• Wind and Structures
• /
• 제27권1호
• /
• pp.1-9
• /
• 2018

In this study, the enhancement of the conventional Savonius wind rotor performance with extension plate has been investigated experimentally and numerically. Experimental models used in the study have been produced with 3D (three dimensional) printing, which is one of the rapid prototyping techniques. Experiments of produced Savonius wind rotor models have been carried out in a wind tunnel. CFD (Computational Fluid Dynamics) analyses have been performed under the same experimental conditions to ensure that experiments and numerical analyses are supported to each other. An additional extension plate has been used in order to enhance the performance of the conventional Savonius wind rotor with a gap distance between blades. It can be called modified Savonius rotor or Savonius rotor with built-in extension plate. Thus, the performance of the rotor has been enhanced without using additional equipment other than the rotor itself. Numerical and experimental analyses of Savonius wind rotor models with extension plate have been carried out under predetermined boundary conditions. It has been found that the power coefficient of the modified Savonius rotor is increased about 15% according to the conventional Savonius rotor.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2006년도 춘계학술대회 논문집
• /
• pp.377-378
• /
• 2006

The knuckle crane mainly consists of six parts such as swing, main boom, outer boom, extension boom, hydraulic rotor and knuckle. And the hydraulic rotor is connected at the end of extension boom has rotor block, rotor body, rotor vane. In this study, we carried out kinematics analysis of the hydraulic rotor block curvature for a knuckle crane. Then, we showed the formula to establish the radius of a circumscribed circle to form the rotor block curvature. Third, we analyzed the stress at each point of the rotor block curvature according to the contact angle. From the result of this study, we designed the rotor block curvature with a proper contact angle for a knuckle crane to guarantee the stability of hydraulic rotor.

• International Journal of Aeronautical and Space Sciences
• /
• 제16권4호
• /
• pp.614-623
• /
• 2015

When the speed of a coaxial rotor helicopter in forward flight increases, the wake skew angle of the rotor increases and consequently the position of the vena contracta of the upper rotor with respect to the lower rotor changes. Considering ambient air and the effect of the upper rotor, this study proposes a nonuniform inflow model for the lower rotor of a coaxial rotor helicopter in forward flight. The total required power of the coaxial rotor system was compared against Dingeldein's experimental data, and the results of the proposed model were well matched. A plant model was also developed from first principles for flight simulation, unknown parameter estimation and control analysis. The coaxial rotor helicopter used for this study was manufactured for surveillance and reconnaissance and does not have any stabilizer bar. Therefore, a feedback controller was included during flight test and parameter estimation to overcome unstable situations. Predicted responses of parameter estimation and validation show good agreement with experimental data. Therefore, the methodology described in this paper can be used to develop numerical plant model, study non-uniform inflow model, conduct performance analysis and parameter estimation of coaxial rotor as well as other rotorcrafts in forward flight.

• 한국산학기술학회논문지
• /
• 제17권10호
• /
• pp.21-26
• /
• 2016

산업체에서 널리 사용되고 있는 유도전동기의 회전자를 제작하기 위하여 rotor core slot에 Cu bar를 열박음(shrinkage fit)작업으로 고정한 후 bar 표면을 punch로 원주방향으로 순차적으로 1.5~3mm 압입(swaging)작업시 rotor core slot과 bar 접촉면에 작용하는 contact tangential force의 크기와 분포를 단순화된 2차원 plane strain 해석모델을 사용하여 각각의 압입조건에 대하여 평가하였으며 또한 생산성 향상을 고려한 rotor core slot 설계시 slot 형상에 따른 접촉력 분포를 평가하여 rotor core slot 설계시 필요한 정보를 제공하고자 수치해석적인 방법을 사용하여 parametric study를 수행하였다. 이러한 탄소성 수치해석 결과 1) rotor core 압입작업시 bar 접촉면에 작용하는 contact force는 소성변형이 먼저 발생하는 bar 상부에 크게 작용하며 2) 순차적인 rotor core 압입작업시 bar 접촉면에 작용하는 total contact force는 바로 인접한 bar에 대한 압입작업에 의해서만 영향을 받으며 그 영향으로 약 55% 정도 total contact force가 증가하며 3) 생산성을 고려하여 rotor core를 설계하는 경우에 contact force를 증가시키기 위해서는 core slot의 폭보다 길이를 길게 하는 것이 바람직하다는 사실을 알 수 있었다.

• 전기의세계
• /
• 제21권2호
• /
• pp.5-8
• /
• 1972

The purpose of this paper is, as a preliminary step to study on the method of analysing the torque of toothed solid iron rotor, to make an inquiry into the torque calculation formula of homogenious solid iron rotor without slot. The starting point for its theoretical analysis on torque generated by eddy current in solid iron rotor is based on the maximum air gap flux density. In solid rotor induction motor, torque generated by rotor core is considerably large in the range of large slip. The calculated value and observed value on the test machine are also examined in this paper.

• 한국안전학회지
• /
• 제9권4호
• /
• pp.42-48
• /
• 1994

A rotor flux error-based approach for correcting the rotor time constant estimation used in the slip frequency calculator of indirect field oriented controller is presented in this paper. The controller was derived from the d-q induction machine model. Slip frequency gain is dependent on the machine parameter errors. And parameter errors result in rotor flux error. Thus, estimated rotor flux is compared to commanded rotor flux. The error between them is used for the estimation of rotor time constant. Simulation results which demonstrate the performance of this approach are presented.

• 전자공학회논문지B
• /
• 제33B권6호
• /
• pp.1-11
• /
• 1996

The rotor flux level need be changed frequently for field weakening or power efficiency control. Motor inductances depend on rotor flux but not on machine temperature. On the other hand, rotor resistance varies greatly with the machine temperature. Motor parameters such a sinductances and rotor resistance should be known precisely in order to attain high dynamic performance of inductin motor. In this paper, efficient an dnovel identification algorithms for motor inductances and rotor resistance are presented. The rotor flux is changed. As the result, the slip frequency is varied. The identificatin algorithm for rotor resistance measures the varied slip frequency and alters the estimated rotor resistance. Then, the estimated value of rotor resistance will approach its real value. The proposed identification algorithms are computationally simple and have very small identification errors.

• 소음진동
• /
• 제10권3호
• /
• pp.401-409
• /
• 2000

Vibration of a BLDC motor is a coupled phenomenon between mechanical characteristics and magnetic origins through the motor air-gap. When a relative misalignment of rotor in the air-gap center exists on the assemblage it is considered to influence the motor system characteristics, depending on the degree of misalignment. The rotor-motor system used in a washing machine is modeled using FE-TM and a magnetic force of BLDC motor with radial rotor eccentricity is analyzed. And the transient whirl responses of a rotor system with relative misalignment in the motor air-gap are investigated considering mechanical origins and magnetic effects. Results show that rotor misalignment in the air-gap affect the vibration of the rotor-motor system.

• Journal of Advanced Marine Engineering and Technology
• /
• 제27권6호
• /
• pp.776-782
• /
• 2003

This paper describes a newly developed double squirrel cage induction motor in which the rotor is located outside the stator. The outside rotor type brushless dc motor has been used for VTR's head drum and PC's cooling fan, but this kind of induction motor has not been developed yet. The parameters of outside rotor type induction motor were measured from the locked rotor test and no load test. It is possible to determine the parameters which are presented in the steady-state equivalent-circuit of the outside rotor type induction motor. Load test of induction motor was carried out using a dynamometer. For the characteristics of torque, efficiency, power factor and output. the developed double squirrel cage induction motor is compared with the ordinary induction motor It is believed that the results of this paper can be used for the development of the outside rotor type induction motor.

• 전기학회논문지
• /
• 제60권9호
• /
• pp.1783-1787
• /
• 2011

The slip frequency is included in feature frequency for fault diagnosis of rotor bar, so rotating rotor speed is needed. In this study, rotor slot harmonic(RSH) method is suggested for speed estimation of induction motor. When the rotor is rotating, motor current signal include the harmonic signal of back-emf voltage related with number of rotor slot. So from the power spectrum of current signal, the rotor speed can be founded. This method of rotor speed estimation gives the slip frequency, and the feature frequency of rotor bar fault can be calculated. Comparing with stroboscope speed meter, the error rate of suggested method is less than 0.1[%].