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Modified Double-Modulation Signal PWM Control for Large Motor Drive using Five-Level Converter
Noriyuki Kimura,Tomoyuki Hamada,Toshimitu Morizane,Katsunori Taniguchi 전력전자학회 2007 ICPE(ISPE)논문집 Vol.- No.-
This paper shows the newly developed modification of the double sinusoidal wave modulation used for multilevel converter. The proposed modulation makes it possible to change the modulation factor for each level of the converter to control the balance of each dc voltage and also can reduce the higher harmonics as same as sinusoidal modulation. This multilevel converter system has prospective configuration for the high voltage application such as the large motor drive without transformer.
Imbalanced Fault Detection using Real Time Symmetrical Coordinate Calculation with Memorized Data
Noriyuki Kimura,Xiao-xiao Yu,Koji Niijima,Toshimitsu Morizane,Hideki Omori 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6
This paper proposes a real time symmetrical coordinate transformation applied for detection of imbalanced fault in utility power system. The power conditioner of the photovoltaic system in Japan is required to remain connected when the utility power system fault occurs under certain condition. The most popular fault is 1 line-to-ground fault. The next is 2 line-short fault. Both cause the imbalance voltages and currents in 3-phase power system. To optimize the output from the power conditioner of the photovoltaic system, the detection of the imbalanced condition is important factor. In this paper, new development of the signal processing method by using the complex number algebra in real time system is shown. The fast detection of the imbalanced condition is verified by the computer simulations.
Reduction of Circulating Current of Double Converter Configuration for Additional Regeneration
Noriyuki Kimura,Toshimitsu Morizane,Yasuyuki Nishida 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents the analysis and solution about the circulating current appeared in the double converter configuration used to add the regenerative ability for a conventional diode rectifier.
Harmonic Analysis of High Power Factor Active Converter with New Soft-Switching Circuit
Noriyuki Kimura,Katsunori Taniguchi 전력전자학회 1995 ICPE(ISPE)논문집 Vol.1995 No.10
This paper describes about an analysis of input and output waveforms of high power factor active converter with novel loss-less snubber. This active converter is used in the discontinuous mode of the dc reactor current. The control circuit for that mode is simple. In this mode, turn on of chopper device occurs at zero current, that is zero current switching. The switching off operation of proposed circuit achieves a zero voltage switching. It results in drastical decrease of the switching loss in the device. It is also indicated that total harmonic distortion of the input ac current waveform is improved by the excess current from the snubber capacitor. In this paper, we describe the analytical reslults of harmonic ditortion of the input and output current waveform of the proposed circuit.
Capacitor Voltage Control of Multi-Pulse PWM 5-Level Converter System
Noriyuki Kimura,Toshimitsu Morizane,Katsunori Taniguchi,Takanori Oono 전력전자학회 2004 ICPE(ISPE)논문집 Vol.- No.-
This paper shows a new PWM method for the multilevel converter. This method can control dc current flow of each dc capacitor by using multi-modulation signal. It is applied to the dual multilevel converter configuration to stabilize the dc capacitor voltage balance.
DC Output Wind Generator with Modified Trapezoidal Modulated Converter and Solid-State Transformer
Noriyuki KIMURA,Naoki KAWABATA,Toshimitsu MORIZANE,Hideki OMORI 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
This paper proposes the Modified Trapezoidal Modulation (MTM) as a new modulation technique for a voltage source converter (VSC) for the wind power generator with HVDC transmission. The experimental results show that the MTM is more effective than the conventional sinusoidal modulation (SM) for the reduction of the VSC cost and the switching loss. It is also expected to reduce the torque ripple by optimizing the rectangular ratio in the MTM to reduce the disadvantage of generated harmonic currents. Simulation and experimental results show the good feasibility of using MTM. It is expected to use solid-state transformer (SST) to have galvanic isolation in the proposed system. MPPT simulation with SST shows the good performance of the total unit.
DC-DC converter current measurement for MPPT control
Noriyuki Kimura,Yoshinori Sakoda,Toshimitsu Morizane 전력전자학회 2011 ICPE(ISPE)논문집 Vol.2011 No.5
This paper presents the possibility to use the MOS-FET as the current measuring resistance. The shunt resistance is often used to measure the current in power electronics circuit since it is low cost and high reliable. However the reduction of components is always desirable for reduction of the cost and high reliability. Maximum power point tracking is indispensable for the renewable energy source, though the precise measurement of the power is not necessary. So the authors propose to use the MOS-FET switching device installed in the dc-dc converter circuit as the current measuring resistance. Simulation and experimental results of the first stage investigation are shown.
Poroelasticity of cellulose hydrogel
Isobe, Noriyuki,Kimura, Satoshi,Wada, Masahisa,Deguchi, Shigeru Elsevier 2018 Journal of the Taiwan Institute of Chemical Engine Vol.92 No.-
<P><B>Abstract</B></P> <P>The poroelasticity of cellulose hydrogels was studied by a series of compression tests. The stiffness of the cellulose hydrogel was found to be independent on the crystallinity of a skeletal gel matrix, suggesting that the poroelasticity made a significant contribution to mechanical properties of the hydrogel. Indeed, typical poroelastic responses were observed when the cellulose hydrogels were subjected to the compression tests with varied compression strain rates (i.e. softness upon slow compression but stiffness upon fast compression). The fluid mechanics theory showed that sub-micrometer-scale morphological difference of the gel matrix, which was observable by scanning electron microscopy, affected the flow behavior of water inside porous structure, leading to the increased stiffness upon fast compression.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Stiffness of cellulose hydrogel is independent on crystallinity of skeletal matrix. </LI> <LI> Poroelasticity of cellulose hydrogel stands out upon fast compression. </LI> <LI> Sub-micrometer-scale morphology generates poroelasticity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Isobe, Noriyuki,Komamiya, Takehiro,Kimura, Satoshi,Kim, Ung-Jin,Wada, Masahisa Elsevier 2018 INTERNATIONAL JOURNAL OF BIOLOGICAL MACROMOLECULES Vol.117 No.-
<P><B>Abstract</B></P> <P>Cellulose hydrogel from aqueous solution of lithium bromide demonstrated excellent tunability of mechanical property and shape. A series of compression tests showed that cellulose hydrogel covered a wide range of mechanical property, where the compressive Young's modulus was controllable from 30 kPa to 1.3 MPa by changing the initial concentration of cellulose solution. Meanwhile, the diameter of the building block of gel, namely nano-fibrous cellulose, was constant at 15–20 nm irrelevant of the initial concentration of cellulose solution. Moreover, thanks to the biocompatibility of cellulose, the cultivation of cartilage tissue was successful in the micro-porous sponge-like cellulose hydrogel prepared by salt-leaching process. These findings show that this environmentally-benign versatile gel offers a new substrate for the biomaterial-based nanomaterial in biomedical applications.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Cellulose hydrogel with various shapes from rigid cylinder to soft sponge is prepared. </LI> <LI> Mechanical property of hydrogel is controllable by the initial input of cellulose. </LI> <LI> Compressive modulus is classed in the stiffest porous material. </LI> <LI> Nano-fibrous network structure is a building block of cellulose hydrogel. </LI> <LI> Biocompatibility is evidenced by successful cultivation of tissue inside soft gel. </LI> </UL> </P>