• Proceedings of the Materials Research Society of Korea Conference
• /
• 2009.05a
• /
• pp.56.1-56.1
• /
• 2009

The intermediate operating temperature of solid oxide fuel cells (IT-SOFCs) have achieved considerable importance in the area of power fabrication. This is because to improve materials compatibility, their long-term stability and cost saving potential. However, to conserve rational cell performance at reduced-temperature regime, cathode performance should be obtained without negotiating the internal resistance and the electrode kinetics of the cell. Recently, double perovskite structure cathodes have been studied with great attention as a potential material for IT-SOFCs. In this study, double-perovskite structured cathodes of $GdBaCoCuO_{5+\delta}$, $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ compositions and $(1-x)GdBaCo_2O_{5+\delta}+xCe_{0.9}Gd_{0.1}O_{1.95}$ (x = 10, 20, 30 and 40 wt.%) composites were evaluated as the cathode for intermediate temperature solid oxide fuel cells(IT-SOFCs). Electrical conductivity of the cathodes were measured by DC 4-probe method, and the thermal expansion coefficient of each sample was measured up to $900^{\circ}C$ by a dilatometer study. Area specific resistances(ASR) of the $GdBaCo_{2/3}Cu_{2/3}Fe_{2/3}O_{5+\delta}$ cathode and 70 wt.% $GdBaCo_2O5+\delta$ + 30wt.% Ce0.9Gd0.1O1.95 composite cathode on CGO electrolyte substrate were analyzed using AC 3-probe impedance study. The obtained results demonstrate that double perovskite-based compositions are promising cathode materials for IT-SOFCs.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.2 no.1
• /
• pp.33-38
• /
• 1997

Generally, various semiconductor switching devices for power systems are used in battery chargers for electric vehicle. When these used, it takes the problems of transient-current or distortion of waveforms in power systems near by battery chargers because of harmonics and large peak-current, low power factor, etc., caused by the non-linearity of these devices. Recently, power factor control, line current peak-cut, harmonics reduction which was ignored in past is more and more important. In this paper, to solve those problems we will improve the characteristics of voltage rising and propose the high power factor converter circuit for battery chargers. Our proposed system convert commutated voltage to AC resonant wave in high frequency inverter and rectify the link voltages passed high-frequency transformer and transfer the DC voltages. Especially, the effect using these converter system can be improved very large by power factor control and we have to verify the possibilities of improvement through the experiment of Pb-Acid battery application.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.12 no.1
• /
• pp.65-73
• /
• 2007

This paper presents an on-line correction method of current measurement errors for a pure-integration-based flux estimation down to 1-Hz stator frequency. An observer-based approach is taken as one possible solution of eliminating the dc offset and the negative sequence component of unbalanced gains in the synchronous coordinate. At the same time, the positive sequence component estimation is performed by creating an error signal between a motor model reference and an estimated q-axis rotor flux established by a permanent magnet (PM) in the synchronous coordinate. The compensator utilizes a PI controller that controls the error signal to zero. The proposed technique further contains a residual error compensator to completely eliminate miscellaneous disturbances in the estimated flux. The developed algorithm has been implemented on a 1.1-kW permanent magnet synchronous motor (PMSM) drive to confirm the effectiveness of the proposed scheme.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.22 no.3
• /
• pp.240-248
• /
• 2017

This paper describes the development of a powertrain for a 20 kW experimental electric vehicle using a surface-mounted permanent magnet synchronous motor (SPMSM) and its application to a test vehicle. Two 10 kW SPMSMs are used in the powertrain, and two-level inverters are developed by using IGBTs to derive these motors. To control the SPMSM, a control board based on a TMS320F28335 DSP module, which has fast arithmetic function and floating point operator, is used. We develop a 100 V/40 A battery pack, which includes $32{\times}4$ LiFePO4 battery cells using commercial BMS. A commercial on-board charger with 220 V (AC) input and 100 V (DC) and 18 A output is used to charge the battery pack. The performance of the developed vehicle, such as acceleration availability, maximum speed, and maximum power, is estimated based on vehicle dynamics and verified through experiments.

• Journal of Power Electronics
• /
• v.18 no.1
• /
• pp.70-80
• /
• 2018

A novel strategy based on a zero common mode voltage pulse-width modulation (ZCMV-PWM) technique and zero-sequence circulating current (ZSCC) feedback control is proposed in this study to eliminate ZSCCs between three-level neutral point clamped (NPC) voltage source inverters, with common AC and DC buses, that are operating in parallel. First, an equivalent model of ZSCC in a three-phase three-level NPC inverter paralleled system is developed. Second, on the basis of the analysis of the excitation source of ZSCCs, i.e., the difference in common mode voltages (CMVs) between paralleled inverters, the ZCMV-PWM method is presented to reduce CMVs, and a simple electric circuit is adopted to control ZSCCs and neutral point potential. Finally, simulation and experiment are conducted to illustrate effectiveness of the proposed strategy. Results show that ZSCCs between paralleled inverters can be eliminated effectively under steady and dynamic states. Moreover, the proposed strategy exhibits the advantage of not requiring carrier synchronization. It can be utilized in inverters with different types of filter.

• Journal of the Korean Society of Industry Convergence
• /
• v.23 no.2_1
• /
• pp.115-124
• /
• 2020

In wireless power transfer (WPT) system, the conventional compensation topologies only can provide a constant current (CC) or constant voltage (CV) output under their resonant conditions. It is difficult to meet the CC and CV hybrid charging requirements without any other schemes. In this study, a switching hybrid topology (SHT) is proposed for CC and CV electric vehicle (EV) battery charging. By utilizing an additional capacitor and two AC switches (ACSs), a double-side LCC (DS-LCC) and an inductor and double capacitors-series (LCC-S) topologies are combined. According to the specified CC and CV charging profile, the CC and CV charging modes can be flexibly converted by the two additional ACSs. In addition, zero phase angle (ZPA) also can be achieved in both charging modes. In this method, because the operating frequency is fixed, without using PWM control, and only a small number of devices are added, it has the benefits of low-cost, easy-controllability and high efficiency. A 3.3-kW experimental prototype is configured to verify the proposed switching hybrid charger. The maximum DC efficiencies (at 3.3-kW) of the proposed SHT is 92.58%.

• Proceedings of the KIPE Conference
• /
• 2015.11a
• /
• pp.227-228
• /
• 2015

우리나라가 조달하는 ITER(국제핵융합시험로) 초전도자석 전원장치용 변압기는 CCU/L(Correction Coil Upper/Lower) 컨버터 형식용 6대, CCS(Correction Coil Side) 컨버터 형식용 3대, VS1(Vertical Stabilization 1) 컨버터 형식용 2대, CS(Central Solenoid) 컨버터 형식용 6대 그리고 TF(Toroidal Field) 컨버터 형식용 1대로 구성되어 있다. ITER한국사업단은 (주)효성과 컨버터 변압기의 공급계약을 2011년에 체결하고 예비 설계를 시작하여 2014년에 최종설계를 마친 후 동년 후반부터 CCU/L, CCS 및 VS1 컨버터 형식용 각 1대씩의 초도품 변압기 제작에 착수하였다. 각 변압기는 제작이 완료되어 CCU/L 및 CCS 형식은 FAT(Factory Acceptance Test)를 완료하였고 VS1 형식은 공장 자체시험을 완료하고 현재 전기연구원에서 실시할 단락시험을 준비하고 있다. 이어 CS 형식의 초도품과 1대만 조달하는 TF 형식의 제작을 착수할 예정이고, 각 형식별 초도품 1대씩은 단락시험을 포함하는 형식시험(Type Test)을 실시하여 형식별 적합성을 검증하고, 나머지 물량은 정기시험(Routine Test)을 실시한 후 2017년까지 두 번으로 나누어 프랑스 남부에 위치한 ITER 현장에 운송 및 설치할 예정이다. 설치를 마친 변압기들은 각각의 컨버터 짝과 통합시험을 포함하는 SAT(Site Acceptance Teat)를 거친 후 ITER 기구에 인계될 예정이다.

• Journal of Power Electronics
• /
• v.17 no.6
• /
• pp.1535-1544
• /
• 2017

Advances in FPGA technology have enabled fast real-time simulation of power converters, filters and loads. FPGA based HIL (Hardware-In-the-Loop) simulators have revolutionized control hardware and software development for power electronics. Common time step sizes in the order of 100ns are sufficient for simulating switching frequency current and voltage ripples. In order to keep the time step as small as possible, ideal switching function models are often used to simulate the phase legs. This often produces inferior results when simulating the discontinuous conduction mode (DCM) and disabled operational states. Therefore, the corresponding measurement and protection units cannot be tested properly. This paper describes a new solution for this problem utilizing a discrete-time PI controller. The PI controller simulates the proper DC and low frequency AC components of the phase leg voltage during disabled operation. It also retains the advantage of fast real-time execution of switch-based models when an accurate simulation of high frequency junction capacitor oscillations is not necessary.

• The Journal of the Korea institute of electronic communication sciences
• /
• v.16 no.1
• /
• pp.45-52
• /
• 2021

The space vector control based voltage control method for a three-phase PWM rectifier requires a lot of effort to design an optimal switching pattern since a switching pattern for the switching section must be designed. In this study, a D-Q control based SPWM output voltage control algorithm was studied for the three-phase six-pulse CVS type rectifier. In the output voltage control algorithm, three-phase reference signals are obtained from the D-Q transformation based on the space vector representation method, instead of the switching pattern, SPWM method is used to generate rectifier switching control signals. Next, a three-phase six-pulse CVS PWM rectifier based on D-Q transformation and SPWM was modeled using EMTP-RV. Finally, the validity of the D-Q control-based SPWM voltage control algorithm was confirmed by comparing the output voltage waveform obtained through EMTP-RV simulation works with a reference value and confirming that the output voltage accurately follows the reference voltage.

• KSII Transactions on Internet and Information Systems (TIIS)
• /
• v.15 no.6
• /
• pp.2168-2187
• /
• 2021

The smart grid replaces the traditional power structure with information inventiveness that contributes to a new physical structure. In such a field, malicious information injection can potentially lead to extreme results. Incorrect, FDI attacks will never be identified by typical residual techniques for false data identification. Most of the work on the detection of FDI attacks is based on the linearized power system model DC and does not detect attacks from the AC model. Also, the overwhelming majority of current FDIA recognition approaches focus on FDIA, whilst significant injection location data cannot be achieved. Building on the continuous developments in deep learning, we propose a Deep Learning based Locational Detection technique to continuously recognize the specific areas of FDIA. In the development area solver gap happiness is a False Data Detector (FDD) that incorporates a Convolutional Neural Network (CNN). The FDD is established enough to catch the fake information. As a multi-label classifier, the following CNN is utilized to evaluate the irregularity and cooccurrence dependency of power flow calculations due to the possible attacks. There are no earlier statistical assumptions in the architecture proposed, as they are "model-free." It is also "cost-accommodating" since it does not alter the current FDD framework and it is only several microseconds on a household computer during the identification procedure. We have shown that ANN-MLP, SVM-RBF, and CNN can conduct locational detection under different noise and attack circumstances through broad experience in IEEE 14, 30, 57, and 118 bus systems. Moreover, the multi-name classification method used successfully improves the precision of the present identification.