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This paper proposes an automatic design method of typical parameters such as number of phases, number of poles, stack thickness, stator outer diameter, rotor outer diameter, and number of turns of a switched reluctance motor from the requirement of the N‐T characteristic. In particular, a specific parameter related to the magnetic saturation is defined in order to arbitrarily determine how much to use the magnetic properties of the iron core material. In the proposed method, the typical motor parameters in order to realize a miniaturized volume which satisfies an input N‐T characteristic are obtained by setting the parameter related to magnetic saturation, maximum electrical frequency, maximum current density, maximum copper loss, conductor slot fill factor, magnetic properties of material, and input voltage. The designed motor is analyzed using the Finite Element Method (FEM) in order to validate the proposed method. [ABSTRACT FROM AUTHOR]

The molecular basis for leaf development, a major focus in developmental biology, remains unclear in the monocotyledonous grass, rice (Oryza sativa). Here, we performed a mutant screen in rice and identified an AP2-type transcription factor family protein, NARROW AND DWARF LEAF1 (NDL1). NDL1 is the ortholog of Arabidopsis thaliana (subsequently called Arabidopsis) ENHANCER OF SHOOT REGENERATION1 (ESR1)/DORNRÖSCHEN (DRN) and mediates leaf development and maintenance of the shoot apical meristem (SAM). Loss of function of NDL1 results in bladeless leaves and SAMs that are flat, rather than dome-shaped, and lack cell proliferation activity. This loss of function also causes reduced auxin signaling. Moreover, as is the case with Arabidopsis ESR1/DRN, NDL1 plays crucial roles in shoot regeneration. Importantly, we found that NDL1 is not expressed in the SAM but is expressed in leaf primordia. We propose that NDL1 cell autonomously regulates leaf development, but non-cell autonomously regulates SAM maintenance in rice. [ABSTRACT FROM AUTHOR]

This article proposes a novel continuous pulsewidth modulation (CPWM) method to reduce dc-link current harmonics in voltage source inverters over wide range of load power factor. This modulation method contributes to a current stress reduction of dc-link smoothing capacitor and a suppression of its temperature rise. Furthermore, high-cost digital hardware, such as a field-programmable gate array, is not necessary because this modulation is implemented with only one carrier. The dc-link current harmonics are reduced by shifting voltage references in every half control period to reduce a fluctuation of the dc-link current around its average value. Experimental results confirm that the application of the proposed CPWM reduces the dc-link current harmonics by 24.2% at most and lowers an equilibrium capacitor temperature by 6.0 °C compared to the conventional CPWM. [ABSTRACT FROM AUTHOR]

This paper proposes a control for a single-phase grid-tied inverter operating in both continuous current mode (CCM) and discontinuous current mode (DCM) to minimize inductors without worsening a current total harmonic distortion (THD). In a conventional CCM/DCM control, an inductance is required in a DCM nonlinearity compensation; consequently, the control becomes inductance-dependent. In the proposed control, a duty ratio at a previous calculation period is utilized to compensate for the DCM nonlinearity and detect current modes independently from the inductance. A 4-kW 100-kHz prototype of the inverter with two designs of the inductor is realized to confirm the effectiveness of the proposed control. When the inductor impedance, which is normalized by an inverter impedance, is reduced from 1.8% to 0.5%, volume and material cost of the inductor are reduced by 51% and 62%, respectively, whereas the loss at a light load of 0.1 p.u. is reduced by 35%. However, due to this inductor minimization, the current THD at a rated load increases from 2.3% to 8.7% with the conventional control, violating the grid current harmonic constraint regulated by standard IEEE-1547. The proposed CCM/DCM control reduces the current THD from 8.7% to 2.1%, enabling the inductor minimization and satisfies the grid standard. [ABSTRACT FROM AUTHOR]

This paper proposes a novel space vector pulsewidth modulation (SVPWM) strategy to reduce the switching-frequency-order inverter input current harmonics for a two-level three-phase voltage-source inverter operating over a wide range of the load power factor. The fluctuation of the inverter input current around its average value is minimized by optimization of the utilized voltage space vectors to reduce the inverter input current harmonics, which extends the lifetime of the dc-link electrolytic capacitors. Furthermore, the proposed strategy can be adapted to a motor drive system, where a wide variation of the load power factor is desired, by changing the optimized combinations of the voltage space vectors according to the polarities of the output phase currents. Experiments with the application of the novel SVPWM confirm that the inverter input current harmonics is reduced by up to 29.5% compared to that with the conventional SVPWM strategy. Moreover, the analytical and experimental results confirm that the proposed SVPWM reduces the inverter input current harmonics in both driving mode and regenerative braking mode, as well as with any load power factor. [ABSTRACT FROM AUTHOR]

Abstract: A novel circuit topology for a single‐phase inverter with a power decoupling capability operated in discontinuous current mode (DCM) is proposed in this paper. An inverter connected to a single‐phase grid requires a power decoupling capability to compensate for a power ripple with twice the grid frequency. Bulky capacitors are used as DC‐link capacitors in conventional systems. In contrast, the proposed circuit topology can use ceramic capacitors instead of electrolytic capacitors by reducing the required capacitance based on the active buffer concept. Moreover, this active buffer requires no additional inductor because it uses DCM for the power decoupling capability. In this paper, a control method for the active buffer circuit operated in DCM is introduced. An experimental verification of a 1‐kW prototype shows that the proposed circuit reduces the input current ripple at twice the grid frequency by 96.8%, with a maximum efficiency of 95.2%. In addition, the Pareto optimization of power density and efficiency is used to clarify the maximum power density points. It is found that the maximum power density of the proposed circuit is 1.6 times higher than that of a conventional boost‐type active buffer. [ABSTRACT FROM AUTHOR]

This paper presents a high power density design for a step-down rectifier incorporating a modular multilevel converter (MMC) in a power system connected to a 6.6 kV ac grid. In particular, the relationship among the number of cells, the output voltage of the MMC, and the overall volume is clarified. A proposed design flowchart focuses on minimizing volumes of cell capacitors, heat sinks, and arm inductors by using optimal number of cells. Moreover, the commercial electrolytic capacitors are used as the cell capacitor. Besides, the formulae used to determine the ripple currents in the electrolytic capacitor and the arm inductor are presented, along with that for the semiconductor loss. Each of these formulae were verified experimentally using a miniature model and theoretical values from all formulae agree with the measured values within minimal deviations that are discussed with regard to the design of a practical converter for a 6.6 kV system. Finally, the conditions necessary to achieve high power density in an MMC are provided, based on volume evaluations of the electrolytic capacitor, the arm inductor, and the heat sink. Using this optimization process, an MMC design achieved a volume reduction of approximately 90% compared to a conventional system. [ABSTRACT FROM PUBLISHER]

This paper proposes a hybrid current mode between triangular current mode (TCM) and discontinuous current mode (DCM) in order to improve a wide-load-range efficiency for a high-frequency SiC-based boost converter. At rated load, TCM, where the zero-voltage switching (ZVS) is achieved, is used in order to increase the switching frequency and minimize the boost converter. At light load, the hybrid discontinuous current mode (HDCM), where the TCM current is flown during the zero-current interval of DCM, is applied in order to achieve both ZVS and a reduction of a current ripple. This maintains a high efficiency over a wide load range. A 1-kW prototype is realized to compare HDCM over continuous current mode (CCM), DCM, and TCM. Compared to TCM, the root-mean-square current is reduced up to 56.6% with HDCM. Consequently, the efficiency of HDCM at light load of 0.1 p.u. is improved by 3.1%. Compared to DCM, the average-current ripple in HDCM is reduced by 82.3%, whereas the efficiency of HDCM at light load of 0.1 p.u. is improved by 1.5%. Finally, when the current ripple of CCM is designed to be half of TCM, the efficiency of HDCM at rated load is improved by 0.9% compared to CCM. [ABSTRACT FROM AUTHOR]

SUMMARY In this study, the lowest loss point is calculated using the permeance method when the machine parameters of the interior permanent magnet synchronous motor are changed. Using the proposed method, the motor loss is easily calculated compared to the conventional method. The periodic change in the magnetic resistance in the air-gap according to the rotation of the rotor does not need to be considered because the magnetic equivalent circuits of the rotor and stator are separated. In this study, the motor loss is calculated by the proposed method and a finite element method (FEM). As a result, the error in the calculation results between the permeance method and the FEM is 2.9%. On the other hand, the motor losses are calculated by the permeance method when some machine parameters are changed. As a result, these results agree in principle with those of the FEM. Therefore, the validity of the proposed method is confirmed. In addition, the method for motor design is considered in terms of the loss. [ABSTRACT FROM AUTHOR]

SUMMARY This paper proposes a fault ride through (FRT) method for a matrix converter in a grid-connected system to control the grid reactive current and generator torque during a three-phase short voltage sag. In the proposed method, the control period of the system is divided into three modes. In the first mode, all switches are turned off, and in the second mode, a zero vector is obtained at the output of the matrix converter. By using these two modes along with a snubber circuit in the matrix converter, the generator torque is controlled during the three-phase voltage sag. Further, in the third mode, a nonzero vector is selected to connect the generator to the grid for providing the reactive current to the grid. In addition, the paper proposes a feedback control to obtain a stable ride through operation. From the experimental results, it is confirmed that grid reactive current of 0.86 p.u. and generator torque of 1.07 p.u. are achieved by the proposed FRT method during the three-phase voltage sag. [ABSTRACT FROM AUTHOR]

This paper presents a matrix converter design for achieving maximum power density using a SiC device based on a front-loading design. To design the matrix converter to achieve maximum power density, the conduction loss and the switching loss of the matrix converter are theoretically derived and validated by simulation and experiment. Based on these formulas, the relationship between the efficiency and power density are revealed by using a Pareto–Front curve in order to solve the tradeoff problem between the power density and the efficiency. Moreover, in order to promote the widespread use of the matrix converter instead of a BTB system, it is quantitatively evaluated that the power density in the matrix converter is increased by 4.19 kW/dm3 in comparison to the BTB system. Moreover, the power density of the matrix converter that uses a SiC-MOSFET (ROHM) as the switching device with natural air cooling is 95.0% (2.1 kW/dm3) of the calculated maximum power density. Thus, the power density of the matrix converter is improved by 57.5% by the maximum power density design method. Based on the results, the design method for a high power density ac–ac direct converter is established according to the requisite specifications. [ABSTRACT FROM PUBLISHER]

This paper discusses pulse density modulation (PDM) control methods for a single-phase to three-phase matrix converter (MC) in high-frequency applications. The proposed circuit is used as an interface converter for a wireless power transfer system. This converter can input a frequency of several hundred kilohertz and output a low frequency, that is, 50 Hz or 60 Hz, for a commercial power grid. The proposed circuit implements zero voltage switching (ZVS) operation by using PDM control methods and obtains high efficiency. In this paper, two PDM control strategies are compared: delta-sigma conversion and the PDM pattern generation method based on space vector modulation (SVM), which is proposed here. Also, the experimental results obtained with the proposed system will be presented and discussed. The total harmonic distortions (THDs) of the output voltage with delta-sigma conversion and the PDM pattern generation method based on SVM are found to be 5.96% and 2.15%, respectively. In addition, the maximum efficiencies with delta-sigma conversion and the PDM control based on SVM are 93.4% and 97.3%, respectively. From the results, the validity of the PDM control based on SVM has been confirmed for improvement of the output waveforms and reduction of the switching loss. [ABSTRACT FROM AUTHOR]

SUMMARY This paper provides a fundamental analysis of a power supply and rectifiers for wireless power transfer using magnetic resonant coupling (MRC). MRC enables efficient wireless power transfer over middle-range transfer distances. MRC for wireless power transfer should operate at a high frequency in the industry science medical band, such as 13.56 MHz, because the size of the transfer device decreases at higher transfer frequencies. Therefore, the output frequency of the power supply on the transmitting side should be 13.56 MHz. In addition, the rectifier on the receiving side is operated at a high frequency. This paper focuses on the reflected power in the power supply and rectifiers. Thus, the parametric design method is clarified for the power supply, including a low-pass filter to match the output, the impedance of the power supply with the characteristic impedance of the transmission line. In addition, the effects on the rectifiers of silicon carbide and gallium nitride diodes are confirmed by performing an experiment and a loss analysis. [ABSTRACT FROM AUTHOR]

Background: The rice PLASTOCHRON ( PLA) genes PLA1 and PLA2 regulate leaf maturation and the temporal pattern of leaf initiation. Although the function of PLA genes in the leaf initiation process has been analyzed, little is known about how they affect leaf growth. Previously, we suggested that PLA1 and PLA2 function downstream of the gibberellin (GA) signal transduction pathway. In the present study, we examined the phenotype of a double mutant of pla and slender rice 1 ( slr1), which is a constitutive GA response mutant. By analyzing these double mutants, we discuss the relationship between PLA-related and GA-dependent pathways and the possible function of PLA genes in leaf growth. Findings: Single slr1 and pla mutants exhibited elongated and dwarf phenotypes in the vegetative stage, respectively. The stature and leaf size of the pla1/slr1 and pla2/slr1 double mutants were intermediate between those of the pla and slr1 single mutants. However, the effects of slr1 on leaf elongation were markedly suppressed in the pla1 and pla2 mutant backgrounds. On the other hand, the change in cell length in the double mutants was almost the same as that in the single mutants. An expression analysis of genes involved in GA biosynthesis and catabolism indicated that feedback regulation functioned normally in the pla/slr1 double mutants. Conclusions: Our genetic results confirm that PLA genes regulate leaf growth downstream of the GA pathway. Our findings also suggest that PLA1 and PLA2 are partly required for GA-dependent leaf elongation, mainly by affecting cellular proliferation. [ABSTRACT FROM AUTHOR]

This paper proposes a three‐phase wireless power transfer (WPT) system with a three‐phase‐to‐three‐phase matrix converter. The proposed system directly converts power from an AC grid to high‐frequency AC for WPT. The three‐phase WPT system with the matrix converter is effectively expands the lifetime of the WPT system. A novel hybrid commutation method, which is suitable for the WPT system with a resonant characteristic, is proposed to avoid the commutation failure of the matrix converter. The strategy of the proposed hybrid commutation is based on an estimation of the current direction considering the resonant characteristics and elimination of commutation in the critical area. The proposed commutation method achieves an AC input‐current total harmonic distortion (THD) of 4.7% with the resonant three‐phase load without a current sensor on the high‐frequency side. Furthermore, the proposed WPT system achieves a system efficiency of 88.2% at a load of 4 kW. [ABSTRACT FROM AUTHOR]

This paper discusses a new circuit configuration and a new control method for a single-phase ac–dc converter with power factor (P.F.) correction and a power pulsation decoupling function. The proposed converter can achieve low total harmonic distortion (THD) on the input current and the power pulsation decoupling function between the input and output sides, which allows low output voltage ripple even on a small output energy buffer at the same time using an active buffer. Therefore, the proposed converter does not require large smoothing capacitors or large smoothing inductors. The buffering energy is stored by a small capacitor, which controls the variation of the capacitor voltage through the active buffer. In this paper, the fundamental operations of the proposed converter are investigated experimentally. The experimental results reveal that the input current THD is 1.44%, the rate of the output voltage ripple is 6.33%, and the input P.F. is over 99%. In addition, a maximum efficiency of over 96% is obtained for a 750-W prototype converter. [ABSTRACT FROM PUBLISHER]

Control strategy and loss evaluation is discussed for a proposed dc/ac two-stage boost converter using the neutral point of a motor. The proposed converter consists of a small boost chopper and a three-phase inverter, which has a boost-up function from the use of the leakage inductance of a motor, instead of a boost-up reactor, for dc to ac conversion. A six-step operation strategy is proposed for the circuit. When the inverter part outputs a square waveform of 180^\circ, the input current has a distortion because the neutral point voltage of the motor fluctuates at a frequency three times the output frequency. The input current is also shown distorted due to the neutral point voltage fluctuation. Feedforward compensation is proposed to reduce the input current fluctuation. In addition, the dc current in the proposed circuit is imposed into the phase current of the motor. Loss evaluation is therefore implemented to investigate the influence of the imposed dc current on the experimental results. Also, finite-element method was used to analyze the motor loss for a 1.5-kW interior-permanent-magnet motor. [ABSTRACT FROM PUBLISHER]

In this paper, a beatless control that enables unity input power factor for the single-pulse operation in the matrix converter is proposed. The proposed method controls the output voltage to synchronize with the output current in terms of voltage–time product during the high output frequency operation. Following the proposed synchronous control method, the beat current is suppressed by approximately 1% at output frequency 1432 Hz. The experimental results also demonstrate that the input current waveform achieves sinusoidal waveform with unity power factor. In addition, the voltage transfer ratio of the matrix converter is improved from 0.866 to 0.955 in the high output frequency region. The maximum efficiency 96.4% is achieved at a 1.34-kW RL load. [ABSTRACT FROM AUTHOR]

This paper proposes a new circuit topology for a high-efficiency isolated DC/DC converter using series compensation. The proposed converter consists of a high-efficiency resonance half-bridge converter and a series con-verter. The series converter regulates the output voltage and provides only the differential voltage between the input voltage and output voltage. Therefore, the circuit achieves high efficiency when the input voltage is almost equal to the output voltage, because then only the resonance con-verter will operate. In this paper, the approach employed to achieve high efficiency by using the proposed series com-pensation method is introduced. In addition, the fundamen-tal operation and the method of designing the proposed circuit are described. The suitability of the proposed circuit was confirmed by performing experiment and loss analysis, and the maximum efficiency achieved was 96.2%. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 182(2): 42-52, 2013; Published online in Wiley Online Library (wileyon-linelibrary.com). [ABSTRACT FROM AUTHOR]

This paper discusses two overmodulation controls, namely, square wave and trapezoidal, in the indirect matrix converter (IMC) for motor drive application. The differences between these two modulations are analyzed based on the output–input voltage transfer ratio (VTR), the efficiency, and the current total harmonic distortions under two load conditions. Moreover, the performance is then improved by implementing four-step commutation methods in the primary side of the IMC. The validity of the proposed methods will be demonstrated through simulation and experimentally. The experimental results show that the VTR can be improved from 0.866 to 0.97 in the square wave modulation and 0.92 for the trapezoidal wave modulation in an induction motor drive system. [ABSTRACT FROM PUBLISHER]

Phyllotaxy is defined as the spatial arrangement of leaves on the stem. The mechanism responsible for this extremely regular pattern is one of the most fascinating enigmas in plant biology. In this study, we identified a gene regulating the phyllotactic pattern in rice. Loss-of-function mutants of the DECUSSATE [DEO gene displayed a phyllotactic conversion from normal distichous pattern to decussate. The dec mutants had an enlarged shoot apical meristem with enhanced cell division activity. In contrast to the shoot apical meristem, the size of the root apical meristem in the dec mutants was reduced, and cell division activity was suppressed. These phenotypes indicate that DEC has opposite functions in the shoot apical meristem and root apical meristem. Map-based cloning revealed that DEC encodes a plant-specific protein containing a glutamine-rich region and a conserved motif. Although its molecular function is unclear, the conserved domain is shared with fungi and animals. Expression analysis showed that several type A response regulator genes that act in the cytokinin signaling pathway were down-regulated in the dec mutant. In addition, dec seedlings showed a reduced responsiveness to exogenous cytokinin. Our results suggest that DEC controls the phyllotactic pattern by affecting cytokinin signaling in rice. [ABSTRACT FROM AUTHOR]

RNA silencing is a defense system against "genomic parasites" such as transposable elements (TE), which are potentially harmful to host genomes. In plants, transcripts from TEs induce production of double-stranded RNAs (dsRNAs) and are processed into small RNAs (small interfering RNAs, siRNAs) that suppress TEs by RNA-directed DNA methylation. Thus, the majority of TEs are epigenetically silenced. On the other hand, most of the eukaryotic genome is composed of TEs and their remnants, suggesting that TEs have evolved countermeasures against host-mediated silencing. Under some circumstances, TEs can become active and increase in copy number. Knowledge is accumulating on the mechanisms of TE silencing by the host; however, the mechanisms by which TEs counteract silencing are poorly understood. Here, we show that a class of TEs in rice produces a microRNA (miRNA) to suppress host silencing. Members of the microRNA820 (miR820) gene family are located within CACTA DNA transposons in rice and target a de novo DNA methyltransferase gene, OsDRM2, one of the components of epigenetic silencing. We confirmed that miR820 negatively regulates the expression of OsDRM2. In addition, we found that expression levels of various TEs are increased quite sensitively in response to decreased OsDRM2 expression and DNA methylation at TE loci. Furthermore, we found that the nucleotide sequence of miR820 and its recognition site within the target gene in some Oryza species have co-evolved to maintain their base-pairing ability. The co-evolution of these sequences provides evidence for the functionality of this regulation. Our results demonstrate how parasitic elements in the genome escape the host's defense machinery. Furthermore, our analysis of the regulation of OsDRM2 by miR820 sheds light on the action of transposon-derived small RNAs, not only as a defense mechanism for host genomes but also as a regulator of interactions between hosts and their parasitic elements. [ABSTRACT FROM AUTHOR]

This paper describes a three-phase power converter which utilizes the neutral point of an induction motor and demonstrates the performance of the motor using the proposed method under various operating conditions. Several motor test results, such as the speed-torque characteristic, the torque impact, and the acceleration-deceleration characteristic, are included to confirm the performance of the induction motor. The structure of the proposed circuit consists primarily of an AC/AC converter [indirect matrix converter (IMC)] and a boost converter connected to the neutral point of the induction motor. In addition, this paper also proposes a method to reduce the ripple found in the battery current. Several experimental results show that the motor works well, and even the leakage inductance is utilized in the boost converter. © 2012 Institute of Electrical Engineers of Japan. Published by John Wiley & Sons, Inc. [ABSTRACT FROM AUTHOR]

This paper proposes a new circuit topology for a multilevel pulse width modulation (PWM) rectifier. The proposed method forms a new circuit by combining a diode clamp-type topology with a flying capacitor-type topology. The proposed circuit uses only 12 switches, despite the use of a five-level three-phase PWM rectifier. Further, the proposed circuit can obtain good performance, same as a conventional multilevel circuit. This paper describes about the features of the proposed topology; the control strategy and the loss analysis that is estimated by a circuit simulator. In addition, the basic operation of the proposed method is confirmed by simulation and experimental results. The proposed converter achieved total harmonic distortion of 3.4% for the input current and efficiency of 97.4% for a 1 kW class experimental setup. [ABSTRACT FROM AUTHOR]

This paper proposes a square-wave control strategy for a single-phase power factor correction with a new boost-up converter which uses the leakage inductance of a motor instead of a boost-up reactor. Since the power supply is connected to the neutral point of the motor, the current distortion in the power supply occurs when the inverter outputs square waveforms. First, this paper describes the characteristic of the proposed circuit and the problems in the square-wave operation. Next, a current control method for the square waveform is proposed to suppress the current distortion. Finally, the validity of the proposed converter and its control strategy are demonstrated by experimental results. [ABSTRACT FROM PUBLISHER]

Summary Leaf veins have a complex network pattern. Formation of this vein pattern has been widely studied as a model of tissue pattern formation in plants. To understand the molecular mechanism governing the vascular patterning process, we isolated the rice mutant, commissural vein excessive1 ( coe1). The coe1 mutants had short commissural vein (CV) intervals and produced clustered CVs. Application of 1- N-naphthylphthalamic acid and brefeldin A decreased CV intervals, and application of 1-naphthaleneacetic acid increased CV intervals in wild-type rice; however, coe1 mutants were insensitive to these chemicals. COE1 encodes a leucine-rich repeat receptor-like kinase, whose amino acid sequence is similar to that of brassinosteroid-insensitive 1-associated receptor kinase 1 (BAK1), and which is localized at the plasma membrane. Because of the sequence similarity of COE1 to BAK1, we also examined the involvement of brassinosteroids in CV formation. Brassinolide, an active brassinosteroid, decreased the CV intervals of wild-type rice, and brassinazole, an inhibitor of brassinosteroid biosynthesis, increased the CV intervals of wild-type rice, but coe1 mutants showed insensitivity to these chemicals. These results suggest that auxin and brassinosteroids regulate CV intervals in opposite directions, and COE1 may regulate CV intervals downstream of auxin and brassinosteroid signals. [ABSTRACT FROM AUTHOR]

Recently, renewable resource supplies, such as fuel cells, photovoltaic cells, wind power, and engine generators for distributed power systems have been studied intensely. Conventional compensators with switching devices are constructed based on a voltage source inverter using six arms. Therefore, conventional power quality compensators require a large electrolytic capacitor in the DC link part of the equipment. The use of a large capacitor hinders downsizing efforts and the lowering of equipment costs. Direct converters, which do not have a large electrolytic capacitor and an initial charge circuit, can be used to realize downsizing and lowering of equipment costs, when compared with conventional converters. This paper proposes a new application of a matrix converter to a PM generator for power quality compensation, such as reactive power compensation, harmonic current, and power interruption. The novel point of this work is that the matrix converter provides reactive power with harmonic current. Simulated and experimental results confirm that the matrix converter can maintain high performance the same as a conventional active filter and an uninterruptible power supply (UPS). © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(4): 37–44, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20972 [ABSTRACT FROM AUTHOR]

This paper proposes the safest novel commutation method for a matrix converter. There are two conventional commutation methods which depend on the polarity of the input line voltage (it is called “voltage commutation”) and depend on the polarity of the output current (it is called “current commutation”). However, problem of the voltage commutation is that commutation failure occurs around zero of the input line voltage. It is difficult to detect its polarity due to depending on offset and delay of the sensor. Similarly, the current commutation failure occurs around zero of the load current. A cause of these detection errors are a detection delay and an offset of a sensor. The proposed commutation method combines the input voltage commutation and the load current commutation. Therefore, the proposed commutation method can decrease the commutation failure without high accuracy sensor. In addition, a voltage error compensation based on the proposed commutation method is proposed in this paper. The proposed method can simply compensate for the commutation error of the output voltage and the input current at the same time. The effects of the proposed method are confirmed by experimental results with a 750 W induction motor and a R-L load. Those results confirm that the proposed commutation can decrease commutation failure. Moreover, the total harmonics distortion of the input current and the output current are 2.6 point and 0.9 point lower than that of the condition without the compensation at 100% output power. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(4): 49–57, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20826 [ABSTRACT FROM AUTHOR]

A new bidirectional switch and snubber circuit are proposed for medium-voltage ac/ac converters. The proposed switch can be constructed using 2-in-1 insulated-gate bipolar transistor and 2-in-1 diode modules, and can reduce the voltage stress of the switching device by series connection. The proposed snubber configuration is very simple and can regenerate absorbed energy. On the other hand, timing errors in the switching between the series-connected switches cause a voltage imbalance in the snubber circuit. Therefore, a simple method is proposed for reducing the voltage imbalance that uses one voltage sensor for each switch circuit. This proposed method controls the snubber voltages by adjusting the switch timings. Furthermore, application of the proposed switch circuit to a matrix converter is discussed and is confirmed by experiment. [ABSTRACT FROM AUTHOR]

Members of the Class III homeodomairi leucine zipper (Class III HD-Zip) gene family are central regulators of crucial aspects of plant development. To better understand the roles of five Class III HD-Zip genes in rice (Oryza sativa) development, we investigated their expression patterns, ectopic expression phenotypes, and auxin responsiveness. Four genes, OSHB1 to OSHB4, were expressed in a localized domain of the shoot apical meristem (SAM), the adaxial cells of leaf primordia, the leaf margins, and the xylem tissue of vascular bundles. in contrast, expression of OSHB5 was observed only in phloem tissue. Plants ectopically expressing microRNA166-resistant versions of the OSHB3 gene exhibited severe defects, including the ectopic production of leaf margins, shoots, and radialized leaves. The treatment of seedlings with auxin quickly induced ectopic OSHB3 expression in the entire region of the SAM, but not in other tissues. Furthermore, this ectopic expression of OSHB3 was correlated with leaf initiation defects. Our findings suggest that rice Class III HD-Zip genes have conserved functions with their homologs in Arabidopsis (Arabidopsis thaliana), but have also acquired specific developmental roles in grasses or monocots. In addition, some Class III HD- Zip genes may regulate the leaf initiation process in the SAM in an auxin-dependent manner. [ABSTRACT FROM AUTHOR]

This paper proposes a novel circuit topology for a three-phase power factor correction (PFC) rectifier using a harmonics current injection method. In consideration of lower cost, the harmonics injection method is more suitable than a conventional six-arm pulse width modulation (PWM) rectifier. The harmonics injection current is simply generated by only one switching leg. As a result, the proposed circuit has the advantage of only two switches. An optimal injection current is achieved in order to obtain an input current of sinusoidal waveforms. This paper discusses the basic operation and optimal design method for the proposed circuit. In addition, the validity of the proposed circuit is confirmed by simulation and experimental results. An input current of almost sinusoidal waveform was obtained and an input current total harmonic distortion (THD) of 8.5% was obtained at a load of approximately 1 kW. [ABSTRACT FROM AUTHOR]

Cleistogamy is an efficient strategy for preventing gene flow from genetically modified (GM) crops. We identified a cleistogamous mutant of rice harbouring a missense mutation (the 45th residue isoleucine to threonine; I45T) in the class-B MADS-box gene SUPERWOMAN1 ( SPW1), which specifies the identities of lodicules (equivalent to petals) and stamens. In the mutant, spw1-cls, the stamens are normal, but the lodicules are transformed homeotically to lodicule–glume mosaic organs, thereby engendering cleistogamy. Since this mutation does not affect other agronomic traits, it can be used in crosses to produce transgenic lines that do not cause environmental perturbation. Molecular analysis revealed that the reduced heterodimerization ability of SPW1I45T with its counterpart class-B proteins OsMADS2 and OsMADS4 caused altered lodicule identity. spw1-cls is the first useful mutant for practical gene containment in GM rice. Cleistogamy is possible in many cereals by engineering class-B floral homeotic genes and thereby inducing lodicule identity changes. [ABSTRACT FROM AUTHOR]

The shoot apical meristem (SAM) is a group of stem cells that are responsible for plant development. Mutations in rice SHOOTLESS2 (SHL2), SHL4/SHOOT ORGANIZATION2 (SHO2), and SHO1 cause complete deletion or abnormal formation of the SAM. In this study we showed that defects in SAM formation in shl mutants are associated with the loss of expression of the homeodomain-leucine zipper (HD-ZIPIII) family genes. Rice SHL2, SHL4/SHO2, and SHO1 encoded orthologues of Arabidopsis RNA-dependent RNA polymerase 6, ARGONAUTE (AGO) 7, and DICER-like 4, respectively, whose mutations affect leaf development through the trans-acting siRNA (ta·siRNA) pathway. This suggested that the ta-siRNA pathway regulates the critical step of SAM formation during rice embryogenesis. The gain-of-function experiment by the ectopic expression of SHL4 resulted in reduced accumulation of an microRNA. miR166, and partial adaxialization of leaves, supporting a role for the ta-siRNA pathway in the maintenance of leaf polarity as previously reported in maize. Analysis of the spatiotemporal expression patterns of HD-ZIPIII and miR166 in wild-type and sh mutant embryos suggested that the loss of HD-ZIPIII expression in the SAM region of the developing embryo is the result of ectopic expression of miR166. Our analysis of shl mutants demonstrated that HD-ZIPIII expression regulated by miR166 is sensitive to the ta-siRNA pathway during SAM formation in rice embryogenesis. [ABSTRACT FROM AUTHOR]

Abstract: Since a tokamak fusion reactor will require a fast response and precise power supply to control the coil current, we propose a matrix converter configuration, as a candidate, having a filter in a load side and smaller elements than a conventional matrix converter. Coil current control performance of the candidate converter has been evaluated by a simulation model using the code “PSCAD/EMTDC.” Simulated circuit parameters were: 30mH for the load coil, 1kV for the matrix converter input voltage, and ∼100A for the output coil current. The PWM (pulse width modulation) control using triangular carrier modulation of a 10kHz carrier frequency was adopted as the control method. The simulation results show that the settling delay time of coil current in the step variation is ∼1ms. The transient response performance of the simulated coil current to the reference current was good. We have come to a condition that the matrix converter can be applied to the plasma control coil power supply. [Copyright &y& Elsevier]

Abstract: A kinetic method performed on a flow injection system is described for the determination of ascorbic acid by using its catalytic effect on the complexation reaction of Cu(II) with 5,10,15,20-tetrakis(4-N-trimethyl-aminophenyl)porphyrin. The characteristic spectrum of porphyrin (Soret band), which shows intense absorption around 400nm (ɛ >2.0×105 cm−1 M−1), was used first time for determining ascorbic acid. By incorporating the complexation reaction into a flow injection system, ascorbic acid could be determined either over a broad dynamic range of 0.1–1000μg/ml or at a trace level below 5ng/ml. Good repeatability was also achieved by testing a working standard of 0.1μg/ml with 10 injections at a throughput of 35h−1, obtaining a relative standard deviation of 0.11%. Substances like amino acids, vitamins, sugars, organic acids and metal ions, showed no or little interference even present at high concentrations. The method was validated in the determination of ascorbic acid contents of some commercially available soft drinks by comparison with the official 2,6-dichloroindophenol method with reasonable agreement. [Copyright &y& Elsevier]

While the matrix converter has many advantages that include bidirectional power flow, a size reduction, a long lifetime, and sinusoidal input currents, it is vulnerable to the input voltage disturbances, because it directly exchanges the input voltage to the output voltage. The instantaneous effective power control (IEPC) method has been proposed to compensate the input voltage disturbances, in which the instantaneous effective power is kept constant by controlling input current. However, to date, no method has been proposed to maintain the stability of the system with the IEPC. The purpose of this paper is to propose a method to control the stability of the system with IEPC. First, this paper explains the IEPC theoretically. Next, a model of the system with the IEPC is developed, and stability analyses are conducted. Then, based on the results of the analyses, a stability control method for the system with the IEPC is proposed. Furthermore, the validities of the proposed method are demonstrated by simulation and experiments. Finally, a restart performance of the system after momentary power interruption is discussed. Because the IEPC does not need phase-locked-loop to detect the phase angle of the input voltage, fast restart is expected. [ABSTRACT FROM AUTHOR]

Abstract: A kinetic method for the determination of cysteine on flow injection system is described. Cysteine was found as a catalyst for the complexation reaction of Cu(II) with an ultra sensitive colorimetric reagent of 5,10,15,20-tetrakis (4-N-trimethylammino-phenyl) porphyrin (TTMAPP) (ɛ = 4.8×105 cm−1 M−1 at 433nm), which was used as the indicator reaction in this paper. Soret band of either the porphyrin or the produced complex (ɛ = 4.6×105 cm−1 M−1 at 411nm) can be used for detection. The continuous flow injection system greatly enhanced the analytic precision and efficiency of the kinetic method, giving a relative standard deviation of 0.73% for a 0.1μgml−1 cysteine with 10 injections at a throughput of 30h−1. The detection limits (3S/N) in this case was 15ngml−1 and the working dynamic range was over 25ngml−1 to 1μgml−1. Sugars, organic acids and amino acids that are possible in coexistence with cysteine could be tolerated at high concentrations. This method was critically compared with the Ellman''s reagent in the determinations of cysteine contents of three pharmaceutical injections for hepatic diseases and one permanent wave agent and showed better applicability in the respect of matrix interferences. [Copyright &y& Elsevier]

Abstract: A novel indirect substitution spectrophotometric methodology using porphyrin is developed for the determination of some metals that do not react with porphyrin directly. The methodology is concerned with a multistep reaction system, which consists of 3 complexation reactions that occur in a sequence of EDTA with metal, EDTA with Cu(II) and porphyrin with Cu(II). The complexation reaction of Cu(II) with a cationic porphyrin, meso-tetrakis (4-N-trimethylaminophenyl)-porphine (ttmapp), which has a high molar absorptivity about 5×105 lmol−1 cm−1, serves for spectrophotometric detection. This methodology was verified through individual determinations of 14 species of lanthanides following a batchwise procedure, which was further developed to an automatic procedure on a HPLC post-column flow injection system for simultaneous analysis of the lanthanides. Compared with the conventional post-column derivatization method using 4-(2-pyridylazo) resorcinol (PAR), the analytical sensitivity was greatly improved in this method and the results also showed good linearity. [Copyright &y& Elsevier]

This paper proposes a novel control strategy and a protection circuit and shows the advantage of utilizing a newly developed reverse blocking insulated gate bipolar transistor (RB-IGBT), to solve several practical problems of the matrix converter. The proposed control strategy is based on a virtual indirect control method with a virtual rectifier and a virtual inverter. Pulse-width modulated (PWM) pulses for the matrix converter are obtained by combining PWM pulses for the virtual rectifier and inverter. As a result, the control part of the input current and output voltage can be clearly separated. Thus, the conventional inverter control algorithms can be applied to the virtual inverter control. The advantage of this method is confirmed by experimental results with a 22-kW induction motor drive system. Good sinusoidal waveforms are obtained for the input and output currents, and the total harmonic distortion (THD) of the input and output current are 5.1% and 1.4%, respectively. The conduction loss of the RB-IGBT is decreased to about two-thirds of the conventional ac switch with series connection diode. Thus, the converter loss is about a half to the conventional PWM rectifier-inverter system with the same capacity. Furthermore, the protection problem is solved by a dynamic clamp method without an electrolytic capacitor. This protection circuit directly dissipates reactive load energy by dynamic clamp operation of an IGBT. [ABSTRACT FROM AUTHOR]

This paper proposes a novel control method based on the virtual AC/DC/AC conversion for the matrix converter. The virtual AC/DC/AC conversion method is a very simple strategy to control the input current and the output voltage for the matrix converter. There are two new topics proposed in this paper. First, this paper proposes the minimum switching loss modulation on the virtual rectifier. In our proposed modulation, only two arms switching in the virtual rectifier using DC link current control by the virtual inverter can obtain clean sinusoidal input current. Second, a novel lean controlled carrier modulation on the virtual inverter is proposed. The leans of the triangle carrier are controlled by the duty ratio of the rectifier side pulse. The lean controlled carrier reduces harmonic distortion of the input current by avoiding interference between the rectifier control and the inverter control. These new proposals are confirmed by simulation and experimental results. © 2005 Wiley Periodicals, Inc. Electr Eng Jpn, 152(3): 65–73, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20144 [ABSTRACT FROM AUTHOR]

Rice is becoming a model plant in monocotyledons and a model cereal crop. For better understanding of the rice plant, it is essential to elucidate the developmental programs of the life cycle. To date, several attempts have been made in rice to categorize the developmental processes of some organs into substages. These studies are based exclusively on the morphological and anatomical viewpoints. Recent advancement in genetics and molecular biology has given us new aspects of developmental processes. In this review, we first describe the phasic development of the rice plant, and then describe in detail the developmental courses of major organs, leaf, root and spikelet, and specific organs/tissues. Also, for the facility of future studies, we propose a staging system for each organ. [ABSTRACT FROM AUTHOR]

Examines the effect of the SHOOTLESS2 (shl) and SHOOTLESS1 genes in both initiation and maintenance of the shoot apical meristem through regulating the number of indeterminate cells. Analysis of strains carrying weak alleles of shl; Formation of shoot meristem during embryogenesis by strains bearing the weak alleles; Establishment of proper organization of the shoot meristem.

Presents study which proposed two novel circuits which realized a unity input power factor single-phase to three-phase converter with a motor load. Methodology; Comparison between conventional circuit and proposed circuit; Results of the study; Conclusions.

This paper proposes a multi‐port DC‐AC converter with high efficiency and high‐power density. The proposed circuit consists of a full bridge converter, a series active filter, and an unfolder circuit. The proposed circuit reduces the low switching losses owing to the square waveform operation with low switching frequency. In addition, the proposed converter improves the power density because the number of inductors is significantly reduced compared to the conventional multi‐port converter. As the experimental result, the maximum efficiency of the proposed circuit reached 99.3%. Finally, the power density of the proposed converter is evaluated by the Pareto front curve. As the result, the power density of the proposed circuit was increased by 1.6 times in comparison with the conventional circuit. [ABSTRACT FROM AUTHOR]

The proposed inverter combines two methods which can significantly decrease the on-state and switching losses. The first method, using a current transformer and a single transistor, makes possible the reduction of the on-state loss to less than one-third of the usual Darlington transistor. The second method, using an auxiliary commutation IGBT in parallel with the transistor, makes possible zero-voltage switching, resulting in no switching loss. To realize higher inverter efficiency, a snubber and its loss recovery circuit are employed. Three-phase inverters were fabricated experimentally to evaluate our idea. Device volume and weight can be decreased to one-third those of a conventional three-phase inverter, and an efficiency of 98.0% from 5 kW to 20 kW is obtained at a switching frequency of 16 kHz. © 1997 Scripta Technica, Inc. Electr Eng Jpn, 120(1): 62–69, 1997 [ABSTRACT FROM AUTHOR]

In this paper, a DC–single-phase AC power converter with an LLC resonant converter is presented for a photovoltaic (PV) micro-inverter application. This application requires the leakage current suppression capability. Therefore, an isolated power converter is usually combined for DC/AC systems. The LLC resonant converter is the one of the isolated power converter topologies, and it has good performance for conversion efficiency with easy control. On the other hand, a double-line frequency power ripple has to be compensated for in order to improve the performance of the maximum power point tracking (MPPT). Therefore, a bulky electrolytic capacitor is usually necessary for the power converter. However, the electrolytic capacitor may limit the lifetime of the micro-inverter. This paper introduces the PV micro-inverter with a LLC resonant converter. In addition, the active power decoupling circuit is applied in order to compensate the double-line frequency power ripple by the small capacitor in order to eliminate the electrolytic capacitor. Finally, the transformer design is considered in order to reduce the transformer losses. As a result, the conversion efficiency of the LLC converter is improved by 1% when the litz wire has many strands. [ABSTRACT FROM AUTHOR]

This article proposes a novel method of improving the overall coupling coefficient of a wireless power transfer system by using a four‐winding transformer of which two pairs of windings each are connected in parallel in the primary side and secondary side. By weakening the coupling coefficients kc between the parallel windings, the overall magnetic coupling between the primary side and secondary side of the transformer is improved. In order to confirm the validity of the proposed method, a conventional high‐kc four‐winding transmission coil and the proposed low‐kc four‐winding transmission coil are experimentally assessed. Then, the coils are introduced into a nonresonant inductive power transfer system utilizing a dual active bridge converter in order to confirm the correction of the input power factor. As a result, the overall magnetic coupling of the proposed four‐winding coils was found to be improved by 17% compared with the overall magnetic coupling of the conventional coil. Moreover, the input power factor for the entire load is corrected with the proposed four‐winding coil. Therefore, a low kc is effective in improving the overall magnetic coupling. [ABSTRACT FROM AUTHOR]

This paper proposes a zero-voltage ride-through (ZVRT) method and an LCL filter design method to meet the fault ride-through (FRT) requirements for a single-phase grid-connected inverter with a minimized LCL filter. A high inverter output current overshoot occurs at a grid voltage sag and a grid voltage recovery, when a low-inductance LCL filter design is employed in order to minimize the filter volume. In order to suppress the current overshoot, a high-speed gate-block operation and the design method of the minimized LCL filter are proposed. In particular, the filter design considers the delay time in the gate-block operation in order to clarify the reduction limitation of the inductance in the LCL filter. As a result, the maximum inverter output current overshoot is suppressed to 146% by the high-speed gate-block operation and the designed LCL filter, where the impedances of an interconnected inductor and a filter inductor are 1.0% and 0.78% of the inverter normalized impedance, respectively. Therefore, it is possible to meet the FRT requirements with the proposed ZVRT method even with the minimized LCL filter. [ABSTRACT FROM AUTHOR]

Two proposed methods of reducing radiation noise caused by inductive power transfer (IPT) systems using spread spectrum techniques were experimentally demonstrated. In IPT systems for electric vehicles (EVs) or plug-in hybrid EVs (PHEVs), noise reduction techniques are necessary because the radiation noise from the IPT system for EVs or PHEVs must not exceed the limits defined by noise standards, such as the well-known regulation set by the International Special Committee on Radio Interference. In the proposed methods, the radiation noise from the transmission coils of the IPT system is spread in the frequency domain by randomly changing the output frequency of the inverter. The output frequency is selected according to the generation of pseudorandom numbers. In the first proposed method, spread spectrum with a uniform distribution (SSUD), the output frequency is selected from the frequency range of 80 to 90 kHz with an even distribution. In the second method, spread spectrum with a biased distribution (SSBD), the output current of the inverter is considered. The possibility of selecting an output frequency in the given range is biased in proportion to the combined impedance from the transmission coil and the resonance capacitors on the primary side. In experiments with a 3-kW prototype, when SSUD and SSBD were applied, the fundamental components of the radiation noise were suppressed by 4.45 and 8.27 dB · μA, respectively, in comparison with the noise obtained using the conventional system, which operates the inverter at a fixed frequency. [ABSTRACT FROM PUBLISHER]

This paper proposes a bidirectional isolated single-phase matrix converter with a center-tapped transformer, which is used in a battery storage system connecting to a single-phase ac load. The proposed converter consists of a full-bridge inverter, a high-frequency center-tapped transformer, and a matrix converter. The matrix converter is employed with a pulse density modulation in order to achieve zero-voltage switching (ZVS). On the other hand, a common-mode voltage of the center-tapped transformer and a small capacitor are utilized in order to absorb the power ripple of the single-phase ac load without additional switches. Furthermore, the switches in the full-bridge inverter partially achieve ZVS in order to reduce the switching loss. These characteristics result in a high-power-density converter. As the experimental results with a 1 kW-prototype, the proposed converter reduces the dc current ripple generated by a single-phase ac load by 80.2% in the discharging mode and 76.8% in the charge mode. Besides, the low ac-side voltage total harmonic distortion in the discharge are below 3.0% over the entire ac power range. [ABSTRACT FROM AUTHOR]