• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.14-20
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• 1997

Due to several advantages of Pulse Width Modulated(PWM) Converter, such as unity power factor with low-harmonics and energy regeneration, PWM converter has been widely used in industrial application. In every application of energy conversion equipment, the design and implementation must be carried out considering performance and cost. High quality with low cost is the best choice for energy conversion equipment. High dc link voltage can reduce inverter and motor side losses and system dimension compare to low dc link voltage. Analog controller can make PWM converter cheaper without considerable degradation of the performance than digital controller. This paper shows the simplified analog controller-for 600V dc link voltage using stationary reference frame control and the simulation results.

• Proceedings of the KIPE Conference
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• 2001.12a
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• pp.171-174
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• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance .value is changed by the polarity of current or voltage. and this paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse width modulated (PWM) inverter with half pulse-width modulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Journal of Power Electronics
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• v.18 no.4
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• pp.1007-1014
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• 2018

A novel dual DC-DC flyback converter with leakage-energy recycling is presented in this paper. Only an active switch is used for this converter. A pulse-width-modulation strategy is adopeted to control this switch. Two transformers are employed for the proposed converter. During the switch ON-period, the primary windings of the two transformers store energies. At the switch OFF-period, the energies stored in the primary windings of the two transformers are released to the output via the secondary windings of the two transformers. Meanwhile, the leakage energies of the two transformers can be recycled. The operating principles and steady-state analyses of the proposed converter are described in detail. A prototype circuit of the proposed converter is implemented for verifying the performances.

• Proceedings of the KIEE Conference
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• 2001.07b
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• pp.1044-1048
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• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage. This paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is, it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse-width modulated (PWM)inverter with half pulse-width modulated (HPWM) inverter proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2006.06a
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• pp.249-250
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• 2006

In this paper, hardware design and implementation of digital controller for the High Precision Digital Power Supply (HPDPS) based on Digital Signal Processor (DSP) and Field Programmable Gate Array (FPGA) is presented. Developed digital controller is composed of high resolution Digital Pulse Width Modulation (DPWM) and high resolution analog to digital converter circuit with anti-aliasing filter. And Digital Signal Processor (DSP) has the capability of a few micro-second calculation time for one feedback loop. 32-bit DSP and DPWM with 150[ps] step resolution is used to implement the HPDPS. Also 18-bit 2 mega sample per second ADC board is adopted for the developed digital controller. Also, hardware structure of the developed digital controller and experimental results of the first prototype board for HPDPS is described.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.5A
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• pp.514-520
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• 2004

In WDM networt a WDM buffer is one of essential elements for realizing all-optical packet switching system. In this paper, we propose and demonstrate a single loop type all-optical WDM buffer system. The proposed one consists of NOLM and feedback loop, and provides more than 40 turns buffering (more than 20${\mu}\textrm{s}$) for single input pulse (1550nm, width: 20㎱) before selected by control signal pulse (1553nm, width: 30㎱).

• Journal of Power Electronics
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• v.12 no.3
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• pp.448-457
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• 2012

This paper proposes a carrier-based pulse width modulation (PWM) method to control an indirect matrix converter (IMC) by analyzing the relationship between the space vector PWM (SVPWM) and the carrier-based PWM. The complexity of the SVPWM method for an IMC can be reduced by using an equivalent carrier-based PWM method. The advantage of the proposed algorithm is its ability use only one symmetrical triangular carrier signal to generate the gate signals for all of the power switches in both the rectifier and inverter stages as compared to the conventional method where the carrier signal used in the rectifier stage is different from that of the inverter stage. In addition, by using a suitable offset voltage component in the modulation signals, the output voltage magnitude reaches 0.866 of the input voltage magnitude. Simulation and experimental results are provided in order to validate the proposed method.

• Proceedings of the KIEE Conference
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• 1998.07a
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• pp.46-48
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• 1998

This paper introduces the design method of a variable reluctace liner pulse motor to be analysed by a 3-dimensional problem in the 2-dimension. And it shows the thrust force density with respect to the ratio of the slot width to the teeth width, the height of mover and the height of tooth.

• Proceedings of the IEEK Conference
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• 2001.06e
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• pp.241-244
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• 2001

This paper proposes a nonlinear impedance circuit composed by diodes and inductors or capacitors. This circuit needs no control circuits and switches, and the impedance value is changed by the polarity of current or voltage, This paper presents one of these applications to improve the input current of capacitor input diode rectifiers. The rectifier using the nonlinear impedance circuit id constructed with four diodes and four capacitors in addition to the conventional rectifiers, that is it has eight diodes and five capacitors, including a DC link capacitor. It makes harmonic components of the input current reduce and the power factor improve. A circuit design method is shown by experimentation and confirmed simulation. It explained that compared conventional pulse-width modulated (PWM)inverter with half pulse-width modulated (HPWM) inverter. Proposed HPWM inverter eliminated dead-time by lowering switching loss and holding over-shooting.

• Journal of Power Electronics
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• v.16 no.1
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• pp.121-132
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• 2016

In this paper, high-efficiency design methodology of a zero-voltage-switching full-bridge (ZVS-FB) pulse width modulation (PWM) converter for server-computer power supply is discussed based on self-driven synchronous rectifier (SR) performance. The design approach focuses on rectifier conduction loss on the secondary side because of high output current application. Various-number parallel-connected SRs are evaluated to reduce high conduction loss. For this approach, the reliability of gate control signals produced from a self-driver is analyzed in detail to determine whether the converter achieves high efficiency. A laboratory prototype that operates at 80 kHz and rated 1 kW/12 V is built for various-number parallel combination of SRs to verify the proposed theoretical analysis and evaluations. Measurement results show that the best efficiency of the converter is 95.16%.