• Journal of Magnetics
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• 제15권2호
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• pp.85-90
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• 2010

This paper deals with the efficiency evaluations in a synchronous reluctance motor (SynRM) versus a permanent magnet assisted SynRM (PMASynRM), using a coupled transient finite element method (FEM) and Preisach modeling, which is presented to analyze the characteristics under the effects of saturation and hysteresis loss. We herein focus on the efficiency evaluation relative to hysteresis loss and copper loss on the basis of load conditions in a SynRM and PMASynRM. Computer simulation and experimental results for the efficiency, using a dynamometer, show the propriety of the proposed method and the high performance of the PMASynRM.

• Journal of Power Electronics
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• 제11권3호
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• pp.319-326
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• 2011

Nowadays numerous research projects are being conducted in the field of electric motors. Non-modeling of flexible connections such as couplings and the belt-pulley do not show some real behaviors. With an increase in the number of connections and drive factors, these Non-modeled modes become more important. The coupling of two electric motors, instead of one motor, in submarine propeller force is an obvious example which shows that Non-modeled vibration modes caused by flexible connections can disturb controller operation and make undesirable vibrations in the submarine body. In this paper a dynamic model of flexible connections and a completed dynamic model of two different coupled electric models is presented. A robust controller for the completed model is also amended so that the two controlling targets of a desired speed adjustment and an appropriate load division between the two motors with sufficient accuracy are achieved.

• Advances in aircraft and spacecraft science
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• 제10권4호
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• pp.369-391
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• 2023

In our research we have offered a solid solution for aeronautical analysis. which can guarantee the asymptotic stability of coupled nonlinear facilities. According to the theoretical solutions and methods presented, the engine of this aircraft is a small high-bypass turbofan engine. using the non-linear aero-motor control approach and this paper focuses on the power management function of the aero-motor control system. These include static controls and transient controls. A mathematical model of the high-bypass-ratio two-spool unmixed-flow aeroengine was developed through a set of nonlinear dynamic equations verified by experimental data. A single actuator using the displacement method is designed to maintain a certain level of thrust under steady-state conditions. and maintains repeatable performance during transient operation from the requested thrust phase to the next. A single controller can compensate for the effects of noise and harmonic noise at many performance points. And the dynamic performance of a single controller is satisfactory during the transient. for fairness Numerical and computer experiments are described in the perfection of the methods we offer in research.

• Tribology and Lubricants
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• 제6권1호
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• pp.36-51
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• 1990

A parametric study of the thermal effects of a half-circumferential grooved journal bearings under aligned and misaligned conditions has been carried out by solving numerically the coupled Reynolds and energy equation system. Five different sets of boundary conditions for the energy equation have been used which include mixing between recirculating oil and inlet oil and a contraction ratio for the cavitation region. The effects of changes of the inlet oil temperature and pressure, the wall temperature and the L/D ratio have also been examined. For the range of parameters found in internal combustion engines, the mixing effectiveness at the groove and the resulting final mixture temperature have been found to be as important as the wall temperature and the heat transfer rate. The variability of the temperature, though, has been shown to smooth out the peaks of both pressure and friction during misaligned condition Distributions of friction and pressure in the oil are also examined which may be useful in attempts to reduce friction without reducing load. Results for an axial grooved bearing are also presentsed for comparision purpose.

• 한국추진공학회지
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• 제20권1호
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• pp.20-27
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• 2016

연소 불안정 현상은 연료의 응답 함수, 연소율, 국부 연료 표면의 유동 속도에 영향을 미치기 때문에 고체로켓 모터 설계 시 성능이나 구조적 안정성을 다루는 측면에서 매우 중요한 부분이다. 연소 불안정 현상은 음향 모드가 연소/유동과정에서 발생하는 진동수와 결합(coupled)되었을 때 발생한다. 본 연구에서는 비선형 파동방정식으로부터 음향 비선형 불안정 모델을 유도하여 실린더형 고체로켓 모터의 연소 불안정 현상을 분석하였다. 또한 고체로켓 모터 연소실 압력, 연소 속도가 연소 불안정에 미치는 영향을 조사하였다.

• 전기학회논문지
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• 제60권5호
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• pp.1011-1016
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• 2011

This paper presents a robust current controller for a surface-mounted permanent magnet synchronous motor(SPMSM) by using a PI observer. The decoupling PI(proportional-integral) controller combined with an additional feed-forward compensation has been used for the current controller. The classical feed-forward compensation using velocity information and system parameters is not expected to achieve a robust performance against parameter uncertainties. This paper has adopted a PI observer for the feed-forward compensation to cope with parameter uncertainties without using velocity information. A simple PI observer has been designed to compensate the disturbances that represent velocity coupled terms and parameter uncertainties. Experimental results as well as computer simulations with 630W SPMSM confirm that the proposed approach can deal with the effects of the disturbance and improve the control performance.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 춘계학술대회논문집
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• pp.221-226
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• 2005

In this paper, a dynamic model for the rotor shaft-coupling-blade system is developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility is lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations is employed for developing the equation of the motion. The assumed modes method is used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearif, stiffness hardening and softening.

• 한국소음진동공학회논문집
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• 제15권9호
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• pp.1023-1029
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• 2005

In this paper, a dynamic model for the rotor shaft-coupling-blade system was developed. The blades are attached to a disk and driven by an electric motor shaft which is flexible in torsion. We assumed that the shaft torsional flexibility was lumped in the flexible coupling which is usually adopted in rotor systems. The Lagrangian approach with the small deformation theory for both blade-bending and shaft-torsional deformations was employed for developing the equation of the motion. The Assumed Modes Method was used for estimating the blade transverse deflection. The numerical results highlight the effects of both structural damping of the system and the torsional stiffness of the flexible coupling to the dynamic response of the blade. The results showed strong coupling between the blade bending and shaft torsional vibrations in the form of inertial nonlinearity, stiffness hardening and softening.

• The Journal of Korean Physical Therapy
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• 제32권1호
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• pp.1-6
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• 2020

Purpose: This study examined the effects of action observational training to improve the gait function for patients with stroke. Methods: The participants were divided into two groups: right hemiplegia group (n=12) and left hemiplegia group (n=12). All groups received conventional therapy for five sessions for 30 minutes, each for three weeks. Left and right hemiplegia group practiced additional action observational training for five sessions for 20 minutes each for three weeks. They participated in three weeks of action observational training coupled with immediate physical practice (intervention), followed by a final assessment. The duration of each action observation video sequence was 10 minutes, followed immediately by practice of the observed motor skill (10 minutes). The gait velocity, cadence, swing time, step length, and BOS (base of support) were examined using the GAITRite system. Results: The results of this study showed significant improvement in the gait function. The outcomes of the gait abilities from gait velocity, cadence, swing time, step length of the affected side, and BOS (base of support) were improved significantly in the right hemiplegia group (p<0.05). In the left hemiplegia group, there was no significant improvement in the gait velocity, cadence, and BOS except for the swing time and step length of the affected side. The left and right group comparisons between the groups were not significant (p<0.05). Conclusion: Action observation training improves the gait function. These results suggest that action observational training is feasible and suitable for stroke patients.