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Keiki Morimoto,Toshimitsu Doi,Mustuo Nakaoka,Hyun Woo Lee 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper presents a new circuit topology of DC busline switch-assisted full-bridge soft-switching PWM inverter type DC-DC power converter which is composed of conventional voltage source full-bridge type high frequency PWM inverter in addition to a single DC busline side power semiconductor switching device for PWM scheme and a capacitive lossless snubber. Under the newly-proposed high frequency inverter link DC-DC high power conditioning and processing circuit, all active power switches in the full-bridge arms and DC busline can achieve ZVS/ZVT turn-off commutation operation. On the other hand, although the conduction power loss of DC busline switch increases a little, the total turn-off switching losses of full-bridge type PWM inverter and DC busline switch with the single lossless capacitive snubber parallel with DC busline can be significantly decreased. As a result, the switching frequency of high frequency inverter power stage using IGBTs can be actually selected under a condition of switching frequency more than about 10kHz. The more the switching frequency of full-bridge inverter increases, the more newly-proposed soft-switching DC-DC power converter with a high frequency transformer link has remarkable advantage as for the power conversion efficiency and power density as compared with the conventional hard-switching inverter type DCDC<br/> power converter. The effectiveness of this new converter topology is proved for low voltage and large current DC power supplies from a practical point of views.
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Keiki Morimoto,Khairy Fathy,Hiroyuki Ogiwara,Hyun Woo Lee,Mutsuo Nakaoka 전력전자학회 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.3
This paper presents a novel circuit topology of a DC busline series switch and parallel snubbing capacitor-assisted soft-switching PWM full-bridge inverter type DC-DC power converter with a high frequency planar transformer link, which is newly developed for high performance arc welding machines in industry. The proposed DC-DC power converter circuit is based upon a voltage source-fed H type full-bridge soft-switching PWM inverter with a high frequency transformer. This DC-DC power converter has a single power semiconductor switching device in series with an input DC low side rail and lossless snubbing capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge arms and DC busline can achieve ZCS turn-on and ZVS turn-off transition commutation. Consequently, the total switching power losses occurred at turn-off switching transition of these power semiconductor devices; IGBTs can be reduced even in higher switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules can be realized at 60 kHz. It is proved experimentally by power loss analysis that the more the switching frequency increases, the more the proposed DC-DC power converter can achieve a higher control response performance and size miniaturization. The practical and inherent effectiveness of the new DC-DC converter topology proposed here is actually confirmed for low voltage and large current DC-DC power supplies (32V, 300A) for TIG arc welding applications in industry.
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Keiki Morimoto,Nabil A. Ahmed,Hyun-Woo Lee,Mutsuo Nakaoka 대한전기학회 2006 Journal of Electrical Engineering & Technology Vol.1 No.2
This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT tum-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 ㎑ to 100 ㎑. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 ㎑. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.
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Morimoto, Keiki,Fathy, Khairy,Ogiwara, Hiroyuki,Lee, Hyun-Woo,Nakaoka, Mutsuo The Korean Institute of Power Electronics 2007 JOURNAL OF POWER ELECTRONICS Vol.7 No.3
This paper presents a novel circuit topology of a DC bus line series switch and parallel snubbing capacitor-assisted soft-switching PWM full-bridge inverter type DC-DC power converter with a high frequency planar transformer link, which is newly developed for high performance arc welding machines in industry. The proposed DC-DC power converter circuit is based upon a voltage source-fed H type full-bridge soft-switching PWM inverter with a high frequency transformer. This DC-DC power converter has a single power semiconductor switching device in series with an input DC low side rail and loss less snubbing capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge arms and DC bus line can achieve ZCS turn-on and ZVS turn-off transition commutation. Consequently, the total switching power losses occurred at turn-off switching transition of these power semiconductor devices; IGBTs can be reduced even in higher switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules can be realized at 60 kHz. It is proved experimentally by power loss analysis that the more the switching frequency increases, the more the proposed DC-DC power converter can achieve a higher control response performance and size miniaturization. The practical and inherent effectiveness of the new DC-DC converter topology proposed here is actually confirmed for low voltage and large current DC-DC power supplies (32V, 300A) for TIG arc welding applications in industry.
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Morimoto Keiki,Ahmed NabilA.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Electrical Engineers 2005 KIEE International Transactions on Electrical Mach Vol.b5 No.4
This paper presents two new circuit topologies of the dc busline side active resonant snubber assisted voltage source high frequency link soft switching PWM full-bridge dc-dc power converters acceptable for either utility ac 200V-rms or ac 400V-rms input grid. These high frequency switching dc-dc converters proposed in this paper are composed of a typical voltage source-fed full-bridge PWM inverter, high frequency transformer with center tap, high frequency diode rectifier with inductor input filter and dc busline side series switches with the aid of a dc busline parallel capacitive lossless snubber. All the active switches in the full-bridge arms as well as dc busline snubber can achieve ZCS turn-on and ZVS turn-off transition commutation with the aid of a transformer leakage inductive component and consequently the total switching power losses can be effectively reduced. So that, a high switching frequency operation of IGBTs in the voltage source full bridge inverter can be actually designed more than about 20 kHz. It is confirmed that the more the switching frequency of full-bridge soft switching inverter increases, the more soft switching PWM dc-dc converter with a high frequency transformer link has remarkable advantages for its power conversion efficiency and power density implementations as compared with the conventional hard switching PWM inverter type dc-dc power converter. The effectiveness of these new dc-dc power converter topologies can be proved to be more suitable for low voltage and large current dc-dc power supply as arc welding equipment from a practical point of view.
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Morimoto Keiki,Ahmed Nabil A.,Lee Hyun-Woo,Nakaoka Mutsuo The Korean Institute of Electrical Engineers 2006 Journal of Electrical Engineering & Technology Vol.1 No.2
This paper presents a new circuit topology of DC busline switch and snubbing capacitor-assisted full-bridge soft-switching PWM inverter type DC-DC power converter with a high frequency link for low voltage large current applications as DC feeding systems, telecommunication power plants, automotive DC bus converters, plasma generator, electro plating plants, fuel cell interfaced power conditioner and arc welding power supplies. The proposed power converter circuit is based upon a voltage source-fed H type full-bridge high frequency PWM inverter with a high frequency transformer link. The conventional type high frequency inverter circuit is modified by adding a single power semiconductor switching device in series with DC rail and snubbing lossless capacitor in parallel with the inverter bridge legs. All the active power switches in the full-bridge inverter arms and DC busline can achieve ZVS/ZVT turn-off and ZCS turn-on commutation operation. Therefore, the total switching losses at turn-off and turn-on switching transitions of these power semiconductor devices can be reduced even in the high switching frequency bands ranging from 20 kHz to 100 kHz. The switching frequency of this DC-DC power converter using IGBT power modules is selected to be 60 kHz. It is proved experimentally by the power loss analysis that the more the switching frequency increases, the more the proposed DC-DC converter can achieve high performance, lighter in weight, lower power losses and miniaturization in size as compared to the conventional hard switching one. The principle of operation, operation modes, practical and inherent effectiveness of this novel DC-DC power converter topology is proved for a low voltage and large current DC-DC power supplies of arc welder applications in industry.
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Ryuta Egi,Keiki Sugi,Kyoko Oyama-Suzuki,Yoshie Nakajima,Kenji Fukushima,Shintaro Nakano 아시아심장혈관영상의학회 2021 Cardiovascular Imaging Asia Vol.5 No.3
Right-sided infective endocarditis (RSIE) is rare, and the diagnosis is challenging due to fewer cardiac symptoms and signs. It is well recognized that intravenous drug users (IDU) are at significantly increased risk for RSIE. Also, RSIE is associated with a broad array of extra-cardiac complications such as metastatic infection and septic embolism. However, the prevalence is significantly higher in Western populations and has rarely been reported in Japan. We report a case of IDU-induced RSIE that was successfully treated with antibiotic therapy. 18F-fluorodeoxyglucose positron emission tomography was useful to evaluate the activity of extra-cardiac complications.
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DC-DC Converter with Three-Phase Power Factor Correction for Arc Welder
Khairy Sayed,Keiki Morimoto,Soon-Kurl Kwon,Katsumi Nishida,Mutsuo Nakaoka 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents a PWM converter, which enables to maintain high power-factor of arc welding power supply and to suppress input current harmonics. The main function of this system is to maintain unity power-factor by controlling input current to be sinusoidal, and to generate stable DC output voltage through half-bridge inverter and output rectifier. The proposed converter has high power factor, low harmonic distortion, and tight output regulations. A control scheme is employed to reduce the switching and rectification losses. The modeling and simulation analysis are performed to evaluate the performance characteristics. The proposed converter meets the IEC 61000-3-2 regulations with near-unity power factor and high efficiency.
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New DC Rail Side Soft-Switching PWM DC-DC Converter with High Frequency Planar Transformer
Khairy Sayed,Keiki Morimoto,Soon-Kurl Kwon,Katsumi Nishida,Mutsuo Nakaoka 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents a new circuit topology of active edge resonant snubbers assisted half-bridge soft switching PWM inverter type dc-dc high power converter for DC bus feeding power plants. The proposed dc-dc power converter is composed of typical voltage source-fed halfbridge high frequency PWM inverter with a high frequency planar transformer link in addition to input DC busline side power semiconductor switching devices for PWM control scheme and parallel capacitive lossless snubbers. The operating principle of the new DC-DC converter treated here is described by using switching mode equivalent circuits, together with its unique features. All the active power switches in the half-bridge arms and input DC buslines can achieve ZCS turn-on and ZVS turn-off commutation transitions. The total turn-off switching losses of the power switches can be significantly reduced. As a result, a high switching frequency IGBTs can be actually selected in the frequency range of 60 ㎑ under principle of soft switching. The performance evaluations of the experimental setup are illustrated practically. The effectiveness of this new converter topology is proved for low voltage and large current dc-dc power supplies as DC bus feeding from a practical point of view.
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