• The Transactions of the Korean Institute of Power Electronics
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• v.26 no.3
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• pp.227-236
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• 2021

This research proposes a modeling and controller design of a three-level boost (TLB) converter for the implementation of maximum power point tracking (MPPT) in the photovoltaic power conditioning system (PCS). Contrary to the output voltage control of the conventional controller, the Photovoltaic PCS requires an input voltage controller for MPPT operation. A TLB converter has the advantage of decreasing the inductor size and increasing efficiency compared with the existing booster converter. However, an optimal controller is difficult to design due to the complexity of the TLB operations, which have two operational modes on the duty ratio boundary of 0.5. Therefore, the unified linear model equations of the TLB converters, which can be applicable to both operational modes, are derived using linearized solar cell expressions. Furthermore, the transfer functions are obtained for the controller design. The MPPT voltage controller is designed using MATLAB SISOTOOL. In addition, a controller for capacitor voltage unbalancing is described and designed. The simulations and experimental verifications are conducted to verify the effectiveness of the small-signal analysis and control system design.

• ETRI Journal
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• v.46 no.3
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• pp.550-563
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• 2024

A novel inductance simulation circuit employing only two dual-output voltage-differencing buffered amplifiers (DO-VDBAs) and a single capacitance (grounded) is proposed in this paper. The reported configuration is a purely resistor-less realization that provides electronically controllable realized inductance through biasing quantities of DO-VDBAs and does not rely on any constraints related to matched values of parameters. This structure exhibits excellent behavior under the influence of tracking errors in DO-VDBAs and does not exhibit instability at high frequencies. The simple and compact metal-oxide semiconductor (MOS) implementation of the DO-VDBAs (eight MOS per DO-VDBA) and adoption of grounded capacitance make the proposed circuit suitable for on-chip realization from the perspective of chip area consumption. The function of the pure grounded inductance is validated through high pass/bandpass filtering applications. To test the proposed design, simulations were performed in the PSPICE environment. Experimental validation was also conducted using the integrated circuit CA3080 and operational amplifier LF-356.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.6
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• pp.66-73
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• 2002

This paper presents ZVZCS(Zero-Voltage and Zero-Current Switching) Three Level DC/DC Converter without primary freewheeling diodes. The new converter presented in this paper used a phase shirt control with a flying capacitor in the primary side to achieve ZVS for the outer switches. A secondary anxiliary circuit which consists of one small capacitor, two small diodes and one coupled inductor, is added in the secondary to provide ZVZCS conditions to primary switches, ZVS for outer switches and ZCS for inner switches. Many advantages include simple secondary auxiliary circuit topology, high efficiency, and low cost make the new converter attractive for high power applications. Also the circulating current flows through the circuit so that it causes the needless coduction loss to be occurred in the devices and the transformer of the circuit The new converter has no primary auxiliary diodes for freewheeling current. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 1[㎾］ 50[KHz］IGBT based experimental circuit.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.6
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• pp.583-590
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• 2010

In this paper, a novel CRLH-TL unit cell with controllable transmission zeros was proposed. Proposed composite right/left handed transmission line(CRLH-TL) unit cell is implemented in the form of the metal-insulator-metal(MIM) capacitors, the microstrip stub inductors, and the co-planar waveguide(CPW) inductor. And this proposed CRLH-TL generates two transmission zeros in lower/upper passband by the effort of electromagnetic couplings between each MIM capacitors and microstrip stub inductors. Using this proposed CRLH-TL, broad bandpass filter for UWB system was designed and fabricated. The measured results reveal that the two transmission zeros are observed in lower/upper passband and the overall size of the filter, excluding the feed line is about 8 mm$\times$8 mm, less then $\lambda_g$/4 on electric size.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.1
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• pp.59-66
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• 2011

In this paper, a co-planar waveguide(CPW)-fed zeroth-order resonant(ZOR) antenna with an improved radiation efficiency was built and tested. The unit cell of the proposed antenna consists of a series metal-insulator-metal(MIM) capacitor and a shorted shunt stub inductor. In order to reduce the antenna size and to achieve the high radiation efficiency two shorted shunt stub arms bent by 90 degree were connected to the ground plane through the via. The proposed antenna consisting of two unit cells has an open ended composite right/left-handed(CRLH) transmission line structure. As a result the dominantly radiating parts of the antenna comes from shunt stub arms and vertical vias. The total size of the fabricated zeroth-order resonant antenna is $0.22\;{\lambda}_0{\times}0.22\;{\lambda}_0$. The measured gain and efficiency of the fabricated antenna have been enhanced by 3.07 dBi and 75 %, respectively, at the zeroth-order resonant frequency of 2.97 GHz.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.5
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• pp.98-107
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• 2016

An analytical comparison of a synthetic memristor emulator and a M-R mutator-based memristor emulator has been performed. Memristor is an electrical element with the characteristic of variable resistance. It is called the fourth fundamental electrical element following resistor, capacitor, and inductor. Memristor emulator is a circuit which implements the feature of variable resistance via the composition of various electrical devices. It is an essential circuit to study memristor characteristics during the time before it is commercially available. There are two representative memristor emulators depending upon their implementation methods. One is a memristor emulator which is synthesized via combining various electrical devices and the other one is M-R mutator-based memristor emulator implemented by extracting resistance from a nonlinear device. In this paper, implementation methods of these two memristor emulators are studied and their differences are investigated by analysing their characteristics.

• The Transactions of the Korean Institute of Power Electronics
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• v.9 no.4
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• pp.372-380
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• 2004

This paper proposes a single-power-stage high frequency resonant AC-DC converter with high power factor using ZVS(Zero Voltage Switching), and integrates a conventional converter with two stage into single stage converter. Input power factor is possible to be improved as a high power factor because inductor for power factor correction(PFC) is connected in input and converter is operated in discontinued current mode(DCM) with constant duty cycle and variable switching frequency. The conventional converter with two stage need to add a switch in order to control a power factor, but single stage converter have a advantage that system is simple and cost is down, confidence is improved, etc. This paper described a operation principle and characteristic analysis for single stage AC-DC converter with high power factor and have evaluated characteristic values by using normalized parameter. We make a experimental equipment using MOSFET as a switching device on the basis of characteristic values obtained from characteristic evaluations and we conform a rightfulness of theoretical analysis by comparing theoretical waveforms and experimental waveforms.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.50 no.12
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• pp.624-630
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• 2001

The trend of the regulations on environmental issues are getting tight. Responding to this trend new technologies such as moving electrodes, wide pitch and pulsed power supply are also introduced in the electrostatic precipitator(EP) systems. The introduction of wide pitch and moving electrodes enhances the system performance of the EPs by improving air-flow and by improving the ash reentrainment on rapping. The power supplies for the EPs developed up to date include thyristor-based dc or intermittent type, SMPS(switching mode power supply) type and the pulsed-power supply type. The use of the pulsed ones is known to improve dust-collecting efficiency of high resistivity ash and reduces back corona occurrence in the collecting plate. There are two kinds of pulsed-power supplies; one with pulsed transformers and the other with direct dc switching devices. The latter uses rotary spark gap switches or semiconductor switches. Both have the merits and demerits: the spark gap switches are simple and robust but has short life time, hence, high maintenance cost, whereas the semiconductor switches have long life time but are costly. In this study, A high voltage power supply with superimposing voltage pulse on dc source was developed for EPs. This study describes circuit topology, operating principle of the scheme, and analysis of experimental results on Dong-Hae Power Plant. The pulsed power supply consists of a variable dc power supply with ratings of 60kV, 800mA and pulse generator which is made of high voltage thyristor-diode switch strings, an LC resonant tank and a blocking inductor. The pulse generator generates variable pulse-voltage up to 70kV using a high frequency resonant inverter with a variable dc source. Two prototypes were built and tested on 250MW DongHae power plant to verify the possibility of the commercial use and the normal operation in the transient states.

• Journal of Microbiology and Biotechnology
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• v.24 no.11
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• pp.1495-1502
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• 2014

Metarhizium anisopliae is a widely studied model to understand the virulence factors that participate in pathogenicity. Proteases such as subtilisin-like enzymes (Pr1) and trypsin-like enzymes (Pr2) are considered important factors for insect cuticle degradation. In four M. anisopliae strains (798, 6342, 6345, and 6347), the presence of pr1 and pr2 genes, as well as the enzymatic activity of these genes, was correlated with their virulence against two different insect pests. The 11 pr1 genes (A, B, C, D, E, F, G, H, I, J, and K) and pr2 gene were found in all strains. The activity of individual Pr1 and Pr2 proteases exhibited variation in time (24, 48, 72, and 96 h) and in the presence or absence of chitin as the inductor. The highest Pr1 enzymatic activity was shown by strain 798 at 48 h with chitin. The highest Pr2 enzymatic activity was exhibited by the 6342 and 6347 strains, both grown with chitin at 24 and 48 h, respectively. Highest mortality on S. exigua was caused by strain 6342 at 48 h, and strains 6342, 6345, and 6347 caused the highest mortality 7 days later. Mortality on Prosapia reached 30% without variation. The presence of subtilisin and trypsin genes and the activity of these proteases in M. anisopliae strains cannot be associated with the virulence against the two insect pests. Probably, subtilisin and trypsin enzyme production is not a vital factor for pathogenicity, but its contribution is important to the pathogenicity process.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.7
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• pp.111-121
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• 2014

A bi-directional DC-DC converter has been developed for a wireless power transceiver which enables a device to receive and transmit power wireless. Generally, the wireless power transceiver requires two DC-DC covnerter and two external inductors. However, the proposed wireless power transceiver requires only one DC-DC converter and one inductor, allowing small form-factor. The bi-directional DC-DC converter implemented in $0.35{\mu}m$ BCDMOS process operates as a buck converter at the wireless power receiving mode and the power efficiency is 91% when the ouput power is 3W. In the wireless power transmitter mode, the DC-DC converter operates as a boost converter. With the bi-directional DC-DC converter and the proposed efficiency maximizing techniques, the power efficiency of wireless power transceiver is 81.7% in receiver mode and 76.5% in transmitter mode.