• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.568-572
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• 1994

This paper presents equipment for charging and discharging with high power factor aid high efficiency. This equipment is consisted of $3{\phi}$SPWM AC/DC converter for improving input current waveform and input power factor, and bidirectional DC/DC converter for electric isolation in the DC link Part. Therefore, Input power factor and the total efficiency in the proposed system can be increased more than in the conventional phase-controlled thyristor Charging - Discharging System.

• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1034-1036
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• 2006

In this paper, I used microprocessor and sensor and designed to improve the efficiency of the photovoltaic system the photovoltaic position tracker device, and compared the normal photovoltaic system of fixed form with the photovoltaic system of solar position tracked form. Moreover, compared the catalogue of solar cell module and the simulation through a mathematics modelling with the solar cell's characteristic interpreting and, composed an power conversion system with boost converter and voltage source inverter. Used the constant voltage control method for maximum power point tracking in boost converter control and, used the SPWM(Sinusoidal Pulse Width Modulation) control method in inverter control.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.75-77
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• 2008

석유를 포함한 자원고갈과 지구온난화와 같은 환경문제로 인하여 자연에너지를 이용한 소규모 태양광발전이 각광을 받고 있다. 본 논문에서는 web상에서 모니터링이 가능한 3[kW]급 태양광 발전 인버터의 설계 및 구현방법을 제시한다. 설계된 인버터는 독립형이며, Boost Converter를 이용하여 350[Vdc]를 400[Vdc]로 승압한 이후 SPWM 방식을 이용하여 교류 파형을 얻어낸다. LC 필터를 통과한 출력파형은 실효치 220[Vac], 주파수는 60[Hz]의 상용전원이고, THD는 5% 이하이다. 또한 350[Vdc]의 10% 레벨에서는 Boost Converter의 Duty를 자동 조정하여 출력단의 전압을 400[Vdc]로 유지할 수 있는 기능을 포함한다. 또한, 출력단의 전압과 전류를 센싱한 후, PC에서의 모니터링 시스템을 구축하였다. 이를 통해 인버터에 포함된 PC를 서버로 활용하여, LAN이 가능한 곳에서는 인버터의 상태와 발전량을 알 수 있다.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.6
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• pp.579-587
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• 1992

This paper is to study on the step-up DC-DC converter for power system which yields output characteristics of low voltage and high current, such as fuel cell generation system. DC-AC-DC scheme is suggested for high ratio of voltage conversion. Three phase MOSFET-SPWM inverter is adopted for intermediate AC conversion and inverter output frequency is chosen at 400[Hz] in order to reduce the size of magnetic circuit and DC filter. Since control strategy which combines voltage controller with current controller in parallel is used, good output performance is obtained both in steady state and in transient state like load variation, not only in single unit operation but also in parallel operation.

• Journal of Power Electronics
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• v.18 no.1
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• pp.137-146
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• 2018

This paper describes a single pulse-width modulation control strategy using the Single Pulse-Width Modulation (SPWM) method with a soft-switching technique for a wide range of output voltages from a bidirectional Dual-Active Bridge (DAB) converter. This method selects two typical inductor current waveforms for soft-switching, and proposes a rule that makes it possible to achieve soft-switching without any compensation algorithm from the waveforms. In addition, both the step-up and step-down conditions are analyzed. This paper verifies that the leakage inductance is independent from the rule, which makes it easier to apply in DAB converters. An integrated algorithm, which includes step-up and step-down techniques, is proposed. The results of experiments conducted on a 50-kW prototype are presented. The system efficiency is experimentally verified to be from 85.6% to 97.5% over the entire range.

• Proceedings of the KIEE Conference
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• 1995.07a
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• pp.371-375
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• 1995

This paper presents equipment for charging and discharging with high power factor and high efficiency. This equipment is consisted of $3{\phi}$ SPWM AC/DC converter for improving input current waveform and input power factor, and bidirectional DC/DC converter for electric isolation in the DC link Part. Therefore, Input power factor and the total efficiency in the proposed system can be increased more than in the conventional phase-controlled thyristor charging-discharging System.

• Proceedings of the KIPE Conference
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• 2016.11a
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• pp.218-219
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• 2016

This paper present Phase Shifted with carrier based on Sinusoidal PWM(SPWM) by using Cascaded NPC/H-birdge converter. The proposed Phase Shifted PWM method is adding third harmonic injection in switching signal. The advantage of the proposed method is reducing the voltage and capacity of the capacitor. This paper compare general Phase Shifted method with proposed Phase Shifted method that added the third harmonic injection. Each PWM method is tested without considering the switching loss by using PSIM 9.1.4 simulation.

• Proceedings of the KIPE Conference
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• 2010.11a
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• pp.276-277
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• 2010

This paper describes the control of a utility-connected doublefed induction machine (DFIM) for wind power generation systems (WPGS). Real and reactive powers (PQ) at the stator side of DFIM are strictly controlled to supply the power to the grid without any problems. In this paper the control is realized using Fuzzy PI controller based on the stator-flux orientation control.

• Journal of Electrical Engineering and Technology
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• v.11 no.1
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• pp.143-149
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• 2016

The two-stage converter is widely used in traditional DC/AC inverter. It has several disadvantages such as complex topology, large volume and high loss. In order to overcome these shortcomings, a novel half load-cycle worked dual SEPIC single-stage inverter, which is based on the analysis of the relationship between input and output voltages of SEPIC converters operating in the discontinuous conduction mode (DCM), is presented in this paper. The traditional single-stage inverter has remarkable advantages in small and medium power applications, but it can’t realize boost DC/AC output directly. Besides one pre-boost DC/DC converter is needed between the DC source and the traditional single-stage inverter. A novel DC/AC inverter without pre-boost DC/DC converter, which is comprised of two SEPIC converters, is studied. The output of dual SEPIC converters is connected with anti-parallel and half load-cycle control is used to realize boost and buck DC/AC output directly and work properly, whatever the DC input voltage is higher or lower than the AC output voltage. The working principle, parameter selection and the control strategy of the inverters are analyzed in this paper. Simulation and experiment results verify the feasibility of the new inverter.

• Journal of Power Electronics
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• v.16 no.6
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• pp.2099-2108
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• 2016

The cascaded multilevel converter is widely adopted to medium/high voltage and high power electronic applications due to the small harmonic components of the output voltage and the facilitation of modularity. In this paper, the operation principle of a T-type H-bridge topology is investigated in detail, and a carrier phase shifted pulse width modulation (CPS-PWM) based control method is proposed for this topology. Taking a virtual five-level waveform achieved by a unipolar double frequency CPS-PWM as the output object, PWM signals of the T-type H-bridge can be obtained by reverse derivation according to its switching modes. In addition, a control method for the T-type H-bridge based cascaded multilevel converter is introduced. Then a single-phase T-type H-bridge cascaded multilevel static var generator (SVG) prototype is built, and a repetitive controller based compound current control strategy is designed with the DC-link voltage balancing control scheme analyzed. Finally, simulation and experimental results validate the correctness and feasibility of the proposed modulation method and control strategy for T-type H-bridge based cascaded multilevel converters.