• JSTS:Journal of Semiconductor Technology and Science
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• v.6 no.4
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• pp.257-263
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• 2006

New charge pump circuits with low area and high power efficiency are proposed and verified in this paper. These pump circuits do not suffer the voltage stress higher than $V_{DD}$ across their pumping capacitors. Thus they can use the thin-oxide MOSFETs as the pumping capacitors. Using the thin-oxide capacitors can reduce the area of charge pumps greatly while keeping their driving capability. Comparing the new pump (NCP-2) with the conventional pump circuit using the thick-oxide capacitors shows that the power efficiency of NCP-2 is the same with the conventional one but the area efficiency of NCP-2 is improved as much as 71.8% over the conventional one, when the $V_{PP}/V_{DD}$ ratio is 3.5 and $V_{DD}$=1.8V.

• Journal of Advanced Navigation Technology
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• v.14 no.5
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• pp.655-660
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• 2010

This paper examines RF-to-DC conversion efficiency of rectifying circuit for wireless power transmission. The rectifying circuit consists of low pass filter, diode circuits and dc pass filter. All these components may be effect on the conversion efficiency. Using the simulation, we study these components how to effect on the conversion efficiency. On the basis of the simulation results, the 912MHz rectifying circuit with 50% efficiency at low input power such as 0dBm is fabricated and its characteristics are measured.

• The Transactions of the Korean Institute of Power Electronics
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• v.6 no.2
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• pp.164-172
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• 2001

This paper describes common MPPT(Maximum Power Point Tracking) control algorithm; Constant Voltage Control, P&O(Perturbation and Observation), IncCond(Incremental Conductance), and investigated it\`s efficiency. Though simulation and efficiency evaluation, the steady/transient states characteristics and efficiency of control algorithms are analyzed respectively. Also, two-mode MPPT control to improve on the existing control algorithm. Moreover, is proposed for high efficiency this paper suggests a topology for MPPT measuring efficiency and a method of examination.

• ETRI Journal
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• v.35 no.2
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• pp.188-192
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• 2013

Previous work proposed combining multipulse pulse position modulation (MPPM) with pulse amplitude modulation to form multipulse amplitude and position modulation (MPAPM), which is a hybrid modulation that results in an improvement in bandwidth efficiency but a degradation in power efficiency. In this paper, to achieve greater power efficiency and a better data rate, we propose multipulse dual amplitude-width modulation, based on MPAPM and pulse width modulation. The proposed scheme shows a remarkable improvement in data rate and a 1.5-dB improvement in power efficiency over MPAPM, while sustaining the bandwidth efficiency. After introducing symbol structure, we present the theoretical expressions of spectral efficiency, the power requirements, and the normalized data rate, as well as the results of comparing the proposed modulation to MPPM and MPAPM.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.20 no.2
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• pp.107-114
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• 2009

In this paper, high efficiency amplifier configuration is proposed using the reconfigurable power divider. In order to enhance average efficiency of linear power amplifiers for wireless communication, it is required to increase efficiency in low output power region. The proposed power divider operates in two modes, high power mode and low power mode, according to output power. In each mode, it allows impedance matches and low loss, which is made possible by employing two $\lambda/4$ coupled lines and two switches. The fabricated power divider shows the return loss ($S_{11}$) and insertion loss ($S_{21}$) of -16.49 dB and -0.83 dB, respectively, in low power mode. In high power mode, the measured return loss ($S_{11}$) and insertion loss ($S_{31}$) are -16.28 dB and -0.73 dB, respectively. This result successfully demonstrates the reconfigurability of the proposed power divider.

• Journal of Power Electronics
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• v.16 no.5
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• pp.1629-1638
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• 2016

Differential power processing (DPP) systems are among the most effective architectures for photovoltaic (PV) power systems because they are highly efficient as a result of their distributed local maximum power point tracking ability, which allows the fractional processing of the total generated power. However, DPP systems require a high-efficiency, high step-up/down bidirectional converter with broad operating ranges and galvanic isolation. This study proposes a single, magnetic, high-efficiency, high step-up/down bidirectional DC-DC converter. The proposed converter is composed of a bidirectional flyback and a bidirectional isolated switched-capacitor cell, which are competitively cheap. The output terminals of the flyback converter and switched-capacitor cell are connected in series to obtain the voltage step-up. In the reverse power flow, the converter reciprocally operates with high efficiency across a broad operating range because it uses hard switching instead of soft switching. The proposed topology achieves a genuine on-off interleaved energy transfer at the transformer core and windings, thus providing an excellent utilization ratio. The dynamic characteristics of the converter are analyzed for the controller design. Finally, a 240 W hardware prototype is constructed to demonstrate the operation of the bidirectional converter under a current feedback control loop. To improve the efficiency of a PV system, the maximum power point tracking method is applied to the proposed converter.

• Journal of Electrical Engineering and Technology
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• v.9 no.2
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• pp.569-575
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• 2014

A highly efficient class E power amplifier is demonstrated for application to wireless power transfer system. The amplifier is designed with an L-type matching at the output for harmonic rejection and output matching. The power loss and the effect of each component in the amplifier with the matching circuit are analyzed with the current ratio transmitted to the output load. Inductors with a quality factor of more than 120 are used in a dc feed and the matching circuit to improve transmission efficiency. The single-ended amplifier with 20 V supply voltage shows 7.7 W output power and 90.8% power added efficiency at 6.78 MHz. The wireless power transfer (WPT) system with the amplifier shows 5.4 W transmitted power and 82.3% overall efficiency. The analysis and measurements show that high-Q inductors are required for the amplifier design to realize highly efficient WPT system.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.10
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• pp.1823-1831
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• 2010

This paper proposes an automatic tracking control algorithm for efficiency improvement of photovoltaic generation. Increasing the power of PV systems should improve the efficiency of solar cells or the power condition system. The normal alignment of the PV module always have to run perpendicular to the sun's rays. The solar tracking system, able to improve the efficiency of the PV system, was initiated by applying that to the PV power plant. The tracking system of conventional PV power plant has been studied with regard to the tracking accuracy of the solar cells. Power generation efficiency were increased by aligning the cells for maximum exposure to the sun's rays. Using a perpendicular position facilitated optimum condition. However, there is a problem about the reliability of tracking systems unable to not track the sun correctly during environmental variations. Therefore, a novel control algorithm needs to improve the generation efficiency of the PV systems and reduce the loss of generation. This control algorithm is the proposed automatic tracking algorithm in this paper. Automatic tracking control is combined the sensor and program method for robust control in environment changing condition. This tracking system includes the insolation, rain sensor and anemometer for climate environment changing. Proposed algorithm in this paper, is compared to performance of conventional tracking control algorithm in variative insolation condition. And prove the validity of proposed algorithm through the experimental data.

• Journal of Power Electronics
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• v.19 no.6
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• pp.1440-1448
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• 2019

In wireless power transfer systems, it is important to design resonant energy links in order to increase the power transfer efficiency and to obtain desired system performances. This paper proposes a method for designing and analyzing the resonant energy links in a series-series configured IPT (inductive power transfer) system using the FOM-rd plane. The proposed FOM-rd graphical design plane can analyze and design the voltage gain and the power efficiency of the energy links while considering changes in the misalignment between the coils and the termination load condition. In addition, the region of the bifurcation phenomena, where voltage gain peaks are split over the frequency, can also be distinctly identified on the graphical plane. An example of the design and analysis of a 100 W inductive power transfer system with the proposed method is illustrated. The proposed method is verified by measuring the voltage gain and power efficiency of implemented hardware.

• Proceedings of the IEEK Conference
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• 2004.08c
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• pp.499-502
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• 2004

A two-stage Class E power amplifier operated at 2.44GHz is designed in 0.25-$\mu$m CMOS process for Class-l Bluetooth application. The power amplifier employs c1ass-E topology to exploit its soft-switching property for high efficiency. A preamplifter with common-mode configuration is used to drive the output-stage of Class-E type. The amplifier delivers 20-dBm output power with 70$\%$ PAE (power -added-efficiency) at 2-V supply voltage.