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Shigeru Okuma
2001 Volume 121 Issue 4 Pages
431-432
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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Tatsuo Teratani
2001 Volume 121 Issue 4 Pages
433-434
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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Yasuhiko Fujita
2001 Volume 121 Issue 4 Pages
435-436
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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Martina Calais, Lawrence J. Borle, Vassilios G. Agelidis, Michael S. D ...
2001 Volume 121 Issue 4 Pages
437-444
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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A single phase transformerless five level cascaded inverter based grid connected photovoltaic system is discussed in this paper. By avoiding the transformer, advantages such as high efficiency and low embodied energy are achieved. The implementation of the cascaded topology allows for reduced AC filter effort, firstly by generating a five level voltage waveform and secondly by achieving minimum switching frequencies by using its switch state redundancies. Control aspects described in this paper are the switching scheme and the grid current control method. A digital implementation and first experimental results of a multi carrier PWM voltage controller showing the effectiveness of the switching scheme are presented.
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Daisuke Katayama, Ryo Watanabe
2001 Volume 121 Issue 4 Pages
445-452
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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A wavemaker is the essential device to evaluate the performance of marine vehicles to wave by experiment with their models. In this paper, we consider modeling and robust control of the wavemaker. We model the wavemaker in consideration of its operating frequency and design a robust controller based on
H∞ control theory. The validity of the modeling and the performance of the controller are demonstrated in experiments.
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Akihiro Suzuki, Akihiko Iwata, Kenyu Haruta
2001 Volume 121 Issue 4 Pages
453-460
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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A high voltage switch with MOSFETs connected in series and parallel is developed for excimer lasers. The high voltage switch operates with turn on time of 40ns and rise rate of current of 26 kA/μs without pulse compression circuits. High repetition rate operation up to 1.5 kHz of a KrF excimer laser is realized using the high voltage switch with output laser power of 22 W at charging voltage of 18 kV. The switching loss is almost equal to the case using a conventional thyratron as a high voltage switch. To prevent a voltage oscillation after laser pulse, high speed diodes are applied to the laser excitation circuits. Using the high speed diodes, the amplitude of the voltage oscillation of the voltage of peaking capacitors is suppressed to about one third, and the characteristic of high repetition rate operation of a excimer laser is improved.
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Yoshiaki ITOH, Iko MIYAZAWA, Takashi SEKIGUCHI
2001 Volume 121 Issue 4 Pages
461-467
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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Programmable Controllers (PCs) are widely applied in the control of manufacturing systems. The purpose of this paper is to give some basic concepts for the verification methods of sequential control systems. Especially, we propose the modeling method of Ladder Diagram (LD) with the cyclic scan of PC by Petri Nets (PNs). First, some experiments are conducted to examine the relationship between the cyclic scan and the behavior of LD. Second, PNs are used for the qualitative modeling of the behavior of LD, based on IEC61131-3. In addition to LD Boolean logic expressions, we consider the PC operation, described by the cyclic scan, peripherals, memories, scanning ladder rungs. As a result, the difference between the LD description and the behavior, caused by the cyclic scan, can be represented by the proposed PNs. Moreover, the behavior of the PNs can be analyzed by the firing sequences, and then confirmed in good qualitative agreement with that of the experimental results.
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Takahiro Shamoto, Yukinobu Terao, Akihiro Nagaiwa, Yukio Hiraoka, Atsu ...
2001 Volume 121 Issue 4 Pages
468-475
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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This paper presents a new rain-water pump control scheme applying fuzzy control technique and shows evaluation results by using actual operation data. Conventional pump control scheme is called Level Control, where pumps are started-up/stopped when actual water level of a pump well reaches a given set value. In order to prevent flooding caused by heavy stormwater, operators often intervene the Level Control manually and start-up pumping before the water level reaches the set value.
This paper proposes the full-automatic control scheme where the set value of water level in the Level Control is changed by a fuzzy inference that utilizes measured water level data and its difference data as its input. Adopting this control scheme enables us to reduce the tedious procedure for pump operations. Also, the control scheme is easily realized by modifying software for control without introduction of additional hardware.
The effectiveness of the proposed control is confirmed by applying the proposed control to an actually being operated pump station. Furthermore, the superiority of the proposed control to the Level Control is shown by comparing the results of the proposed control and simulated results of the Level Control.
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Yoshitaka Iwaji, Toshiaki Okuyama, Daigo Kaneko, Shigetoshi Okamatsu
2001 Volume 121 Issue 4 Pages
476-483
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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High voltage adjustable speed drive systems offer significant advantages in many applications such as a fan, pump, or blower. In these applications, the adjustable speed drive systems achieves a higher level of system efficiency.
Usually, low voltage inverters with output transformer were used for a high voltage induction motor drive system. Recently, direct drive inverter system without output transformer has proposed and investigated. This inverter system is composed of single phase unit inverters and outputs multilevel voltages.
In this paper, pulse width modulation (PWM) technique suitable for high voltage direct drive inverter systems are discussed. At first, conventional multi-level PWM techniques based on the sub-harmonic method are shown and evaluated using time domain simulation. Next, new PWM method is proposed. This method has advantages that a modulation principle is very simple, distortion of the output voltage is very low, and well balanced switching losses among the unit inverters are achieved. Finally, simulation and experimental result are shown to illustrate the effectiveness of this method.
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Jumpei Baba, Tanzo Nitta, Yasuyuki Shirai, Yukio Hayashi, Yoshihiro Ko ...
2001 Volume 121 Issue 4 Pages
484-492
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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ICB (Inverter-Converter Bridge) energy transfer circuit has been designed as an exciter for pulse superconducting magnets. It has suitable characteristics for SMES exciter also; reduced voltage ripple across the magnet, few effects on a power system and so on. But when the ripple reduction operation is used, the circuit can not always continue the commutation successfully. This instability is caused by several unexpected phenomena. This paper shows that these phenomena can be grouped into three problems. One of the problems, that is, bypass pair caused by current overlap is investigated and solved. The validity of our analyses and solutions is confirmed by experiments.
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Yuya Kubo, Toshihiro Hosoi, Yorie Kaneko, Masaki Ohata, Toru Iwao, Nao ...
2001 Volume 121 Issue 4 Pages
493-500
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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Waste treatment is a very serious problem all over the world today. It is difficult to secure reclaimed land in Japan, so requiring an immediate solution. Hazardous wastes such as fly ash can be melted by plasma which makes possible to reduce its volume into 30% from the original volume. Plasma molten slag from fly ash protects heavy metal elements from melting out again and sinking into soil. So we investigated the solubility of the plasma molten slag from fly ash by changing pH index from 1, 4, 7 and 9 under consideration of acid rain.
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Chikaraishi Hirotaka, Yamada Shuichi, Tanahashi Shugo, Inoue Tomoyuki, ...
2001 Volume 121 Issue 4 Pages
501-507
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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The Large Helical Device (LHD), that is a fusion plasma experimental facility, has three sets of supercon-ducting helical coil blocks and three sets of superconducting poloidal coils. To excite these coils, dc power supplies with large output current are constructed. For these power supplies, high accuracy of current control is required to make the plasma experiment condition. Also low voltage output ripple is required for diagnostics and protection of superconducting coils. In the control of these coil currents, the coil current is affected by the changing of the other coil currents if a conventional current regulation method is adapted because these coils have strong mutual coupling to each other. To resolve this problem, the LHD power system uses a state variable based regulator for the current control. This paper introduces this dc power system for LHD.
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Yasuhiro Watanabe, Hideaki Fujita, Hirofumi Akagi
2001 Volume 121 Issue 4 Pages
508-515
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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This paper describes transient characteristics of a UPFC and its performance of suppressing power flow variation in a power transmission system having two parallel lines. The UPFC is installed in series with the two parallel lines and it controls the total power flow of the lines. Dynamic performance caused by a single line trip is theoretically and experimentally discussed. Experimental results tells us that a conventional control may produce an excessive power flow variation at the instant of the trip. On the other hand, fast control scheme which has been proposed by the authors shows good performance of power flow control without any variation not only in steady state but also in transient state.
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Tinghsu Su, Muneaki Ishida, Takamasa Hori
2001 Volume 121 Issue 4 Pages
516-521
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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3-phase HB-type stepping motors are salient-pole machines. Periodical torque ripple such as cogging torque is produced due to saliency of motors when they rotate. It causes mechanical vibration and acoustic noise. Authors propose a method to reduce the vibration of the 3-phase HB-type stepping motors with cogging torque by the feedforward compensation control. Compensation signals to suppress the vibration of the motor frame are obtained by the repetitive control installing an online Fourier Transformer and utilizing an acceleration sensor attached to the motor frame. The acceleration sensor is used only for the acquisition of the feedforward compensation data. The feedforward compensation signal at an arbitrary operating point is derived from the amplitude and phase data of the frequency components and the operating point data. Compensation signal for actual operating point is generated from compensation data and operating point data (i.e. reference frequency and load condition data) utilizing polynomial equation approximation and linear interpolation methods. Effectiveness of the proposed method is confirmed by the experimental results.
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H. Yamamoto, E. Hiraki, A. Okuno, M. Nakaoka
2001 Volume 121 Issue 4 Pages
522-523
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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This paper presents a novel prototype of auxiliary resonant commutated snubber (ARCS) which incorporates a high frequency pulse current transformer with power regeneration diode loop, along with its practical design considerations.
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Ryozo Itoh, Kouichi Ishizaka, Shintaro Matsueda, Hidehiko Okada
2001 Volume 121 Issue 4 Pages
524-525
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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Three-phase soft-switched current-source rectifier with two resonant switches, connected to a thyristor bridge in series and in parallel in order to provide zero-voltage switching or zero-current switching, is studied. The arrangement tested, using four insulated-gate bipolar transistors and six thyristors, is implemented to investigate the soft-switching operations under the sinusoidal pulsewidth modulation. The experimental results confirm that AC current can be controlled with a reversible power flow and with a near sinusoidal waveshaping.
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Takeshi Nagasawa, Yasushi Nishida, Yasusi Uda, Teruo Kawatsu
2001 Volume 121 Issue 4 Pages
526-527
Published: April 01, 2001
Released on J-STAGE: December 19, 2008
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We examined sterilization effect by the discharge using the floating multipole. The fungus for the measurement was penicillium expansum, and the relationship between discharge time and attenuation of the fungus was examined. As the result, the attenuation of the fungus by the discharge was clarified.
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