• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 전력전자학술대회 논문집
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• pp.571-575
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• 2002

Generation of electrical energy faces many problems today. Solar power converters were used to convert the electrical energy from the solar arrays to a stable and reliable power source. The object of this paper is to analyze and design DC-DC converters in a solar energy system to investigate the performance of the converters. A DC-DC converter can be commonly used to control the power flow from solar cell to load and to achieve maximum power point tracking(MPPT), DC-AC converter can also be used to modulate the DC power to AC power being applied on common utility load. A DC-DC converter is used to boost the solar cell voltage to constant 360(V) DC link and to ensure operation at the maximum power point tracking, If a wide input voltage range has to be covered a boost converter is required. In this paper, author described that simulation and experimental results of PV system contain solar modules, a DC-DC converter(boost type chopper), a DC-AC converter (3-phase inverter) and resistive loads.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2018년도 전력전자학술대회
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• pp.432-433
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• 2018

A new DC-DC converter circuit for LVDC(Low Voltage Direct-Current) distribution is proposed. DC-DC converter consists of two stage which are voltage balancer and converter stage. The balancing circuit adjust balance input voltage of converter circuit and compensate for unbalanced loads and short circuits. The converter circuit control the bipolar output voltage ${\pm}750V$. Simulation is carried out for this DC-DC converter system.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1319-1321
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• 2004

This paper presents a model and simulation for the korean type multi-propulsion system consisting of a gas turbine driven synchronous alternator coupled to a rectifier and dc-to-dc converter. The simulation modules include turbine system, alternator and rectifier, dc-to-dc converter, power management module. A modular, system level simulation of the propulsion system prototype is presented in order to confirm stability for loads with uncertain input impedances and uncertain control loop speeds.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.421-423
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• 2007

In this paper, The authors apply a state feedback control using an optimal control theory to improve the stability of the control and the dynamic response of the DC-DC converter system with a number of different loads. To execute a this state feedback control, The authors present the pole placement technique using Linear Quadratic Regulator(LQR) to optimally control the system. An integrator can also be included in the open-loop path in order to minimize the steady-state error of the output voltage. To confirm the superiority of the controller, The simulation results are presented.

• 전력전자학회논문지
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• 제18권5호
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• pp.422-428
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• 2013

Recently, we use a static synchronous compensator(STATCOM) with cascaded H-bride topologies, because it is easy to increase capacity and to reduce total harmonic distortion(THD). When we use equipment for reactive power compensation, dc-link voltage unbalances occur from several reasons although loads are balanced. In the past, switching pattern change of single phase inverter and reference voltage magnitude change of inverter equipped with power sensor have been used for dc-link voltage balance. But previous methods are more complicated and expensive because of additional component costs. Therefore, this paper explains reasons of dc-link voltage unbalance and proposes solution. This solution is complex method that is composed of reference voltage magnitude change of inverter without additional hardware and shifted phase angle of inverter reference voltages change. It proves possibility through 1000[KVA] system simulation.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2012년도 전력전자학술대회 논문집
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• pp.281-282
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• 2012

본 논문에서는 DC배전에 앞서 AC배전에서 사용하고 있는 부하를 AC에 비교하여 DC전원이 공급될 때 기존의 가전제품들의 전기적 특성을 분석하고, AC를 DC로 전환하기 위한 변환장치를 제거하고 DC를 공급할 때의 전기적 특성에 대하여 살펴 DC배전의 효율성에 대하여 실험을 통하여 검토하였다.

• 전력전자학회논문지
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• 제26권2호
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• pp.120-126
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• 2021

DC-link capacitors are one of the main components in two-level three-phase voltage source inverters (VSIs); they provide the pulsating input current and stabilize the vacillating DC-link voltage. Ideally, the larger the capacitance of DC-link capacitors, the better the DC-link voltage stabilizes. However, high capacitance increases the cost and decreases the power density of VSI systems. Therefore, the capacitance should be chosen carefully on the basis of the DC-link voltage ripple requirement. However, the DC-link voltage ripple is dependent on the pulse-width modulation (PWM) strategy. This study especially presents a DC-link voltage ripple analysis when the minimum loss discontinuous PWM strategy is applied. Furthermore, an equation for the selection of the minimum capacitance of DC-link capacitors is proposed. Experimental results with R-L loads are also provided to verify the effectiveness of the presented analysis.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1852-1863
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• 2018

Direct current(DC) systems have recently attracted attention due to the increase in DC loads and distributed generations, such as renewable energy sources. Among these technologies, there has been much research into DC distribution systems or DC microgrids. Within this body of research, the main topics have been about optimum control and operation methods in terms of improving power efficiency. When DC systems are controlled and operated using power electronic devices such as converters, it is necessary to design and analyze them by considering the power electronics sections. For this reason, we propose a scalable DC system analysis algorithm, which considers various system configurations depending on the operating mode and location of the converter. The algorithm consists of power flow fault current calculations, and the results of the algorithm can be used for designing DC systems. The algorithm is implemented using MATLAB with defined input and output data. The verification of the algorithm is mainly performed using ETAP software, and the accuracy of the algorithm analysis can be confirmed through the results.

• Journal of international Conference on Electrical Machines and Systems
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• 제1권2호
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• pp.53-57
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• 2012

The mathematical model of a three-phase voltage source pulse-width modulation (PWM) DC/AC inverter is non-linear, and in view of the traditional linear control strategy it can not meet the requirements of designing a high-performance inverter. What's more, when the loads are not pure resistive loads, the inverter further requires that the controller possess high-performance. This paper proposes a nonlinear control strategy for the inverter called Passivity-based Control. We can alter the inverter model in three-phase abc coordinate to two-phase synchronous rotating dq coordinate for establishing the port-control Hamiltonian (PCH) model for this system. We can control the distribution of energy in the system to achieve the control aim. Simulation results show that the passivity-based control method can make this system possess a level of high-performance that is both robust and dynamic.

• ETRI Journal
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• 제32권6호
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• pp.940-949
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• 2010

Rack-level DC power supply is the optimal technology for providing DC power to a volume server without any power infrastructure changes in an existing AC data center. In this paper, we propose a smartly controllable and monitorable DC rack power system. The proposed system improves power efficiency by changing the power distribution architecture of a conventional method in the rack. We developed an optimal power control method in multipower modules to provide high efficiency at low loads. In addition, the proposed system provides real-time web monitoring of the rack power and environment around a rack. In our experiments, the proposed system improved the power efficiency by over 10% compared to an AC power system providing N+1 redundant power and power monitoring.