• 한국태양에너지학회:학술대회논문집
• /
• 2012.03a
• /
• pp.325-330
• /
• 2012

A single-phase PVPCS(photovoltaic power conditioning system) that contains a single phase dc-ac inverter tends to draw an ac ripple current at twice the out frequency. Such a ripple current may shorten passive elements life span and worsen output current THD. As a result, it may reduce the efficiency of the whole PVPCS system. In this paper, the ripple current propagation is analyzed, and two methods to reduce the ripple current are proposed. Firslyt, this paper presents notch filter with IP voltage controller to reject specific current ripple in single-phase PVPCS. The notch filter can be designed that suppress just only specific frequency component and no phase delay. The proposed notch filter can suppress output command signal in the ripple bandwidth for reducing output current THD. Secondly, for reducing specific current ripple, the other method is feed-forward compensation to incorporate a current control loop in the dc-dc converter. The proposed notch filter and feed-forward compensation method have been verified with computer simulation and simulation results obtained demonstrate the validity of the proposed control scheme.

• Proceedings of the KIPE Conference
• /
• 2017.11a
• /
• pp.51-52
• /
• 2017

This paper presents an advanced DC droop using both an output current and a grid current. To control parallel-connected converters without communication, the DC droop control is conventionally used. The conventional DC droop control method droops output voltage using an output current. It cannot control the source current causing output voltage errors. This paper proposed the DC droop method using both an output current and a grid current to improve dynamic response of voltage droops. The simulation results with PSIM is provided.

• Proceedings of the KIPE Conference
• /
• 2018.07a
• /
• pp.328-329
• /
• 2018

본 논문에서는 전기자동차용 단상 온-보드 충전기를 위한 Cycloconverter-type High Frequency Link 회로구조와 능동 전력 디커플링 회로를 이용한 전기자동차용 고전력밀도 양방향 온-보드 충전기를 제안한다. 제안된 시스템은 전력변환부 단계를 줄이기 위한 AC-AC 변환회로와 DC링크 캐패시터를 최대한 줄이기 위해서 벅-타입 능동 전력 필터를 사용한다. 이를 통해 전력변환시스템 전체의 부피를 줄일 수 있으며, 전해 커패시터를 필름 커패시터로 대체하여 수명 문제를 해결할 수 있다. 제안된 시스템의 성능은 MATLAB/Simulink 시뮬레이션을 통해 검증하였다.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.5 no.1
• /
• pp.11-18
• /
• 2000

대용량 반도체 소자인 IGCT를 사용하여 철도차량용 AC-to-DC 단상 PWM 컨버터를 제작 실험하였다. 컨버터의 용량을 향상시키기 위해 2대의 PWM 컨버터를 병렬 운전하였으며 병렬운전시 각각의 컨버터 스위칭각을 다르게 제어하여 각 컨버터의 전류 리플을 상쇄시켜 전원의 고조파 함유를 줄였다. 출력전압제어는 입력전류의 측정 없이 내부 계산에 의해 수행하였으며 단위역률을 제어하기 위해 소프트웨어적으로 간단히 PLL을 수행하였다.

• Journal of Power Electronics
• /
• v.11 no.5
• /
• pp.655-661
• /
• 2011

This paper presents two topologies for single-stage single-phase double-buck type PFC converters, designed to operate at high power factor, near sinusoidal input currents and adjustable output voltage. Unlike the known buck type PFC topologies, in which the output voltage is always lower than the maximum input voltage, the proposed converters can operate at output voltages higher than the ac input peak voltage. A reduced number of switches on the main path of the current are another characteristic of the two proposed topologies. To shape the input line currents, a fast and robust controller based on a sliding mode approach is proposed. This active non-linear control strategy, applied to these converters allows high quality input currents. A Proportional Integral (PI) controller is adopted to regulate the output voltage of the converters. This external voltage controller modulates the amplitude of the sinusoidal input current references. The performances of the presented rectifiers are verified with experimental results.

• The Transactions of the Korean Institute of Power Electronics
• /
• v.25 no.4
• /
• pp.319-328
• /
• 2020

The recent use of distributed power generation systems constructed with DC-DC converters has become extremely popular owing to the rising need for environment friendly energy generation power systems. In this study, a new single-phase five-level inverter for off-grid applications constructed with a multilevel DC-DC step-up converter is proposed to boost a low-level DC voltage (36 V-64 V) to a high-level DC bus (380 V) and invert and connect them with a single-phase 230 V rms AC load. Compared with other traditional multilevel inverters, the proposed five-level inverter has a reduced number of switching devices, can generate high-quality power with lower THD values, and has balanced voltage stress for DC capacitors. Moreover, the proposed topology does not require multiple DC sources. Finally, the performance of the proposed topology is presented through the simulation and experimental results of a 400 W hardware prototype.

• Journal of IKEEE
• /
• v.12 no.4
• /
• pp.239-245
• /
• 2008

In this paper, a dc-dc power converter scheme with the FPGA based technology is proposed to apply for solar power system which has many features such as the good waveform, high efficiency, low switching losses, and low acoustic noises. The circuit configuration is designed by the conventional control type converter circuit using the isolated dc power supply. This new scheme can be more widely used for industrial power conversion system and many other purposes. Also, I proposed an efficient photovoltaic power interface circuit incorporated with a FPGA based DC-DC converter and a sine-pwm control method full-bridge inverter. The FPGA based DC-DC converter operates at high switching frequency to make the output current a sine wave, whereas the full-bridge inverter operates at low switching frequency which is determined by the ac frequency. As a result, we can get a 1.72% low THD in present state using linear control method. Moreover, we can use stepping control method, we can obtain the switching losses by Sp measured as 0.53W. This paper presents the design of a single-phase photovoltaic inverter model and the simulation of its performance.

• Proceedings of the KIEE Conference
• /
• 2006.10b
• /
• pp.154-158
• /
• 2006

The switching-mode power converter has been widely used because of its features of high efficiency and small weight and size. These features are brought by the ON-OFF operation of semiconductor switching devices. However, this switching operation causes the surge and EMI(Electromagnetic Interference) which deteriorate the reliability of the converter themselves and entire electronic systems. This problem on the surge and noise is one of the most serious difficulties in AC-to-DC converter. Random Pulse Width Modulation (RPWM) is peformed by adding a random perturbation to switching instant while output-voltage regulation of converter is performed. RPWM method for reducing conducted EMI in single switch three phase discontinuous conduction mode boost converter is presented. The more white noise is injected, the more conducted EMI is reduced. But output-voltage is not sufficiently regulated. This is the reason why carrier frequency selection topology is proposed. In the case of carrier frequency selection, output-voltage of steady state and transient state is fully regulated. A RPWM control method was proposed in order to smooth the switching noise spectrum and reduce it's level. Experimental results are verified by converter operating at 300v/1kW with $5%{\sim}30%$ white noise input. Spectrum analysis is performed on the Phase current and the CM noise voltage. The former is measured with Current Probe and the latter is achieved with LISN, which are connected to the spectrum analyzer respectively.

• Journal of information and communication convergence engineering
• /
• v.4 no.4
• /
• pp.170-173
• /
• 2006

Recently, with increasing efficiency of DSC (photo-electrochemical using a nano-particle), The Performance of DSC solar generation system also needs improvement. The approach consists of a Fly-back DC-DC (transfer ratio 1:10) converter to boost the DSC cell voltage to 300VDC. The four switch (MOSFET) inverter is employed to produce 220V, 60Hz AC outputs. High performance, easy manufacturability, lower component count., safety and cost are addressed. Protection and diagnostic features form an important part of the design. Another highlight of the proposed design is the control strategy, which allows the inverter to adapt to the: requirements of the load as well as the power source. A unique aspect of the design is the use of the DSP TMS320LF2406 to control the inverter by current and voltage feed-back. Efficient and smooth control of the: power drawn from the DSC Cell is achieved by controlling the front end DC-DC converter in current mode.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
• /
• 2003.11a
• /
• pp.63-68
• /
• 2003

Recently, a fuel cell is remarkable for new generation system. The fuel cell generation system converts the chemical energy of a fuel directly into electrical energy. The fuel cell generation is characterized by low voltage and high current. For connecting to general load, it needs both a step up converter and an inverter. The step up converter makes DC to DC and the inverter changes DC to AC. In this paper, full bridge converter and the single phase inverter are designed and installed for fuel cell. Simulation and experimental results are displayed under several load conditions.