• Journal of Power Electronics
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• v.4 no.1
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• pp.46-55
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• 2004

This paper presents a high-frequency ZVS-PWM boost chopper-fed DC-DC converter with a single active auxiliary edge resonant snubber in the load-side which can be designed for power conditioners such as solar photovoltaic generation, fuel cell generation, battery and super capacitor energy storages. Its principle operation in steady-state is described in addition to a prototype setup. The experimental results of ZVS-PWM boost chopper-fed DC-DC converter proposed here, are evaluated and verified with a practical design model in terms of its switching voltage and current waveforms, the switching v-i trajectory, the temperature performance of IGBT module, the actual power conversion efficiency and the EMI of radiated and conducted emissions. And then discussed and compared with the hard switching scheme from an experimental point of view. Finally, this paper proposes a practical method to suppress parasitic oscillation due to the active auxiliary resonant switch at ZCS turn off mode transition with the aid of an additional lossless clamping diode loop, and reduced the EMI conducted emission in this paper.

• 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.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.17 no.4
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• pp.325-332
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• 2005

This paper addresses the development of a scroll expander for power generation from relatively low temperature steam source. It has a double-sided orbiting scroll member so that no thrust bearing is needed to support the base plate of the orbiting scroll. Three power transmission shafts are placed at the periphery of the orbiting scroll base plate, and these shafts can also function as anti-rotation devices. Final output is obtained from the main central shaft engaged with the three power transmission shafts through gear assembly. The clearance between the fixed and orbiting scroll elements was estimated by comparing measurement of the mass flow rate with calculation results of a computer simulation. Due to large clearance, the expander total and volumetric efficiencies were measured to be $34\%\;and\;43\%$, respectively. It has been shown through the computer simulation that the total and volumetric efficiencies could be improved to $65\%\;and\;83\%$, respectively, if the current clearance is reduced by half.

• Journal of Power Electronics
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• v.11 no.6
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• pp.801-810
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• 2011

An open circuit fault diagnostic method in IGBTs for the ac to dc converters used in microgrid applications is developed in this paper. An ac to dc converter is a key technology for microgrids in order to interface both distributed generation (DG) and renewable energy resources (RES). Also, highly reliable ac to dc converters are necessary to keep converters in continuous operation as long as possible during power switch fault conditions. Therefore, the proposed fault diagnostic method is developed to reduce the fault detection time and to avoid any other fault alarms because continuous operation is desired. The proposed diagnostic method is a combination of the absolute normalized dc current technique and the false alarm suppression algorithm to overcome the long fault detection time and fault alarm problems. The simulation and experimental results show that the developed fault diagnostic method can perform fault detection within about one cycle. The results illustrate that the reliability of an ac to dc converter interfaced with a microgrid can be improved by using the proposed fault diagnostic method.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.5
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• pp.615-621
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• 2014

With development of electrical power system, the DC distribution system has been considered as a promising technology to be used in the future smart distribution system. Among the various components comprising the DC distribution system, the bi-directional DC/DC converter is one of the most important equipment to interconnect between main power system and various renewable resources such as photovoltaic power generation, wind power generation, and electrical vehicles. In this paper, a bi-directional DC/DC converter based on three-phases interleaved method which is effective to reduce ripple of input current and output voltage is modeled using ElectroMagnetic Transient Program(EMTP), and the verification of modeled bi-directional DC/DC converter is conducted.

• Journal of Power Electronics
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• v.15 no.1
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• pp.246-255
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• 2015

This paper presents experimental results and its assessment of a variable-speed wind power generation system (VSWPGS) using permanent magnet synchronous generator (PMSG) and boost chopper circuit (BCC). Experimental results are obtained by a test bench with a wind turbine emulator (WTE). WTE reproduces the behaviors of a windmill by using servo motor drives. The mechanical torque references to drive the servo motor are calculated from the windmill wing profile, wind velocity, and windmill rotational speed. VSWPGS using PMSG and BCC has three speed control modes for the level of wind velocity to control the rotational speed of the wind turbine. The control mode for low wind velocity regulates an armature current of generator with BCC. The control mode for middle wind velocity regulates a DC link voltage with a vector-controlled inverter. The control mode for high wind velocity regulates a pitch angle of the wind turbine with a pitch angle control system. The hybrid of three control modes extends the variable-speed range. BCC simplifies the maintenance of VSWPGS while improving reliability. In addition, VSWPGS using PMSG and BCC saves cost compared with VSWPGS using a PWM converter.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.6
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• pp.508-519
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• 2006

In solar power system, the height and azimuth of the sun are important parameters which control generated power magnitude. The tracking method that controls the daily generation magnitude according to latitude and longitude using the two axles is often used in the existing sunlight tracking system today. In this two-axle PV track control system, the self-load is concentrated on one FRAME. It is influenced of the regular load, snow load and the wind load, etc. It is difficult to set up the system in the conventional building. This research is a development about the small-scale economy track device of independent load-dispersing solar generation system. The position tracking algorithm is through the new coordinates transformation calculating the height and azimuth of the sun.

• Journal of the Korean Society of Safety
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• v.29 no.1
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• pp.7-14
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• 2014

Inverter module, which feeds the converted power to the traction motor for EMU. Consists of the power semiconductors with their gate drive unit(GDU)s and the control computer for driving, voltage, current and speed controls. Electrolytic condenser, connected to the gate drive unit and a core component to drive the power semiconductor, has problems such as reduction in lifetime and malfunction caused by electrical and mechanical characteristic changes from heat generation during high speed switching for generation of stable power. In this study, To check the service life of electrolytic condenser, the test was carried out in two ways. First, In the case of accelerated life testing of condenser, the Arrhenius model is a way of life testing. Another way is to analyze the reliability of the failure data by the method of parametric data analysis. Eventually, life time by accelerated life test than a method of failure data analysis(Weibull distribution) was found to be slightly larger output.

• Progress in Superconductivity and Cryogenics
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• v.10 no.1
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• pp.52-56
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• 2008

According to the improvement of HTS conductor, HTS tapes which have the high current capacity have been recently researched in several nations. For large power application, AC loss is the most important issue in the development of AC superconducting power devices because it is closely related to the system operation efficiency. In 1st generation wire of HTS conductor, BSCCO, AC loss is too large to use for power application. Also, It is well known in recently years that YBCO CC, the 2nd generation wire, has also too much AC loss to apply to AC power devices. There are many trials to develop the new HTS wire having the low AC loss around the world. In this research, we present the measurment result of magnetization losses in SmBCO coated conductors. We measured the magnetization loss generated by perpendicularly exposed external magnetic field and compared with the analytic value of the strip model. Also, we presented the results compared with measured magnetization loss of an YBCO coated conductor.

• International journal of advanced smart convergence
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• v.13 no.3
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• pp.376-387
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• 2024

This paper examines the performance improvement of a photovoltaic power generation system with a surge protection function by applying a digital surge detection device for surge suppression in a direct current distribution panel applied to a photovoltaic power generation system. The main components used for surge protection are mainly SAD, MOV, and GTA components, and a digital surge detection device was additionally applied to this. Each component has advantages and disadvantages in terms of performance and functionality for surge protection, so a surge protection device with meaningful performance and functionality must be designed in a complex device structure that harmonizes the advantages and disadvantages of each component in order to construct a surge protection device with meaningful performance and function. Through empirical experiments, a performance analysis of a complex surge detection device to which a digital surge detection device is applied was conducted. As a result of the experiment, through absorption and blocking of surges detected through a digital surge detection device, it has both absorption and blocking performance for surges and exhibits surge absorption characteristics for hundreds of voltages in micro second. This performance showed a relatively stable state against surge noise compared to conventional devices, which produced an output waveform of stable quality in the inverter output waveform.