• 전기학회논문지
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• 제59권12호
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• pp.2278-2283
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• 2010

This paper deals with the pendubot control using disturbance observer. Experimental results for the motion of pendubot with balancing control show that the limit cycle can be attributed to the disturbance. Therefore, we propose the disturbance compensation method using by disturbance observer to compensate for the disturbance. Through the experimental results, the effectiveness of the proposed method is verified.

• Journal of Astronomy and Space Sciences
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• 제28권4호
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• pp.311-317
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• 2011

Momentum changing actuators like reaction wheels and control moment gyros are generally used for spacecraft attitude control. This type of actuators produces force and torque disturbances. These disturbances must be reduced since they degrade the quality of spacecraft attitude control. Major disturbances are mainly due to static and dynamic imbalances. This paper gives attention to the reduction of the static and dynamic imbalance. Force/torque measurement system is used to measure the disturbance of the test reaction wheel. An identification method for the location and magnitude of the imbalance is suggested, and the corrections of the imbalance are performed using balancing method. Through balancing, the static and dynamic imbalance is remarkably reduced.

• 한국CDE학회논문집
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• 제22권1호
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• pp.1-9
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• 2017

This research develops dispatching rule for a wafer FABs with dedication constraints. Dedication, mostly considered in a photolithography step, is a feature in a modern FABs in order to increase the yield of machines and achieve the advance of manufacturing technology. However, the dedication has the critical problem because it causes dedication load of machines to unbalance. In this paper, we proposes the dedication load based dispatching rule for load balancing in order to resolve the problem. The objective of this paper is to balance dedication load of photo machines in wafer FABs with dedication constraint. Simulation experiments show that the proposed rule improves the performance of wafer FABs as well as load balance for dedication machines compared to open-loop control based conventional dispatching rule.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제48권10호
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• pp.544-554
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• 1999

Multi-level inverters are now receiving widespread interest form the industrial drives for high power variable speed applications. Especially, for the high power variable speed applications, a diode clamped multi-level inverter has been widely used. However, it has the inherent problem that the voltage of the link capacitors fluctuates. This paper describes a voltage control scheme effectively to suppress the DC-link potential fluctuation for a diode clamped four-level inverter. The current to flow from/into the each link capacitor is analyzed and the operation limit is obtained when a conventional SVPWM is used. To overcome the operation limit, a modified carrier-based SVPWM is proposed. Various simulation and experiment results are presented to verify the proposed voltage control scheme for DC-link voltage balancing.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2015년도 전력전자학술대회 논문집
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• pp.177-178
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• 2015

This paper presents a neutral point deviation compensating control algorithm applied to a 3-level NPC converter. The neutral point deviation is analyzed with a focus on the current flowing out of or into the neutral point of the dc link. Based on the zero sequence components of the reference voltages, this paper analyzes the neutral point deviation and balancing control for 3-level NPC converter. An analytical method is proposed to calculate the injected zero sequence voltage for NP balancing based on average neutral current. This paper also proposes a control scheme compensating for the neutral point deviation under generalized unbalanced grid operating conditions. The positive and negative sequence components of the pole voltages and ac input currents are employed to accurately explain the behavior of 3-level NPC converter. Simulation and experimental results for a test set up of 30kW are shown to verify the validity of the proposed algorithm.

• Journal of Power Electronics
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• 제16권6호
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• pp.2099-2108
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• 2016

The cascaded multilevel converter is widely adopted to medium/high voltage and high power electronic applications due to the small harmonic components of the output voltage and the facilitation of modularity. In this paper, the operation principle of a T-type H-bridge topology is investigated in detail, and a carrier phase shifted pulse width modulation (CPS-PWM) based control method is proposed for this topology. Taking a virtual five-level waveform achieved by a unipolar double frequency CPS-PWM as the output object, PWM signals of the T-type H-bridge can be obtained by reverse derivation according to its switching modes. In addition, a control method for the T-type H-bridge based cascaded multilevel converter is introduced. Then a single-phase T-type H-bridge cascaded multilevel static var generator (SVG) prototype is built, and a repetitive controller based compound current control strategy is designed with the DC-link voltage balancing control scheme analyzed. Finally, simulation and experimental results validate the correctness and feasibility of the proposed modulation method and control strategy for T-type H-bridge based cascaded multilevel converters.

• 한국지능시스템학회논문지
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• 제16권2호
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• pp.209-214
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• 2006

회전 기기에서 회전체의 편심은 언밸런스를 유발하는데 이를 보정하는 밸런싱은 회전 기기에서의 방진 및 저소음 설계에 중요한 항목일 뿐 아니라 회전기기의 안정성과 사용수명에 큰 영향을 미치기 때문에 매우 중요하다. 이러한 밸런싱 머신을 구현하기 위하여 편심을 정확히 측정하여야 하는데, 본 논문에서는 기존의 밸런싱 기기에 일반적으로 사용되고 있는 계측 원리와는 다르게 홀-이펙트 센서를 이용하여 편심을 측정하는 방식을 제안함으로써 저가의 계측 시스템 구성이 가능함을 보이고, 밸런싱 머신의 편심 측정부를 PC통신을 이용하여 제어하고자 한다.

• 한국기계연구소 소보
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• 통권13호
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• pp.143-161
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• 1984

The mass balancing of rotors is an integral part of the study practice of the rotor dynamics. Any machine with rotating components is considered to be rotating machine. The part of a rotating machine that rotates in normal operation is generally reffered to as a rotor. A rotor is flexible if it deforms when the machine is operating at any speed up to its maximum design speed. Otherwise, the rotor is rigid. The general Purpose of the study of rotor dynamics is to increase understanding of rotor vibration phenomena and thus provide a means for controlling or eliminating these vitrations. As the efficiency of rotating machinery has been increased through reduced weight and increased speed, which implies increasement of rotor flexibility, the control of rotor vibration has become essential. Thus, the study and practice of rotor dynamaics has taken on an increasingly important role in recent years. Therefore many workers have studied about this and introduced a few balancing methods of flexible rotor, which can be classified mainly in following four sorts, 1. Polar plotting methed 2. Modal balancing method 3. Influence coefficient method 4. Unified balancing approach In this paper practical theories of rotor dynamics related to flexible rotor balancing have been reviewed and confirmed the calculation results of flexible balancing of typical rotor, as an example, respectively

• Journal of Electrical Engineering and Technology
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• 제11권4호
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• pp.829-838
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• 2016

This paper focuses on the engineering trade-offs in designing capacitor voltage balancing schemes for modular multilevel converters (MMC) HVDC: regulation performance and switching loss. MMC is driven by the on/off switch operation of numerous submodules and the key design concern is balancing submodule capacitor voltages minimizing switching transition among submodules because it represents the voltage regulation performance and system loss. This paper first introduces the state-of-the-art MMC-HVDC submodule capacitor voltage balancing methods reported in the literatures and discusses the trade-offs in designing these methods for HVDC application. This paper further proposes a submodule capacitor balancing scheme exploiting a control signal to flexibly interchange between the on-state and the off-state submodules. The proposed scheme enables desired performance-based voltage regulation and avoids unnecessary switching transitions among submodules, consequently reducing the switching loss. The flexibility and controllability particularly fit in high-level MMC HVDC applications where the aforementioned design trade-offs become more crucial. Simulation studies for MMC HVDC are performed to demonstrate the validity and effectiveness of the proposed capacitor voltage balancing algorithm.

• 센서학회지
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• 제27권3호
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• pp.165-169
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• 2018

A single-axis Cubli frame realized simply with an IMU sensor and DC motor is presented herein. To maintain the balance on the Cubli frame, an LQR controller based on a Lagrangian derivation of the dynamics was designed, which utilized the state variables of the frame angle and its angular acceleration, as well as the wheel angle and its angular acceleration. The designed LQR controller showed a settling time balancing capability of approximately two seconds and 40% of the maximum overshoot in Matlab/Simulink simulations. Our experimental results of the fabricated Cubli frame matched with the simulation results. It maintained balancing at the reference position even though an initial offset as well as external disturbance during the balancing was applied.