• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1437-1443
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• 2017

Electric energy is consumed or regenerated according to an operation of electric rail cars in urban railway power substations. A thyristor dual converter system is used to deal with the electric energy. Since the AC input voltage of power substations is $22.9kV{\pm}10%$, the magnitude of the AC voltage fluctuates according to load conditions, so the secondary side voltage of the DDY transformer also fluctuates. In the thyristor dual converter, the response characteristics of the DC output voltage and the DC output current are changed based on an initial firing angle in the cross mode conversion between the forward mode and the reverse mode. Therefore, this paper proposes the initial firing angle tracking algorithm considering fluctuation of the AC input voltage. The effectiveness of the proposed algorithm is verified by a simulation compared with the conventional algorithm.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.102-110
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• 2016

In this paper, a high-frequency dual mode control LLC resonant converter with wide input voltage range is proposed through zero voltage switching (ZVS) under the universal line input voltage and every load conditions. Conventional small power adapter driving should be satisfied with universal line input voltage because it has no power factor correction circuit regulation. The conventional LLC resonant converter for an adapter can reduce the size of transformer in terms of high-frequency driving and ZVS. However, this converter has a disadvantage in terms of design of resonant tank under various input voltages because the frequency modulation range is very wide to satisfy voltage conversion gain. Compared with the conventional one, the proposed LLC converter can be adapted to universal line input voltage and high-frequency driving because it is controlled by pulse width modulation and pulse frequency modulation with control voltage. The validity of the proposed LLC converter is proved through the 60 W prototype.

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.43-46
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• 2003

The dc reactor type high-Tc superconducting fault current limiter(SFCL) is composed of three parts, a power converter, a magnetic core reactor(MCR) and a dc reactor. This study concerned with the power converter of the DC reactor type high-Tc SFCL. The rectifying devices which power converter of 6.6kV/200A SFCL consists of have to endure high voltage. We propose the dual mode power converter to reduce the voltage which each rectifying device endures. In the single phase the experiment and simulation of dual mode power converter and the simulation of power converter with one bridge rectifier are performed. The current of each system with different power converter has a same tendency and the voltage which rectifying device of dual mode power converter endures is reduced in half by comparison with that of power converter with one bridge rectifier. We found dual mode power converter can be applied to SFCL.

• Journal of Power Electronics
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• v.15 no.6
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• pp.1609-1618
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• 2015

DC microgrids are considered as prospective systems because of their easy connection of distributed energy resources (DERs) and electric vehicles (EVs), reduction of conversion loss between dc output sources and loads, lack of reactive power issues, etc. These features make them very suitable for future industrial and commercial buildings' power systems. In addition, the bipolar-type dc system structure is more popular, because it provides two voltage levels for different power converters and loads. To keep voltage balanced in such a dc system, a bidirectional dual buck-boost voltage balancer with direct coupling is introduced based on P-cell and N-cell concepts. This results in greatly enhanced system reliability thanks to no shoot-through problems and lower switching losses with the help of power MOSFETs. In order to increase system efficiency and reliability, a novel burst-mode control strategy is proposed for the dual buck-boost voltage balancer. The basic operating principle, the current relations, and a small-signal model of the voltage balancer are analyzed under the burst-mode control scheme in detail. Finally, simulation experiments are performed and a laboratory unit with a 5kW unbalanced ability is constructed to verify the viability of the bidirectional dual buck-boost voltage balancer under the proposed burst-mode control scheme in low-voltage bipolar-type dc microgrids.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.4
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• pp.71-79
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• 2015

This paper proposes a new touch screen sensing method that improves the drawback of conventional single-line sensing methods for mutual capacitance touch screen panels (TSPs). It introduces a dual sensing and voltage shifting method, which reduces the ambient noise effectively and enhances the touch signal strength. The dual sensing scheme reduces the detection time by doubling the integration speed using both edges of excitation pulse signals. The voltage shifting method enhances the signal-to-noise ratio (SNR) by increasing the voltage range of integrations, and maximizing the ADC's input dynamic range. Simulation and experimental results using a commercial 23" large touch screen show an SNR performance of 43dB and a scan rate 2 times faster than conventional schemes - key properties suited for a large touch screen panels. We implemented the proposed method into a TSP controller chip using Magnachip's CMOS 0.18um process.

• Journal of Electrical Engineering and Technology
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• v.12 no.2
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• pp.674-682
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• 2017

This paper presents an optimal initial firing angle control based on the energy consumption and regenerative energy of a parallel multi-pulse thyristor dual converter for urban railway power substations. To prevent short circuiting the thyristor dual converter, a hysteresis band for maintaining a zero-current discontinuous section (ZCDS) is essential during mode changes. During conversion from the ZCDS to forward or reverse mode, the DC trolley voltage can be stabilized by selecting the optimal initial firing angle without an overshoot and slow response. However, the optimal initial firing angle is different depending on the line impedance of each converter. Therefore, the control algorithm for tracking the optimal initial firing angle is proposed to eliminate the overshoot and slow response of DC trolley voltage. Simulations and experiments show that the proposed algorithm yields the fastest DC voltage control performance in the transient state by tracking the optimal firing angle.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.56-62
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• 2002

A new high speed and low voltage swing on-chip BUS using threshold voltage swing driver and dual sense amplifier receiver is proposed. The threshold voltage swing driver reduces the rising time in the bus to 30% of the full CMOS inverter driver and the dual sense amplifier receiver increases twice the throughput. of the conventional reduced-swing buses using sense amplifier receiver. With threshold voltage swing driver and dual sense amplifier receiver combined, approximately 60% speed improvement and 75% power reduction are achieved in the proposed scheme compared to the conventional full CMOS inverter for the on-chip bus.

• 한국정보통신설비학회:학술대회논문집
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• 2006.08a
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• pp.179-182
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• 2006

This paper introduce a different-type voltage-controlled oscillator (VCO) for PLL frequency synthesizer, And also the architecture of a high speed low-power-consumption CMOS dual-modulus frequency divider is presented. It provides a new approach to high speed operation and low power consumption. The proposed circuits simulate in 0.35 um CMOS standard technology.

• Journal of Power Electronics
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• v.9 no.1
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• pp.93-99
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• 2009

A new plasma display panel sustaining driver using single side sustaining technique with a dual resonant method is proposed in this paper. Since this circuit enables to keep device voltage stress same as the prior circuit, it can be a low cost circuit compared to a conventional driver. To integrate the sustaining function into one side with a single power source in the driver, a charge pump method is adopted to make negative sustaining voltage and to achieve dual resonant energy recovery on the sustaining modes.

• Journal of IKEEE
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• v.26 no.2
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• pp.271-279
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• 2022

This paper proposes an advanced dead-time compensation method for dual inverter with a floating capacitor. The dual inverter with floating capacitor is composed of double two-level inverters and a bulk electrolytic capacitor. The output voltage of the dual inverter is dropped by the conduction voltage of the power semiconductors. The voltage drop and dead-time cause the fundamental and harmonic distortions of output currents. When supplied power for OEW-load is low, the dual inverter operates as single inverter for effective operation. The dead-time compensation method for the dual inverter operated as single inverter is needed for reliability. The proposed method using band pass filter in this paper compensates dead-time, dead-time error and changed voltage drop error of power semiconductors for the dual inverter and dual inverter operated as single inverter. The effectiveness of the proposed method is verified by simulation results.