• Proceedings of the KIEE Conference
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• 2003.10b
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• pp.166-170
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• 2003

This paper presents the TTFC(Two Transistor Forward Converter) using Synchronous Rectifier of Compulsory Control-driver. The two transistor forward circuit is used to decrease voltage stress of primary side and the synchronous rectifier is used to reduce current stress of secondary side. Previous synchronous rectifier's MOSFET of TTFC have long dead time This paper presents synchronous rectifier of compulsory control-driver for minimized dead time. This paper compared with diode rectifier, self-driven synchronous rectifier and compulsory control-driver synchronous rectifier of TTFC. The principle of operation, feature and design considerations are illustrated and verified through the experiment with a 200W 100kHz MOSFET based experimental circuit.

• Journal of Power Electronics
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• v.16 no.3
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• pp.905-914
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• 2016

A high-performance rectifier is introduced in this study. The proposed rectifier combines the conventional pulse width modulation, soft commutation, and instantaneously average line current control techniques to promote circuit performance. The voltage stresses of the main switches in the rectifier are lower than those in conventional rectifier topologies. Moreover, conduction losses of switches in the rectifier are certainly lower than those in conventional rectifier topologies because the power current flow path when the main switches are turned on includes two main power semiconductors and the power current flow path when the main switches are turned off includes one main power semiconductor. The rectifier also adopts a ZCS-PWM auxiliary circuit to derive the ZCS function for power semiconductors. Thus, the problem of switching losses and EMI can be improved. In the control strategy, the controller uses the average current control mode to achieve fixed-frequency current control with stability and low distortion. A prototype has been implemented in the laboratory to verify circuit theory.

• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.232-233
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• 2010

This paper investigates occupational exposure to time-varying magnetic field generation in high power rectifier systems. Two different kinds of high power rectifier systems of 25kA are modeled and analyzed. The performance is compared and evaluated on the basis of exposure guidelines from ICNIRP. In order to focus on the qualitative effect of rectifier operation, the mechanical structure of current carrying conductors is simplified as infinite long bus-bar model and low frequency harmonic contents up to 65kHz are considered. Thyristor rectifier generates a significant amount of low frequency magnetic field harmonic contents both at ac and dc side of rectifier infringing the limit from ICNIRP. The multilevel rectifier-IGCT type has almost negligible field generation from ac input side and smaller harmonic contents in dc load side complying with ICNIRP guideline. This remarkable advantage of multilevel rectifier-IGCT type can lead to very simple site layout design for installation and cost-effective compliance to guideline of occupational exposure against magnetic field.

• Proceedings of the KIEE Conference
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• 2005.10c
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• pp.178-181
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• 2005

This paper presents a synchronous rectifier in a LLC half bridge topology. The proposed synchronous rectifier is used to a current driven synchronous rectifier(SR). If FET is driven without dead times. Voltage driven synchronous rectifier may introduce voltage and current surge during the zero dead times. To solve this problem, we propose to use modified current driven synchronous rectifier. Finally, the prototype is built and comparison on the current and voltage driven synchronous rectifier(SR).

• Proceedings of the KIEE Conference
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• 1998.07f
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• pp.1940-1943
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• 1998

A new PWM rectifier which offers a unity power factor is proposed. The circuit has same inductance as the conventional boosting type PWM rectifier in powering mode, but the inductance is splitted to 2 part in freewheeling mode. So the period of freewheeling mode is shorter than that of conventional boosting type PWM rectifier, and discontinuous input current is obtained in wide duty range. Therefore the proposed PWM rectifier accomplishs a unity power factor in wide range of duty ratio and boosting factor. And the conventional boosting type PWM rectifier has poor power factor near the unity boosting ratio, the proposed PWM rectifier improves this problem. The mathmatical analysis are presented and experimental results are given.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.648-653
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• 1998

The conventional three-phase rectifier with bulky LC output filter has been widely used in the industry because of its distinctive advantages over the active power factor correction rectifier such as simple circuit, high reliability, and low cost. Over than 0.9 power factor can be achieved, which is acceptable in most of industry applications. This rectifier, however, is not easy to use for high power density applications since the LC filter is bulky and heavy. To solve this problem, a new simple rectifier is presented in this paper. By eliminating the bulky LC filter from the conventional diode rectifier without losing most of the advantages of the conventional rectifier, very high power density power conversion with high power factor can be achieved. Operation principle and design considerations are illustrated and verified by Pspice simulation and experimental results from a prototype of 3.3 kW rectifier followed by 100KHz zero voltage switching full bridge PWM converter

• Journal of electromagnetic engineering and science
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• v.14 no.1
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• pp.25-30
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• 2014

This paper discusses the design of a high frequency Greinacher voltage multiplier as rectifier; it has a greater conversion efficiency and higher output direct current (DC) voltage at high power compared to a simple halfwave rectifier. Multiple diodes in the Greinacher voltage multiplier with distributed circuits consume excited power to the rectifier equally, thereby increasing the overall power capacity of the rectifier system. The proposed rectifiers are a Greinacher voltage doubler and a Greinacher voltage quadrupler, which consist of only diodes and distributed circuits for high frequency applications. For each rectifier, the RF-to-DC conversion efficiency and output DC voltage for each input power and load resistance are analyzed for the maximum conversion efficiency. The input power with maximum conversion efficiency of the designed Greinacher voltage doubler and quadrupler is 3 and 7 dB higher, respectively;than that of the halfwave rectifier.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.3
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• pp.15-26
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• 2008

This paper proposes a new sinusoidal rectifier which improves input factor and input current waveform without complicated switching modulation such as pulse width or a complicated feed back control. The proposed rectifier consists of a pair of capacitors connected in series, a full bridge diode rectifier, a pair of inductors, and a pair of switching devices connected in series. While the configuration of the sinusoidal rectifier is simple in itself, it effectively reduces the reactive power and harmonics involved(IEC555-2 SC77A90 Class C) in input line current. The excellent properties of the new sinusoidal rectifier are verified by theoretical analysis and experimental results.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.48 no.2
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• pp.90-94
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• 2011

In this paper, the energy transfer is associated with high frequency band and try to analysis the rectifier circuit structure and characteristics and find ways to maximum efficiency. Input signal at 13.56MHz is converted output DC signal with the experiments and measurements. Rectifier cirsuits can be divided into the half-wave, full-wave, bridge rectifier circuit. Research to the present with the passive components are carried out with a focus on efficiency improvements. Factors affecting the efficiency of rectification is dependent on the characteristics of the device. In this experiment, about 70% efficiency can be measured. By using an improved device for high efficiency could be obtained higher efficiency.

• Journal of Electrical Engineering and Technology
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• v.9 no.3
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• pp.1132-1136
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• 2014

In the context of increasing electric energy consumption in a data center, energy efficiency improvement is strongly emphasized. In a data center, electric energy is largely consumed by DC power supply system, which is based on a rectifier composed by multiple parallel converters. Therefore, rectifier efficiency must be improved for minimizing loss of DC power supply system. Rectifier efficiency can be modulated by load allocation to converters because converter efficiency depends on input AC power. In this paper, we propose a new control method to maximize rectifier efficiency. The method can control load allocation to converters by introducing active power converter control scheme and start-and-stop of converters. In order to illustrate optimal load allocations in a rectifier, a maximization problem of rectifier efficiency is formulated as a nonlinear optimization one. The problem is solved by Lagrangian relaxation method and the computation results provide the validity of proposed method.