• Journal of Power Electronics
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• 제16권3호
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• pp.849-860
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• 2016

The high-switching-frequency operation of power converters can achieve high power density through size reduction of passive components, such as capacitors, inductors, and transformers. However, a small-output capacitor that has small capacitance and low effective series resistance changes the small-signal model of the converter power stage. Such a capacitor can make the converter unstable by increasing the crossover frequency in the transfer function of the small-signal model. In this paper, the design and implementation of a high-frequency LLC resonant converter are presented to verify the power density enhancement achieved by decreasing the size of passive components. The effect of small output capacitance is analyzed for stability by using a proper small-signal model of the LLC resonant converter. Finally, proper design methods of a feedback compensator are proposed to obtain a sufficient phase margin in the Bode plot of the loop gain of the converter for stable operation at 500 kHz switching frequency. A theoretical approach using MATLAB, a simulation approach using PSIM, and experimental results are presented to show the validity of the proposed analysis and design methods with 100 and 500 kHz prototype converters.

• JSTS:Journal of Semiconductor Technology and Science
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• 제10권1호
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• pp.55-60
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• 2010

For battery-powered device applications, which grow rapidly in the electronic market today, low-power becomes one of the most important design issues of CMOS VLSI circuits. A multi-VDD system, which uses more than one power-supply voltage in the same system, is an effective way to reduce the power consumption without degrading operating speed. However, in the multi-VDD system, level converters should be inserted to prevent a large static current flow for the low-to-high conversion. The insertion of the level converters induces the overheads of power consumption, delay, and area. In this paper, we propose a new level converter which can provide the level up/down conversions for the various input and output voltages. Since the proposed level converter uses only one power-supply voltage, it has an advantage of reducing the complexity in physical design. In addition, the proposed level converter provides lower power and higher speed, compared to existing level converters.

• 전력전자학회논문지
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• 제26권3호
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• pp.222-226
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• 2021

To comply with CE marking requirements, the electromagnetic compatibility (EMC) and low-voltage directive (LVD) tests are conducted on the sub-racks of International Thermonuclear Experimental Reactor (ITER) AC/DC converters and bypass switches. The EMC tests consist of a series of tests, including the electromagnetic interference test, the electromagnetic field immunity test, and the rapid transient burst immunity test. In the LVD test, the electric shock protection test, the xcessive temperature limit and heat resistance of equipment tests, and the fire spread prevention test are performed. This work presents and reviews the European Directive for EMC/LVD and introduces the methods of EMC and LVD tests for the sub-racks of AC/DC converters and bypass switches. It also evaluates the test method and results to meet the European Directive requirements for CE marking. The sub-racks of ITER AC/DC converters and bypass switches successfully pass the EMC and LVD tests.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2017년도 추계학술대회
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• pp.83-84
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• 2017

The heat treatment performed during the welding of the structure should adjust the temperature of the structure in several steps in order to further improve the welding performance. This paper proposes a technique to control multiple SCR power converters to control the temperature of each ceramic heater at various stages according to a specified time.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1999년도 전력전자학술대회 논문집
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• pp.122-125
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• 1999

The AC-to-DC single-phase PWM rectifier for traction applications using high power semiconductor, IGCT is made and tested. Parallel operation of two PWM converter is adopted for increasing capacity of converters. For reducing harmonics, the harmonic content is eliminated by the phase shift between two converters switching phase. The output voltage control is achieved by interns calculation without detecting the input current. The part of PLL used for controlling power factor is simply implemented by software.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.258-263
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• 1998

A comparative study of single-phase PWM converters having active filtering functions both on ac-input and dc-output sides have been carried out. Based on the function of the dc-output side active filter, two types of configurations, the RPM (ripple power managing) type and the APM (average power managing) type are compared to show their contrastive characteristics. The prototype system using DSP based control algorithms, i.e. deadbeet current control and voltage sensor-less technique using full-order observer, show the availability of the proposed system.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1998년도 추계종합학술대회 논문집
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• pp.991-994
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• 1998

We demonstrate wavelength conversion of 2.5 Gb/s optical signals by cross-gain modulation (XGM) in a semiconductor optical amplifier (SOA). We investigate the effect of input pump and probe powers on the extinction ratio and power penalty to be a measure of performance in wavelength converters. As a result, we show that the best bit error rate (BER) performance can be obtained when the probe power is kept 3 dB weaker than the pump power. And we investigate the effect of wavelength detuning on performance in wavelength converters.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1992년도 하계학술대회 논문집 B
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• pp.988-991
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• 1992

A new zero voltage switching PWN converter family is presented by using a new ZVS PWN module (ZPM) with a saturable inductor which prevents diode junction capacitors and a commutation inductor from resonating. The new converters show almost all characteristics of the conventional PWN converters. A boost ZVS PWN converter is applied to a power factor correction circuit. It operates on an continuous conduction mode. Experimental results for output power of 1kW are presented.

• Journal of Power Electronics
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• 제10권3호
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• pp.270-276
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• 2010

In this paper, a capacitance estimation scheme for DC-link capacitors for single-phase AC/DC PWM converters is proposed. Under the no-load condition, a controlled AC current (30[Hz]) is injected into the input side, which then causes AC voltage ripples at the DC output side. Or, a controlled AC voltage can be directly injected into the DC output side. By extracting the AC voltage/current and power components on the DC output side using digital filters, the capacitance value can be calculated, where the recursive least squares (RLS) algorithm is used. The proposed methods can be simply implemented with software only and additional hardware is not required. From the experiment results, a high accuracy estimation of capacitances less than 0.85% has been obtained.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.898-902
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• 1998

Voltage and harmonic stability characteristics of capacitor commutated converters applied to a BTB (back to back) system (CCC-BTB) are analyzed and compared to characteristics of a BTB system composed of conventional line commutated converters (LCC-BTB). About 1.6 times larger safe operating regions can be obtained for the CCC-BTB system compared to the latter. The CCC-BTB system results in no harmonic instability problem as it has no shunt reactive compensators in the station and the adjoining AC system generates no low anti-res onance points.