• Journal of Power Electronics
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• v.19 no.5
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• pp.1278-1288
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• 2019

A DC-DC Non-Isolated Three-Port Cuk-Cuk (NI-TPCC) converter for interfacing renewable energy sources (RESs) such as Fuel Cell (FC) and Photovoltaic (PV) energy with a DC load is presented in this paper. It features single-stage power conversion from both of the input ports to the load port. The proposed NI-TPCC converter is designed based on the classical Cuk converter. The operational modes and power flow are analyzed in the continuous conduction mode (CCM), and the relationships among the port voltages are derived. Continuous currents in all three ports with less ripple enhance the performance of a fuel cell and its operating life. Furthermore, the output inductor is shared with both of the input ports, which reduces the number of active and passive components. The effectiveness of the designed NI-TPCC converter has been validated through simulation and experimental results.

• Journal of Power Electronics
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• v.19 no.1
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• pp.58-67
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• 2019

This study presents a new portable eight-output light emitting diode (LED) driver. The eight output-channels are divided into two equal groups, and their output powers can be controlled individually by three active switches. In addition, a simple capacitor-based passive current balancing circuit (CBC) is employed in each port to guarantee that the currents of the four LEDs are the same. When compared with the conventionally used separate two-output isolated converters, the proposed one uses one less active switch. Moreover, zero-voltage-switching (ZVS) is achieved, which improves the power efficiency of the driver. Finally, a highly compact prototype is built, which can reach an efficiency of 94.6%.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.49 no.2
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• pp.39-46
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• 2012

The newly designed sense amplifier in this paper has rail-to-rail input range achieving low power consumption. Reducing static power consumption generated due to DC path to ground is key element for low power consumption in this paper. The proposed sense amplifier performs power-saving operation using negative feedback circuit that controls the current flow with the newly added PMOS input terminal. As a simulation result, the proposed sense amplifier consumed about over 50 % efficiency of the average power consumed by the typical Rail-to-Rail sense amplifier.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.481-483
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• 2008

본 논문은 다양한 종류의 전원을 구비해야 하는 다중출력 전원 시스템을 위한 영전류 스위칭 LLC 공진형 Post-regulator를 제안한다. 기존의 LLC 공진형 컨버터는 정밀한 다중 출력을 얻기 위해 추가의 DC/DC 컨버터가 구성되었고, 이는 전력 변환 효율 감소 및 제조 원가 상승의 단점을 갖고 있다. 제안된 컨버터는 각 소자의 내압 및 전류 스트레스가 작고, 요구되는 출력 당 1 개의 보조 스위치만으로 구현되므로 저가격화에 유리하다. 또한 전력이 전달되는 시점의 공진 전류의 초기값을 가변함으로서 정밀하게 제어되는 다중 출력 전압을 획득할 수 있고, 각 전압의 출력 순서 제어도 가능한 장점이 있다. 뿐만 아니라, 독립된 공진탱크를 이용하기 때문에 공진탱크 설계가 용이하며, 최근 전자 제품의 추세인 슬림화의 요구에 부응할 수 있다. 또한, 제안된 Post-regulator의 모든 전력 스위치는 ZCS가 가능하므로 스위칭 손실을 최소화 할 수 있다. 최종적으로 본 논문에서 제안한 영전류 스위칭 LLC 공진형 Post-regulator를 제작하고, 고찰된 실험결과를 제시하여 제안된 컨버터 및 전원시스템의 우수성과 이론적 분석의 타당성을 검증한다.

• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.5
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• pp.325-333
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• 2021

A 3 kW grid-tied PV inverter with Gallium nitride high-electron mobility transistor (GaN HEMT) for domestic commercialization was developed using boost converter and full-bridge inverter with LCL filter topology. Recently, many GaN HEMTs are manufactured as surface mount packages because of their lower parasitic inductance characteristic than standard TO (transistor outline) packages. A surface mount packaged GaN HEMT releases heat through either top or bottom cooling method. IGOT60R070D1 is selected as a key power semiconductor because it has a top cooling method and fairly low thermal resistances from junction to ambient. Its characteristics allow the design of a 3 kW inverter without forced convection, thereby providing great advantages in terms of easy maintenance and high reliability. 1EDF5673K is selected as a gate driver because its driving current and negative voltage output characteristics are highly optimized for IGOT60R070D1. An LCL filter with passive damping resistor is applied to attenuate the switching frequency harmonics to the grid-tied operation. The designed LCL filter parameters are validated with PSIM simulation. A prototype of 3 kW PV inverter with GaN HEMT is constructed to verify the performance of the power conversion system. It achieved high power density of 614 W/L and peak power efficiency of 99% for the boost converter and inverter.

• Journal of Power Electronics
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• v.12 no.1
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• pp.181-192
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• 2012

The increased penetration of Distributed Energy Resources (DER) is challenging the entire architecture of conventional electrical power system. Microgrid paradigm, featuring higher flexibility and reliability, becomes an attractive candidate for the future power grid. In this paper, an overview of microgrid configurations is given. Then, possible structure options and control methods of DER units are presented, which is followed by the descriptions of system controls and power management strategies for AC microgrids. Finally, future trends of microgrids are discussed pointing out how this concept can be a key to achieve a more intelligent and flexible power system.

• Proceedings of the KIPE Conference
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• 2009.11a
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• pp.293-295
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• 2009

In this paper, a shunt active power filter (SAPF) has been used to eliminate the harmonic distortion and to improve the power quality of three-phase grid-connected power conditioning system (PCS). The adopted control strategy in active power filter system is based on the instantaneous reactive power theory (P-Q theory). Based on the theoretical analysis, the overall system of three-phase grid-connected with non-linear load PCS has been built and modeled using PSCAD$^{(R)}$/EMTDC$^{TM}$. The simulation results are shown to verify the high effective performance of the implemented SAPF in power system and to verify the reasonableness of the system structure.

• Journal of Power Electronics
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• v.9 no.3
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• pp.365-376
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• 2009

In this paper, the implementation of a three-phase shunt active power filter is presented. The filter is essentially three independent single-phase current-controlled voltage source inverters (CC-VSI) with a common DC bus. The CC- VSI is operated to directly control the AC grid current to be sinusoidal and in phase with the grid voltage without detecting the load currents. The APF consists of a current control loop, which shapes the grid currents to be sinusoidal and a voltage control loop, which regulates the active power balance of the system. The experimental results indicate that the active filter is able to handle predominantly the harmonics, as well as the unbalance and reactive power, so that the grid currents are sinusoidal, in phase with the grid voltages and symmetrical.

• Journal of Power Electronics
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• v.10 no.3
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• pp.219-227
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• 2010

Telecom supplies need to conform to low Total Harmonic Distortion (THD) and high Power Factor (PF) as per IEC 61000-3-2 and IEEE 519-1992 standards. These high rating power supplies use a three phase utility in which low THD and high PF are realized via various passive and active wave shaping schemes. In this paper, a new design for three phase telecom power supplies is presented with circuit parameter values optimized for high performance in terms of a low THD, high PF, low ripple and high line and load regulation using a suitable combination of various strategies. The performance of the power supply is validated by extensive simulations.

• Journal of Power Electronics
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• v.12 no.3
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• pp.429-438
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• 2012

This paper presents the use of a novel, single-stage high-power-factor electronic ballast with a symmetrical class-DE low-$d{\upsilon}$/$dt$ resonant rectifier as a power-factor corrector for fluorescent lamps. The power-factor correction is achieved by using a bridge rectifier to utilize the function of a symmetrical class-DE resonant rectifier. By employing this topology, the peak and ripple values of the input current are reduced, allowing for a reduced filter inductor volume of the EMI filter. Since the conduction angle of the bridge rectifier diode current was increased, a low-line current harmonic and a power factor near unity can be obtained. A prototype ballast, operating at an 84-kHz fixed frequency and a 220-$V_{rms}$, 50-Hz line input voltage, was utilized to drive a T8-36W fluorescent lamp. Experimental results are presented which verify the theoretical analysis.