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Hirachi, Katsuya,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2003 JOURNAL OF POWER ELECTRONICS Vol.3 No.4
The rapid expansion of small computers over the last 10-odd years has brought about great changes in the circumstances affecting UPSs. There are strong demands that UPSs become much smaller and lighter, and more economical, which has resulted in the wide application of the circuit topology without transformer. A disadvantage of such UPS topology is that the DC link voltage is very high, which invites decreased reliability and increased cost of battery bank. Some circuit configurations were proposed to eliminate this disadvantage, but they still had problems. In this paper, a novel circuit configuration which eliminates these problems is proposed and evaluated by the experimental results of prototype UPS.
Hirachi, Kengo Korean Mathematical Society 2000 대한수학회지 Vol.37 No.2
All scalar CR invariants of weight $\leq$ 6 are explicitly given for 3-dimensional strictly pseudoconvex CR structures, as an application of Fefferman's ambient metric construction and its generalization by he author.
Katsuya Hirachi,Mutsuo Nakaoka 전력전자학회 2003 JOURNAL OF POWER ELECTRONICS Vol.3 No.4
The rapid expansion of small computers over the last 10-odd years has brought about great changes in the circumstances affecting UPSs. There are strong demands that UPSs become much smallei and lighter, and more economical, which has resulted m the wide application of tbe circuit topology without transformer A disadvantage of such UPS topology is that the DC link voltage is very high, which invites decreased reliability and increased cost of battery bank Some circuit configurations were proposed to eliminate this disadvantage, but they still had problems In this paper, a novel circuit configuration which eliminates these problems is proposed and evaluated by the experimental results of prototype UPS.
SINGLE-PHASE CURRENT SOURCE INVERTER WITH PULSE AREA MODULATION SCHEME FOR SOLAR POWER CONDITIONER
K.Hirachi,K.Matsumoto,M.Ishitobi,M.Ishibashi,M.Nakaoka 전력전자학회 1998 ICPE(ISPE)논문집 Vol.- No.-
In general, a singte-phase current-fed PWM inverter using IGBTs has some unique advantages for small scale distributed utility-interactive power supply system as compared with voltage-fed PWM inverter. In particular, this is more suitable and acceptable for a non-isolated type utility-interactive power conditioner, which is going to be widely used for residential solar photovoltaic (PV) power generation system in Japan However, this current-fed PWM inverter has a significant disadvantage. The output current of this inverter includes large harmonic contents when the inductance of smoothing reactor in its DC side is not large enough to eliminate its current ripple components of this inverter In order to overcome this problem, a new conceptual pulse area modulation scheme for this inverter is introduced in difference with conventional PWM strategy. This paper presents a new effective control implementation of this PV power conditioner which is able to reduce the harmonic component in the output current produced by the single-phase current-fed PWM inverter even when the npple current in the smoothing DC reactor is relatively large. The operating principle of the proposed control strategy introdued for this inverter system is described, and its simulation results are evaluated and discussed herein.<br/>
Katsuya Hirachi,Makoto Sakane,Takanori Mii,Mutsuo Nakaoka 전력전자학회 1995 ICPE(ISPE)논문집 Vol.1995 No.10
It is essential characteristics for uninterruptible power supply (UPS) to eliminate harmonic currents in its input current and to get unity power factor. Switched mode rectifier (SMR) with a high -frequency transformer link has promising characteristics as a AC/DC conversion circuit for UPS. It does not only eliminate harmonic currents but also provides an isolation between AC input and DC output with a small high frequency transformer. We applied the SMR for the development of UPS with capacity of 2kVA, 3kVA and 5kVA. This paper presents circuit configurations and control strategies of the SMR and the test results of the developed UPS.
Nishimura Kazunori,Hirachi Katsuya,Hiraki Eiji,Ahmed Nabil A.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Power Electronics 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.4
This paper presents an improved three-phase PFC power rectifier with a three-phase diode rectifier cascaded four-switch boost converter. Its operating principle contains the operating principle of two conventional three-phase PFC power rectifiers: one switch boost converter type and a two switch boost converter type. The operating characteristics of the four switch boost converter type three-phase PFC power rectifier are evaluated from a practical point of view, being compared with one switch boost converter type and two switch boost converter topologies.
Kazunori Nishimura,Katsuya Hirachi,Eiji Hiraki,Nabil A. Ahmed,Hyun Woo Lee,Mutsuo Nakaoka 전력전자학회 2006 JOURNAL OF POWER ELECTRONICS Vol.6 No.4
This paper presents an improved three-phase PFC power rectifier with a three-phase diode rectifier cascaded four-switch boost converter. Its operating principle contains the operating principle of two conventional three-phase PFC power rectifiers: one switch boost converter type and a two switch boost converter type. The operating characteristics of the four switch boost converter type three-phase PFC power rectifier are evaluated from a practical point of view, being compared with one switch boost converter type and two switch boost converter topologies.
A Transcutaneous Energy Transformer for A Non Invasive Rechargeable Cardiac Pacemaker Battery
Toshi Hiro Nishimura,Tetsuji Eguchi,Takeshi Inoue,Katsuya Hirachi,Masafumi Majima,Kouji Kuwana 전력전자학회 1995 ICPE(ISPE)논문집 Vol.1995 No.10
The improvement method of a flat secondary transcutaneous transformer for a resonant converter that transfers several W of power across a large variable human skin gap is presented and built The converter can power a novel cardiac pacemaker battery through intact skin by using a transcutaneous transformer with an air gap, which is 10 mm The secondary transformer is piled and the coupling coefficient and the conversion efficiency are measured with an experimental set up Coupling coefficient and conversion efficiency is increased compared with conventional transformer.