• Proceedings of the KIEE Conference
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• summer
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• pp.1498-1500
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• 2004

A novel technique for efficiently extracting maximum power from PV panels is proposed, consisting of a modified buck-boost converter, witch is controlled by a DSP. A variation of the proposed MPPT technique is directly use the modified buck-boost converter current reference as a control parameter. Also 4 parallel boost converters have division of load. A theoretical analysis of the proposed converter is performed and compared with experimental results obtained from a 1k[W] prototype solar panel under a controlled experimental setup.

• Proceedings of the KIEE Conference
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• 2005.07b
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• pp.1534-1536
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• 2005

A DC-DC converter is being widely used for various household appliances and for industry applications. The DC-DC converter is powered from single battery, and the voltage is varied according to the purpose. In the vehicle, various accessories whose electric power is different are being used. Thus, plural number of DC-DC converter should be provided, so these situations bring complicated circuits, and accordingly, higher cost. Under such backgrounds, in this paper, we propose a novel buck-boost chopper circuit with simply configuration which can supply to two or more different output loads. The propose chewer circuit can control output voltages by controlling duty ratio by using typically two switching devices, which is composed by single boost-switch and single buck-switch. The output voltage can be controlled widely. A few modified circuits developed from the fundamental circuit are represented including the general multi-load circuit. And all this merits and appropriateness was proved by computer simulation and experience.

• Journal of Power Electronics
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• v.19 no.1
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• pp.11-23
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• 2019

In this study, a novel zero voltage zero current transition (ZVZCT) bidirectional DC-DC converter is proposed by employing coupled inductors. This converter can turn the main switch on at ZVZCT and it can turn it off with zero voltage switching (ZVS) for both the boost and buck modes. These characteristics are obtained by using a simple auxiliary sub-circuit regardless of the power flow direction. In the boost mode, the auxiliary switch achieves zero current switching (ZCS) turn-on and ZVS turn off. Due to the coupling inductors, this converter can make further efficiency improvements because the resonant energy in the capacitor or inductor can be transferred to the load. The main diode operates with ZVT turn-on and ZCS turn-off in the boost mode. For the buck mode, there is a releasing circuit to conduct the currents generated by the magnetic flux leakage to the output. The auxiliary switch turns on with ZCS and it turns off with ZVT. The main diode also turns on with ZVT and turns off with ZCS. The design method and operation principles of the converter are discussed. A 500 W experimental prototype has been built and verified by experimental results.

• Proceedings of the KIPE Conference
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• 2005.07a
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• pp.116-118
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• 2005

In this paper, a three phase PWM noninverting Buck-Boost AC-AC converter for WCF applications is presented. The PWM noninverting Buck-Boost AC-AC converter is modelled by using vector DQ transformation whereby the basic DC characteristics equation is analytically obtained. Finally, the PSIM simulation shows the validity of the modelling and analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.1
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• pp.19-26
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• 2016

In this study, a bidirectional DC-DC converter for idle stop and go (ISG) is developed to reduce fuel consumption. A three-phase non-isolated half-bridge converter is selected through a design method by considering efficiency and volume. According to the state of charge of the batteries at both the low-voltage and high-voltage sides, buck mode, which charges a low-voltage battery from the generated motor energy, and boost mode, which provides power to the motor from the low- and high-voltage battery sides, are required in the ISG system. Hence, an autonomous and seamless bidirectional control method using a variable current limiter is proposed for mode change. A 1.8 kW engineering sample of the proposed converter has been built and tested to verify the validity of the proposed concept. The maximum efficiencies, including gate driver and control circuit losses, are 96.4% in charging mode and 96.1% in discharging mode.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.4
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• pp.334-341
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• 2011

This paper presents a design and implementation of DC/DC converter with very wide input voltage ranges for EPBS whose input voltage is from 30V to 400V and output voltage is 48V. This converter is comprised of two stages that one is for control and the other is for only galvanic isolation. The proposed converter uses the hard-switched buck-boost topology for control purpose and soft-switched LLC resonant converter for isolation. The proposed converter has been verified with 300W design.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.610-614
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• 2004

Recently, an active-clamp, full-bridge boost converter has been actively studied for high-power applications such as power factor correction and battery discharger. However, DC and AC modeling for this converter has not conquered. In this paper, a DC and small-signal AC modeling for the active-clamp, full-bridge boost converter is described. Based on the operation principle, the ac part of the converter can be replaced by a do counterpart. Then, a conceptual equivalent circuit is derived by rearranging the switches. The equivalent circuit for this converter consists of CCM (Continuous conduction mode) boost and DCM (Discontinuous conduction mode) buck converter. The analyses for the equivalent CCM boost and DCM buck converter are done using the model of PWM switch. The theoretical modeling results are confirmed through experiment or SIMPLIS simulation.

• Journal of the Korean Solar Energy Society
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• v.32 no.spc3
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• pp.235-244
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• 2012

This paper presents a design and simulation of bi-directional DC/DC boost converter for a fuel cell system. In this paper, we analyze the equivalent model of both a boost converter and a buck converter. Also we propose the controller of bi-directional DC-DC converter, which has buck mode of charging a capacitor and boost mode of discharging a capacitor. In order to design a controller, we draw bode plots of the control-to-output transfer function using specific parameters and incorporate proper compensator in a closed loop. As a result, it has increased PM(Phase Margin) for better dynamic performance. The proposed bi-directional DC-DC converter's 3pole-2zero compensation method has been verified with computer simulation and simulation results obtained demonstrates the validity of the proposed control scheme.

• Journal of Power Electronics
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• v.13 no.4
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• pp.592-599
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• 2013

This paper investigates a new isolated single-phase AC-DC converter, which integrates a modified AC-DC buck-boost converter with a DC-DC forward converter. The front semi-stage is operated in discontinuous conduction mode (DCM) to achieve an almost unity power factor and a low total harmonic distortion of the input current. The rear semi-stage is used for step-down voltage conversion and electrical isolation. The front semi-stage uses a coupled inductor with the same winding-turn in the primary and secondary sides, which is charged in series during the switch-on period and is discharged in parallel during the switch-off period. The discharging time can be shortened. In other words, the duty ratio can be extended. This semi-stage can be operated in a larger duty-ratio range than the conventional AC-DC buck-boost converter for DCM operation. Therefore, the proposed converter is suitable for universal input voltage (90~264 $V_{rms}$) and a wide output-power range. Moreover, the voltage stress on the DC-link capacitor is low. Finally, a prototype circuit is implemented to verify the performance of the proposed converter.

• Journal of the Korean Society of Industry Convergence
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• v.20 no.4
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• pp.275-284
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• 2017

As the high-level of the industrial and information age, the electricity become the indispensable element in the daily life including OA, FA, and computer, electric home appliances, and etc. In particular, The continuous use of the high capacity power supply system by applying a Switching Mode Power Supply(SMPS) according to the increase of the secondary side output terminal of the power load of the refrigerator of the home appliance or automation of the plant is pressed. The purpose using the way with this kind of high-capacity altogether is to supply the output voltage and output current regardless of the input voltage or to the external environmental conditions of the secondary-side load fluctuation. In this paper, a combination of a Buck Converter with Boost Converter by making a constant current source to control the inductor current and maintain stable power supply side operating characteristics, when load variations. While maintaining the same characteristics as conventional Buck Converter, and offer a DC-DC Converter system with the new switch pattern having a wide output range capable of operating in Buck-Boost Converter. In addition, after theoretical analysis, we carry out simulations and experiments to verify the validity and performance comparing with a conventional DC-to-DC converter.