Showing papers by "Mitsubishi Electric published in 1987"

Secondary Resistance Identification of an Induction-Motor Applied Model Reference Adaptive System and Its Characteristics

Abstract: Induction-motor torque is not accurately controlled when the estimated secondary resistance of an induction-motor model in a vector controller differs from the true secondary resistance. An algorithm which identifies the secondary resistance on-line is developed. The motor operating condition for secondary resistance identification, the stable identifier organization, and the experimental investigation confirming the identification algorithm performance are presented. The algorithm is based on the theory of model reference adaptive systems (MRAS). The proposed algorithm stably identifies the secondary resistance under any load and any speed when a sinusoidal signal is injected into the flux axis primary current. The vector controller adopting this algorithm controls motor torque accurately under any load and any speed.

Dead beat control of three phase PWM inverter

Abstract: This paper proposes new method of high performance current and/or voltage control of three phase PWM inverter, especially suitable for high speed switching devices such as Transistor and BIMOS. As the controller for calculation of the dead beat algorism, a high speed digital controller, such as the digital signal processor is assumed. Following new methods are successfully adopted and combined to realize high quality. (1) Three phase inverter current and voltage are transformed to synchronizing d-q-0 frame, and discretized equations of current and voltage are derived, which clearly reveal coupling of voltage and current of inverter on d-q frame. (2) Using above discretized equation of main circuit, algorism of Dead Beat control with compensation for decoupling is developed. (3) New method for compensation of computing time delay and full utilization of sampling interval for inverter output pulse width is developed, which utilizes 2nd order load current prediction and discretization with twice time of sampling period. (4) Double Dead Beat control system is developed for sinusoidal output voltage inverter, which has high speed current minor loop to constrain inverter current within safety limit. Validity of these techniques has been confirmed by simulation using a hybrid computer.

Time synchronization method in data transmission system

Abstract: A method for synchronizing the times of a master clock provided in the master station and slave clocks provided in the slave stations in a data transmission and receiving system consisting of the master station as a data transmission control station and slave station and/or stations for two-way data transmission. An encoded time survey command including master clock time is transmitted from the master station to each slave station. This is followed by an encoded response from each slave station which includes the slave clock time, from which the transmission delay to and from the slave station is determined along with the time difference between master and slave clocks. Time correction data is then transmitted to correct the time of the slave station clock.

Artificial intelligence in power system operations

Abstract: Power system operators often reach a cognitive barrier when information arrives too fast during a power system emergency At such times it becomes difficult to reach a correct diagnosis of the problem or to formulate the correct decision when actions must be taken Artificial Intelligence gives designers of Energy Management Systems a way to solve many of the diagnosis and decision problems so as to make the EMS more useful This paper explores reasons why AI techniques, such as knowledge-based expert systems, are being used in EMS designs and the differences between knowledge-based expert systems and traditional numeric algorithm development The differences between expert systems and the numeric approach extend to the basic conception and design of the applications This is illustrated using a relay fault diagnosis system, showing both the traditional and rapid prototyping approaches to its development Finally, issues concerned with the implementation of AI in EMS computers are explored along with the authors' predictions of possible AI applications to power system operations

Motor-driven power steering system for front and rear road wheels

Abstract: A motor-driven power steering system for front and rear road wheels which is capable of preventing uncontrolled steering resulting from abnormal movement of the rear road wheels in case of a failure in various sensors and/or an electric motor or breakage in the wiring, and enabling vehicle to continuously travel in a safe manner by means of front wheel steering alone after occurrence of such troubles.

Effects of Antimony Oxide on the Characteristics of ZnO Varistors

Abstract: Observations des experiences: Sb 2 O 3 augmente la tension du varistor et la non-linearite; SiO 2 augmente la tension du varistor et la linearite. Le parametre cristallin du spinelle avec le β-Bi 2 O 3 est plus grand que celui avec le γ-Bi 2 O 3 ; Sb 2 O 3 se disperse d'abord puis se regroupe avec d'autres elements qui peuvent ameliorer les caracteristiques du varistor

New PWM Method for Fully Digitized Inverters

Abstract: The development of digital devices has led to the production of PWM inverters for driving induction motors having high-frequency carriers over 10 000 Hz. However, the popular digital devices exhibit difficulties in arriving at the precise switching instants because of limitation of available memory capacity and of bits, especially in the low-frequency region. Basic discussions on the magnetic flux and torque ripple and an introduction to a memory-saving and low-torque-ripple new PWM (split zero vector) method are given. The experiments show fairly good current waveforms, low iron loss, and low acoustic noise.

Reduction of Dislocation Density in GaAs/Si by Strained-Layer Superlattice of InxGa1-xAs-GaAsyP1-y

Abstract: Dislocation density in GaAs layers grown on Si substrates has been investigated by measuring in-depth profile of the etch pit density (EPD) using a molten KOH. Reduction of EPD into 107 cm-2 level for the layer of 2-3 µm thickness is attained by the post annealing at 900°C for 30 min. Further reduction of dislocation has been achieved using InxGa1-xAs-GaAsyP1-y strained-layer superlattices (SLS's); step-like reduction of the dislocation at the SLS's and its continuous decrease even passing through the SLS's have been observed.

Three dimensional IC for high performance image signal processor

Abstract: The three-dimensional (3-D) image processing test IC designed with parallel processing architecture is fabricated. The device consists of 5-by-5 array of photosensors, 2-bit CMOS A-to-D converters, 40 arithmetic logic units (ALU) and shiftregisters arranged in a 3-layer structure. The total operation from photosensor on top layer to ALU on bottom layer is confirmed, and it is also demonstrated the feasibility of very high speed system operation with the implement of parallel processing. This device gives a clear image of the intelligent image processor on one chip as a future application of 3-D ICs.

Preparation of positive photoreactive polyimides and their characterization

Abstract: Polyimide precursors were synthesized from a diamine and a diacid chloride that was derived from the reactant with promellitic dianhydride and o-nitrobenzyl alcohol. Their thermal properties were studied in nitrogen using dynamic thermogravimetry, and the photoreaction mechanism was investigated by ultraviolet and infrared spectrophotometry. The polyimide precursors were spin-coated onto silicon wafers, prebaked, and then exposed to UV light from a high pressure Hg–Xe lamp. When the films were dipped into 2% aqueous KOH after irradiation, the exposed area dissolved forming high resolution patterns. Relative sensitivities of the polymers were determined.

A 34-ns 1-Mbit CMOS SRAM using triple polysilicon

Abstract: A 128-kb word/spl times/8-b CMOS SRAM with an access time of 3 ns and a standby current of 2 /spl mu/A is described. This RAM has been fabricated using triple-polysilicon and single-aluminum CMOS technology with 0.8-/spl mu/m minimum design features. A high-resistive third polysilicon load has been developed to realize a low standby current. In order to obtain a faster access time, a 16-block architecture and a data-output presetting technique combined with address transition detection (ATD) are used. This RAM has a flash-clear function in which logical zeros are written into all memory cells in less than 1 /spl mu/s.

The influence of geometric parameters on F.C. centrifugal fan noise

Abstract: Influence des caracteristiques geometriques sur le bruit d'un ventilateur centrifuge a ailettes incurvees vers l'avant

A very narrow-beam AlGaAs laser with a thin tapered-thickness active layer (T 3 laser)

Abstract: A very narrow-beam and high-power laser which has a thin tapered-thickness active layer is developed. The property of LPE on a ridged substrate is utilized to obtain the thin tapered-thickness active layer. In the T3laser, the active layer is thinner near the mirror than in the inner region. The main feature of the T3laser is the independent control of the beam divergence perpendicular to the junction ( \theta_{\perp} ) and the threshold current ( Ith ). That is, the narrow beam is obtained with little increase of Ith . Thus \theta_{\perp} as narrow as 10° has been obtained with Ith about 60 mA. The large near-field spot size of the laser is also suitable for high-power operation. The maximum output power of 120 mW in the fundamental transverse mode has been realized for a laser emitting at 780 nm. Stable 30 mW operation at 50°C has been confirmed over 7000 h.

A highly reliable selective CVD-W utilizing SiH4 reduction for VLSI contacts

Abstract: Selective CVD-W process by using silane (SiH4) reduction of WF6 has been developed for VLSI contacts The reaction occurs very fast resulting in a deposition rate of as high as 06 µm/min, and completely suppresses undesirable phenomena such as encroachment and wormholes An X-ray diffraction analysis shows that a small W5Si3 peak can be observed although W peaks are dominant The junction leakage current for the new selective CVD-W process is almost the same as that for conventional AlSi one Contact resistance of submicron holes is more stable and lower for this process than for the conventional one This new process has been successfully applied to CMOS 1Mbit DRAM

Radial Magnetic Pull in Salient Pole Machines with Eccentric Rotors

Abstract: A new simple analytical method for radial magnetic pull force in salient pole machines with eccentric rotors is presented. Calculation results are verified by experiments. As this method presents the precise calculation of flux density in the air gap of the entire circumference and the saturation effect of magnetization, the estimation of radial magnetic pull has been improved.

H-mode phenomena during ICRF heating on JFT-2M

Abstract: Significant improvement of energy confinement has been observed on JFT-2M during ICRF heating. This improvement is preceded by a sudden drop in the Hα/Dα emission and a successive increase in stored plasma energy, electron density and radiation loss. This is believed to be the same phenomenon as the H-mode transition observed in ASDEX, and in PDX divertor experiments with neutral beam injection. However, in JFT-2M, this transition is observed both in limiter discharges and in open divertor configurations.

Ic card and ic card system

Abstract: An IC card system comprises an IC card (10) containing a semiconductor module (1) with a CPU (1a) and a memory (1b) and a display region (3) for displaying the contents of the memory (1b). The IC card is inserted into a terminal (30) which, reads the contents of the memory, and controls the display provided on the card in accordance with the contents of the memory.

A design method of systolic arrays under the constraint of the number of the processors

Abstract: This paper proposes a systemtic method to design systolic arrays under the constraint of the number of the processors. Our basic approach is to partition the large systolic array into the smaller number of groups, whose number is coincident with the number of processors to be used. We give the mathematical method to make at most one processor execute computation in each group. Then, each group can be replaced by one processor to satisfy the constraint of the number of the processors.

An improved thinning method for density tapering of planar array antennas

Abstract: A thinning method is presented to realize the desired aperture distribution in a planar array antenna with elements fixed on an array lattice. In this method elements to be excited are determined by quantizing cumulative weights which are calculated from the desired aperture distribution. At first, this method is applied to density tapering on orthogonal axes of a planar array. Radiation patterns of the planar array determined by this method are compared with those by the desired amplitude distribution, and the results show good coincidence. Next, this method is extended to density tapering on four axes, that is, orthogonal and diagonal axes of a planar array. Moreover, this method is applied to density tapering with multi-amplitude level elements in order to enhance directive gain of thinned array. Lastly, a rectangular planar array was fabricated, and its radiation patterns were measured. Measured results were in good coincidence with calculated ones, and the usefulness of this method was verified.

Positive Photoreactive Polyimides. II. Preparation and Characterization of Polyimide Precursors Containing α-(2-Nitrophenyl)ethyl Ester Side Chains

Abstract: The monomers were derived from pyromellitic dianhydride and α-(2-nitrophenyl)ethanol, which was prepared by selective reduction of 2-nitroacetophenone. Polyimide precursors were synthesized by an interfacial polycondensation technique. Their thermal properties in nitrogen were studied by dynamic thermogravimetry. The photore-arrangement of 2-nitrobenzyl ester having a methyl group at the α-position compared to that of the unsubstituted ester was investigated by infrared spectrophotometry. The polymers obtained in this study gave a high proportion of photorearrangement to show high sensitivity. The exposed areas dissolved in 2% aqueous KOH, forming high resolution patterns because they did not swell during the developing process.

1.3μm InGaAsP/InP distributed-feedback P-substrate partially inverted buried-heterostructure laser diode

Abstract: A novel 1.3μm InGaAsP/lnP distributed-feedback buried-heterostructure laser diode on p-type InP substrate has been developed utilising a dopant diffusion technique. The laser has achieved a threshold current as low as 20 mA and high output power of 32 mW under CW and SLM operation.

An auto-tuning controller

Abstract: An auto-tuning controller comprising: a controller for controlling a controlled system; a reasoning rule memory for storing a reasoning rule to be used for reasoning an optimum control parameter of said controller; and an adjustment section for adjusting said optimum control parameter of said controller by a fuzzy reasoning with the use of said reasoning rule.

A 90ns 4Mb DRAM in a 300 mil DIP

Abstract: A 4Mb DRAM employing a folded-bitline adaptive sidewall - isolated capacitance cell with 2μm deep trenches, a 72.3mm2chip size and 90ns access time will be described. Also incorporated are full bonding options for 4Mb×1 or 1Mb×4 organizations and for static column or page-mode operation.

Interaction between the reinforcement and matrix in carbon-fiber-reinforced composite: effect of forming the thin layer of polyimide resin on carbon fiber by in situ polymerization

Abstract: For the purpose of enhancing the reinforcement–matrix interaction in carbon-fiber-reinforced polymer composite, mechanical and spectroscopic studies were made on the epoxy resin composite reinforced with the carbon fiber coated with thin Layer of polyimide resin. On the loss modulus and loss tangent vs. temperature curves, a subtransition appears at a temperature above the primary transition. The T-peel strength of a laminated specimen and the fiber efficiency factors for modulus and strength are larger than those of the composite reinforced with nonpolyimide treated fiber. These results show the increased interaction between the epoxy resin and the carbon fiber coated with polyimide resin. The occurrence of specific interaction between an epoxy resin and the polyimide resin are recognized on fourier transform infrared spectra.

Characterization of Silicon Implanted with Focused Ion Beam by Raman Microprobe

Abstract: Damage to silicon implanted with Si++, Au++ and Be++ ions using focused ion beams has been evaluated by a Raman microprobe technique. A quantitative evaluation of damage to ion-implanted silicon was made by comparing the intensities of Raman scattering from implanted and unimplanted areas. The minimum dose at which damage is detectable by Raman measurements is 9×1011 ions/cm2 for Au++, 7.5×1012 ions/cm2 for Si++ and 7.5×1013 ions/cm2 for Be++. From the depth distribution of the damage measured using laser lines of different wavelengths, it is inferred that damage at the near-surface region in Be++ implanted silicon is reduced by self annealing during high-dose-rate implantation and that a channeling effect causes the saturation dose in Be++ implantation to be higher than that in other ion implantations.

Large Scale and Large Area Amorphous Silicon Thin Film Transistor Arrays for Active Matrix Liquid Crystal Displays

Abstract: The preparation and properties of hydrogenated amorphous silicon thin film transistor arrays for active matrix liquid crystal displays are reported. The effect of amorphous silicon film preparation conditions on the field effect mobility of thin film transistors was investigated. The dry etching rate of silicon nitride film was studied.The thin film transistor arrays have 408 ˜ 640 transistors on the first version and 450 ˜ 640 ˜ 3 transistors on the second version. The liquid crystal panel fabricated using the first version arrays showed good characteristics.