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In this paper, we propose a new capacitor degradation evaluation method aimed at failure prediction and suitable for digitally controlled switching mode power supply (SMPS) for servers. Electrolytic capacitors have one of the highest component failure rates in SMPS; therefore, we attempt to detect an equivalent series resistance degradation of the electrolytic capacitor directly from the data fetched...
Solar-to-hydrogen energy conversion is a promising technology because it enables high-capacity, long-term storage of solar energy. We propose a new highly efficient solar-to-hydrogen conversion system consisting of multiple converter-electrolyzer sets connected in parallel to a photovoltaic (PV) array. This system is flexible to apply to various PV configurations. One-day simulations based on measured...
Among various converters, the LLC electric current resonant converter attracts attention because of high power density, low noise and high efficiency. However, this converter cannot apply the analysis of averaging method, and impossible to derivate the transfer function, so designing is difficult. In this study, we devised a method to derive a frequency response characteristic with a transfer function...
We developed a high-current-density, point-of-load (POL) converter for high performance Field Programmable Gate Array (FPGA) used in telecommunications systems. We applied the model-based development (MBD) method to realize the high-current density converter. Model in the loop simulation (MILS) was applied for precise loss analysis of the converter. The rapid control prototyping process (RCP) was...
In smartphone and tablet devices, surface temperature management is required to ensure safety for the prevention of burn injuries. Therefore, mobile devices must have a mechanism of functional restriction to control the surface temperature, but this in turn also leads to performance degradation. It is preferable to control the surface temperature under the safety threshold while minimally affecting...
In this paper, we report the low stability phenomenon of digitally controlled switching mode power supply (SMPS) caused by Equivalent Serial Resistance (ESR) degradation of electrolytic capacitor. The ESR of the output capacitor stack of SMPS is known as the dumping factor in a control loop that enhances SMPS stability. However, while studying electrolytic capacitor degradation in digitally controlled...
This paper presents a new cost effective method for a failure prediction of a digitally controlled Switching Mode Power Supply (SMPS). Electrolytic capacitor is known as one of the highest failure rate components in SMPS, so we tried to detect an Equivalent Series Resistance (ESR) degradation of the electrolytic capacitor directly from the data fetched to a digital controller of SMPS. With a SPICE...
This paper reports an attempt to generate production-ready embedded software for a digital controller of two phase double-ended forward converter designed as a part of server power supply. We developed an automatic code generation environment based on MATLAB/Simulink, and made a controller model which realizes an appropriate execution management. Newly developed custom block enabled it. Furthermore,...
In this paper, we report the first rapid control prototyping (RCP) system with a sub-nanosecond (ns) high-resolution Pulse Width Modulation (PWM) for server power supply circuits. Conventional RCP systems are designed mainly for engine and motor control. Based on the relevant response time and control accuracy requirements, their PWM update periods and resolutions are over 100 microseconds (µs) and...
The purpose of this study is to improve the efficiency of a boost-type power factor correction (PFC) circuit with a digital controller. One of the biggest losses in PFC circuits is the switching loss. Switching loss can be reduced by low boost ratio operation, but these results in a greater voltage drop at transient response. The voltage drop can be suppressed by using a high gain setting for the...
Optimal techniques for power supply with transient current circuit are introduced in this paper. The circuit reduces switching loss of buck converter's main switch effectively. However, in our previous researches, it could be operated with high efficiency only at heavy loading. The techniques to get rid of this disadvantage are proposed and the validity of it is verified through experiments.
Tow phase double-ended forward converter is suitable for more than 2kW high efficiency power supply by the feature of low surge voltage. One issue of the converter is dead-time loss of synchronous rectifier FETs. In this paper, we propose a precise digital dead-time control method for a 2.5 kW (12 V / 208 A) output power supply. Proposed method is confirmed by experiment and theoretical analysis that...
Wide-gap semiconductors such as SiC and GaN have seen widespread increase in interest as promising materials for use in next-generation power devices. In this paper, we present a 2.5-kW power supply unit (PSU) designed for ICT systems with engineering samples of Fujitsu Semiconductor Ltd. (FSL) 's GaN-HEMTs installed in the power factor collection (PFC) circuit. A new PFC circuit specially designed...
Soft switching for power factor collection (PFC) of high-end server power supply unit (PSU) is studied. FET loss of PFC circuit is caused by Ron-related loss and switching loss. The switching loss consists of switching-speed-related part and output capacitance (Coss)-related part. The switching-speed related-part can be reduced by using a high-speed FET and high-power gate driver; however, Coss-related...
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