• Proceedings of the KIEE Conference
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• 2009.04b
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• pp.139-142
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• 2009

Comparison of three converter topologies for single phase switched reluctance motor is proposed in this paper. Due to the limitation of do-link voltage, conventional asymmetric converter is difficult to build up enough phase current in the high speed operation. In order to solve this problem, boost converter is used to improve the performance. Two active boost converters are reviewed: one is series-connected type, another is parallel-connected. Otherwise, a novel active boost converter is proposed. The comparison of these converters is based on the voltage raring of capacitor, stability and converter topology. Because the converter selection depends on the motor design, the single phase 6/6 SRM is considered in this paper. Some simulations results are executed. And the results verified the analysis in this paper.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.319-326
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• 2019

The use of high-voltage gain converters is essential for distributed power generation systems with renewable energy sources, such as fuel and solar cells, due to their low-voltage characteristics. In this study, a novel high-voltage gain non-isolated buck boost converter topology is proposed to cope with the need of a high-voltage conversion ratio without the transformer for the renewable energy sources. Given that the proposed topology utilizes the cascode structure, the voltage gain and the efficiency are higher than those of other conventional non-isolated converters. To demonstrate the feasibility of the proposed topology, the operation principle is presented, and the steady-state characteristics are analyzed in detail. The validity of the proposed converter is verified by experiments with a 400 W prototype converter.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.656-659
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• 2001

In this paper a neural network controller for achieving maximum power tracking as well as output voltage regulation, for a wind energy conversion system(WECS) employing a permanent magnet synchronous generator, is proposed. The permanent magnet generator (PMG) supplies a dc load via a bridge rectifier and two buck-boost converters. Adjusting the switching frequency of the first buck-boost converter achieves maximum power tracking. Adjusting the switching frequency of the second buck-boost converter allows output voltage regulation. The on-times of the switching devices of the two converters are supplied by the developed neural network(NN). The effect of sudden changes in wind speed ,and/or in reference voltage on the performance of the NN controller are explored. Simulation results showed the possibility of achieving maximum power tracking and output voltage regulation simultaneously with the developed neural network controller. The results proved also the fast response and robustness of the proposed control system.

• Journal of Electrical Engineering and Technology
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• v.10 no.6
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• pp.2307-2314
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• 2015

In this paper, a discontinuous conduction mode (DCM) frequency control algorithm is proposed to reduce the input current ripple of a multi-phase interleaved boost converter. Unlike conventional variable duty and constant frequency control, the proposed algorithm controls the switching frequency to regulate the output voltage. By fixing the duty ratio at 1/N in the N-phase interleaved boost converter, the input current ripple can be minimized by ripple cancellation. Furthermore, the negative effects of the diode reverse recovery current are eliminated because of the DCM characteristic. A frequency controller is designed to employ the proposed algorithm considering the magnetic permeability change. The proposed algorithm is analyzed in the frequency domain and verified by a 600 W three-phase boost converter prototype that achieved 57% ripple current reduction.

• Proceedings of the KIPE Conference
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• 2008.06a
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• pp.529-531
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• 2008

Generation system using regenerative energy like photovoltaic, fuelcell is increased, PCS technology coming into the spotlight. The efficiency of DC-DC converter as part of the PCS is very important, multi-phase boost converter has more advantage than other topology. Input current of the multi-phase boost converter is divided into two inductor current because of parallel structure of the boost converters, thus it has features of decreasing input current ripple and output voltage ripple. Also multi-phase boost converter with soft switching can decrease switching loss using ZCS and ZVS. In this paper, simulation and experiment are performed to verify operation of the proposed converter, and efficiencies of the conventional and proposed converter are compared.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.33B no.10
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• pp.148-156
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• 1996

Increasing the switching frquency is essential to achieve the high density of switched mode power supplies, but this leads to the increase of switching losses. A number of new soft switching converters have been presented ot reduce switching losses, but most of them may have some demerits, such as the increase of voltage/current stresses and high conduction losses. To overcome these problems, the ZVT-PWM converter has recently been presented. in this paper, the operation characteristics of the ZVT-PWM boost converter is analyzed, and the steady-states (DC) and small-signal model of this converter are derived and analyzed, and then the transfer functions of this converter are derived. The transfer functions of ZVT-PWM boost converter are similar to those of the conventional PWM boost converter, but the transfer characteristics are affecsted by te duty ratio and the switching frequency.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.5
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• pp.372-378
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• 2019

This study proposes a new zero-current-zero-voltage-transition (ZCZVT) boost-flyback converter using a soft switching auxiliary circuit. The proposed converter integrates the boost and flyback converters to increase the voltage with a low duty ratio. The main and auxiliary switches turn the ZCZVT conditions on and off. Thus, the proposed converter has high efficiency. The voltage gain at the steady state is derived, and the inductor volt-second balance and the design guidelines are presented. Finally, the performance of the proposed converter is validated by experimental results from a 200 W, 30 V DC input, 400 V DC output, and 200 kHz boost-flyback converter prototype.

• The Transactions of the Korean Institute of Power Electronics
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• v.16 no.3
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• pp.250-257
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• 2011

This paper analyzes characteristic of the three-phase coupled inductor connected to ac source to effectively mitigate the high-frequency circulating current generated in parallel three-phase boost converters. The three-phase coupled inductor analysis presented in this paper uses the three-phase coupled inductor structure and voltage equations. Based on this analysis, the three-phase coupled inductor is added to the conventional low-frequency averaged model. As a result, the novel averaged model which can reduce the low and high-frequency circulating current simultaneously is developed. Using the zero-sequence component of the novel averaged model, each total inductance to the circulating current of the three-phase coupled inductor and line inductor can be obtained. Simulation and experiment results verify the usefulness of three-phase coupled inductor in parallel three-phase boost converters.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.256-260
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• 2001

This paper presents boost and buck and buck-boost DC-DC converter circuit topologies of high-frequency soft switching transition PWM chopper type DC-DC high power converters with a single auxiliary passive resonant snubber. In the proposed boost power converter circuits operating under a principle of ZCS turn-on and ZVS turn-off commutation schemes, the capacitor and inductor in the auxiliary passive resonant circuit works as the loss less resonant snubber. In addition to this, the switching voltage and current peak stresses as well as EMI and RFI noises can be basically reduced by this single passive resonant snubber. Moreover, it is proved that converter circuit topologies with a passive resonant snubber are capable of solving some problems of the conventional hard switching PWM processing based on high-ferquency pulse modulation operation principle. The simulation results of this converter are discussed as compared with the experimental ones. The effectiveness of this power converter with a single passive resonant snubber is verified by the 5kW experimental breadboad set up.

• Journal of Navigation and Port Research
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• v.31 no.10
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• pp.839-844
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• 2007

This paper describes the performance of DC-DC converters for buoy such as buck, boost, and buck-boost. The operating characteristic and charging efficiency with battery, which has a considerable properties about converters with PV(photovoltaic) system, is analyzed in this paper. It is performed by using the MPPT(Maximum Power Point Tracker) algorithm The basic equations of switching operation for converter are described, and the equations are analyzed with according to switch state. Whereas this analysis is directed toward the selection of converter for buoy, it also provides the insight into the behaviour of converter and performance of the proposed algorithm Finally, the suitable DC-DC converter is proposed for buoy, and the characteristic experiment is performed with the buck converter.