Abstract: An inverter device has a three-phase inverter for converting DC electric power into AC power for supplement to an AC electric motor and a control device operatively associated therewith, and the control device includes a phase current detection section for outputting a phase current waveform based on a DC input current and an operational processor section for performing operational processing for control of said inverter device based on the phase current waveform. Thereby, the inverter device can be constructed to be very compact.

Abstract: A single-phase PWM converter system in accordance with the present invention employs a sample-and-hold circuit which samples and holds a direct current in the state wherein one of two-phase gate signals of a positive or negative side arm is ON and the other phase is OFF, determines the sign of an output of the sample-and-hold circuit according to the two-phase gate condition, detects a phase current at the input side of the converter, and controls a voltage at the input side of the converter so that the detected current value agrees with a power supply current command.

Abstract: Filter capacitor voltage “Ecf1” is detected and then after d-axis voltage correction value “dvd”, q-axis voltage correction value “dvq”, q-axis current correction value “diq”, and frequency correction value “d&ohgr;1” have been computed from the AC components of “Ecf1” and the results have been added to the corresponding d-axis voltage command, q-axis voltage command, q-axis current, and frequency command, the DC current of the power converter is controlled. Thus, the AC components included in the DC current are offset and the AC components are suppressed effectively.

Abstract: In detecting an output current of a power converter based on a DC current Idc of the power converter, the pulse width of the DC current Idc becomes narrower when the pulse width of a line voltage is narrower, and its detection becomes difficult. A voltage command correction unit 9 according to the present invention corrects voltage commands such that pulse width of a line voltage becomes zero when the pulse width of the line voltage is less than the minimum pulse width, not to output a line pulse, and an error generated by the correction is integrated. This integrated error is added to the line voltage in the next time, and the integrated pulse width of the line voltage is outputted when the pulse width becomes larger than or equal to the minimum pulse width.

Abstract: An inverter device in the present invention comprises a three-phase inverter for converting DC electric power into AC power for supplement to an AC electric motor and a control device operatively associated therewith, and said control device includes a phase current detection section for outputting a phase current waveform based on a DC input current and an operational processor section for performing based on said phase current waveform operational processing for control of said inverter device. Thereby, the inverter device can be constructed to be very compact.

Abstract: An induction motor control apparatus includes a first constant correction unit for correcting primary resistance based on quantity obtained by multiplying quantity of a voltage command from a frequency voltage control unit by the output of a correction unit, the quantity of the voltage command being a result of partial differentiation with the primary resistance; a second constant correction unit for correcting the inductance based on quantity obtained by multiplying quantity of the voltage command, the quantity of the voltage command being a result of partial differentiation with the inductance; and a third constant correction unit for correcting the inductance ratio based on quantity obtained by multiplying quantity of the voltage command, the quantity of the voltage command being a result of partial differentiation with the inductance ratio, suppressing the deterioration of control performance caused by the setting errors.

Abstract: This invention relates to a process for producing aromatic divalent carboxylic acid ester and diatomic alcohol by reacting aromatic polyester and super critical monatomic alcohol, and by the process, PET is decomposed for recovering monomer components therefrom, and thus recovered monomer components can be used as the material for reproduction of new PET. In accordance with the present invention, there is provided a process for producing continuously monomer components from aromatic polyester, the process including the steps of: feeding continuously the above aromatic polyester and the above monatomic alcohol into a reactor while the above reactor is kept to be under the super critical condition of the above monatomic alcohol; reacting the above aromatic polyester and the above super critical monatomic alcohol and discharging the resultant reaction products, i.e.

Abstract: A hydrophobic textile product of the present invention is obtained through graft polymerization of an ethylenically unsaturated organic acid. The textile product characterized by: a graft polymerization rate of about 8 wt % or more; substantially no agglutination of a byproduct polymer from the graft polymerization process; a hygroscopicity of about 2.5 wt % or more under a 20° C.×65% RH environment; and an ammonia deodorizing property.

Abstract: A heat exchanger tube for a falling film evaporator has fins provided on the outer periphery of the tube body and extending in a direction transverse or in oblique to the axial direction of the tube. The fins have heights in a range of 0.2 to 0.8 mm. The fins are arranged in a density to have 905 to 1102 in number of fins per 1 m in the axial direction. Grooves formed in the tip end of the fins and extending substantially along the fins, the mutually opposing inner peripheral wall surface of the groove defining an angle within a range of 70° to 150°. Cut-outs formed in the tip end of the fins, the cut-outs being provided at a pitch in a range of 0.5 to 1.0 mm. With this construction, the heat exchanger tube for the falling film evaporator which exhibits a high refrigerant wetting and spreading ability as well as large surface area for providing remarkably improved heat transmission performance.

Abstract: A vector control apparatus having a DC braking function which is insusceptible to trip even upon DC braking and scarcely suffers vibration upon stoppage is provided.The control apparatus includes a DC braking control arithmetic unit 1 and switches S1, S3 and S4 controlled thereby, wherein in a vector control mode, the DC braking control arithmetic unit 1 sets all the switches S1, S3 and S4 to position a for realizing the vector control. When a DC control state is to be validated from the above-mentioned state, phase of voltage vector is calculated to change over the switches S1 and S3 to position b, and the absolute value of the q-axis current is compared with a reference value .alpha.. When the absolute value of the q-axis current is smaller than the reference value .alpha., the switch S4 is changed over to the position b to thereby effectuate only the d-axis current control.According to the present invention, there is provided a vector control apparatus having a tripless DC braking function.

Abstract: An inverter apparatus includes a basic control section including a main circuit which includes an inverter, and a control unit which controls the main circuit. The inverter apparatus also includes an I/O block which is connected to the basic control section, and is selected from a plurality of different types of I/O blocks. The I/O block includes an input/output interface. The input/output interface includes a signal connection terminal which transmits an input/output signal to/from the control unit. Operation management specifications of the main circuit are fixed independently of operation management specifications of the input/output interface.

Abstract: The invention provides an electric power converter system which uses a standard low-priced control processor and is suitable for improving the voltage utilization factor in the output voltage. D-axis and q-axis voltage commands and a rotation angle .theta. defining a voltage command vector on a rotating coordinate system are input to a voltage calculation circuit. The voltage command vector is transformed in a rotating coordinate transformation unit into a .alpha. axis and .beta. axis voltage commands to be defined relative to stationary coordinate system. A judgment unit determines which section contains the voltage command vector, from among three sections on the stationary coordinate system having one axis thereof (.alpha.-axis for example) coinciding with one axis of the three phases. A three phase voltage generation unit then selects a method of calculation on the basis of a result of the section determination, and calculates three phase voltage command values respectively utilizing the .alpha.

Abstract: A heat transfer tube for an absorber, including a plurality of crest portions and trough portions extending in parallel to each other in an axial direction of the tube and arranged alternately in a circumferential direction of the tube. The ratio d/P of a depth d of each of the trough portions to a pitch P of the crest portions defined as P=.pi.D/n is set in the range of 0.1 to 0.4; the depth d is set in the range of 1.50 to 2.00 mm; the ratio R.sub.2 /d is set in the range of 2.5 to 6.0; the ratio R.sub.1 /R.sub.2 is set larger than 1, where n represents a positive integer, R.sub.1 represents a radius of curvature of an outer top surface of each crest portion, R.sub.2 represents a radius of curvature of an outer bottom surface of each trough portion, and D represents a diameter of a circumscribed circle of the crest portions.

Abstract: A trip-resistant frequency control inverter which prevents an overcurrent and overvoltage by frequency control of a motor. Such arrangement provides for generating an accelerating or decelerating rate from the output from a fuzzy controller, which inputs the difference between limiting values and detected values and their changes. The arrangement also provides at the time of acceleration a control which automatically generates an accelerating rate which maintains the current in the vicinity of the limiting value, and a normal acceleration part which adjusts the set accelerating rate. The arrangement further provides at the time of deceleration a control which automatically generates a decelerating rate which maintains the current and voltage in the vicinity of their limiting values, and a normal deceleration part which adjusts the set decelerating rate.

Abstract: A method of applying a surface hydrophilic treatment to a heat-transfer tube with a good productivity, which obtains an excellent surface hydrophilic property not deteriorated for a long term. The method includes the steps of: heating a copper or copper alloy heat-transfer tube for 5 to 10 min at a temperature ranging from 250.degree. to 350.degree. C. in an atmosphere mainly containing an inert gas; and applying corona discharge or plasma discharge to the copper or copper alloy heat-transfer tube. To prevent the coloring, the atmosphere preferably contains O.sub.2 in a concentration of 3% or less and CO in a concentration of 1 to 5%, the balance being an inert gas.

Abstract: Inverter control method and apparatus which are immune to the influence of load disturbance and detection noise and permit stable minimization control of motor current, in order to attain high efficiency of an AC motor and of an inverter adapted to drive the same. A memory group is provided having a plurality of sets of memories for storage of data pieces representative of exciting current commands standing for manipulated variables and data pieces representative of motor currents standing for controlled variables. An upper limit value (IDUP) and a lower limit value (IDLW) defining a fluctuation region of the exciting current command are determined so that an exciting current command data piece corresponding to a motor current data piece which is the smallest of all the current data pieces in the memory group falls within the fluctuation region. The fluctuation region is determined so as to minimize the motor current, the exciting current command being fluctuated within the fluctuation region.

Abstract: An air/fuel ratio control system is provided for use with an internal combustion engine. The system includes a first air/fuel ratio detector arranged on an upstream side of a catalytic converter so as to detect the air/fuel ratio of the engine from components of exhaust gas, a second air/fuel ratio detector arranged in the exhaust system and having a detection response speed slower than the first air/fuel ratio detector, a device for controlling the air/fuel ratio of the engine on the basis of results of a comparison between a detection value from the first air/fuel ratio detector and a predetermined first reference value, a device for effecting a correction to the control of the air/fuel ratio by the air/fuel ratio control device on the basis of results of a comparison between a detection value from the second air/fuel ratio detector and a predetermined second reference value, and a device for shifting the second reference value to a lean air/fuel ratio side in a specific operation state of the engine.

Abstract: An air/fuel ratio control system is provided for use with an internal combustion engine. The system includes an air/fuel ratio detector arranged on an upstream side of a catalytic converter so as to detect the air/fuel ratio of the internal combustion engine from components of exhaust gas, a device for controlling the air/fuel ratio of the internal combustion engine on the basis of results of a comparison between a detection value from the air/fuel ratio detector and a predetermined reference value; and a device for shifting the reference value to a lean air/fuel ratio side in a specific operation state of the internal combustion engine.

Abstract: There is provided between a concentrate tank and a membrane filter a circulating line which consists of a feed line and a return line. It is also possible to use an ultrafilter as the membrane filter. There is provided a leveling tube connected by respective pipes to the concentrate tank at top and bottom portions thereof, respectively. A buoy floats within the leveling tube and a position of this buoy is detected by means of transparency of the leveling tube itself or photosensors in order to detect a degree of concentration of the culture fluid progressing within the concentrate tank. There may be provided multi-stage circulating lines each connecting the associated concentrate tank to the associated membrane filter so that the culture fluid can be transferred during the process of concentration from the stage of the largest volume treatment to the state of the least volume treatment in order to concentrate the culture fluid more efficiently.