• Journal of Power Electronics
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• v.10 no.6
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• pp.673-679
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• 2010

Input-series-output-parallel (ISOP) connected DC-DC converters enable low voltage rating switches to be used in high voltage input applications. In this paper, a DSP is adopted to generate digital phase-shifted PWM signals and to fulfill the closed-loop control function for ISOP connected two full-bridge DC-DC converters. Moreover, a stable output current sharing control strategy is proposed for the system, with which equal sharing of the input voltage and the load current can be achieved without any input voltage control loops. Based on small signal analysis with the state space average method, a loop gain design with the proposed scheme is made. Compared with the conventional IVS scheme, the proposed strategy leads to simplification of the output voltage regulator design and better static and dynamic responses. The effectiveness of the proposed control strategy is verified by the simulation and experimental results of an ISOP system made up of two full-bridge DC-DC converters.

• The Transactions of the Korean Institute of Power Electronics
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• v.19 no.5
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• pp.422-430
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• 2014

This study proposes a small-signal model and control design for a two-stage DC-DC-AC converter to investigate its dynamic characteristics in relation to battery energy storage system. When the circuit analysis of the two-stage DC-DC-AC converter is attempted simultaneously, the mathematical procedure of deriving the dynamic equation is complex and difficult. The main idea of modeling the two-stage DC-DC-AC converter states that this topology is separated into a bidirectional DC-DC converter and a single-phase inverter with an equivalent current source corresponding to that of the inverter or converter. The dynamic equations for the separated converter and inverter are then derived using the state-space averaging technique. The procedures of building the small-signal model of the two-stage DC-DC-AC converter are described in detail. Based on the derived small-signal model, the individual controllers are designed through a frequency-domain analysis. The simulation and experimental results verify the validity of the proposed modeling approach and controller design.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.247-250
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• 1997

A novel zero-voltage-switching(ZVS) isolated PWM converter for single stage power factor correction (PFC) is presented to improve the performance of the previously presented ZVT converter[5]. A simple clamp circuit in the primary side provides zero-voltage-switching condition to all semiconductor devices. This ZVS is achieved with minimum device voltage and current stresses. Operation principle, control strategy and features of the proposed converter are presented and verified by the experimental results from a 1.5 ㎾, 100 KHz laboratory prototype

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.140-145
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• 2001

This paper proposes to use a 20[kHz] phase­shifted Full-Bridge (FB) Zero-Voltage-Switched (ZVS) PWM converter in order to drive a 600[W] magnetron, and analyzes the operational modes in a switching period. Additionally, the controller of the average anode current is designed. Simulation studies and experiments verify that the proposed converter and the average anode current controller shows good performance to drive the magnetron.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1322-1327
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• 2005

This paper presents a single-stage ZVT full-bridge AC/DC converter for aerospace applications. The detailed operating principle and design consideration of this soft-switched converter are analyzed and described. The proposed circuit topology and control scheme are proposed to exhibit optimum performances (i.e. high power factor, high efficiency, ring-free and low EMI features). A laboratory prototype, 500W 5V/100A AC/DC converter was implemented. The simulation and experimental waveforms verify the feasibility of the proposed design.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.3
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• pp.394-400
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• 2012

In this paper, charging modes of series resonant converter for a high voltage energy storage capacitor are compared in terms of charging time, peak resonant current, normalized peak resonant current and voltage in each operation mode. Operating principles of the full bridge series resonant converter with capacitor load are explained and analyzed in discontinuous and continuous operation mode. Based on the analysis and simulation result, $0.6{\omega}_r$ < ${\omega}_s$ < $0.75{\omega}_r$ and $1.3{\omega}_r$ < ${\omega}_s$ < $1.4{\omega}_r$ are evaluated to the best range of switching frequency for charging of an high voltage energy storage capacitor. 1.8 kJ/s SRC prototype is assembled with TI 28335 DSP controller and 40 kJ, 7 kV energy storage capacitor. Design rules based on the comparative analysis are verified by experiment.

• Journal of Electrical Engineering and Technology
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• v.1 no.4
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• pp.496-502
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• 2006

In this paper, we studied the development of the electronic ballast for 250W MH (Metal-Halide) lamps. We were able to improve the input power factor by using a PFC IC. To provide the lamp with the rated voltage required, we used the buck-type dc-dc converter. The stress of the switching devices in the inverter could be reduced by this method. To eliminate the acoustic resonance phenomena of MH lamps, the voltage of the lamp added the high frequency sine-wave to the low frequency square-wave by using the full bridge typed inverter. We have developed a simple igniter using the L and C elements. We could control the dimness of the lamp by varying the output voltage of the buck converter. The buck converter output voltage could be controlled by using a microprocessor.

• Proceedings of the KSR Conference
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• 1999.05a
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• pp.328-335
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• 1999

Three phase full bridge rectifier has been used to obtain dc voltage from three phase ac voltage source. The rectifier system has drawbacks that power factor is low and power flow is unidirectional. Therefore, when dc voltage increases due to regeneration of power the dynamic resister for dissipation of regeneration power must be installed. But three phase PWM converter can be controlled to operate with unity power factor and bidirectional power flow. Therefore when the PWM converter is used as do supply system, the dissipating resistor is not necessary. On this thesis, in order to design a controller having good performance, the hee phase PWM converter is completely modeled by using circuit DQ-transformation and thus a general and simple instructive equivalent circuit is obtained; the inductor set becomes a second order gyrator-coupled system and three phase inverter becomes a transformer as well. Under given phase angle(${\alpha}$) and modulation index(MI) of the three phase inverter, the dc and ac characteristics are obtained by analysis of the transformed equivalent circuit The validity of the equivalent circuit is confirmed through PSPICE simulation. And based on the dc and ac characteristics a controller with unity power factor is proposed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.30 no.3
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• pp.65-72
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• 2016

This paper discussed the LCL-type & Isolated bidirectional dc-dc converter(BDC) with dual full bridge inverter. In order to verify the analysis of the BDC, Experimental prototype has been designed and implemented to supply constant voltage regardless of loads and proposed a method to select switching frequency that depended on two inductors' inductance ratio and transformer parameters. The proposed converter has been composed of LCL resonant network with unit inductance ratio ($L_r/L_f$=1) and then operated with fixed duty, 50% duty ratio and fixed frequency. There are some characteristics that input voltage and output voltage of the BDC is nearly identical and zero voltage turn-on switching is possible in forward and reverse mode. Finally, it has been showed that BDC is possible to commutate operating mode normally and provide constant output voltage in selected switching frequency.

• Journal of Power Electronics
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• v.5 no.3
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• pp.212-217
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• 2005

In order to correct the power boost topology has been used for easy control. But conventional boost topology has the following drawbacks: switching voltage surge, cross conduction current and right-half-plane zero of its control transfer function. Furthermore, in this topology the output voltage is always higher than the input voltage. As a result, a first-stage boost PFC converter needs to be connected with a second-stage DC-DC converter. A new topology which can be used as single stage PFC converter is proposed in this paper.