• Journal of international Conference on Electrical Machines and Systems
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• 제1권4호
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• pp.505-508
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• 2012

A permanent magnet flux switching (PMFS) machine has a simple rotor, whilst both magnets and coils are set in the stator, resulting in easy removal of heat due to both copper loss and eddy current loss in magnets. However, the volume of magnets used in PMFS machines is usually larger than in conventional PM machines, and leakage flux does exist at the non-airgap side. To make full use of the magnets and gain higher power density, a novel 3-dimensional (3D) field PMFS machine is developed. It combines merits of the tubular linear machine, external-rotor rotary machine and axial-flux rotary machine, hence, offers high power density and peak torque capability, as well as efficient utility of magnets owing to the unique configuration of triple airgap fields.

• 전기의세계
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• 제24권2호
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• pp.63-70
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• 1975

The solid-iron rotor induction motor is the squirral cage type induction motor with its rotor core consisting of solid iron in stead of a laminated core. The specific feature of this motor are that its structure is simple and firm, and therefore provides the great convenience in its operation and that its starting characteristic are excellent. this study is aimedto derive the equation for theroretical evaluation of the speed-torque characteristics of the motor by use of maxwell's equation. Through the series of test on the speed-torque characteristics of this motor which is experimentally constructed, we have proved the feasibility of the equaiton which is derived theoretically to calculate the torque of the motor. In addition we have obtained its general charastristics experimentally.

• International Journal of Fluid Machinery and Systems
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• 제4권3호
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• pp.324-333
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• 2011

Phase resonance in a centrifugal compressor was experimentally observed and simulated with a commercial CFD code. It was found that pressure fluctuation at the volute outlet becomes the maximum when the rotational speed of the modes caused by the rotor-stator interaction agrees with the sound velocity. A simple one-dimensional theory is presented to explain the phase resonance in turbomachinery.

• 한국전산유체공학회지
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• 제11권3호
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• pp.1-7
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• 2006

Euler and Navier-Stokes flow analyses for helicopter rotor in hover were performed as low and high fidelity analysis models respectively for the future multidisciplinary design optimization(MDO). These design-oriented analyses possess several attributes such as variable complexity, sensitivity-computation capability and modularity which analysis models involved in MDO are recommended to provide with. To realize PC-based analyses for both fidelity models, reduction of flow domain was made by appling farfield boundary condition based on 3-dimensional point sink with simple momentum theory and also periodic boundary condition in the azimuthal direction. Correlations of thrust, torque and their sensitivities between low and high complexity models were tried to evaluate the applicability of these analysis models in MDO process. It was found that the low-fidelity Euler analysis model predicted inaccurate sensitivity derivatives at relatively high angle of attack.

• 한국진공학회지
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• 제6권S1호
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• pp.89-95
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• 1997

A new type of piexoelectric membrane traveling wave motor has been designed and forbricated. The small motor is composed by the stator which is the combination of annular/circular membrane and metal elastic base using as the common electrode at some time and the rotor which is placed on the metal elastic body. Thus the motor structure is simple and easy to fabricate. The material of a piezoelectric membrane is fabricated by sol-gel method or wear-down method. A piezoelectric traveling wave motor has been fabricated with the stator diameter 8mm The total thickness of the stator is 350$\mu$m. Under the alternative excitation voltage 10-12V the revolving speed of the rotor is more than 100RPM.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2009년도 정기총회 및 추계학술대회 논문집
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• pp.268-270
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• 2009

This paper proposes a simple starting method to arrange the rotor position of the blushless DC motor (BLDC) without additional sensors and any information of motor parameters. Both the stator current and time period for arranging the rotor position can be easily adjusted by modulating a pulse width of switching devices. Using the proposed method, it is demonstrated experimentally that the BLDC starts up very smoothly.

• 동력기계공학회지
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• 제8권2호
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• pp.45-52
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• 2004

This paper describes the optimum design for journal bearings by using simulated annealing method. Simulated annealing algorithm is an optimization technique to calculate global and local optimum solutions. Dynamic characteristics of the journal bearing are calculated by using finite difference method (FDM), and these values are used for the procedure of journal bearing optimization. The objective is to minimize the resonance response (Q factor) of the simple rotor system supported by the journal bearings. Bearing clearance and length to diameter ratio are used as the design variables.

• Journal of Advanced Marine Engineering and Technology
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• 제27권1호
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• pp.100-107
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• 2003

This study was to control magnetic field orientation-typed sensorless vector control by applying the theory of a rotor flux observer to drive an induction motor. This research suggested a new speed estimation method that estimates speed with the rotor flux obtained by using a flux observer and the variable of state current detected by a current sensor without a speed sensor. Because the speed estimation method is independent from the motor constants, it is not necessary to control the gain of the parameters and the algorithm is simple. In the findings of the study, the researcher was convinced of the control function and the possibility of realization in the simulation experiment of sensorless vector control system by using DSP(Digital Signal Prosessor).

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.160-162
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• 2007

Switched-reluctance motor(SRM) has advantages such as simple structure, low cost and so on compared with induction motor. This paper proposes a new sensorless method that is based on the impressed voltage pulse method to estimate rotor position. Current sensors detect the SRM currents in the unenergised phases and output the voltage. The rotor position can be inferred by the above calculations when the peak values exceed a fixed threshold value.

• 조명전기설비학회논문지
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• 제25권1호
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• pp.59-63
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• 2011

In small-power applications, variable-speed motors having high efficiency and controllability become more dominant than brushed DC motors. BLDC motors with permanent magnets in the rotor and SRMs directed by reluctance torque due to no permanent magnets have been strongly studied as a candidate. Compared to the BLDC motors, SRMs are more suitable for low-cost applications since the magnetic structure is simple, mechanically robust, and cheap due to no additional excitation in the rotor such as copper wire, aluminum, and permanent magnets. In addition, relatively small number of phases in single and two-phase SRMs allows more cost savings with regards to material in the motor and switching devices in the converter. In this paper, several 2 phase SRMs are compared to a 3 phase 6/4 SRM in terms of flux distribution in key parts of the motors.