• ETRI Journal
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• v.38 no.4
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• pp.654-664
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• 2016

This paper presents a transformer-based reconfigurable synchronous boost converter. The lowest maximum power point tracking (MPPT)-input voltage and peak efficiency of the proposed boost converter, 20 mV and 88%, respectively, were achieved using a reconfigurable synchronous structure, static power loss minimization design, and efficiency boost mode change (EBMC) method. The proposed reconfigurable synchronous structure for high efficiency enables both a transformer-based self-startup mode (TSM) and an inductor-based MPPT mode (IMM) with a power PMOS switch instead of a diode. In addition, a static power loss minimization design, which was developed to reduce the leakage current of the native switch and quiescent current of the control blocks, enables a low input operation voltage. Furthermore, the proposed EBMC method is able to change the TSM into IMM with no additional time or energy loss. A prototype chip was implemented using a $0.18-{\mu}m$ CMOS process, and operates within an input voltage range of 9 mV to 1 V, and an output voltage range of 1 V to 3.3 V, and provides a maximum output power of 37 mW.

• Journal of Institute of Control, Robotics and Systems
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• v.17 no.1
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• pp.54-60
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• 2011

The flight control law designed for prototype aircraft often leads to degraded stability and performance, although developed control law verify by non-real time simulation and pilot based evaluations. Therefore, the proper evaluation methods should be applied such that flight control law designed can be verified in real flight environment. The one proposed in this paper is IFS (In-Flight Simulator). Currently, this system has been implemented into the F-18 HARV (High Angle of Attack Research Vehicle), SU-27 and F-16 VISTA (Variable stability In flight Simulation Test Aircraft) programs. The IFS necessary switching control law such as fader logic and integrator stand-by mode to reduce abrupt transient and minimize the integrator effect for each flight control laws switching. This paper addresses the concept of switching mechanism with fader logic of "TFS (Transient Free Switch)" and stand-by mode of "feedback type" based on SSWM (Software Switching Mechanism). And the result of real-time pilot evaluation reveals that the aircraft is stable for inter-conversion of flight control laws and transient response is minimized.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1533-1546
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• 2015

This study presents a novel method for reducing the switching losses of an asymmetric half-bridge converter for a three-phase, 12/8 switched reluctance motor operated in low speed. In particular, this study aims to reduce the switching-off losses of chopping switches in the converter when operated in the current regulated mode (chopping mode). The proposed method uses the mixed parallel operation of IGBT (chopping switch) and MOSFET (auxiliary switch). MOSFET is precisely controlled to momentarily conduct prior to the turn-off interval of the IGBT. Consequently, the voltage across the switches is clamped to approximately zero, substantially decreasing the turn-off switching losses. The analytical expressions of power losses are extensively elaborated. Compared with the conventional asymmetric half-bridge converter, the modified converter can effectively minimize the switching losses. Therefore, the efficiency of the converter is eventually improved. Computer simulation and experimental results confirm the effectiveness of the proposed technique.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.7
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• pp.694-702
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• 2007

The SSWM(Software Switching Mechanism) of I-processor concept using non-real time in-house software simulation program is an effective method in order to develop the flight control law in desktop or HQS environment. And, this system has some advantages compare to HSWM(Hardware Switching Mechanism) such as remove the time delay effectiveness and reduce the costs of development. But, if this system loading to the OFP(Operational Flight Program), the OFP guarantee the enough throughput in order to calculate the two control law at once. Therefore, the HSWM(Hardware Switching Mechanism) of 2-processor concept is necessary. This paper addresses the concept of HSWM of the HQS-PC interface using TCP/IP(Transmission Control Protocol/Internet Protocol) communication based on flight control law of advanced supersonic trainer. And, the fader logic of TFS(Transient Free Switch) and stand-by mode of reset '0' type are designed in order to reduce the abrupt transient response and minimize the integrator effect in pitch axis. The result of the analysis based on HQS pilot simulation using HSWM reveals that the flight control systems are switching between two computers without any problem.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1689-1697
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• 2016

Continuous conduction mode (CCM) boost converters are commonly used in home appliances and various industries because of their simple topology and low input current ripples. However, these converters suffer from several disadvantages, such as hard switching of the active switch and reverse recovery problems of the output diode. These disadvantages increase voltage stresses across the switch and output diode and thus contribute to switching losses and electromagnetic interference. A new topology is presented in this work to improve the switching characteristics of CCM boost converters. Zero-current turn-on and zero-voltage turn-off are achieved for the active switches. The reverse-recovery current is reduced by soft turning-off the output diode. In addition, an input current sensorless control is applied to the proposed topology by pre-calculating the duty cycles of the active switches. Power factor correction is thus achieved with less effort than that required in the traditional method. Simulation and experimental results verify the soft-switching characteristics of the proposed topology and the effectiveness of the proposed input current sensorless control.

• The Transactions of the Korean Institute of Power Electronics
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• v.24 no.4
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• pp.237-243
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• 2019

A high-efficiency and small-sized switched-mode line transformer (SMLT) is proposed in this study. The conventional structure of an adapter is composed of line transformer and rectifiers. This structure has a limit in miniaturizing due to low-frequency line transformer. Another structure is composed of power factor correction (PFC) and DC/DC converter. This structure has a limit in reducing volume due to two-stage structure. As the proposed SMLT is composed of an LLC resonant converter, a high-frequency transformer can be adopted to achieve isolation standards and size reduction. This proposed structure has different operation modes in accordance with line input voltage to overcome poor line regulation. In addition, the proposed SMLT is applied to the front of a conventional PFC converter, because the SMLT output voltage is restored to rectified sinusoidal wave by using a full-bridge rectifier in the secondary side. The design of the PFC converter is easy, because the SMLT output voltage is controlled as rectified sinusoidal wave. The validity of the proposed converter is proven through a 350 W prototype.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.4_1
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• pp.387-395
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• 2021

Distributed resources such as renewable energy sources and ESS are connected to the low voltage direct current(LVDC) distribution network through the power conversion system(PCS). Control power is required for the operation of the PCS. In general, controller power is supplied from AC power or DC power through switch mode power supply(SMPS). However, the conventional SMPS has a low input voltage, so development and research on high input voltage self-power suitable for LVDC is insufficient. In this paper, to develop Self-Power that can be used for LVDC, the characteristics of the conventional topology are analyzed, and a series-input single-output flyback converter using a flux-sharing transformer for high voltage is designed. The high input voltage Self-Power was designed in the DCM(discontinuous current mode) to reduce the switching loss and solve the problem of current dissipation. In addition, since it operates even at low input voltage, it can be applied to many applications as well as LVDC. The validity of the proposed high input voltage self-power is verified through experiments.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.137-142
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• 2023

When designing a SMPS(Switched Mode Power Supply) circuit, a part that is easily overlooked without special consideration is a snubber circuit. However, the performance degradation of the SMPS due to the snubber circuit and the effect on the entire SET cannot be ignored. In addition, a snubber circuit is added to both ends of the switch to protect the device from peak voltage and current during switching and to reduce loss during on/off switching. Therefore, in this paper, for a sufficient understanding of snubber circuits, theoretical analysis and experimental formulas that can be applied by designers during actual circuit design are arranged to promote optimization of snubber circuits.

• Progress in Superconductivity and Cryogenics
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• v.11 no.1
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• pp.30-34
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• 2009

This paper deals with charging and persistent-current mode operating characteristics of BSCCO magnet load using high-temperature superconducting (HTS) power supply. The HTS power supply consists of two heater-triggered switches, an iron-core transformer with the primary copper winding and the secondary BSCCO solenoid, and a BSCCO magnet load. The magnet load was fabricated by double pancake winding and its inductance is about 21 mH. A hall sensor was installed at the middle of the magnet load to measure the current in the load. In order to investigate the efficient pumping characteristics, operating tests of heater-triggered switch with respect to dc heater current were carried out, and the electromagnet current was determined by considering saturation characteristics of its iron core. The saturation characteristics of charged current in the magnet load were observed with respect to various pumping periods: 12 s, 14 s, 24 s and 32 s. After charging the magnet load, the persistent current was measured. The operating characteristics of the persistent current mode were mainly determined by joint resistance and magnet load.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.212-216
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• 2001

Because conventional switching converters have been usually using unbalanced circuit topologies, parasitic capacitance between the drain/collector of an active switch and the frame ground through its heat sink may generate the common-mode conducted noise. We have proposed a balanced switching converter circuit, which is an effective way to reduce the common-mode conducted noise. As an example, a boost converter version of the balanced switching converter was presented and the mechanism of the common-mode noise reduction was explained using equivalent circuits. This paper extends the concept of the balanced switching converter circuit and presents a buck-boost converter version of the balanced switching converter. The feature of common-mode noise reduction is confirmed by experimental results and the mechanism of the common-mode noise reduction is explained using equivalent circuits.