSRM) for the purpose of replacing the universal motor in commercial blenders are presented. The proposed motor is easy to manufacture due to its simple yet robust structure with minimized power switches and no torque dead-zone. Moreover, the proposed HSRM is able to deliver a high starting torque as a requirement for blending hard food or even ice. The stator has permanent magnets (PMs) mounted on its inner surface and the rotor has a wide pole arc and salient poles that contribute to its high starting torque profile and the elimination of the torque dead-zone. Finite element method (FEM) is used to analyze the characteristic of the proposed motor. Finally, the prototype is manufactured and its performance is verified through experiments.

• Journal of Electrical Engineering and Technology
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• v.12 no.5
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• pp.1864-1871
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• 2017

This paper presents a design of a 2-phase segmental stator type 4/3 switched reluctance motor (SRM) for air-blower application. The air-blower requires only one direction rotation, high rotor speed without torque dead-zone. In order to satisfy the requirements of the load, the rotor of the 4/3 proposed SRM is designed with wider rotor pole arc and non-uniform air-gap is applied on the rotor shape. With a special rotor structure, the motor generates a wider positive torque region and has no torque dead-zone. The stator of the proposed SRM is constructed with two segmental C-cores, and there are no magnetic connections between 2 C-cores. The flux follows in a short closed loop in each C-core and has no reversal flux in the stator. The static and dynamic characteristics of the proposed motor are analyzed by the finite element method (FEA) and Matlab-Simulink, respectively. In order to verify the design, a prototype of the proposed motor has manufactured for laboratory test. The performance of the proposed motor is verified by the simulation and experimental results.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.12
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• pp.608-616
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• 2006

Recently, a switched reluctance motor is widely used in various industries because it has many advantages such as a simple structure, robustness, less maintenance, high torque/weight ratio, and easy speed control over other types of motors. However, a switched reluctance motor inherently produces acoustic noise and vibration caused by torque ripple. Applications of these motors where silent operation is desirable have thus been limited. In this paper, a new stator pole face having a non-uniform air-gap and a pole shoe attached to the lateral face of the rotor pole are suggested in order to minimize torque ripple. The effects of each design parameter are validated using a time-stepping finite element method. The parameters are optimized by utilizing response surface method (RSM) combined with (1+1) evolution strategy. The result shows that the optimized shape gives higher average torque and drastically reduced torque ripple.

• Journal of international Conference on Electrical Machines and Systems
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• v.2 no.1
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• pp.40-44
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• 2013

This paper presents a design and characteristics analysis of novel 2-phase 4/3 switched reluctance motor (SRM) with short flux path for an air-blower application. The desired air-blower is unidirectional application, and requires a wide positive torque region without torque dead-zone. In order to get a wide positive torque region without torque dead-zone during phase commutation, asymmetric inductance characteristic with non-uniform air-gap is considered. The proposed motor could be started at any rotor position with high efficiency drive. The proposed 2-phase 4/3 SRM is verified by finite element method analysis.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.91-98
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• 2007

This paper presents the induced mathematical modeling equations for evaluating the operation stability with automatic transmission of heavy duty vehicle. This theoretical approach indicates that linearized governing equations of system can be converted into eigen-value problems. if the eigen-value has positive number, we can predict the engine operating point locates an unstable operating region. To be a stable state, the unstable operating point diverges toward a stable point which is able to maintain uniform velocity. Based on the previous theoretical analysis, we carry out dynamic simulation to show the behavior of engine operating point and torque converter in transient state. As a result of the dynamic simulation, the suggested theoretical method is found to be reasonable for evaluating the operation stability of a torque converter. In addition, the numerical results explain the engine stops and fluctuating phenomenon in reality.

• Journal of Institute of Control, Robotics and Systems
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• v.19 no.12
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• pp.1119-1124
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• 2013

In this paper we propose a novel torque control method for permanent magnet synchronous motors using the SVPWM (Space Vector PWM). The control law is described in the rotating d-q frame and is devised to track a given reference flux with which the reference torque is generated. The key feature of the proposed control is that it provides uniform dynamics with desired closedloop poles independent of the rotating speed and the desired poles can be selected to yield a fast response with only a small amount of torque ripple.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.828-829
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• 2008

This paper proposes a new pole shaped magnetizing fixture with a non uniform air gap for sinusoidal magnetizing a ring type permanent magnet (PM) to reduce the cogging torque. To obtain more sinusoidal distributed magnetic flux density, the magnetizing fixture's pole shape is optimized by using the sequential response surface method (RSM). And the effects of each design parameter were investigated using the magnetic analysis combined a time stepping finite element method (FEM) with Preisach model. It has been shown, through numerical analysis the optimized modelgives near sinusoidal distributed air gap flux density and drastically reduced cogging torque.