• Journal of Power Electronics
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• v.19 no.6
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• pp.1575-1581
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• 2019

Due to the mismatched line impedance among distributed generation units (DGs) and uncontrolled harmonic current, the droop controller has a number of problems such as inaccurate reactive power sharing and voltage distortion at the point of common coupling (PCC). To solve these problems, this paper proposes a resistive-capacitive virtual impedance control method. The proposed control method modifies the DG output impedance at the fundamental and harmonic frequencies to compensate the mismatched line impedance among DGs and to regulate the harmonic current. Finally, reactive power sharing is accurately achieved, and the PCC voltage distortion is compensated. In addition, adaptively controlling the virtual impedance guarantees compensation performance in spite of load changes. The effectiveness of the proposed control method was verified by experimental results.

• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.262-262
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• 2000

This paper presents a new torque sharing function method that extends the definition region of the conventional TSF to both the positive and negative torque production regions. By using this definition, all kinds of the control inputs that consider switching on/off angle control as well as the current profiling can be described. A parametrized representation of the current profiles is proposed by using a series of B-spline functions, which reduces memory requirement and enables additional controllers. Optimal determination of the TSFs are also investigated for various control objectives. Moreover, the comparison study of each objective is presented. Since this method generalizes all of the possible control input, the current and torque profiles obtained from the optimization are the most suitable control input that satisfy the objectives.

• Journal of the Korea Institute of Military Science and Technology
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• v.3 no.2
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• pp.42-52
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• 2000

A torque control method of a switched reluctance motor for the position control of a tank gun is presented. One of the widely used torque control scheme, torque sharing function method, is investigated and a new torque sharing function method is proposed that extends the definition region of the conventional TSF to both the positive and negative torque production regions. By using this definition, all kinds of the control inputs that consider switching on/off angle control as well as the current profiling can be described. A parametrized representation of the current profiles is proposed by using a series of B-spline functions, which reduces memory requirement and enables additional controllers. Optimal determination of the TSFs are also investigated for various control objectives. Moreover, the comparison study of each objective is presented. Since this method generalizes all of the possible control input, the current and torque profiles obtained from the optimization are the most suitable control input that satisfy the objectives.

• Journal of international Conference on Electrical Machines and Systems
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• v.1 no.1
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• pp.99-103
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• 2012

This paper presents a new switch-control approach for multiphase interleaved converters. Development of the proposed technique is based on control-signal generation for multi-unit synchronization. Current sharing among the switching cells and voltage regulation are achieved by means of a multi-loop control scheme regardless of changes in input voltage and load. System stability is ensured by single-pole compensation. This proposed technique is straightforward, reliable and inexpensive, and can be applied to any higher number of cells without difficulty.

• Journal of the Korea Institute of Building Construction
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• v.7 no.2 s.24
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• pp.107-112
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• 2007

Recently, a lot of domestic construction companies have implemented Knowledge Management System. However, most of the knowledge in the construction fields still cannot written down on papers, and it is just locked in people's heads. The purpose of this study was to analyze the current situation of knowledge sharing in the construction fields. For this research, questionnaires were distributed and the results of this study was as follows; the essential factor of successful knowledge sharing is not introducing a high quality of electronic system but developing culture of knowledge sharing. When positive culture of knowledge sharing is combined with technical infrastructure, knowledge sharing will be actively promoted.

• Journal of Digital Convergence
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• v.18 no.4
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• pp.101-112
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• 2020

This study aims to discuss the current status of the ride-sharing platform industry, which embodies the core values of the 4th Industrial Revolution, sharing and connectivity, as well as economic, industrial, and legal issues. To understand the position of competing groups, the research conducted extensive literature reviews on domestic and international cases of technical and legal issues of the sharing economy. The result indicates that the ride sharing industry showed the economy of synthesis in which production, supply, distribution, and consumption are on one platform. It made possible to share values to users and synthesize them with new services through easy-access mobile application technology. To resolve the conflicts between the taxi industry and the ride sharing industry, this study suggests the following: Ride-sharing companies should make contributions to provide legitimate services. The taxi industry needs to understand the value of the new industry and consumers who chose the shared platform service. The significance of the current study is that it proposed a comprehensive analysis and policy direction toward the issue of balance between public and private interests and legal stability.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.18 no.3
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• pp.74-80
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• 2004

If the withdrawal force of strand driven roll which is controlled with predetermined speed isn't distributed regularly in continuous casting process, mold level is changed cyclically and slab quality is not good. In this paper, both casting speed control and load sharing control algorithm of strand driven roll according to ratio which is set up by operator at same time is proposed. The proposed algorithm is to share the withdrawal force by following torque current of each driven roll as average torque current by changing speed reference of each driven roll motor. The load sharing control with anti-wind up for improvement transient state is adopted and the proposed algorithm is implemented in POSCO pilot caster.

• Proceedings of the KIPE Conference
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• 2007.11a
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• pp.148-150
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• 2007

A novel torque sharing function (TSF) is presented. To improve efficiency and to reduce torque ripple in commutation region, only a phase torque under commutation is regulated to produce a uniform torque. And the torque developed by the other phase remains with the previous state under a current limit of the motor and drive. If the minimum change of a phase torque reference can not satisfy the total reference torque, two-phase changing mode is used. Since a phase torque is constant and the other phase torque is changed at each rotor position, total torque error can be reduced within a phase torque error limit. And the total torque error is dependent on the change of phase torque. To consider non-linear torque characteristics and to suppress a tail current at the end of commutation region, the incoming phase current is changed to torque increasing direction, but the outgoing phase current is changed to torque decreasing direction. So, the torque sharing of the outgoing phase and incoming phase can be smoothly changed with a minimum current cross over. The proposed control scheme is verified by some computer simulations and experimental results.

• Proceedings of the KIEE Conference
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• 2007.10c
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• pp.138-140
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• 2007

A novel non-linear logical torque sharing function (TSF) is presented. To improve efficiency and to reduce torque ripple in commutation region, only a phase torque under commutation is regulated to produce a uniform torque. And the torque developed by the other phase remains with the previous state under a current limit of the motor and drive. If the minimum change of a phase torque reference can not satisfy the total reference torque, two-phase changing mode is used. Since a phase torque is constant and the other phase torque is changed at each rotor position, total torque error can be reduced within a phase torque error limit. And the total torque error is dependent on the change of phase torque. To consider non-linear torque characteristics and to suppress a tail current at the end of commutation region, the incoming phase current is changed to torque increasing direction, but the outgoing phase current is changed to torque decreasing direction. So, the torque sharing of the outgoing phase and incoming phase can be smoothly changed with a minimum current cross over. The proposed control scheme is verified by some computer simulations and experimental results.

• Journal of Power Electronics
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• v.5 no.2
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• pp.160-165
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• 2005

In a parallel operation of UPS, there are two types of circulating currents between UPS. One is the low order circulating current with a fundamental frequency caused by the amplitude and phase differences of UPS output voltages, and the other is the harmonic circulating current with PWM switching frequency caused by non-synchronized PWM waveforms among UPS. The elimination of the low order circulating current is essential for optimal load sharing in parallel operations of UPS, which can be accomplished by the phase and magnitude control at each UPS. The harmonic circulating current may cause troubles and deteriorate in performance of the controller for optimal load sharing in parallel operation of UPS. This paper presents a PWM synchronizing method to eliminate the harmonic circulation current in parallel operation of UPS. The effectiveness of the proposed scheme has been investigated and verified through experiments by a 50kVA UPS.