• 전력전자학회논문지
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• 제27권2호
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• pp.157-164
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• 2022

This study proposes an enhanced quadruple-Active-Bridge (QAB) converter that can solve power coupling problems. By adopting a multiple winding transformer, the equivalent circuit of a conventional QAB converter has power couplings between arbitrary output ports. This coupling is an unintended power relationship that complicates the regulation of output voltage of the multiple ports. The proposed converter can carry out power decoupling by changing the arrangement of the coupling inductor. Power transfer equations for the proposed converter and its operating principles are analyzed in detail. The power coupling caused by the transformer's leakage inductance is verified by using a proposed coupling factor that presents the relationship between inductance ratio and coupling power. In addition, the decoupling power control performance of the proposed converter is verified by simulation and a 3 kW prototype converter.

• 공학기술논문지
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• 제5권4호
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• pp.349-353
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• 2012

Recently, Mobile multimedia equipments as smart phone and tablet pc requirement is increasing and this market is also being expanded. These mobile equipments require large multi-media function, so more power consumption is required. For these reasons, the needs of power management IC as switching type dc-dc converter and linear regulator have increased. DC-DC buck converter become more important in power management IC because the operating voltage of VLSI system is very low comparing to lithium-ion battery voltage. There are many people to be concerned about digital DC-DC converter without using external passive device recently. Digital controlled DC-DC converter is essential in mobile application to various external circumstance. This paper proposes the DC-DC Buck Converter using the AVR RISC 8-bit micro-processor control. The designed converter receives the input DC 18-30 [V] and the output voltage of DC-DC Converter changes by the feedback circuit using the A/D conversion function. Duty ratio is adjusted to maintain a constant output voltage 12 [V]. Proposed converter using the micro-processor control was compared to a typical boost converter. As a result, the current loss in the proposed converter was reduced about 10.7%. Input voltage and output voltage can be displayed on the LCD display to see the status of the operation.

• Journal of Power Electronics
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• 제15권3호
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• pp.652-659
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• 2015

This paper presents a new hybrid soft switching dc-dc converter with a low circulating current and high circuit efficiency. The proposed hybrid converter includes two sub-converters sharing two power switches. One is a three-level PWM converter and the other is a LLC converter. The LLC converter and the three-level converter share the lagging-leg switches and extend the zero-voltage switching (ZVS) range of the lagging-leg switches from nearly zero to full load since the LLC converter can be operated at f_sw (switching frequency) $\approx$ f_r (series resonant frequency). A passive snubber is used on the secondary side of the three-level converter to decrease the circulating current on the primary side, especially at high input voltage and full load conditions. Thus, the conduction losses due to the circulating current are reduced. The output sides of the two converters are connected in series. Energy can be transferred from the input voltage to the output load within the whole switching period. Finally, the effectiveness of the proposed converter is verified by experiments with a 1.44kW prototype circuit.

• Journal of Power Electronics
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• 제9권6호
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• pp.929-939
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• 2009

This paper presents a new soft-switching boost converter based on the LC resonance and passive clamping technique without additional active switches. The circuit achieves high efficiency and low voltage stress by adopting a soft switching method using LC resonance. This paper gives a mathematical analysis of each mode and a detailed design procedure of the proposed boost converter. First of all, the operational principles are verified through simulation results. Then, according to the design procedure, we designed and built a 1.5[kW] prototype soft switching boost converter. Through the experimental results, we demonstrated the validity and usefulness of the proposed boost converter.

• Journal of Electrical Engineering and Technology
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• 제10권4호
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• pp.1566-1577
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• 2015

A novel high step-up converter is presented herein, which combines the conventional buck-boost converter, the charge pump capacitor and the coupling inductor. By doing so, a quite high voltage conversion ratio due to not only the turns ratio but also the duty cycle, so as to increase design feasibility. It is noted that the denominator of the voltage conversion ratio is the square of one minus duty cycle. Above all, there is no voltage spike across the switch due to the leakage inductance and hence no passive or active snubber is needed, and furthermore, the used switch is driven without isolation and hence the gate driving circuit is relatively simple, thereby upgrading the industrial application capability of this converter. In this paper, the basic operating principles and the associated mathematical deductions are firstly described in detail, and finally some experimental results are provided to demonstrate the effectiveness of the proposed high step-up converter.

• Journal of Power Electronics
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• 제14권6호
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• pp.1189-1196
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• 2014

A modular multilevel-clamped composited multilevel converter ($M-MC^2$) is proposed. $M-MC^2$ enables topology reconfiguration, power device reuse, and composited clamping. An advanced five-level converter ($5L-M-MC^2$) is derived from the concept of $M-MC^2$. $5L-M-MC^2$ integrates dual three-level T-type modules and one three-level neutral point clamped module. This converter can also integrate dual three-level T-type modules and one passive diode module by utilizing the device reuse scheme. The operation principle and SPWM modulation are discussed to highlight converter performance. The proposed $M-MC^2$ is comprehensively compared with state-of-the-art five-level converters. Finally, simulations and experimental results are presented to validate the effectiveness of the main contributions of this study.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.636-641
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• 1998

In this paper, operation characteristics of the Zero-voltage-Switching(ZVS) mode and Non-Zero-Voltage-Switching (NZVS) mode of the active clamp (ACL) forward converter are compared through the loss analysis. The losses of semiconductor devices, transformer and passive elements of the converter are analyzed and compared for each type of operation mode. In order to verify the validity of the analysis, we have built a 50W ACL forward converter and measured the losses of the converter. From the experiment it is known that the ACL forward converter shows nearly same loss distribution for both of operation modes

• 한국수소및신에너지학회논문집
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• 제19권5호
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• pp.417-422
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• 2008

In this paper, a novel DC/DC low-voltage high-current converter circuit is proposed to improve the efficiency of power converter used in the grid-connected fuel-cell generator system. We proposed a novel high efficiency grid-connected power conditioning system for RPG fuel cell. On the result of that, the loss of system was decreased rapidly by driving stack within the condition of maximum efficiency. The peak currents of the current-type inductor and the transformer's coil are reduced by synchronizing switching frequency of Buck-type converter is increased twice as the Push-Pull converter's switching frequency. The novel structure of DC/DC converter is able to realize ZVS-ZCS in fuel-cell system is proposed. The proposed switching component of Push-Pull converter has the ZVS and ZCS function by using the circuit of new passive clamp.

• Journal of Power Electronics
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• 제17권6호
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• pp.1402-1412
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• 2017

This paper presents a new high step-up dc/dc converter for renewable energy systems in which a high voltage gain is provided by using a coupled inductor. The operation of the proposed converter is based on a charging capacitor with a single power switch in its structure. A passive clamp circuit composed of capacitors and diodes is employed in the proposed converter for lowering the voltage stress on the power switch as well as increasing the voltage gain of the converter. Since the voltage stress is low in the provided topology, a switch with a small ON-state resistance can be used. As a result, the losses are decreased and the efficiency is increased. The operating principle and steady-states analyses are discussed in detail. To confirm the viability and accurate performance of the proposed high step-up dc-dc converter, several simulation and experimental results obtained through PSCAD/EMTDC software and a built prototype are provided.

• Journal of Power Electronics
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• 제19권5호
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• pp.1278-1288
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• 2019

A DC-DC Non-Isolated Three-Port Cuk-Cuk (NI-TPCC) converter for interfacing renewable energy sources (RESs) such as Fuel Cell (FC) and Photovoltaic (PV) energy with a DC load is presented in this paper. It features single-stage power conversion from both of the input ports to the load port. The proposed NI-TPCC converter is designed based on the classical Cuk converter. The operational modes and power flow are analyzed in the continuous conduction mode (CCM), and the relationships among the port voltages are derived. Continuous currents in all three ports with less ripple enhance the performance of a fuel cell and its operating life. Furthermore, the output inductor is shared with both of the input ports, which reduces the number of active and passive components. The effectiveness of the designed NI-TPCC converter has been validated through simulation and experimental results.