• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.660-667
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• 2001

Power electronics plays an important role in providing an interface between fuel cells and loads. Furthermore, power electronic converters ensure that the power is reliably and efficiently delivered to the load in the required DC or AC form. In this paper, major types of fuel cells are presented. Basic structures, operating principles, and different applications of fuel cells are described. In addition, current status and future trends in the areas of power electronics for fuel cell applications are explained. A review of fuel cell power electronic system topologies and basic requirements are given as well.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.278-281
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• 1999

In a utility interactive photovoltaic system, a PWM inverter is used for the connection between the photovoltaic arrays and the utility. The DC current becomes pulsated causes the distortion of the AC current waveform. This paper presents the reduced pulsation of DC input current by operating the inverter with buck-boost chopper in the discontinuous conduction mode. The DC current with contains harmonics component is analyzed by means of separating into two terms of a ripple component and a direct component. The constant DC current without pulsation is supplied from photovoltaic array to the inverter. The proposed inverter system provide a sinusoidal AC current for domestic loads and the utility line with unity power factor.

• Proceedings of the KIEE Conference
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• 2008.07a
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• pp.721-722
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• 2008

This paper deals with comparison and analysis for rotor losses of permanent magnet synchronous generator using phase current harmonic analysis according to dc and ac load. On the basis of analytical field analysis, the rotor losses are analysed. Particularly, rated speed and ac load and the rated speed and dc load conditions are considered. This paper compared rotor losses considered dc load with rotor losses considered ac load. Although our analytical modes is low speed, the rotor losses must be considered by results.

• Journal of Power Electronics
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• v.1 no.2
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• pp.133-144
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• 2001

Power electronics plays an important role in providing an interface between fuel cells and loads. Furthermore, power electronic converters ensure that the power is reliably and efficiently delivered to the load in the required DC or AC form. In this paper, major types of fuel cells are presented. Basic structures, operating principles, and different applications of fuel cells are described. In addition, current status and future trends in the areas of power electronics for fuel cells are described. In addition, current statue and future trends in the areas of power electronics for fuel cell applications are explained. A review of fuel cell power electronic system topologies and basic requirements are given as well.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.8-13
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• 2012

DSTATCOM is active filter that reduces nonlinear and unbalanced currents. Researches about DSTATCOM are mainly divided two parts, one is the reference value calculation of compensation current depending on the calculation of the load-side average active power and dc-link capacitor average voltage, the other part is actual current control depending on the reference value of compensation current. This paper proposes a calculation of dc-link capacitor average voltage ripple voltage extraction instead of conventional method using LPF. The utility of the proposed algorithm is verified through the theoretical analysis and the experiment under unbalance loads and non-linear load.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.65-72
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• 2016

This paper discussed the LCL-type & Isolated bidirectional dc-dc converter(BDC) with dual full bridge inverter. In order to verify the analysis of the BDC, Experimental prototype has been designed and implemented to supply constant voltage regardless of loads and proposed a method to select switching frequency that depended on two inductors' inductance ratio and transformer parameters. The proposed converter has been composed of LCL resonant network with unit inductance ratio ($L_r/L_f$=1) and then operated with fixed duty, 50% duty ratio and fixed frequency. There are some characteristics that input voltage and output voltage of the BDC is nearly identical and zero voltage turn-on switching is possible in forward and reverse mode. Finally, it has been showed that BDC is possible to commutate operating mode normally and provide constant output voltage in selected switching frequency.

• Proceedings of the KIPE Conference
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• 2014.07a
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• pp.443-444
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• 2014

Using the ESS(Energy Storage System) as a UPS(Uninterruptible Power Supply) is being studied recently. When the system is operating at UPS mode in integrated ESS and UPS system, the grid supplying power is disconnected and power from PV generation and battery are supplying to load. Operating in UPS mode, when PV generation power is diminished by partial or total clouded situation, DC-link voltage fluctuates. The fluctuation of DC-link voltage influences the load and system as sensitive loads may malfunction. This paper suggests the DC-link ripple voltage compensation algorithm in bi-directional converter. The algorithm stabilize the DC-link and load voltage.

• Journal of Electrical Engineering and Technology
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• v.6 no.6
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• pp.750-759
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• 2011

This paper focuses on the control of bidirectional power flow in the electric shipboard power systems, especially in the Medium-Voltage Direct Current (MVDC) shipboard power system. Bidirectional power control between the main MVDC bus and the local zones can improve the energy efficiency and control flexibility of electric ship systems. However, since the MVDC system contains various nonlinear loads such as pulsed power load and radar in various subsystems, the voltage of the MVDC and the local zones varies significantly. This voltage variation affects the control performance of the bidirectional DC-DC converters as exogenous disturbances. To improve the control performance regardless of uncertainties and disturbances, this paper proposes a novel controller design method of the bidirectional DC-DC converters using $L_1$ control theory and intelligent optimization algorithm. The performance of the proposed method is verified via large-scale real-time digital simulation of a notional shipboard MVDC power system.

• Transactions of the Korean Society of Automotive Engineers
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• v.16 no.1
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• pp.1-7
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• 2008

This paper presents electromagnetic interference(EMI) suppression method applied on the direct current(DC) motor driver for power tail gate control. EMI noise is generated by the fast switching of power devices connected to electric loads. It has become a matter of concern because of the vast increase in the number and sophistication of electronic system in automotive environment. The proposed EMI reduction method is based on the principle of reducing the transient speed of power devices by changing the parameters of the driver circuit related to the power MOSFET. In this paper, power losses were calculated by loss equations and thermal simulation was used to evaluate the effect on printed circuit board. Based on these results, the DC motor driver was fabricated and tested. The proposed method can help to design a DC motor driver which allows it to obtain an acceptable compromise between power losses and EMI.

• Journal of Power Electronics
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• v.14 no.6
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• pp.1178-1188
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• 2014

This study proposes a finite-state model predictive controller to regulate the load current and balance the DC-link capacitor voltages of a four-leg neutral-point-clamped converter. The discrete-time model of the converter, DC-link, inductive filter, and load is used to predict the future behavior of the load currents and the DC-link capacitor voltages for all possible switching states. The switching state that minimizes the cost function is selected and directly applied to the converter. The cost function is defined to minimize the error between the predicted load currents and their references, as well as to balance the DC-link capacitor voltages. Moreover, the current regulation performance is improved by using a two-step prediction horizon. The feasibility of the proposed predictive control scheme for different references and loads is verified through real-time implementation on the basis of dSPACEDS1103.