이중 변환 UPS의 병렬 운전 시 외란 저감 성능 향상을 위한 정지 좌표계 상의 전향 보상 기법

류효준,윤영두,모재성,최승철,우태겸 전력전자학회 2022 전력전자학회 논문지 Vol.27 No.5

Generally, a proportional-resonant controller is used to eliminate steady-state errors during the voltage– current control of a double-conversion uninterruptible power supply (UPS) in a stationary reference frame. Additionally, the feed-forward control compensating for the load current, which can be considered a disturbance of the voltage controller, can be used to improve the disturbance rejection performance. However, during the parallel operation of UPSs, circulating current can occur between UPS modules when performing both feed-forward control and droop control because feed-forward control reduces the circulating current impedance. This study proposes a feed-forward compensation technique that considers the impedance of circulating current. An additional feed-forward compensation technique is developed to enhance the disturbance rejection performance. The validity of the proposed feed-forward compensation technique is verified by the experiment results of the parallel operation of a 500 W double-conversion UPS module.

Analysis of the Assistance Characteristics for the Plantarflexion Torque in Elderly Adults Wearing the Powered Ankle Exoskeleton

Kyung Kim,Jae-Jun Kim,Seung-Rok Kang,Gu-Young Jeong,Tae-Kyu Kwon 제어로봇시스템학회 2010 제어로봇시스템학회 국제학술대회 논문집 Vol.2010 No.10

Ankle exoskeleton with an artificial pneumatic actuator, which is intended for the assistance and enhancement of muscular activity, was developed. In this study, the effectiveness of the system was investigated during plantarflexion motion of ankle joint. To find an effectiveness of the system, the subjects performed maximal voluntary isokinetic plantarflexion contraction on a Biodex-dynamometer. Plantarfexion torque of the ankle joint is assisted by subject’s soleus muscle that is generated when ankle joint do plantarflexion motion. We used the muscular stiffness signal of a soleus muscle for feed-forward control of ankle-foot orthosis as physiological signal. For measurement of this signal, we made the muscular stiffness force sensor. We compared a muscular stiffness force of a soleus muscle between with feed-forward control and without it and a maximal plantarflexion torque between not wearing a ankle-foot orthosis, without feed-forward control wearing it and with feed-forward control wearing it in each ten elderly adults. The experimental result showed that a muscular stiffness force of a soleus muscle with feed-forward control was reduced and plantarflexion torque of an ankle joint only wearing ankle-foot orthosis was reduced but a plantarflexion torque with feed-forward control was increased.The amount of a increasing with feed-forward control is higher than the amount of a decreasing only wearing it. Therefore, we confirmed the effectiveness of the developed ankle-foot orthosis with feed-forward control.

Torque Control for Sensor Equipped Motor-harmonic Drive System

Miran Lee,Bumjoo Lee 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.1

In this paper, the torque control algorithm for Sensor Equipped Motor-Harmonic Drive System is proposed. For the model-based control, the dynamic equation of the harmonic drive and the electric motor was derived as a lumped model, and the frictions of the harmonic drive and the bearings were regarded as disturbance. Consequently, a linear model in which the disturbance acts on the second order system without damping was formulated. The disturbance was estimated from the disturbance observer (DOB) and forward-compensated. Subsequently, the second order system without damping was stabilized by the three different kind of feedback algorithms. First, the integral differentiator control (ID control) algorithm was developed by using pole-zero cancellation. When the model parameters are incorrect, however, the system becomes unstable. To resolve this, the PID controller was considered to make the closed loop system as a second order standard form with damping. The PID controller is stable but has some chattering in steady state. Lastly, PD control with feed-forward augmentation was examined. Among the three controllers, the Feed-forward Augmented PD controller (FAPD controller) gived best result even with parameter inaccuracy. Control performances were verified by computer simulations and experiments with the developed.

기준모델과 피드포워드 적응제어를 사용한 위치제어기

윤명하,최남열,이치환 전력전자학회 2002 전력전자학회 논문지 Vol.7 No.5

This paper proposed a feed-forward adaptive position controller that is robust for variable inertia. The control system consists of PI Position controller, feed-forward and model reference adaptive control. A parameter g(t) of the feed-forward adaptive position controller is adapted by using both the reference model speed and position error. So it improves the transient response and reduces the settling time. And normalization function is used to make linear adaptation time. The validity of the feed-forward adaptive controller is confirmed by simulation results. 본 연구는 관성의 변화에 견실한 피드포워드 적응 위치제어기를 제안한다. 제안된 피드포워드 적응 위치제어기는 PI 위치제어기에 피드포워드와 기준모델 적응제어기를 추가한 구조를 가진다. 제어기의 특징은 과도상태에서 적응제어기가 위치오차와 기준모델의 속도 정보를 이용하여 피드포워드 이득을 조정한다. 이것은 과도응답 특성을 향상시키고, 정상상태의 수렴 시간을 개선시킨다. 위치 오차에 속도의 정보를 받아들여 기존의 PI 위치제어 및 기준모델 적응제어에 비하여 속응성이 우수하다. 그리고, 적응제어기에 규준화 함수를 사용하여 입력크기에 대해 출력신호가 일정한 응답특성을 가지도록 하였다. 시뮬레이션을 통하여 제안된 피드포워드 적응 위치제어기 동작의 타당성을 보였다.

이중 변환 UPS 병렬 운전의 제어 동특성 향상을 위한 동기 좌표계 전압 제어기 구조

모재성,윤영두,류효준,이민성,최승철,김성민,김석민,강호현,김희중 전력전자학회 2022 전력전자학회 논문지 Vol.27 No.4

This study proposes a voltage control scheme in a synchronous reference frame to improve the dynamic characteristics of double-conversion UPSs. UPSs need to control positive and negative sequence voltage, so that positive and negative sequence extractors are generally used to obtain each sequence of the voltage and current. Voltage and current controllers for each sequence are implemented. However, the extractor causes considerable delay, and the delay restricts the control performance, especially for the current controller. To improve the dynamics of the current controller, the proposed scheme adopts a unified current controller without separating positive and negative sequences. By using discrete-time current controller, the control bandwidth can be extended significantly so that negative sequence current can be controlled. To enhance the performance, an additional feed-forward technique for output voltage regulation is proposed. The validity of the proposed controller is verified by experiments.

Implementation of Fuzzy Self-Tuning PID and Feed-Forward Design for High-Performance Motion Control System

Ngo Ha Quang Thinh,Won-Ho Kim 한국지능시스템학회 2014 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.14 No.2

The existing conventional motion controller does not perform well in the presence of nonlinear properties, uncertain factors, and servo lag phenomena of industrial actuators. Hence, a feasible and effective fuzzy self-tuning proportional integral derivative (PID) and feed-forward control scheme is introduced to overcome these problems. In this design, a fuzzy tuner is used to tune the PID parameters resulting in the rejection of the disturbance, which achieves better performance. Then, both velocity and acceleration feed-forward units are added to considerably reduce the tracking error due to servo lag. To verify the capability and effectiveness of the proposed control scheme, the hardware configuration includes digital signal processing (DSP) which plays the main role, dual-port RAM (DPRAM) to guarantee rapid and reliable communication with the host, field-programmable gate array (FPGA) to handle the task of the address decoder and receive the feed-back encoder signal, and several peripheral logic circuits. The results from the experiments show that the proposed motion controller has a smooth profile, with high tracking precision and real-time performance, which are applicable in various manufacturing fields.

Multi-layer Feed-forward Neural Network Deep Learning Control with Hybrid Position and Virtual-force Algorithm for Mobile Robot Obstacle Avoidance

Wei Zheng,Hong-Bin Wang,Zhi-Ming Zhang,Ning Li,Peng-Heng Yin 제어·로봇·시스템학회 2019 International Journal of Control, Automation, and Vol.17 No.4

This paper addresses the trajectory tracking and obstacle avoidance control problems for a class ofmobile robot systems. Two classes of controllers are designed for the mobile robot system in the free motion,respectively. A new hybrid position virtual-force controller is designed to adjust the distance between the mobilerobot and the obstacles. Since the uncertainties between the mobile robot dynamics model and obstacles degradethe performance of the obstacle avoidance system, a multi-layer feed-forward neural networks (NNs) deep learningmethod with hybrid position and virtual-force is proposed, such that the distance between the mobile robot andthe obstacles converges to an adjustable bounded region. It is shown that the proposed controller in this paperis smooth, effective, and only uses the system output. The control design conditions are relaxed because of thedeveloped multi-layer feed-forward NNs deep learning compensator. The simulation results and obstacle avoidancecases are performed to show the effectiveness of the proposed method.

단상 PVPCS 출력 전류의 리플 개선을 위한 노치 필터 및 피드 포워드 제어기 설계

김승민(Kim Seung-Min),양승대(Yang Seung-Dae),최주엽(Choi Ju-Yeop),최익(Choy Ick),이영권(Lee Young-Gwon) 한국태양에너지학회 2012 한국태양에너지학회 학술대회논문집 Vol.2012 No.3

A single-phase PVPCS (photovoltaic power conditioning system) that contains a single phase dc-ac inverter tends to draw an ac ripple current at twice the out frequency. Such a ripple current may shorten passive elements life span and worsen output current THD. As a result, it may reduce the efficiency of the whole PVPCS system. In this paper, the ripple current propagation is analyzed, and two methods to reduce the ripple current are proposed. Firslyt, this paper presents notch filter with IP voltage controller to reject specific current ripple in single-phase PVPCS. The notch filter can be designed that suppress just oily specific frequency component and no phase delay. The proposed notch filter can suppress output command signal in the ripple bandwidth for reducing output current THD. Secondly, for reducing specific current ripple, the 이:her method is feed-forward compensation to incorporate a current control loop in the dc-dc converter. The proposed notch filter and feed-forward compensation method have been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control scheme.

Implementation of Fuzzy Self-Tuning PID and Feed-Forward Design for High-Performance Motion Control System

Thinh, Ngo Ha Quang,Kim, Won-Ho Korean Institute of Intelligent Systems 2014 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.14 No.2

The existing conventional motion controller does not perform well in the presence of nonlinear properties, uncertain factors, and servo lag phenomena of industrial actuators. Hence, a feasible and effective fuzzy self-tuning proportional integral derivative (PID) and feed-forward control scheme is introduced to overcome these problems. In this design, a fuzzy tuner is used to tune the PID parameters resulting in the rejection of the disturbance, which achieves better performance. Then, both velocity and acceleration feed-forward units are added to considerably reduce the tracking error due to servo lag. To verify the capability and effectiveness of the proposed control scheme, the hardware configuration includes digital signal processing (DSP) which plays the main role, dual-port RAM (DPRAM) to guarantee rapid and reliable communication with the host, field-programmable gate array (FPGA) to handle the task of the address decoder and receive the feed-back encoder signal, and several peripheral logic circuits. The results from the experiments show that the proposed motion controller has a smooth profile, with high tracking precision and real-time performance, which are applicable in various manufacturing fields.

Adaptive Feed-forward Automatic Gauge Control in Hot Strip Finishing Mill

Lee, Young Kow,Jang, Yu Jin,Kim, Sang Woo Iron and Steel Institute of Japan 2007 ISIJ international Vol.47 No.10

<P>The conventional roll force automatic gauge control (RFAGC) adjusts the roll gap to reduce the delivery thickness variation in the hot strip finishing mills. In this process, the information about the roll force is used to control the roll gap indirectly because the strip gauge cannot be measured owing to insufficient space in the mill and the hostile environment. Moreover, there exists an uncertainty in thickness due to roll eccentricity. Therefore, a small gain is preferable in avoiding product defects when this uncertainty is taken into account in RFAGC. However, in such a case, partially uncontrolled variation still remains on delivery thickness because of insufficient control input. To overcome this drawback, a feed-forward controller (FFAGC) was developed.<SUP>12)</SUP> This scheme adjusts the roll gap to reduce variations in the current stand by using an estimated uncontrolled delivery thickness variation of the previous stand. Although this FFAGC has an advantage over RFAGC, it still has a problem: The FFAGC cannot cope with the continuous variation of system parameters and circumstance because the existing feed-forward controller has been designed as a low pass filter with constant weights. In other words, desirable control performance in the automatic gauge control system cannot be obtained owing to a phase delay and filtering errors.To overcome the problem, it is essential to estimate the long-term thickness variation exactly in the hard environment, to select a proper gain and to synchronize the feed-forward control input under a time varying speed of the gauge control process. In this paper, an enhanced adaptive filtering structure is proposed to improve the controller performance. And the relation between the gains of RFAGC and FFAGC are discussed to select a proper gain. The proposed controller can readily be implemented on the conventional control system, improving the performance of the system without additional cost. This improvement was demonstrated by using the real coil data which are collected under the proposed control scheme in POSCO.</P>