• Journal of Power Electronics
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• v.19 no.1
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• pp.34-43
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• 2019

An improved half-bridge LLC converter with a magamp auxiliary post-regulator is proposed in this paper. The function of the magamp is bypassed when the converter works within the low input-voltage range. Meanwhile, it operates as an auxiliary post-regulator when the input voltage is high. By changing the blocking time of the magamp, the dc gain of the converter can be extended. Hence, the input voltage range of the converter is extended. The realization of proposed topology does not require a complicated circuit. The controller of the magamp can be easily implemented using only passive components, transistors and an OP amp. The generalized operational principle is analyzed and the design criterion for the magamp is presented. Finally, a 25V output, 400W experimental prototype was built and tested for a 160-300V input-voltage range to verify the feasibility of the proposed method.

• Journal of Power Electronics
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• v.10 no.2
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• pp.115-124
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• 2010

In this paper, a simple yet efficient auto mode-hop ripple control structure for buck converters with light load operation enhancement is proposed. The converter, which operates under a wide range of input and output voltages, makes use of a state-dependent hysteretic comparator. Depending on the output current, the converter automatically changes the operating mode. This improves the efficiency and reduces the output voltage ripple for a wide range of output currents for given input and output voltages. The sensitivity of the output voltage to the circuit elements is less than 14%, which is seven times lower than that for conventional converters. To assess the efficiency of the proposed converter, it is designed and implemented with commercially available components. The converter provides an output voltage in the range of 0.9V to 31V for load currents of up to 3A when the input voltage is in the range of 5V to 32V. Analytical design expressions which model the operation of the converter are also presented. This circuit can be implemented easily in a single chip with an external inductor and capacitor for both fixed and variable output voltage applications.

• Journal of Power Electronics
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• v.9 no.5
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• pp.736-747
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• 2009

A new type of single-phase Z-source AC/AC converter based on a single-phase matrix converter is proposed in this paper. The proposed single-phase Z-source AC/AC converter has unique features; namely that the output voltage can be bucked and in-phase/out-of-phase with the input voltage; that the output voltage can be boosted and in-phase/out-of-phase with the input voltage. The converter employs a safe-commutation strategy to conduct along a continuous current path, which results in the elimination of voltage spikes on switches without the need for a snubber circuit. The operating principles of the proposed single-phase Z-source AC/AC converter are described, and a circuit analysis is provided. To verify the performance of the proposed converter, a laboratory prototype based on a TMS320F2812 DSP was constructed. The simulation and the experimental results verified that the output voltage can be bucked-boosted and in-phase with the input voltage, and that the output voltage can be bucked-boosted and out-of-phase with the input voltage.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.434-435
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• 2018

In this paper, a single-phase single-stage three-level AC/DC converter with a wide controllable output voltage is presented. It integrates a PFC converter and a three level DC/DC converter into one. The proposed converter operates at a fixed frequency and provides a wide controllable output voltage ($200V_{dc}-430V_{dc}$) with high efficiencies over a wide load range. In addition, the input boost inductors operate in a discontinuous mode to improve the input power factor. Moreover, all the switching devices operate with ZVS, and the converter's THD is small especially at full load. The feasibility of the proposed converter is verified with experimental results of a 1.5kW prototype.

• Proceedings of the KIEE Conference
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• 1988.11a
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• pp.465-468
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• 1988

A n-well CMOS Operational Transconductance Amplifier -C(OTA-C) integrator with a wide linear input range is designed. The circuit designed has superior linearity of input voltage range compared with the conventional source-coupled pair OTA. The OTA developed in this paper is versatile in application: diverse applications are in the fields of linear amplifiers, continuous-time filters, gain control circuits, and analog multipliers, etc..

• Journal of Power Electronics
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• v.18 no.5
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• pp.1303-1314
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• 2018

To match the dynamic lower voltage of a fuel cell stack and the required constant higher voltage (400V) of a DC bus, an H-type structural Boost three-level DC-DC converter with a wide voltage-gain range (HS-BTL) is presented in this paper. When compared with the traditional flying-capacitor Boost three-level DC-DC converter, the proposed converter can obtain a higher voltage-gain and does not require a complicate control for the flying-capacitor voltage balance. Moreover, the proposed converter, which can draw a continuous and low-rippled current from an input source, has the advantages of a wide voltage-gain range and low voltage stress for power semiconductors. The operating principle, parameters design and a comparison with other converters are presented and analyzed. Experimental results are also given to verify the aforementioned characteristics and theoretical analysis. The proposed converter is suitable for application of fuel cell systems.

• The Transactions of the Korean Institute of Power Electronics
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• v.22 no.6
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• pp.517-526
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• 2017

In this paper, we propose an LLC resonant converter that operates over a wide controllable output voltage ($50V_{DC}$ to $800V_{DC}$) and shows high efficiency characteristics under all load conditions and output voltages. Two 3.3kW prototypes are designed for an experimental comparison between the variable frequency control (control scheme 1) and the variable input voltage($V_{IN}$) control (control scheme 2) mechanisms. The experimental results show that the variable input control mechanism demonstrates high efficiency under all loads and output voltages.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.512-517
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• 2001

In this paper, a wide input range active multi-pulse rectifier for utility interface of power electronic converters is proposed. The scheme combines multi-pulse method using a V-A transformer and boost rectifier modules. A current control scheme for the rectifier modules is proposed to achieve sinusoidal line currents in the utility input over a wide input range of input voltage and output load conditions. A design example is included for a 208V to 460V input, $700V_{dc}$ do 10kW output rectifier system. Simulation results are shown.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.587-590
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• 2005

We investigated the input impedance characteristics of UHF-band RFID tag chip for increased reading range. A voltage multiplier designed using 0.4 ${\mu}m$ $zero-V_T$ MOSFET showed that DC output voltage of 2 V can be obtained using standard CMOS process. The input impedance of the voltage multiplier was examined to achieve impedance level for maximum reading distance using analytical and numerical approaches. The input impedance of the voltage multiplier could be varied in a wide range by selecting the size of MOSFET and the number of multiplying stages of the voltage multiplier, and thus, the impedance level required for the tag antenna can be obtained in presence of other tag circuit blocks.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.45 no.3
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• pp.54-59
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• 2008

A highly accurate wide swing BiCMOS cascode current mirror is proposed. It uses the base-current compensated BJT current mirror. It increases both output impedance and output voltage range by using the npn-NMOS cascode instead of the NMOS-NMOS cascode. The npn transistor copies the input current and the NMOS transistor increases the output impedance for the accurate current mirroring. The proposed current mirror achieves highly constant current for wide output voltage range. Simulation results were verified with measurements performed on a fabricated chip using a 5/16V 0.5um BCD process. It has only $-2.5%{\sim}1.0%$ current error for $0.3V{\sim}16V$ output voltage range.