• The Transactions of the Korean Institute of Power Electronics
• /
• v.18 no.6
• /
• pp.579-586
• /
• 2013

This paper proposes a mode transition algorithm between the grid-tied and the stand-alone operations for the single-phase inverter with the energy storage system. For the grid-tied operation, the dc-link voltage and the output current are required to be control. For the stand-alone mode, both the output voltage and the output current should be regulated. In order to mitigate a falling-off in control performance during transients in mode change, the load power estimation and the current selection schemes are proposed. The proposed method allows an optimized current reference is selected to reduce an output voltage drop and an excessive over-current in transient. To verify the effectiveness of the proposed method, both the simulation and the experiments for a 3kW single-phase inverter with the energy storage system have been conducted. From the results, it has been confirmed that the proposed method reduces a transient error as well as implementing smooth mode transition.

• Journal of Power Electronics
• /
• v.12 no.3
• /
• pp.487-494
• /
• 2012

A new low cost high power density photovoltaic power conditioning system (PV PCS) with an energy storage system is proposed in this paper. Its high power density and cost effectiveness can be achieved through the unification of the maximum power point tracker and the battery charger/discharger. Despite the reduced power stage, the proposed system can achieve the same performance in terms of maximum power point tracking and battery charging/discharging as the conventional system. When a utility power failure happens, the proposed system cannot perform maximum power point tracking at the UPS mode. However, the predetermined battery voltage near the maximum power point of the PV array can effectively generate a reasonable PV power even at the UPS mode. Therefore, it features a simpler structure, less mass, lower cost, and fewer devices. Finally, to confirm the operation, validity, and features of the proposed system, a theoretical analysis and experimental results from a single phase AC 220Vrms/1.5kW prototype are presented.

• Proceedings of the KIPE Conference
• /
• 2014.07a
• /
• pp.253-254
• /
• 2014

본 논문에서는 무정전전원장치(UPS : Uninterruptible Power Supply 이하 UPS)에서 사용되는 단상인버터의 전압 제어기의 낮은 대역폭으로 인하여 발생될 수 있는 전압 위상 지연 문제를 해결한다. 제안하는 방법은 전압 명령에 대한 전향보상을 이용한 새로운 전압 제어기를 제안하고 이를 MATLAB Simulink를 사용한 시뮬레이션을 통하여 효과를 입증하였다.

• Proceedings of the KIEE Conference
• /
• 1994.11a
• /
• pp.159-161
• /
• 1994

A new control technique which generates high-quality sinusoidal output voltage from a single-phase resonant do link inverter suitable for the UPS systems is presented. The inverter output voltage control system has the PID controller with a minor loop of the filter inductor current and tile feedforward controller. The proposed control scheme also solves resonant voltage overshoot without any additional switch or passive component, resulting in pulses with uniform amplitude and high efficiency. Experimental results in the case of linear and nonlinear loads are presented to confirm the usefulness of the Proposed control algorithms.

• Proceedings of the KIPE Conference
• /
• 2013.11a
• /
• pp.206-207
• /
• 2013

UPS 부하시험의 에너지와 비용 저감을 위해 단상 풀브릿지 토폴로지에 기반한 전력시스템을 제안하고, 이 시스템을 위해 병렬로 구성된 단상 PWM컨버터들 사이에 반드시 존재해야하는 Blocking 제어기법과 그 모델링에 대해 연구하였다. 주요 목적은 병렬로 연결된 두 컨버터사이에 발생되는 순환전류영향과 그 영향으로 인해 반드시 필요하게 된 컨버터들 스위치의 Blocking 제어기법에 관해 연구하였다.

• Proceedings of the KIEE Conference
• /
• 2008.07a
• /
• pp.998-998
• /
• 2008

It is difficult to find for analysis solution of the synchronous generator exciter system. Recently, it had good performance UPS converter system using CRA method. The single converter of synchronous generator excitor system under considerations : (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load condition, and (ii) the digital controller shall be employed at a fixed sampling. It is shown that the synchronous exciter system can be achieved by the proposed controller using Characteristic Ratio Assignment.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2008.05a
• /
• pp.449-450
• /
• 2008

It is difficult to find for analysis solution of the synchronous generator exciter system. Recently, it had good performence UPS converter system using CRA method. The single converter of synchronous generator excitor system under considerations : (i) the overall system shall keep very low AC-voltage tracking error as well as no phase delay over different load condition, and (ii) the digital controller shall be employed at a fixed sampling. It is shown that the synchronous exciter system can be achieved by the proposed controller using Characteristic Ratio Assignment.

• Proceedings of the KIPE Conference
• /
• 1998.10a
• /
• pp.336-340
• /
• 1998

In this paper, an effective control scheme of a single phase UPS inverter is proposed to have no steady state error of the output voltage and the fast response for the load request. The cosine wave tranfer function is proposed to control the output voltage. This controller clearly removes errors of magnitude and phase both in the steady state. On the other hand, a current controller is proposed to reduce the transient time of the voltage control and to improve the bad distorted factor of the output voltage waveform by the load fluctuation and the presences of nonlinear parameters in the plant. The current controller is designed parallel to the voltage controller and performs separately from it.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.28 no.2
• /
• pp.60-69
• /
• 2014

This paper proposed the circulation current control scheme in the single phase inverter system. The load experiment of the power conversion system including the UPS usually uses the passive components such as resistors and inductors. Therefore, the energy consumption is serious problem. In addition, the system is out of order when it is installed in the local area, and the load experiment can not perform adequately after troubleshooting, because there is no the load equipment, and the power capacity is not enough in the local area. The paper does the research on the circulation current control scheme, it does not need the load equipment, and the load current can reuse as the input current of the equipment. Instead of the conventional method the voltage-voltage and voltage-current control scheme introduced the parallel converter concept is newly proposed, and the validity of the proposed control scheme is investigated by both simulation and experimental results.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
• /
• 2001.05a
• /
• pp.427-430
• /
• 2001

Computers and automated manufacturing processes in industry are very susceptible to voltage sags and surges. The need for greater power reliability makes the end-users to use the uninterruptible power supply and other electronic power conditioning means to maintain the stable voltage. In this paper, a single-phase buck ac-ac converter for Custom Power Applications is presented. The presented converter uses IGBT's as switching module and maintains the stable voltage through PWM technology in spite of the input voltage sags and load rejections. In this paper, the operation characteristics of the power converter at steady state are illustrated using PSPICE simulations.