• Journal of Power Electronics
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• v.17 no.4
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• pp.1037-1047
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• 2017

The Differential Power Processing (DPP) converter is a promising multi-module photovoltaic inverter architecture recently proposed for photovoltaic systems. In this paper, a DPP converter architecture, in which each PV-panel has its own DPP converter in shunt, performs distributed maximum power point tracking (DMPPT) control. It maintains a high energy conversion efficiency, even under partial shading conditions. The system architecture only deals with the power differences among the PV panels, which reduces the power capacity of the converters. Therefore, the DPP systems can easily overcome the conventional disadvantages of PCS such as centralized, string, and module integrated converter (MIC) topologies. Among the various types of the DPP systems, the feed-forward method has been selected for both its voltage balancing and power transfer to a modified H-bridge inverter that needs charge balancing of the input capacitors. The modified H-bridge multi-level inverter had some advantages such as a low part count and cost competitiveness when compared to conventional multi-level inverters. Therefore, it is frequently used in photovoltaic (PV) power conditioning system (PCS). However, its simplified switching network draws input current asymmetrically. Therefore, input capacitors in series suffer from a problem due to a charge imbalance. This paper validates the operating principle and feasibility of the proposed topology through the simulation and experimental results. They show that the input-capacitor voltages maintain the voltage balance with the PV MPPT control operating with a 140-W hardware prototype.

• Journal of the Korean Society of Physical Medicine
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• v.17 no.1
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• pp.21-30
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• 2022

PURPOSE: This study examined the effects of treadmill training with taping on the affected ankle joint on the gait and balancing ability in patients with sub-acute stroke. METHODS: Nineteen patients with sub-acute hemiplegic stroke in a rehabilitation hospital were assigned randomly to either the experimental group (n = 10), who received treadmill training with taping on the affected ankle joint or the control group (n = 9), who received general treadmill training. All participants performed 60 min of comprehensive rehabilitation therapy (five sessions per week for four weeks). Each group received treadmill training with or without taping on the affected ankle joint for 20 min (three sessions per week for four weeks). The gait and balancing ability were measured before and after the four-week training. RESULTS: Post-training scores of 10-meter walk test (10 MWT), timed up and go (TUG) test, and center of pressure (COP) path length and velocity for the experimental group increased significantly compared to that pre-training (p < .05). The experimental group showed a larger decrease in the 10 MWT and TUG test than the control group (-3.5 s vs. -1.01 s, p < .05; -4.9 s vs. -1.7 s, p < .05; respectively) CONCLUSION: Treadmill training with taping on the affected ankle joint might improve the gait and balancing ability of stroke patients and is considered a more effective method for improving gait and balancing ability than the method of general treadmill training.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.11
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• pp.123-129
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• 2016

Disturbance Observer(DOB) based control is considered for the purpose of the balancing performance enhancement in a single-wheel robot. Design of DOB can be folded into two parts, the inverse model of the plant and the Q-filter. The inverse model is derived from the inverted stick model and a Q-filter is designed to stabilize the inverse model. In this paper, a Q31 filter is designed and its effect is evaluated by experimental studies. The time constant provides a complimentary characteristic between the disturbance suppression and the sensor noise immunity. Therefore, suitable selection of the time-constant must be considered. Comparative experiments are conducted to investigate the control performances when three different Q filters are respectively applied in the DOB. Through the analysis of the experimental results, a time constant is designed to have a proper value in the design of DOB for balancing control of a single-wheel robot.

• KIISE Transactions on Computing Practices
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• v.22 no.2
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• pp.101-106
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• 2016

A femtocell network has been attracting attention as a promising solution for providing high data rate transmission over the conventional cellular network in an indoor environment. In this paper, we propose a distributed power control algorithm considering both indoor coverage and data load balancing in the femtocell network. As data traffic varies by time and location according to user distribution, each femto base station suffers from an unbalanced data load, which may degrade network performance. To distribute the data load, the base stations are required to adjust their transmission power dynamically. Since there are a number of base stations in practice, we propose a distributed power control algorithm. In addition, we propose the simple algorithm to detect the faulty base station and to recover coverage. We also explain how to insert a new base station into a deployed network. We present the simulation results to evaluate the proposed algorithms.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2012.05a
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• pp.529-532
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• 2012

This paper presents the system modeling, analysis, and controller design and implementation with a inverted pendulum system in order to test robust algorithm for sweeping machine. The balancing of an inverted pendulum by moving pendulum robot like as 'segway' along a horizontal track is a classic problem in the area of control. This paper will describe two methods to swing a pendulum attached to a cart from an initial downwards position to an upright position and maintain that state. The results of real experiment show that the proposed control system has superior performance for following a reference command at certain initial conditions.

• Journal of Power Electronics
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• v.15 no.5
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• pp.1207-1216
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• 2015

In order to suppress the low frequency oscillation of the neutral-point voltage for three-level inverters, this paper proposes a new discontinuous pulse width modulation (DPWM) control method. The conventional sinusoidal pulse width modulation (SPWM) control has no effect on balancing the neutral-point voltage. Based on the basic control principle of DPWM, the relationship between the reference space voltage vector and the neutral-point current is analyzed. The proposed method suppresses the low frequency oscillation of the neutral-point voltage by keeping the switches of a certain phase no switching in one carrier cycle. So the operating time of the positive and negative small vectors is equal. Comparing with the conventional SPWM control method, the proposed DPWM control method suppresses the low frequency oscillation of the neutral-point voltage, decreases the output waveform harmonics, and increases both the output waveform quality and the system efficiency. An experiment has been realized by a neutral-point clamped (NPC) three-level inverter prototype based on STM32F407-CPLD. The experimental results verify the correctness of the theoretical analysis and the effectiveness of the proposed DPWM method.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.4
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• pp.210-217
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• 2014

This paper presents experimental studies on controlling one-wheel robot, GYROBO. The previous one has the problem of falling down because the inside gimbal leans against one direction to make it balancing. This structural problem has been solved by redesigning the system. Gains obtained through experimental tasks are used as a gain scheduling method so that GYROBO is more stabilized. A line trajectory following control task is performed to test the driving control as well.

• Journal of the Korean Institute of Intelligent Systems
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• v.21 no.5
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• pp.595-601
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• 2011

This paper presents balancing control of inverted pendulum on the ROBOKER arm using visual information. The angle of the inverted pendulum placed on the robot arm is detected by a stereo camera and the detected angle is used as a feedback and tracking error for the controller. Thus, the overall closed loop forms a visual servoing control task. To improve control performance, neural network is introduced to compensate for uncertainties. The learning algorithm of radial basis function(RBF) network is performed by the digital signal controller which is designed to calculate floating format data and embedded on a field programmable gate array(FPGA) chip. Experimental studies are conducted to confirm the performance of the overall system implementation.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.12
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• pp.74-83
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• 2014

This paper proposes a study on the configuration of balancing of plant(BOP) and implementation of battery management system(BMS) functions for vanadium redox flow battery(VRFB) and propose a method consists of sensor and required design specifications BOP system configuration. And it proposes an method of the functions implementation and control algorithm of the BMS for flow battery. Functions of BMS include temperature control, the charge and discharge control, flow control, level control, state of charge(SOC) estimation and a battery protection through the sensor signal of BOP. Functions of BMS is implemented by the sensor signal, so it is recognized as a very important factor measurement accuracy of the data. Therefore, measuring a mechanical signal(flow rate, temperature, level) through the BOP test model, and the measuring an electrical signal(cell voltage, stack voltage and stack current) through the VRFB charge-discharge system and analyzes the precision of data in this paper. Also it shows a good charge-discharge test results by the SOC estimation algorithm of VRFB. Proposed BOP configuration and BMS functions implementation can be used as a reference indicator for VRFB system design.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.31 no.11
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• pp.133-140
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• 1982

In recent years, a number of thyristor-controlled shunt compensators have been used in industrial and utility systems for phase balancing, power-factor correction and flicker reduction. This paper describes a simple and basic control scheme and circuits for shunt compensator with a fixed capacitor and thyristor-controlled reactor. Feedforward-control scheme is applied, and compensating currents are computed from the symmetrical components of the disturbed system. A 8 bit microprocessor is used for the computation of the compensating currents as well as for the measurements of the symmetric components. A 3-phase 1 KVA compensator is developed and a good reduction of the unbalance factor of the power source is achieved using it.