• Journal of Power Electronics
• /
• v.5 no.3
• /
• pp.233-239
• /
• 2005

In this paper, a new conceptual circuit configuration of a 3-phase voltage source, soft switching AC-DC-AC converter using an IGBT module, which has one ARCPL circuit and one ARDCL circuit, is presented. In actuality, the ARCPL circuit is applied in the 3-phase voltage source rectifier side, and the ARDCL circuit is in the inverter side. And more, each power semiconductor device has a novel clamp snubber circuit, which can save the power semiconductor device from voltage and current across each power device. The proposed soft switching circuits have only two active power semiconductor devices. These ARCPL and ARDCL circuits consist of fewer parts than the conventional soft switching circuit. Furthermore, the proposed 3-phase voltage source soft switching AC-DC-AC power conversion system needs no additional sensor for complete soft switching as compared with the conventional 3-phase voltage source AC-DC-AC power conversion system. In addition to this, these soft switching circuits operate only once in one sampling term. Therefore, the power conversion efficiency of the proposed AC-DC-AC converter system will get higher than a conventional soft switching converter system because of the reduced ARCPL and ARDCL circuit losses. The operation timing and terms for ARDCL and ARCPL circuits are calculated and controlled by the smoothing DC capacitor voltage and the output AC current. Using this control, the loss of the soft switching circuits are reduced owing to reduced resonant inductor current in ARCPL and ARDCL circuits as compared with the conventional controlled soft switching power conversion system. The operating performances of proposed soft switching AC-DC-AC converter treated here are evaluated on the basis of experimental results in a 50kVA setup in this paper. As a result of experiment on the 50kVA system, it was confirmed that the proposed circuit could reduce conduction noise below 10 MHz and improve the conversion efficiency from 88. 5% to 90.5%, when compared with the hard switching circuit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.20 no.4
• /
• pp.21-28
• /
• 2006

In this paper, the proposed full-bridge high frequency isolated zoo voltage and zero current switching phase shifted pulse width modulation(ZVZCS PS-PWM)DC-DC converter among fuel cell generation system consist of 1.2[kW] fuel cell of Nexa Power Module, full-bridge DC-DC converter to boost the fuel cell low voltage($28{\sim}43[%]$) to 380[VDC] and a single phase full-bridge inverter is implemented to produce AC output(220[VAC], 60[Hz]). A tapped inductor filter with freewheeling diode is newly implemented in the output filter of the proposed full-bridge high frequency isolated ZVZCS PS-PWM DC-DC converter to suppress circulating current under the wide output voltage regulation range, thus to eliminate the switching and transformer turn-on/off over-short voltage or transient phenomena. Besides the efficiency of $93{\sim}97[%]$ is obtained over the wide output voltage regulation ranges and load variations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.17 no.6
• /
• pp.23-30
• /
• 2003

This paper analyzes the characteristic of utility connection type solar power generation system which it is available to connect the utility. And the operation characteristic of this system is compared and analyzed when it is operated in the real system. The constructional and operational problem were obtained by that result. Overcoming that defect is that finding the proper place to be well operated and to find the best place for getting the sunshine data. This method could increase the efficiency of the generation system. And more, current OS in operating system and monitoring management couldn't solve the problem so that improving OS and constructing data backup system should be implemented, This paper proposes the plan to solve that defect in the real system.

• 제어로봇시스템학회:학술대회논문집
• /
• 1994.10a
• /
• pp.708-713
• /
• 1994

A new flux observer based vector control system of an induction motor is constructed by using an observer in which the commanded stator currents are used to estimate the rotor flux. In this system, the flux observer is formulated by using a model of induction motor in a stationary coordinate system. By considering an observer of induction motor in a fixed co-ordinate system located on its secondary flux, a slip frequency controlled type of vector control system is also proposed. From these control schemes, the relation between the conventional slip frequency controlled type system and the observer based one is clarified. The steady-state error of the developed torque which is caused by the parameter change of induction motor is analyzed and discussed for the selection of observer gains. The poles of the observer error dynamics and those of the observer based vector control system are calculated analytically by neglecting the machine parameter change. In order to analyze the robust stability, a linear model of the observer based vector control system is proposed taking into account the machine parameter change. By using this model, the trajectories of the poles and zeros of the torque transfer function are computed and discussed. To test validity of the theoretical analysis, experiments are conducted by using a digital signal processor (TMS320C30) and a current controlled voltage source PWM inverter.

• The Transactions of the Korean Institute of Electrical Engineers A
• /
• v.54 no.3
• /
• pp.107-116
• /
• 2005

The paper addresses modeling and analysis of a grid-connected photovoltaic generation system (PV system). PSCAD/EMTDC, an industry standard simulation tool for studying the transient behavior of electric power system and apparatus, is used to conduct all aspects of model implementation and to carry out extensive simulation study. This paper is aimed at sharing with the PSCAD/EMTDC user community our user-defined model for PV system applications, which is not yet available as a standard model within PSCAD/EMTDC. An equivalent circuit model of a solar cell has been used for modeling solar array. A series of parameters required for array modeling have been estimated from general specification data of a solar module. A PWM voltage source inverter (VSI) and its current control scheme have been implemented. A maximum power point tracking (MPPT) technique is employed for drawing the maximum available energy from the PV array. Comprehensive simulation results are presented to examine PV array behaviors and PV system control performance in response to irradiation changes. In addition, dynamic responses of PV array and system to network fault conditions are simulated and analysed.

• Journal of Hydrogen and New Energy
• /
• v.17 no.3
• /
• pp.338-346
• /
• 2006

In this paper, the test results of medium-size(120 kW class) PV system which was installed in the Taeahn thermal power station of Korea Western Power Co., Ltd., were summarized for developing the practical technology to applicate high voltage grid connection PV system. The 120 kW photovoltaic system which was consisted of 1,300 modules, PCS, and 150 kVA transformer station has been operated since Aug. 05, 2005. For verifying the modeling results of PV system, the operation data was compared with modeling results which was executed commercial PSCAD/EMTD and Psim tools. An equivalent circuit model of a solar cell has been also used for solar array modeling. A series of parameters required for array modeling have been estimated from general specification data of a solar module. A PWM voltage source inverter(VIS) and its current control scheme have been analyzed by using P&O (perturbation and Observation) MPPT algorithms technique.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.61 no.12
• /
• pp.1848-1856
• /
• 2012

This paper proposes a new grid-tied power conditioning system for battery energy storage, which is composed of a 2-stage DC-DC converter and a PWM inverter. The 2-stage DC-DC converter is composed of an LLC resonant converter connected in cascade with a 2-quadrant hybrid-switching chopper. The LLC resonant converter operates in constant duty ratio, while the 2-quadrant hybrid-switching chopper operates in variable duty ratio for voltage regulation. The operation of proposed system was verified through theoretical analysis and computer simulations. Based on computer simulations, a hardware prototype was built and tested to confirm the technical feasibility of proposed system. The proposed system could have relatively higher efficiency and smaller size than the existing system.

• Proceedings of the KIPE Conference
• /
• 2005.07a
• /
• pp.313-316
• /
• 2005

본 논문은 대용량 진력변환장치인 멀티-레벨 인버터 시스템에서 출력 전압가변이 손쉬운 HBML(H-Bridge Multi-Level) 인버터의 Master와 Cell 제어기 구성에 관한 것이다. HBML 인버터는 각각의 단위 Cell을 저압에서 사용하는 인버터로 구성하면, 구조적으로 풀-브릿지(Full-Bridge) 인버터를 캐스케이드 방식으로 연결하여 고압출력을 얻을 수 있는 토폴로지이다. 시스템에서 Master와 Cell의 제어 처리를 한곳에 집중하지 않는 분산 제어 방식을 적용하여 통신 Data를 최적화하도록 구성하고, 이를 바탕으로 두 제어기를 고성능 원-칩(One-Chip) DSP로만 설계하였다. 모든 외부 모듈을 내장한 CPU로 제어기가 구성될 경우, 외부 노이즈에 강하며, 추가되는 하드웨어 결선을 최소화할 수 있다. 본 논문에서는 HBML 인버터 출력 생성 시 반드시 요구되는 출력 PWM 동기 및 위상전이(Phase Shift)를 각 제어기 자체에 내장된 모듈만을 이용해서 구현하였다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.16 no.1
• /
• pp.20-29
• /
• 2011

This paper proposes critical load following back-up system using MCFC stack. This system enables MCFC generation system to supply power to critical load without UPS and to generate rated power under grid fault state. This back-up system includes 'Load Leveler' that is connected with 3-phase inverter and is controlled by additional algorithm that includes critical load following. The proposed system and algorithm are verified by computer simulation based on 5kW system.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.62 no.11
• /
• pp.1640-1646
• /
• 2013

Conventional power conversion unit that is a major part of the propulsion system has applied GTO thyristor as a switching semiconductor device of main circuit since introduction of the 8200 electric locomotive. But problem that quick maintenance is difficult and its cost is increasing occurs because major components of the power conversion unit are slowly discontinued. To solve these, in this paper, it was analyzed the response characteristic of the propulsion system modeling of the 8200 electric locomotive using IGBT which is applied recently to ensure propulsion control technology. As results of response for a Propulsion system modeling, it show that a power conversion unit is controlled by PLL(Phase-locked loop) and SVPWM(Space Voltage PWM) respectively.