• Journal of Power Electronics
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• v.10 no.2
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• pp.155-164
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• 2010

This paper presents a voltage control algorithm for a hybrid multilevel inverter based on a staged-perception of the inverter voltage vector diagram. The algorithm is applied to control a three-stage eighteen-level hybrid inverter, which has been designed with a maximum number of symmetrical levels. The inverter has a two-level main stage built using a conventional six-switch inverter and medium- and low- voltage three-level stages constructed using cascaded H-bridge cells. The distinctive feature of the proposed algorithm is its ability to avoid the undesirable high switching frequency for high- and medium- voltage stages despite the fact that the inverter's dc sources voltages are selected to maximize the number of levels by state redundancy elimination. The high- and medium- voltage stages switching algorithms have been developed to assure fundamental switching frequency operation of the high voltage stage and not more than few times this frequency for the medium voltage stage. The low voltage stage is controlled using a SVPWM to achieve the reference voltage vector exactly and to set the order of the dominant harmonics. The inverter has been constructed and the control algorithm has been implemented. Test results show that the proposed algorithm achieves the desired features and all of the major hypotheses have been verified.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2009.11a
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• pp.160-160
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• 2009

In recent years, the merging of nanomaterials and nano-technology into electro-optic (EO) device technology such as liquid crystal displays (LCDs) has attracted much attention because of their unique electro- and magneto-optic properties and novel display applications. One example of hybrid LC-inorganic systems is semiconductor nanorods added to LC for their strong reorientation effect and tunable refractive index. Doping of nanoparticles in LC or polymers can lead to changes in performance characteristics such as electro-optical, dielectric, memory effect, phase behavior, etc. Due to the tunability of LCDs with mixed inorganic materials, low voltage operation of a LC system can also be achieved using the significant electro-optical effect achieved through suspension of ferroelectric nanoparticles in NLC.

• JOURNAL OF ELECTRICAL WORLD
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• s.451
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• pp.46-58
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• 2014

At the end of 2013, there were 434 nuclear power reactors in operation worldwide, with a total capacity of 371.6 GW(e), approximately 80 % had been in service 20 years and more. Many Member States have given high priority to licensing their nuclear power plants to operate for terms longer than the time frame originally anticipated(e.g. 30 or 40 years). One of challenges for long term operation is cable ageing management. How can qualify the existing cable under harsh environment in nuclear power plant? The paper described the approaches on qualification, condition monitoring, and management of low voltage cables in nuclear power plant.

• ETRI Journal
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• v.34 no.4
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• pp.518-526
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• 2012

This paper proposes LC voltage-controlled oscillator (VCO) phase-locked loop (PLL) and ring-VCO PLL topologies with low-phase noise. Differential control loops are used for the PLL locking through a symmetrical transformer-resonator or bilaterally controlled varactor pair. A differential compensation mechanism suppresses out-band spurious tones. The prototypes of the proposed PLL are implemented in a CMOS 65-nm or 45-nm process. The measured results of the LC-VCO PLL show operation frequencies of 3.5 GHz to 5.6 GHz, a phase noise of -118 dBc/Hz at a 1 MHz offset, and a spur rejection of 66 dBc, while dissipating 3.2 mA at a 1 V supply. The ring-VCO PLL shows a phase noise of -95 dBc/Hz at a 1 MHz offset, operation frequencies of 1.2 GHz to 2.04 GHz, and a spur rejection of 59 dBc, while dissipating 5.4 mA at a 1.1 V supply.

• Proceedings of the KIPE Conference
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• 2002.07a
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• pp.124-128
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• 2002

This Paper propose a novel sensorless drive system for the trapezoidal brushless DC motor in Bow speed region. The inverter DC input voltage is controlled by step-down converter for low speed operation. A indirect rotor position sensing technique based on a detailed analysis of the terminal voltage characterisrics is proposed in this paper. A sensorless drive system is implemented using a TMS320F240 for the main process and IPM(Intelligent Power Module) for the inverter.

• Journal of Power Electronics
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• v.13 no.4
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• pp.507-515
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• 2013

This paper presents an isolated bidirectional dc/dc converter based on primary parallel isolated boost converter (PPIBC). This topology is an efficient solution in low voltage high power applications due to its ability to handle high currents in the low voltage side. In this paper, the converter has been modeled using non-ideal components and operated without any additional circuitry for startup using a digital soft-start procedure. Simulated and measured loop gains have been compared for the validity of the model. On-the-fly current direction change has been achieved with a prototype interconnecting two battery banks. A second prototype has been constructed and tested for supercapacitor operation in constant power charge mode.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.350-352
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• 1996

A Hight Efficiency Quasi-Parallel Resonant DC-Link Inverter which shows highly improved PWM capability, low loss characteristic and low voltage stress is presented. A method to minimize freewheeling interval, which is able to largely decrease DC-link operation losses and to steadily guarantee soft switching in the wide operation region is proposed. Analysis and simple experiments were performed to verify validity of the proposed inverter topology.

• Proceedings of the KIEE Conference
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• 2006.07c
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• pp.1372-1373
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• 2006

An electrostatic discharge (ESD) protection device, so called, N-type SCR with P-type MOSFET pass structure (NSCR_PPS), was analyzed for high voltage I/O applications. A conventional NSCR_PPS device shows typical SCR-like characteristics with extremely low snapback holding voltage, which may cause latchup problem during normal operation. However, a modified NSCR_PPS device with proper junction/channel engineering demonstrates highly latchup immune current- voltage characteristics.

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.190-193
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• 2006

we implemented pentacene TFTs able to operate at low voltage less than 2V by using ultrathin Al2O3 layer as a gate insulator. The OTFTs exhibited a mobility of $0.27{\pm}0.05\;cm^2/Vs$, an outstanding subthreshold slope of $0.109{\pm}0.027$, and an on/off current ratio of $2.87{\pm}1.07{\times}10^4$. OTFT operated at low voltage, producing 3.5uA at $V_GS$= 2V and $V_DS$= 1.5V.

• 한국정보디스플레이학회:학술대회논문집
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• 2000.01a
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• pp.143-144
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• 2000

The aerosol pyrolysis technique was introduced to prepare the spherical phosphors for enhancing low-voltage phosphor efficiency. The density, the shape, and the crystallinity of phosphors were controlled by thermal decomposition temperature and phosphor annealing condition. The particle size was adjusted by the precursor concentration and reactor pressure. It was fond that the efficiency of phosphors synthesized in this work was superior to the commercial products at the low-voltage excitation by 1.5 times and the screen efficiency was also higher than that of any value reported in literature.