• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.105-107
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• 2018

This paper presents a new hybrid multilevel converter topology, which consists of a combination of the series connected switched capacitor units with boost ability, and an H-bridge with T-type bidirectional switches. The proposed converter boosts the input voltage without any bulky inductors, and has the small number of components, which can make the size and cost of a power converter greatly reduced. The output filter size and harmonics are also reduced by the high quality multilevel output. In addition, there is no need for complicated methods to balance the capacitor voltage. Simulation and experimental results with a nine-level converter system are presented to validate the proposed topology and modulation method.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.261-265
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• 2005

This paper describes the DC-DC Converter for Ancillary Power Supply in Hybrid Electric Vehicle. DC-DC Converter is used for charging 12V auxiliary battery supplying electric power to head ramp, audio, ECU etc in automobiles. used DC-DC Converter Topology is PS-ZVS FB(Phase Shifted Zero Voltage Switching Full-Bridge) to reduce switching loss and EMI noise induced by high frequency operating condition. And For easy compensation and stable system response characteristic, current mode control method including slope compensation is employed. Constant current / constant voltage charging control method guarantee stable electric charging of auxiliary battery. Simulation toll PSIM6.0 is used for initial circuit parameter settings and H/W debuging. Thermal problems of Switching components in DC-DC Converter is improved by using Thermo Tracer.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.551-555
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• 2004

The two-transformer full bridge (TTFB) PWM converter has two transformers which act as the output inductor as well as the main transformer, i.e. as the forward and the flyback transformer. Although the doubled leakage inductor of the TTFB makes it easier to achieve the zero-voltage switching (ZVS) of the lagging leg switch along the wide load range, it instigates a serious voltage ringing in the secondary rectifier diodes, which would require the dissipative snubber circuit, cause the serious power dissipation, and increase the voltage stress across those diodes. To overcome these problems, a, new lossless diode-clamp rectifier (LDCR) is employed as the output rectifier, which helps the voltage across rectifier diodes to be clamped on a half the output voltage $(V_o/2)$ or the output voltage $(V_o)$. Therefore, no dissipative snubber for rectifier diodes is needed and a high efficiency as well as low noise output voltage can be realized. The operations, analysis and design consideration of proposed converter are presented in this paper. To verify the validity of the proposed converter, experimental results from a 425W, 385-170Vdc prototype for the plasma display panel (PDP) sustaining power module (PSPM) are presented.

• The Transactions of the Korean Institute of Power Electronics
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• v.5 no.3
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• pp.209-214
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• 2000

In this paper, we propose a FB ZVT(full bridge zero voltage transition) PWM OC~OC converter which uses a a saturable reactor, instead of two additional switches, to achieve zero voltage switching. The conventional h high frequency phase shifted FB ZVT PWM OC-OC converter has a disadvantage that a circulating current f flows through high frequency transformer and switching devices during the free-wheeling interval. Due to this c circulating current, conduction loss increases. In order to reduce such the loss as this, we propose circuit of r reducing conduction loss at the secondary side of transformer. The operation principles are explained in detail a and the several interesting simulations and experimental results verify the validity of the proposed circuit.

• Journal of Power Electronics
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• v.17 no.4
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• pp.1037-1047
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• 2017

The Differential Power Processing (DPP) converter is a promising multi-module photovoltaic inverter architecture recently proposed for photovoltaic systems. In this paper, a DPP converter architecture, in which each PV-panel has its own DPP converter in shunt, performs distributed maximum power point tracking (DMPPT) control. It maintains a high energy conversion efficiency, even under partial shading conditions. The system architecture only deals with the power differences among the PV panels, which reduces the power capacity of the converters. Therefore, the DPP systems can easily overcome the conventional disadvantages of PCS such as centralized, string, and module integrated converter (MIC) topologies. Among the various types of the DPP systems, the feed-forward method has been selected for both its voltage balancing and power transfer to a modified H-bridge inverter that needs charge balancing of the input capacitors. The modified H-bridge multi-level inverter had some advantages such as a low part count and cost competitiveness when compared to conventional multi-level inverters. Therefore, it is frequently used in photovoltaic (PV) power conditioning system (PCS). However, its simplified switching network draws input current asymmetrically. Therefore, input capacitors in series suffer from a problem due to a charge imbalance. This paper validates the operating principle and feasibility of the proposed topology through the simulation and experimental results. They show that the input-capacitor voltages maintain the voltage balance with the PV MPPT control operating with a 140-W hardware prototype.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.1
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• pp.105-111
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• 2010

This article studies the design of DC-DC Converter to convert low-voltage energy sources generated from renewable power like battery power, photovoltaic power, or fuel cells into high-voltage ones. The circuit topology of H-bridge Converter to convert input voltage, 24[V], into out voltage, 400[V], was realized through applying phase shift angle control so as to manage electric power and voltage in the output side. The advantages of the converter system suggested are the low cost as well as current stress reduction, high efficiency, reliability, and simplified maintenance. It is also found that the system is highly useful to produce residential electric power.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.433-434
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• 2017

기존의 전력 시스템에서 큰 부피를 차지하는 계통 주파수(50/60Hz) 변압기를 대체하기 위해서, 최근 전력용 반도체 변압기 SST(Solid State Transformer)에 대한 연구가 많이 수행되고 있다. AC/DC 컨버터는 높은 시스템 입력 전압에 대응 가능한 기존의 다양한 멀티레벨 컨버터 중 CHB (Cascaded H-bridge) 컨버터는 시스템 모듈화의 용이성과 상용 소자의 정격전압을 고려했을 때 반도체 변압기 시스템에 가장 많이 적용되고 있는 토폴로지이지만 각각의 H-bridge 컨버터 DC-link 전압의 불평형 문제가 발생한다. 본 논문에서는 CHB 컨버터의 전압 불평형을 해결하기 위하여 추가적인 센서가 필요없는 간단하고 실용적인 전압 불평형 보상 제어기를 제안한다.

• Proceedings of the KIPE Conference
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• 2008.10a
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• pp.130-132
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• 2008

In this paper, we have proposed a novel zero-voltage-switching (ZVS) soft-switching H-bridge inverter. Because the conventional H-Bridge inverter generates switching losses at turn on and off, the efficiency is reduced. The proposed inverter operates ZVS switching using an auxiliary switch and resonant circuit to improve the efficiency. in the DC-DC converter stage, it can reduce not only switching loss but also capacity and size of passive devices due to the resonant elements. DC-AC inverter stage supplies load with energy through the ZVS operation of 4 switches. A detail mode analysis of operating is in presented. We have presented the inverter topology, principle of operation and simulation results obtained from the PSIM simulator.

• Journal of Power Electronics
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• v.18 no.1
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• pp.56-69
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• 2018

In this paper, an improved Space Vector Modulation (SVM) based fault tolerant operation on a nine-level Cascaded H-Bridge (CHB) inverter with an additional backup circuit is proposed. Any type of fault in a power converter may result in a power interruption and productivity loss. Three different faults on H-bridge modules in all three phases based on the SVM approach are investigated with diagrams. Any fault in an inverter phase creates an unbalanced output voltage, which can lead to instability in the system. An additional auxiliary unit is connected in series to the three phase cascaded H-bridge circuit. With the help of this and the redundant switching states in SVM, the CHB inverter produces a balanced output with low harmonic distortion. This ensures high DC bus utilization under numerous fault conditions in three phases, which improves the system reliability. Simulation results are presented on three phase nine-level inverter with the automatic fault detection algorithm in the MATLAB/SIMULINK software tool, and experimental results are presented with DSP on five-level inverter to validate the practicality of the proposed SVM fault tolerance strategy on a CHB inverter with an auxiliary circuit.

• Proceedings of the KIPE Conference
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• 2012.07a
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• pp.189-190
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• 2012

최근 전기 자동차가 현실화 되면서 자동차 내부의 Li-Ion 배터리와 전장 부품들 및 납축전지 간의 에너지를 변환하는 회로에 대한 요구가 커지고 있다. 이 회로는 높은 전압을 갖는 Li-Ion 배터리와 낮은 구동 전압을 갖는 다른 전장 부품들로 인해 출력 단이 대 전류를 취한다는 특징을 갖고 있는데 이로 인하여 출력 단의 도통 손실을 줄이기 위한 연구들이 계속되고 있다. 본 논문은 기존의 2 Transformer 형식의 브릿지 컨버터를 Parallel-Series로 연결시킨 회로를 제안하고 이 회로의 동작을 분석하였다. 제안한 회로는 2차 측에 인덕터가 존재하지 않는 Current-Fed방식으로 구동 되며, 이를 통해 도통 손실을 감소 시켰으며, 2차 측을 Series 형태로 쌓아 배터리 연계 시스템에서 문제가 되었던 Wide Range 입. 출력 시스템에서의 동작 문제를 해결하였다.