• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.677-687
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• 2018

This paper presents a novel power decoupling control scheme with the bidirectional buck-boost converter for primary-side regulation photovoltaic (PV) micro-inverter. With the proposed power decoupling control scheme, small-capacitance film capacitors are used to overcome the life-span and reliability limitations of the large-capacitance electrolytic capacitors. Then, an improved flyback PV inverter is employed in continuous conduction mode with primary-side regulation for the PV power conditioning. The proposed power-decoupling controller shares the reference for primary side current regulation of the flyback PV inverter. The decoupling controller shapes the input current of the bidirectional buck-boost converter. The shared reference eliminates the phase-delay between the input current to the bidirectional buck-boost converter and the double frequency current at the PV primary current. The elimination of the phase-delay in dynamic response enhances the ripple rejection capability of the power decoupling buck-boost converter even with small film capacitor. With proposed power decoupling control scheme, the additional advantage of the primary-side regulation of flyback PV inverter is that there is no need to have an extra current sensor for obtaining the ripplecurrent reference of the decoupling current-controller of the power-decoupling buck-boost converter. Therefore, the proposed power decoupling control scheme is cost-effective as well as the size benefit. A new transient analysis is carried out which includes the source voltage dynamics instead of considering the source voltage as a pure voltage source. For verification of the proposed control scheme, simulation and experimental results are presented.

• Journal of Power Electronics
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• v.10 no.3
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• pp.235-244
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• 2010

This paper presents a new isolated soft-switching bidirectional buck-boost inverter for fuel cell applications. The buck-boost inverter combines an isolated DC-DC converter with a conventional inverter to implement buck-boost DC-DC and DC-AC conversion. The main switches achieve zero voltage switching and zero current switching by using a novel synchronous switching SVPWM and the volume of the transformer in the forward and fly-back mode is also minimized. This inverter is suitable for wide input voltage applications due to its high efficiency under all conditions. An active clamping circuit reduces the switch's spike voltage and regenerates the energy stored in the leakage inductance of the transformer; therefore, the overall efficiency is improved. This paper presents the operating principle, a theoretical analysis and design guidelines. Simulation and experimental results have validated the characteristics of the buck-boost inverter.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.267-270
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• 2014

This paper presents a CMOS interface circuit for vibration energy harvesting. The proposed circuit consists of an AC-DC converter and a DC-DC boost converter. The AC-DC converter rectifies the AC signals from vibration devices(PZT), and the DC-DC boost converter generates a boosted and regulated output at a predefined level. A full-wave rectifier using active diodes is used as the AC-DC converter for high efficiency, and a schottky diode type DC-DC boost converter is used for a simple control circuitry. A MPPT(Maximum Power Point Tracking) control is also employed to harvest the maximum power from the PZT. The proposed circuit has been designed in a 0.35um CMOS process. The chip area is $530um{\times}325um$. Simulation results shows that the maximum efficiencies of the AC-DC converter and DC-DC boost converter are 97.7% and 89.2%, respectively. The maximum efficiency of the entire system is 87.2%.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.838-848
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• 2018

This paper proposes a single-phase buck-boost AC-AC converter. It consists of three legs with six switching units (each unit is composed of an active switch and a diode) and its input and output ports share a common ground. It can provide buck-boost voltage operation and immune from shoot-through problem. Since only two switching units are involved in the current paths, the conduction losses are low, which improves the system efficiency. The operation principle of the proposed circuit is firstly presented, and then, various operation conditions are introduced to achieve different output voltages with step-changed frequencies. Additionally, the parameters design and comparative analysis of the power losses are also given. Finally, experimental results verify the correctness of the proposed converter.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.223-226
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• 2003

This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge-resonant snubber which is used for power conditioner such as solar photovoltaic generation and fuel cell generation. The experimental results of boost chopper fed ZVS-PWM DC-DC converter are evaluated. In audition to its switching voltage and current waveforms, and the switching v-i trajectory of the power devices are discussed and compared with the conventional hard switching DC-DC converter treated here. The temperature performance of IGBT module,, efficiency, and EMI noise characteristics of this ZVS-PWM DC-DC converter using IGBTs are measured and evaluated from an experimental point of view.

• The Transactions of the Korean Institute of Power Electronics
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• v.27 no.3
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• pp.247-255
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• 2022

This paper proposes a multiphase interleaved zero-voltage-transition boost converter with a single soft-switching cell for high-voltage DC-DC converter (HDC) of fuel cell systems. The proposed single soft-switching cell structure can reduce the system volume by minimizing the passive and active elements added even in the multiphase-interleaved structure. To analyze the feasibility of the proposed structure, this paper mathematically analyzes the operation modes of the converter with the proposed single soft-switching cell structure and presents guidelines for design and considerations. In addition, the feasibility of the 210[kW] HDC was confirmed through PSIM simulation, and the system volume reduction of up to 10.48% was confirmed as a result of the 5[kW] HDC test-bed experiment considering the fuel cell system. Through this, the validity of the proposed structure was verified.

• Proceedings of the KIPE Conference
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• 1998.07a
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• pp.401-404
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• 1998

This paper proposes a new soft switching single stage AC/DC full bridge converter with unit power factor and isolated output. This circuit shows that it is possible to combine the boost converter which is for PFC(Power Factor Correction) and full bridge converter which is for DC/DC converter. A simple auxiliary circuit which includes neither lossy components nor active switches eliminates ringing of secondary side of the transformer. The characteristics of the proposed circuit are investigated and the validity is verified by the simulation results.

• Proceedings of the KIPE Conference
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• 2017.07a
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• pp.237-239
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• 2017

The isolated boost DC-DC converter based on three switches in fuel cell applications is presented in this paper. The major advantages of the proposed converter are as follows: continuous input current; decrease one active switch and no use snubber circuit. The operating principles and analysis of the proposed converter have been discussed. A 400 W prototype has been tested in the laboratory to verify the performance of the proposed converter and a PID controller was used to clarify the DC output voltage at 400 V. The simulation and experimental results are shown to validate the theoretical analysis.

• The Transactions of the Korean Institute of Power Electronics
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• v.10 no.1
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• pp.78-86
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• 2005

Recently, a fuel cell with low voltage and high current output characteristics is remarkable for new generation system. It needs both a dc-dc boost converter and dc-ac inverter to be used in fuel cell generation system. Therefore, this paper presents dc-dc active clamp current-fed half-bridge converter with ZVS for fuel cell generation system. The proposed converter has outstanding advantages over the conventional dc-dc converters with respect to high efficiency and high component utilization. The Fuel Cell generation system consist of active clamp current-fed half-bridge converter to boost the Fuel Cell(PEMFC) voltage(28∼43[Vdc]) to 380[Vdc]. A single phase full-bridge inverter is implemented to produce 220[Vac], 60[Hz] AC outputs.

• Proceedings of the KIEE Conference
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• 2003.07e
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• pp.158-161
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• 2003

A new soft switching technique that improves performance of the high power factor boost rectifier by reducing switching losses is introduced. The losses are reduced by air active snubber which consists of an inductor, a capacitor a rectifier, and an auxiliary switch. Since the boost switch turns off with zero current, this technique is well suited for implementations with insulated gate bipolar transistors. The reverse recovery related losses of the rectifier are also reduced by the snubber inductor which is connected in series with the boost switch and the boost rectifier. In addition, the auxiliary switch operates with zero voltage switching. A complete design procedure and extensive performance evaluation of the proposed active snubber using a 1.2[kW] high power factor boost rectifier operating from a $90[V_{rms}]$ input are also presented.