• The Transactions of the Korean Institute of Power Electronics
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• v.15 no.3
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• pp.244-251
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• 2010

High speed motors have been widely used in industries to reduce system size and improve power conversion efficiency. However, the high speed motors sometimes suffer from core losses caused by PWM current ripple; noting that the phase inductance, $L_s$, of high speed motor is smaller than that of ordinary motors. In the proposed topology, three PWM inverters are connected in parallel through nine coupled inductors. Compared to the PWM current ripple of the conventional single inverter system, that of the proposed scheme can be conspicuously reduced without the voltage drop at the inductors. In this paper a theoretical analysis of the output voltage of the proposed topology is presented, and then the validity of the proposed method is verified by experimental results.

• Journal of Power Electronics
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• v.13 no.1
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• pp.20-30
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• 2013

This paper presents a soft switching DC/DC converter for high voltage application. The interleaved pulse-width modulation (PWM) scheme is used to reduce the ripple current at the output capacitor and the size of output inductors. Two converter cells are connected in series at the high voltage side to reduce the voltage stresses of the active switches. Thus, the voltage stress of each switch is clamped at one half of the input voltage. On the other hand, the output sides of two converter cells are connected in parallel to achieve the load current sharing and reduce the current stress of output inductors. In each converter cell, a half-bridge converter with the asymmetrical PWM scheme is adopted to control power switches and to regulate the output voltage at a desired voltage level. Based on the resonant behavior by the output capacitance of power switches and the transformer leakage inductance, active switches can be turned on at zero voltage switching (ZVS) during the transition interval. Thus, the switching losses of power MOSFETs are reduced. The current doubler rectifier is used at the secondary side to partially cancel ripple current. Therefore, the root-mean-square (rms) current at output capacitor is reduced. The proposed converter can be applied for high input voltage applications such as a three-phase 380V utility system. Finally, experiments based on a laboratory prototype with 960W (24V/40A) rated power are provided to demonstrate the performance of proposed converter.

• Korean Journal of Materials Research
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• v.13 no.8
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• pp.503-508
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• 2003

The purpose of this study is to investigate the effect of $V_2$$O_{5}$ addition on the Ag and Cu precipitation in the NiCuZn ferrite layers of 7.7${\times}$4.5${\times}$1.0 mm sized multi-layer chip inductors prepared by the screen printing method using 0∼0.5 wt% $V_2$$O_{5}$ -doped ferrite pastes. With increasing the $V_2$$O_{5}$ content and sintering temperature, Ag and Cu oxide coprecipitated more and more at the polished surface of ferrite layers during re-annealing at $840^{\circ}C$. It was thought that during the sintering process, V dissolved in the NiCuZn ferrite lattice and the Ag-Cu liquid phase of low melting point was formed in the ferrite layers due to the Cu segregation from the ferrite lattice and Ag diffusion from the internal electrode. During re-annealing at $840^{\circ}C$, the Ag-Cu liquid phase came out the polished surface of ferrite layers, and was decomposed into the isolated Ag particles and the Cu oxide phase during the cooling process.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.12a
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• pp.109-111
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• 2006

This paper presents characterization and analysis of integrated ferromagnetic inductors in RF regime. Two different materials (CoFe/NiFe) are used as ferromagnetic material. Systematic studies of the inductance (L), the Q-factor (Q) and the structure of the inductor have been performed.

• Journal of Power Electronics
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• v.15 no.2
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• pp.366-377
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• 2015

In order to minimize switching losses for high power applications, a boost PFC rectifier with a novel passive lossless snubber circuit is proposed. The proposed lossless snubber is composed of coupled inductors merged into a boost inductor. This method compared with conventional methods does not need additional inductor cores and it reduces extra costs to implement a soft switching circuit. Especially, the proposed circuit can reduce the reverse recovery current of output diode rectifiers due to the coupling effect of the inductor. During turn-on and turn-off operating modes, the proposed PFC converter operates under soft switching conditions with high power conversion efficiency. In addition, the performance improvement and analysis of the operating effects of the coupled inductors were also presented and verified with a 3.3 kW prototype rectifier.

• Journal of Power Electronics
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• v.11 no.3
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• pp.264-270
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• 2011

In this paper a novel passive snubber is proposed, which can suppress the voltage spike across the bridge leg of the isolated full-bridge boost topology. The snubber is composed of capacitors, inductors and diodes. Two capacitors connected in series are used to absorb the voltage spike and the energy of each capacitor can be transferred to the load during one switching cycle by the resonance of the inductors and capacitors. The operational principle of the passive snubber is analyzed in detail based on a three-phase power factor correction (PFC) converter, and the design considerations of both the converter and the snubber are given. Finally, a 3kW laboratory-made prototype is built. The experimental results verify the theoretical analysis and evaluations. They also prove the validity and feasibility of the proposed methods.

• Journal of Power Electronics
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• v.19 no.4
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• pp.894-906
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• 2019

In this paper, a DC-DC converter is proposed based on the Cuk converter. The proposed converter has high efficiency and it can be used in multilevel DC-DC converters. A reduction of the inductors size in comparison to Cuk converter and a reduction in the inductors resistance negative effects on efficiency are the important points of the proposed converter. Its voltage ripple is reduced when compared to other converters. Its output voltage has a high quality and does not contain spikes. A theoretical analysis demonstrates the positive points of the proposed converter. The design and analysis of the converter are done in continues conduction mode (CCM). Experiments confirm the obtained theoretical equations. The proposed converter voltage gain is similar to that of a conventional Boost converter. As a result, they are compared. The comparison illustrates the advantages of the proposed converter and its higher quality. Furthermore, a prototype of the proposed converter and its combination with a 2x multiplier are built in the lab. Experimental results validate the analysis. In addition, they are in good agreements with each other.

• Journal of the Korean Magnetics Society
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• v.13 no.3
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• pp.109-114
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• 2003

The purpose of this study Is to investigate the effect of $V_2$O$_{5}$ addition on the microstructures and magnetic properties of 7.7${\times}$4.5${\times}$1.0 mm sized multi-layer chip inductors prepared by the screen printing method using 0∼0.5 wt％ $V_2O_{5}$-doped NiCuZn ferrite pastes. With increasing the $V_2O_{5}$ content, the exaggerated grain growth of ferrite layers was developed due to the promotion of Ag diffusion and Cu segregation into the grain boundaries oi ferrites, which affected significantly the magnetic properties of the chip inductors. After sintering at $900^{\circ}C$, the inductance at 10 MHZ of the 0.5 wt％ $V_2O_{5}$-doped chip inductor was 3.7 ${\mu}$H less than 4.2 ${\mu}$H of the 0.3 wt% $V_2O_{5}$-doped one, which was thought to be caused by the residual stress at the ferrite layers increased with the promotion of Ag diffusion and Cu segregation. The quality factor of the 0.5 wt% $V_2O_{5}$-doped chip inductor decreased with increasing the sintering temperature, which was considered to be caused by the electrical resistivity of the ferrite layer decreased with the promotion of Ag/cu segregation at the grain boundaries and the growth of the mean grain size of ferrite due to exaggerated grain growth of ferrite layers.

• Korean Journal of Materials Research
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• v.7 no.3
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• pp.175-179
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• 1997

bliniaturization oi microwave circuit components is an important issue with the development in the mobile communication. Capacitors, inductors anti hybrid devices of these are building blocks of electric circuits, and the fabrication of these devices using thin film technology will influence on the miniaturization of electronic devices In this paper, we report the successful fabrication of the inductors, capacitors and LC hybrid devices using a ferroelectric and a ferromagnetic oxide thin iilm. Au, stable at high temperatures in oxidizing ambient, is patterned by lift-off process, and oxide thin films are deposited by ion beam sputtering and chemical vapor deposition. These devices are characterized by a network analyzer in 0.5-15GtIz range We got the inductance of 5nH, capacitance oi 10, 000 pF and resonant frequencies of $10^{6}-10^{9}Hz$.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2001.11a
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• pp.55-60
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• 2001

RF MEMS is an exciting emerging technology that has great potential to develop TOC (Transceiver-on-Chip). Applications of the RF MEMS to wireless communications systems are presented. The ability of the RF MEMS technology to enhance the performance and to reduce the size of passive components, in particular, switches, inductors, and tunable capacitors, is addressed. A number of potential wireless system opportunities for the TOC are awaiting the maturation of the RF MEMS technology.