• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.19 no.3
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• pp.179-184
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• 2019

In many countries, such as developing countries where electricity is scarce, small wind turbines in the form of Off Grid are an effective solution to solve power supply problems. In some countries, the expansion of power systems and the decline of electricity-intensive areas have led to the use of small wind power in urban road lighting, mobile communications base stations, aquaculture and seawater desalination. With this change, the size of the small wind power industry is expected to have greater potential than large-scale wind power. In the case of small wind power generators, the generator is controlled at a variable speed, and the voltage and current generated by the generator have many harmonic components. To solve this problem, the AC to DC converter to be studied in this paper is a three-phase step-up type converter with a single switch. The inductor current is controlled in discontinuous mode, and has a characteristic of having a unit power factor by eliminating the harmonic of the input current. The proposed converter is composed of LCL filter and three phase rectification boost converter at the input stage and a single phase full bridge for grid connection. It is a control system with energy storage system(ESS) that the system stabilization can be pursued against the electric power.

• Proceedings of the KIPE Conference
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• 2001.07a
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• pp.201-204
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• 2001

In this paper, a single-phase to three-phase PWM converter topology using six switches only for low cost induction motor drive is proposed. The converter topology is of lower cost than the conventional one, which gives sinusoidal input current, unity power factor, dc output voltage control and bidirectional power flow In addition, the source voltage sensor is eliminated by controlling the deviation between the model current and the system current to be zero. The performance of the proposed converter has been demonstrated through the computer simulation.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.186-187
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• 2010

최근 직류 출력을 갖는 분산전원 시스템의 증가와 높은 에너지 변환효율을 갖는 직류(DC) 배전 시스템에 대한 관심이 증가하고 있다. 직류(DC) 배전을 빌딩에 적용하기 위해서는 계통연계형 AC/DC 컨버터가 필수적이다. 빌딩용 직류(DC)배전 시스템에서는 다양한 부하들이 상시 대용량의 AC/DC 컨버터에 연결되어 있기 때문에 컨버터의 기동시 과도상태를 최소화한 안정적인 DC전압 확보가 필수적이다. 본 논문에서는 외부 파라미터 변화나 외란에 대한 강인한 성능을 가지는 슬라이딩 모드 제어기를 사용하여 3상 AC/DC 컨버터의 초기 운전 시 발생할 수 있는 DC전압의 오버슈트 저감을 시뮬레이션에 의해 검증하였다.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.438-440
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• 1997

This paper proposed a partial resonant switching three-phase high power factor converter using a $PRS^2$(Partial Resonant Soft Switch). The proposed converter has a merit of simple controlled circuit because the input current control DCM(Discontinuous Conduction Mode). And it is improve to input power factor that the snubber capacitor's energy regenerate to the AC source side. This topology is reduced a current/voltage stresses of resonant devices in addition to a partial resonant strategy. The result of simulations with the proposed topology included in this paper.

• Journal of Electrical Engineering and Technology
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• v.5 no.4
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• pp.606-613
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• 2010

This paper proposes a novel current-based maximum power point tracking (CMPPT) method for a single-phase photovoltaic power conditioning system (PV PCS) by using a modified incremental conductance method. The CMPPT method simplifies the entire control structure of the power conditioning system and uses an inherent current source characteristic of solar cell arrays. Therefore, it exhibits robust and fast response under a rapidly changing environmental condition. Digital phase locked loop technique using an all-pass filter is also introduced to detect the phase of grid voltage, as well as the peak voltage. Controllers of dc/dc boost converter, dc-link voltage, and dc/ac inverter are designed for coordinated operation. Furthermore, a current control using a pseudo synchronous d-q transformation is employed for grid current control with unity power factor. A 3 kW prototype PV PCS is built, and its experimental results are given to verify the effectiveness of the proposed control schemes.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.2
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• pp.158-165
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• 2012

In this paper, the test bed using three-phase PWM converter connected with single phase inverter in series is set up to configure an active AC electric load. Since the two topologies, three-phase PWM converter and single-phase inverter, can be operated bidirectionally, the system not only re-generates surplus power to grid but also prevents power dissipation. However, the construction of system has a drawback. That is, ripple components two times of inverter operation frequency occur at DC-Link due to cascade connection, it can be cause of three phase unbalance Since the operational characteristic of the active AC electric load, the power frequency entered into the electric load can be varied, and the ripple of DC-Link is changed as well. In this paper, the three-phase PWM converter using a variable notch filter is proposed, and the reduction of three-phase current unbalance is presented. the validity of the proposed PWM converter using a variable notch filter is verified by the simulation and experimental results.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.86-87
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• 2017

본 논문에서는 3상 22kW급 전기자동차 탑재형 충전기를 위한 단일단 AC-DC 컨버터를 제안한다. 제안하는 3상 단일단 AC-DC 컨버터는 제안하는 인터리빙 회로와 스위칭 기법으로 입력필터가 작고 넓은 전압 및 부하영역에서 소프트스위칭을 성취하여 높은 효율을 성취할 수 있으며 전해커패시터를 제거하고 필름커패시터를 사용하여 높은 수명 및 전력밀도를 기대할 수 있다. 또한 제안하는 컨버터는 단상 단일단 AC-DC 컨버터를 모듈구조로 구성하여 출력전류에 포함된 120Hz 맥동전류를 출력에서 상쇄시켜 저주파 성분이 없는 직류전류로 충전이 가능하다. 제안하는 3상 단일단 AC-DC 컨버터의 동작원리를 제시하고 시작품을 통해 본 논문의 타당성을 검증하였다.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.430-432
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• 2019

본 논문에서는 ESS용 3상 AC/DC 컨버터 배터리 전류 제어 시 발생하는 문제에 대해 분석하고, 제안된 제어기의 유효성을 시뮬레이션을 통하여 입증한다.

• The Journal of the Korea institute of electronic communication sciences
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• v.17 no.3
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• pp.459-466
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• 2022

Switching surges are a common type of phenomenon that occur on any sort of power system network. These are more pronounced on long transmission lines and in high voltage converter stations. At AC/DC hybrid transmission lines, the insulation coordination of such lines is mainly dictated by the peak level of switching surges, the most dangerous of which include three phase line energization and AC/DC converter station. The power system structure consist of AC/DC hybrid transmission lines which is combination of AC 765kV and ±500kV HVDC 1 bipole system for contingency analysis. The power system under study and its components are simulated using EMTDC software package, the effects of the various AC/DC mixing power lines are reviewed. The developed models of EMTDC conversion lines based on combination of AC/DC system are simulated and the characteristics of switching surge over-voltage from its results are discussed.

• Proceedings of the KIEE Conference
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• 1993.07b
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• pp.856-859
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• 1993

Line-current harmonics resulting from AC to DC power conversion interfere with power system operation and reduce power factor, hence resulting in increasing power source unnecessarily. This paper investigates the harmonic reduction methods of a three-phase phase-controlled converter on AC and DC sides using passive filters and notches.