• Proceedings of the KIEE Conference
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• 대한전기학회 2003년도 하계학술대회 논문집 B
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• pp.1184-1186
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• 2003

In this paper, a charge controlled asymmetrical half-bridge (ASHB) dc-to-dc converter is presented. For ASHB do-to-dc converter, the peak current-mode control was found to be problematic primarily due to the oscillatory behavior of the current feedback signal. To resolve this problem, a charge control method is applied to the ASHB do-to-dc converter. A 50W prototype ASHB dc-to-dc converter was built, and successfully tested.

• Proceedings of the KIEE Conference
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1151-1153
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• 2004

In this paper, small-signal modeling and closed-loop performance of charge control employed to an asymmetrical half-bridge (ASHB) dc-to-dc converters are investigated. The charge control is selected as an alternative to the conventional voltage-mode control and peak current-mode (PCM) control, which have their respective limitations and problems when adapted to ASHB dc-to-dc converters. The current-loop dynamics of the charge control are presented in comparison with those of voltage-mode and PCM control. This paper demonstrates that the charge control offers better dynamic performance compared to voltage-mode control and superior noise characteristics compared to PCM control. The potential problem of charge control are also addressed.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제10권7호
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• pp.1266-1274
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• 2006

A non-overlap boosted-clock charge pump(NBCCP) with internal pumping capacitor, an advantageous circuit from a minimizing point of TFT-LCD driver IC module, is proposed in this paper. By using the non-overlap boosted-clock swinging in 2VDC voltage, the number of pumping stages is reduced to half and a back current of pumping charge from charge pumping node to input stage is also prevented compared with conventional cross-coupled charge pump with internal pumping capacitor. As a result, pumping current of the proposed NBCCP circuit is increased more than conventional cross-coupled charge pump, and a layout area is decreased. A proposed DC-DC converter for TFT-LCD driver IC is designed with $0.18{\mu}m$ triple-well CMOS process and a test chip is in the marking.

• Proceedings of the KIPE Conference
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.350-352
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• 2007

Modularized charge equalization converter for HEV lithium-ion battery cells is proposed in this paper, in which intra-module and inter-module charge equalization can be achieved at the same time. For intra-module charge equalization, the conventional flyback DC/DC converters of low power and small size are employed, in which all of the primary sides are coupled in parallel for selective charge of the specific under charged cell within the module. For inter-module charge equalization, the flyback DC/DC converters are also added, in which all the secondary windings are electrically linked in parallel for automatic charge balancing among the modules. An engineering sample of forty cells hiring the proposed cell balancing scheme is implemented and its experimental result shows that the proposed modularized charge equalization circuit has good cell balancing performance.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 한국전기전자재료학회 2001년도 춘계학술대회 논문집 유기절연재료 전자세라믹 방전플라즈마 연구회
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• pp.96-100
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• 2001

We have measured the space charge distribution and PD patterns simultaneously in XLPE under AC voltages by modified PEA method in order to investigate the effect of space charge on PD patterns in XLPE with air-gap. From the experimental results, we found that the dynamic space charge accumulated on the surface of XLPE due to the PD dominantly affects the PD pattern in the dielectric-barrier structure and governs the voltage across the air-gap. Moreover, the space charge formed by applying DC voltage still remained after applying AC voltage, which means that the space charge formed during DC strength test is likely to be fatal to the long-time AC insulating characteristics of HV equipments. On the other hand, the PD patterns was much influenced by the pre-formed space charge by DC application. Therefore, it is possible to detect the effects of space charge by monitoring the infinitesimal change of PD patterns before and after DC strength.

• JSTS:Journal of Semiconductor Technology and Science
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• 제14권5호
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• pp.549-556
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• 2014

This paper proposes a highly power-efficient single-inductor multiple-outputs (SIMO) DC-DC converter with a gate charge sharing method in which gate charges of output switches are shared to improve the power efficiency and to reduce the switching power loss. The proposed converter was fabricated by using a $0.18{\mu}m$ CMOS process technology with high voltage devices of 5 V. The input voltage range of the converter is from 2.8 V to 4.2 V, which is based on a single cell lithium-ion battery, and the output voltages are 1.0 V, 1.2 V, 1.8 V, 2.5 V, and 3.3 V. Using the proposed gate charge sharing method, the maximum power efficiency is measured to be 87.2% at the total output current of 450 mA. The measured power efficiency improved by 2.1% compared with that of the SIMO DC-DC converter without the proposed gate charge sharing method.

• 한국정보디스플레이학회:학술대회논문집
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• 한국정보디스플레이학회 2004년도 Asia Display / IMID 04
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• pp.1011-1014
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• 2004

In this paper, we present a new DC-DC converter for gate driver circuit in low temperature poly-Si TFT technology. It is composed of a newly developed charge pump circuit and a regulator circuit. When the input voltage is 5V, the efficiency of a positive charge pump used in the DC-DC converter and that of a negative charge pump is 69.0% and 57.1%, respectively. The output voltage of DC-DC converter varies 200mV when the target voltages of DC-DC converter are 9V, -6V and the threshold voltage of TFTs varies ${\pm}$ 0.5V.

• The Journal of the Korea institute of electronic communication sciences
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• 제10권12호
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• pp.1337-1344
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• 2015

Formation process through charge/discharge operation is needed in manufacturing Li-ion battery. In the process battery is discharged by a load resistor of discharger. Here, energy losses happen. Therefore, in this paper, the efficient energy operation of battery is studied in the charge/discharge system based on DC ${\mu}-Grid$. A result of computer simulation shows that if in the charge/discharge system based on DC ${\mu}-Grid$, the number of discharge batteries in comparison with three charge battery sets exceeds 133%, voltage fluctuation that occurs while the grid voltage stabilizes, which makes the system fatal. Therefore, it was demonstrated that a remarkable energy saving effect could be achieved when the number of discharge battery set is maintained to be 133% in comparison with three charge battery sets.

• Journal of Power Electronics
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• 제11권6호
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• pp.811-818
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• 2011

Modulation strategies for multilevel inverters have typically focused on synthesizing a desired set of sinusoidal voltage waveforms using a fixed number of dc voltage sources. This makes the average power drawn from different dc voltage sources unequal and time varying. Therefore, the dc voltage sources are unregulated and require that corrective control action be incorporated. In this paper, first two new selections are proposed for determining the dc voltage sources values for asymmetric cascaded multilevel inverters. Then two modulation strategies are proposed for the dc power balancing of these types of multilevel inverters. Using the charge balance control methods, the power drawn from all of the dc sources are balanced except for the dc source used in the first H-bridge. The proposed control methods are validated by simulation and experimental results on a single-phase 21-level inverter.

• Transactions on Electrical and Electronic Materials
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• 제7권5호
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• pp.224-229
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• 2006

Many studies have been done on the application of residual charge measurement in cable degradation diagnosis. In this paper, the behavior of residual charges measured with water-tree degraded XLPE sheets and cable are discussed. At charge injection process, the charge is injected by applying dc voltage as a conventional method, suddenly cut-off ac voltage or impulse voltage. Therefore the residual charge is influenced by the applying process. At charge release process, transient dc current flows when applying ac high voltage and also ac high voltage superimposed to dc low voltage. From the results, new diagnosis method is suggested.