• Proceedings of the KIEE Conference
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• 2003.07b
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• pp.1157-1159
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• 2003

In this paper, resonant characteristics of the asymmetrical soft switching half bridge converter is analyzed. The operation principle for proposed converter is explained in steady-state and its operation characteristics by switching frequency is presented with experimental result. Experimental results carried out on a system prototype are included in this paper.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.945-946
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• 2013

• Journal of the Semiconductor & Display Technology
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• v.21 no.3
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• pp.80-86
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• 2022

In this paper, the optimal design and circuit simulation verification results of an LLC resonant half-bridge dc-dc converter using a steady-state model with internal loss resistance are reported. Above all, the input/output voltage gain and frequency characteristic equations in the steady-state were derived by reflecting the internal loss resistance in the equivalent circuit. Based on the results, an LLC resonant half-bridge dc-dc converter with an input voltage of 360-420V, an output voltage of 54V, and a maximum power of 3kW was designed, and to verify the design, the PSIM circuit simulation was executed to compare and analyze the result. In particular, the operating range of the converter could be drawn from the frequency characteristic graph of the voltage gain, and when the converter was operated under light and maximum load conditions, it was confirmed that similar results were obtained by comparing simulation results and calculation results in the switching frequency characteristic graph. In addition, the change of the switching frequency with respect to the load current at each input voltage was compared with the calculated value and the simulation result. As a result, it was possible to confirm the usefulness of the analysis result reflecting the internal loss resistance proposed in this paper and the process of the optimal design.

• The Transactions of the Korean Institute of Power Electronics
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• v.2 no.4
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• pp.19-27
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• 1997

This paper has described about principle and form of proposed circuit made use of soft switching technology ZVS(Zero Voltage Switching) to reduce turn on and off loss at switching. Also, the analysis of the proposed circuit has described generally by using normalized parameter and operating characteristics have been evaluated as to switching frequency and parameters. Based on the characteristics value, a method of the circuit design is proposed. In addition, this paper proves the propriety of theoretical analysis in terms of the experimental waveforms. In the future, this proposed inverter shows that it can be practically used as power source system for induction cooker etc.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.12 s.91
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• pp.1161-1167
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• 2004

The conventional PLL(phase locked loop) frequency synthesizer takes a long switching time because of the inherent closed-loop structure. The digital hybrid PLL(DH-PLL) which includes the open-loop structure into the conventional PLL synthesizer has been studied to overcome this demerit. It operates in high speed, but the hardware complexity and power consumption are the serious problem because the DLT(digital look-up table) is usually implemented by the ROM which contains the transfer characteristic of VCO(voltage controlled oscillator). This paper proposes a new DH-PLL using a very simple DLT-replacement digital logic instead of the complex ROM-type DLT. Also, a timing synchronization circuit for the very small over-shoot and shorter settling time is designed for the ultra fast switching speed at every frequency synthesis. The hardware complexity gets decreased to about $28\%,$ as compared with the conventional DH-PLL. The high speed switching characteristic of the frequency synthesis process can be verified by the computer simulation and the circuit implementation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.2
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• pp.353-360
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• 2017

Recently, due to physical limitation of Si based power semiconductor, development speed of switching power semiconductors is falling and it is difficult to expect any further performance improvements. SiC based power semiconductor with superior characteristic than Si-based power semiconductor have been developed to overcome these limitations. however, there is not method to apply for real system. Therefore, suggested the feasibility and solution for SiC-based power semiconductor system. design to 1kW class DC-DC boost converter and demonstrated the superiority of SiC MOSFET under the same operating conditions by analyzing switching frequency, duty ratio, voltage and current, and comparing with Si based power semiconductor through experimental efficiency according to each system load. The SiC MOSFET has high efficiency and fast switching speed, and can be designed with small inductors and capacitors which has the advantage of volume reduction of the entire system.

• Proceedings of the KIPE Conference
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• 2000.07a
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• pp.468-471
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• 2000

This paper investigates the harmonics of TCSC power transmission system having nonlinear VI characteristic loads. Nonlinear VI characteristic components are modelled with Nortons harmonic current sources. The system parameters such as line impedances admittances and node voltages and the thyristor switching action are described in complex Fourier series. EMTP simulation studies with a detailed three-phase TCSC power transmission system are also performed in order to verify the harmonic analysis at the steady state.

• Proceedings of the KIPE Conference
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• 1999.07a
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• pp.256-259
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• 1999

A new PWM method for voltage source inverters is described. The switching instants determination of the proposed PWM scheme is simple. Therefore, hardware implementation with a microprocessor system is easy and high frequency operation of an inverter can be obtained. The maximum line-to-line output voltage of 3-phase inverter with the proposed scheme is larger than that of the SPWM inverter under a linear modulation region. Principle of the proposed PWM method is described and harmonic characteristic analysis is carried out.

• Proceedings of the KIEE Conference
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• 2001.04a
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• pp.301-303
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• 2001

This paper proposes the boost input type active clamp DC-DC converter featuring the high efficiency and improved EMI characteristics. The main characteristic of the converter is to operate with the non-pulsating input and output currents. Besides, it has the zero-voltage switching (ZVS) and low voltage stress characteristics. For the proposed converter, the detailed operation principles and the simulation results are presented.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.122-124
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• 1998

The inverter circuit of brushless do moter(BLDCM) needs feedback diodes to protect the switching element from counterelectromotive force. In this paper, we describe the computational method of characteristic analysis of BLDCM with feedback diodes by using the FEM.