• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2014년도 추계학술대회 논문집
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• pp.306-310
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• 2014

The purpose of this study is the stability evaluation of a vacuum pump through modal test and rotor dynamics. Eigenvalue was solved by the finite-element method(FEM) using 2D and 3D models, then the modal test result was compared with the FEM result. According to the comparison, the analysis result using the 2D was more accurate than the 3D model. Therefore, rotor dynamics was performed by the 2D model. Campbell diagram and root-locus maps, which were calculated by complex-eigenvalue analysis, were used to evaluate the stability of the rotors of the vacuum pump. And displacement solved by unbalance response analysis was compared with the minimum clearance between two rotors of the vacuum pump. Thus, the vacuum pump is assumed operated under steady state through the evaluation of the rotor dynamics.

• 소음진동
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• 제3권4호
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• pp.383-394
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• 1993

An automotive suspension system generally behaves like a low frequency band-pass filter(0.5 - 10 Hz). Passengers are very sensitive to this frequency range in terms of ride quality and road holding ability. In this paper, a LQG/ LTR controller is suggested to improve the ride quality and road holding ability in the specified frequency rage. It has been found by numerical simulation that the ride quality and road holding ability can be improved in the frequency ranges of 0.5 - 3.0 Hz and 0.3 - 2.1 Hz respectively. In addition, a new approach using root locus to evaluate the stability robustness of the active suspension system is studied. It is shown that the stability robustness of the LQG/LTR controller designed in this paper is improved, compared to the passive system.

• 드라이브 ㆍ 컨트롤
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• 제14권3호
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• pp.25-31
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• 2017

This study presents a methodology for simulating a unified approach that controls interaction force between tool and objective by using a synthesis method of robot interacting control law for stabilizing the transient process of motion. Root locus is used to analyze stabilization of motion deviation characteristics. Based on responses of motion deviation, contact force is derived to satisfy exponential stability and we generate control input with respect to motion trajectories and interaction force. Moreover, simulation is applied to experimental application of a Cartesian robot driven by two stepper motors, and the noise of feedback signals is considered as presence of system inaccuracies, and the unified approach of interaction force control is examined precisely.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2005년도 학술대회 논문집 전문대학교육위원
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• pp.180-183
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• 2005

A programmable dynamometer is the proposed system improved the problem of the torque measuring delay with torque transducer, and the load torque is estimated by the minimal order state observer based on the torque component of the vector control induction moter. Therefore, the torque controller is not affected by a load torque disturbance. To verify a superiority of the proposed control algorithm, the analysis for a root locus of a conventional control method and the proposed one, and simulation and experiment is performed. Therefore we hope to be extended in industrial application.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1999년도 제14차 학술회의논문집
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• pp.244-247
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• 1999

This paper presents a methodology of the technique for controlling DC motor drive by implementation of 2-quadrant operating mode which can ensure the torque controlling and speed with response time less than 2 seconds at all loading conditions. By implementation of BRM technique, energy is fed with definite values of BRM 256 bits, with different patterns of high accuracy, and fixing scan time at 0.667 ms, the ripple is less than 1%, thus high efficiency can be achieved, from the consequence of the accuracy of energy feeding at low current. The stability of the whole system can be determined from circle criterion by root locus method . The instant reverse direction of rotation can be done by decreasing the energy to the lowest level while motor is running with no load and variable load at the speed about 100-120 rpm and 50-60 rpm.

• 대한전자공학회논문지
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• 제24권3호
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• pp.376-380
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• 1987

The closed-loop transfer function of 2-nd order PLL (phase-looked loop)of which loop filter has active-lag 1-st order is found. Considering the three criteria of system performance: the transient response time of the circuit, noise bandwidth by the linear analysis and stability which uses root-locus method, the optimum value of damping factor is 1.0 and the natural frequency which depends upon the signal frequency can be determined after consideration of the trade-off relationship between the transient response time and the noise bandwidth.

• Journal of Power Electronics
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• 제14권3호
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• pp.444-457
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• 2014

This paper presents the design and realization of a digital PV simulator with a Push-Pull Forward (PPF) circuit based on the principle of modular hardware and configurable software. A PPF circuit is chosen as the main circuit to restrain the magnetic biasing of the core for a DC-DC converter and to reduce the spike of the turn-off voltage across every switch. Control and I/O interface based on a personal computer (PC) and multifunction data acquisition card, can conveniently achieve the data acquisition and configuration of the control algorithm and interface due to the abundant software resources of computers. In addition, the control program developed in Matlab/Simulink can conveniently construct and adjust both the models and parameters. It can also run in real-time under the external mode of Simulink by loading the modules of the Real-Time Windows Target. The mathematic models of the Push-Pull Forward circuit and the digital PV simulator are established in this paper by the state-space averaging method. The pole-zero cancellation technique is employed and then its controller parameters are systematically designed based on the performance analysis of the root loci of the closed current loop with $k_i$ and $R_L$ as variables. A fuzzy PI controller based on the Takagi-Sugeno fuzzy model is applied to regulate the controller parameters self-adaptively according to the change of $R_L$ and the operating point of the PV simulator to match the controller parameters with $R_L$. The stationary and dynamic performances of the PV simulator are tested by experiments, and the experimental results show that the PV simulator has the merits of a wide effective working range, high steady-state accuracy and good dynamic performances.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제52권5호
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• pp.211-220
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• 2003

The control method of programmable dynamometer for overall test of machine is to load the reference torque which is computed from torque transducer into motor under test. But the torque information detected from torque transducer have a lot of noise when the load torque of meter is a small quantity or changing. Thus, torque transducer must have a low pass filter to detect a definite torque information. But The torque delay generated by filter with torque transducer occur a torque trouble for meter torque of programmable dynamometer. Therefore, this kind of system could not perform dynamic and nonlinear load. In this paper, the control method using the load torque observer without a measure for torque transducer is Proposed. The proposed system improved the problem of the torque measuring delay with torque transducer, and the load torque is estimated by the minimal order state observer based on the torque component of the vector control induction meter. Therefore, the torque controller is not affected by a load torque disturbance. To verify a superiority of the proposed control algorithm, the analysis for a root locus of a conventional control method and the proposed one, and simulation and experiment is performed. Therefore we hope to be extended in industrial application.

• 조명전기설비학회논문지
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• 제14권1호
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• pp.38-46
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• 2000

본 연구에서는 브러시리스 직류모터의 적합한 수학적 동가 모텔링을 구성하였으며 제어대상 BLOC 모터에 스 웹입력이 있는 상태로 역기전력의 측정에 의한 모터 파라미터를 측정하였다. 그리고 제시된 측정법의 타당성은 스템웅답의 실험결과에 의해서 확인하였다. 또한 훌센서로된 BLOC 모터의 오픈루프 전달함수로부터 얻은 근궤 적법의 결과에 따라 적합한 디지털제어기를 셜계하였으며 속도제어 가변을 위한 제어이득을 결정하였다. 여기서 수정된 Ziegler-Nichols의 동조법은 적합한 디지털 게인 설정을 위해서 적용되었으며 시스템의 안정성은 보드선 도와 실험으로 주파수영역의 해석에 의해서 입증하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2001년도 학술대회논문집
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• pp.65-72
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• 2001

Power system stabilizer act efficiently to damp the electromechanical oscillations in interconnected power systems. This paper presents an algorithm for the optimal parameter selection of a power system stabilizer in two-area power systems with a series HVDC link. This method is one of the classical techniques by allocating properly pole-zero positions to fit as closely as desired the ideal phase lead between the voltage reference and the generator electrical power and by changing the gain to produce a necessary damping torque over the matched frequency range. Control of HVDC converter and inverter are used a constant current loop. Proper parameters of PI controllers are obtain based on the Root-locus technique in other to have sufficient speed and stability margin to cope with charging reference values and disturbance. The small signal stability arid transient stability studies using the PSS parameters obtained from this method show that a natural oscillation frequency of the studycase system is adequately damped. Also the simulation results using the HVDC converter and inverter parameters obtained from this proposed method show proper current control characteristics. The simulation used in the paper was performed by the Power System Toolbox software program based on MATLAB.