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Typically full-bridge (FB) converter is used as DC-DC converters for ICT equipment such as routers or servers,. FB converter has essential problem which occurs surge voltage associated with the recovery phenomenon of secondary-side diode. Attaching snubber circuit is the poplar solution, but the circuit occurs another problem such as increasing of the size of circuit and degradation of power efficiency...
Output-inductor-less full-bridge converter for a High-Voltage Direct-Current power distribution system has been proposed. This proposed circuit topology suppresses the surge voltage due to the secondary-side diode's recovery, and miniaturizes the converter because the number of circuit components is reduced. On the other hand, some problems occur, such as the increasing switching-loss of primary switches...
A circularly polarized square MSA with one pair of crank-shaped slit at each edge is proposed for wireless sensor network. The simulated bandwidths of 3dB-axial ratio with 10dB-return loss is 2.398GHz-2.482GHz (3.5%). Moreover, the antenna has the radiation characteristic with wide beam width. The size of the antenna patch is approximately (0.16 wavelength)2. The designed antenna is small in size.
To achieve high power-density isolated dc-dc converter, gallium nitride high electron mobility transistors (GaN-HEMTs) and planar transformer have been used. Also, for the high power-density design, these components are placed close to each other. GaN-HEMTs are significantly affected by the leakage flux of the planar transformer, because of their lateral structure. Therefore, the mutual effects of...
In this paper, a high power-density output-inductor-less full-bridge converter for the HVDC power distribution system is proposed. The new reduction techniques of switching loss and noise in the output-inductor-less full-bridge converter by using SiC-MOSFETs are applied. As the result, the power loss is reduced by 20W in a wide load range, and the noise is also reduced. Furthermore, a high power density...
The Dual Active Bridge (DAB) DC-DC converter is one of the most popular circuits for bi-directional applications because of simple structure. However, DAB DC-DC converter has few problems such as the surge voltage and hard switching in specific conditions. These problems are caused by the relationship between the output power and phase difference, which causes device breakdown and deterioration of...
In this paper, the influence of parasitic components of LLC resonant dc-dc converters operated at MHz-level switching frequency is investigated. In MHz-level switching frequency, value of the parasitic components are getting closer to value of circuit parameters. Therefore, influence of the parasitic components cannot be neglected even in the initial step of the circuit design. In particular, undesirable...
In this paper, a nanosecond level response digital pulse width modulation (PFM) control circuit for the current resonant converter such as LLC has been proposed. The proposed circuit is composed of a unique analog to digital converter and logic based digital controller. With the experimental results, it was confirmed that the switching frequency can be varied from 0.8 to 1.2MHz in regard to 20% variation...
This paper proposes a method to improve the power efficiency in the half-bridge LLC resonant DC-DC converter. The optimum design of a transformer is discussed to improve power efficiency. The interlinkage magnetic flux in the primary and secondary wires causes eddy currents, which results in a power loss. This study demonstrates that power loss can be reduced through optimum design of the strand diameter...
This paper proposes a power-loss reduction technique for a kW-scale isolated dc-dc converter, which installs a novel PWM control to achieve the soft-switching of primary side MOS-FETs. As a result, the efficiency is achieved over 90% in a wide load range. Moreover, the temperature of the primary side MOS-FETs can be reduced by 30 degrees when compared with the conventional method, and the power-density...
A high-voltage full bridge dc-dc converter has a big problem of high-voltage surge occurrence across secondary-side rectifying diodes. In order to solve this problem, a simple solution with a snubber capacitor has been proposed. This technique provides a prominent effect of surge-voltage suppression. On the other hand, it deteriorates the control characteristics of this converter. In this paper, the...
Recently, the power supply network with energy storage devices such as battery has been focused. This network topology uses bi-directional isolated DC-DC converter of low or medium capacity is required for the diversification of power supply network. The dual active bridge (DAB) DC-DC converter is one of the effective bi-directional isolated DC-DC converters. However, the circuit has some instinct...
This paper will discuss about the proposed hard-ware logic type digital controller for on-board SMPS which has a very small time-delay in control loop. Some experimental has been done including estimation of the load current change experiment and the frequency characteristic of open loop transfer function. These result reveal the proposed circuit could be suppressed the time delay to sub-microsecond...
In this study, integrated H-bridge converter with the Matrix-POL power supply system is proposed. From the simulation results, the validity of the Matrix-POL is revealed. The results revealed that the fast response to the load current and the voltage change can be done with duty and parallel number control by the proposed system.
In this paper, the method of the realization of a MHz level switching frequency DC-DC converter for high power-density is presented. For high power-density, Gallium Nitride field effect transistor (GaN-FET) and current-mode resonant DC-DC converter are adopted. In addition, the proposed pulse width modulation (PWM) control method which is suitable for the isolated current-mode resonant DC-DC converter...
In this paper, the proposed hardware logic type digital controller for on-board SMPS which has a very small time-delay in control loop has been described. Some experimental has been done including evaluation of load current change and frequency characteristic of open loop transfer function. These results have been revealed that the proposed circuit could be suppressed the time delay to sub — micro...
In this paper, a proposed pulse width modulation (PWM) control method for the isolated current-mode resonant DC-DC converter with MHz level switching frequency is presented. The circuit topology is same as a conventional resonant converter with synchronous rectification and without any additional components. The control technique for the output voltage regulation is proposed with the unique PWM control...
Recently, the bi-directional dc-dc converter has been focused on because of the huge demand for diversification of power supply network including battery. The dual active bridge (DAB) dc-dc converter is one of the most popular circuits for bi-directional applications because of its simple structure. However, power efficiency at light load is the intrinsic problem of a bi-directional DAB DC-DC converter...
In this study, integrated buck-boost converter with the Matrix-POL power supply system is proposed. From the simulation results, the validity of the Matrix-POL is revealed. The results revealed that the fast response to the load current and the voltage change can be done with duty and parallel number control by the proposed system.
This paper will discuss about the proposed hardware logic type digital controller for on-board SMPS which has a very small time-delay in control loop. Experimental results of the load current change experiment and the frequency characteristic of open loop transfer function has been described respectively. These results reveal the validity of the proposed technique.
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