Abstract: The present invention provides a variable-speed controlling device for use with an induction motor, which includes a means for compensating for the discrepancy between a secondary magnetic flux instruction value and a secondary magnetic flux actually occurring in an induction motor, realizes a satisfactory control by generating the secondary magnetic flux according to the instruction value, and can generate desired torque and improve a motor efficiency. The variable-speed controlling device according to the present invention, for use with an induction motor, includes a voltage instruction value calculating unit, an integrating unit, a power converting circuit, a current detecting unit, an induced voltage calculating unit, a position discrepancy amount calculating unit, and a compensating unit.

Abstract: The apparatus calculates a torque that an induction motor generates while considering an iron loss even in a boosting state for exceeding the rated excitation. The calculation is based on a reference voltage value fed to an inverter for driving the induction motor, a q-axis current component and a d-axis current component resolved from a detected current of the induction motor on a rotating coordinate system, a primary resistance of the induction motor and a primary angular frequency. The apparatus includes an iron loss calculator that calculates the iron loss of the induction motor based on hysteresis characteristics of the stator core, a divider that divides the calculated iron loss by the primary angular frequency and an adder that calculates the generated torque by subtracting the result of the division from the torque calculated without considering the iron loss.

Abstract: A PWM power converter is provided which includes an adder that adds a high-frequency signal from a high-frequency generator to a voltage command signal, and a PWM generator of carrier comparison type or space vector type that generates a PWM signal based on the output of the adder, which PWM signal is used for driving switching devices to provide a desired output voltage.

Abstract: A control apparatus for an induction motor includes a current detector for detecting the current of the induction motor; a first coordinate transformer for resolving the current into an exciting current component and a load current component; a slip value calculator for calculating a slip angular frequency of the induction motor based on the load current component; a correction value calculator for calculating a correction value for the slip angular frequency of the induction motor in response to the change of the exciting current component; a multiplier for correcting the slip angular frequency by using the correction value calculated in the correction value calculator; an adder for calculating a reference primary angular frequency based on the corrected slip angular frequency; a voltage vector calculator for calculating a reference voltage value based on the reference primary angular frequency; and a second coordinate transformer for feeding the calculated reference voltage value to the inverter.

Abstract: An ac/dc converting circuit adapted to output a direct voltage that is higher than a full wave rectified voltage of an alternating input voltage is provided which includes an alternating current filter, and a condenser with a positive electrode and a negative electrode coupled to a dc output side of a full wave rectifying circuit. The full wave rectifying circuit includes a switching portion having upper and lower arms each having a semiconductor rectifying element and a self-commutated semiconductor switching element, and a rectifying portion having upper and lower arms each having a semiconductor rectifying element. The semiconductor rectifying elements in the upper arms of the full wave rectifying circuit has a common cathode coupled to the positive electrode, and the semiconductor rectifying elements in the lower arms has a common anode coupled to the negative electrode.

Abstract: A driving circuit for driving an IGBT includes a forward-bias power supply, a reverse-bias power supply, a forward-bias semiconductor switch, a reverse-bias semiconductor switch, a first resistor for limiting forward-bias current, and a second resistor for limiting reverse-bias current. In this driving circuit, one terminal of a capacitor is connected to a common node of the resistor for limiting forward-bias current, the resistor for limiting reverse-bias current, and a gate of the IGBT. A mode switching semiconductor switch is connected at one terminal to the other terminal of the capacitor. The other terminal of the mode switching semiconductor switch is connected to a common node of the forward-bias power supply and the reverse-bias power supply. In operation, the mode switching semiconductor switch is turned on and turned off so as to establish a given rate of change of voltage which is independently selected for turn-on and turn-off of the IGBT.

Abstract: An ac/dc converting circuit adapted to output a direct voltage that is higher than a full wave rectified voltage of an alternating input voltage is provided which includes an alternating current filter, and a condenser with a positive electrode and a negative electrode coupled to a dc output side of a full wave rectifying circuit. The full wave rectifying circuit includes a switching portion having upper and lower arms each having a semiconductor rectifying element and a self-commutated semiconductor switching element, and a rectifying portion having upper and lower arms each having a semiconductor rectifying element. The semiconductor rectifying elements in the upper arms of the full wave rectifying circuit has a common cathode coupled to the positive electrode, and the semiconductor rectifying elements in the lower arms has a common anode coupled to the negative electrode.

Abstract: An output voltage control apparatus for performing feedback control on an output voltage of an inverter which drives an AC machine. The output voltage control apparatus converts a command value for the output voltage of the inverter into a pulse density using a converter (PDM), and converts a detection value of the output voltage of the inverter into a pulse density using a .DELTA.-.SIGMA. modulation converter. The proportional control ability and integral control ability for the output voltage are realized by digital hardware including an up-counter, a down-counter and a shift circuit.

Abstract: An AC-DC converter includes an adjusting unit 13 which operates to zero the difference between a DC output voltage instruction value and a DC output voltage detection value; and a modulator 16 which compares a carrier wave based on an output signal of the adjusting unit 13 with a modulating wave to output drive pulses, a switching element 3 is turned on and off with the drive pulses to provide a DC output voltage which is higher than a full-wave rectification voltage of an AC input voltage. In order to obtain the carrier wave, the AC-DC comprises further includes an AC input voltage polarity detector 7, a PLL circuit 11, and a multiplier 14 for multiplying the sine wave by an output signal of the adjusting unit 13.

Abstract: A control circuit for controlling a power converting apparatus, maintaining a stable operation of an induction motor. The control circuit includes an exciting current obtaining circuit which obtains the exciting current component from a detected signal of primary currents of the induction motor, a circuit which obtains an exciting current oscillation component from the exciting current correlate, a circuit which obtains correcting quantity from the exciting current oscillation component, and circuits which correct the voltage command or the flux command by the correcting quantity, and provide it to the power converting apparatus as stator axis voltage command values.

Abstract: An apparatus for restarting an inverter after momentary interruption by detecting a power restoration after a momentary outage of a power supply that supplies power to the inverter for driving a synchronous motor. The apparatus includes a frequency detecting portion that detects the frequency of a terminal voltage of the synchronous motor, a phase difference detector that detects the phase difference between the terminal voltage of the synchronous motor and the output voltage command value of the inverter, a phase controller that performs synchronous control so that the frequency and phase of the output voltage command value of the inverter and those of the terminal voltage of the synchronous motor agree with each other, and a restarting portion that restarts the inverter under the condition that the synchronization has been completed after the power restoration of the power supply.

Abstract: A cap for a reservoir comprises cylindrical baffles with different diameters concentrically arranged in the cap, and breathers arranged to the cylindrical baffles.

Abstract: A semisubmersible system for collecting a desired material from the sea water includes a submersible collection chamber which is defined by a pair of non-porous, buoyant side walls, a pair of non-porous end walls, a porous top wall and a porous bottom wall. A quantity of collecting agent is contained in the collection chamber. The buoyancy force applied to the present system by the pair of buoyant side walls is so set to keep the collection chamber substantially at a predetermined depth from the sea surface, so that the sea water is permitted to move into and out of the collection chamber due to wave motion while keeping the collection chamber virtually stationary in the vertical direction. There is obtained a large relative motion between the sea water and the collection chamber so that a large quantity of sea water is brought into contact with the collecting agent, thereby allowing a useful material contained in the sea water to be collected by the collecting agent by adsorption or absorption.

Abstract: A protease adsorbent wherein valyl-glycyl-argininal is bound to a water-insoluble carrier and a process for purifying TPA utilizing the same.

Abstract: This invention provides an aerator comprising a jet stream generator for ejecting a gas and a liquid in a mixed state from a nozzle, and a tubular flow straightener for mixing the bubble-containing stream ejected from the nozzle with ambient water and discharging the resulting mixture from the discharge orifice thereof, characterized in that the flow straightener has a tubular form whose internal diameter is reduced from the inlet toward the discharge orifice through at least a part of its length.This aerator can produce a stream containing minute gas bubbles, even when a gas is supplied thereto in such a large amount as to give a gas-to-liquid volume ratio of 3/1.

Abstract: The present invention provides a hollow-fiber filter module comprising a straight tube, a bundle of hollow fibers having at least a part thereof disposed within the straight tube, a fastening member for bundling and fixing the open ends of the hollow fibers, and at least a branch tube having an end protruding to the outside of the straight tube, that surface of the fastening member which includes the open ends of the hollow fibers being attached to the branch tube in a fluid-tight manner, as well as a filtration method in which a plurality of such hollow-fiber filter modules are connected in series to form a filter module assembly and a fluid to be treated is filtered by utilizing one end of the connected straight tubes of the assembly as an inlet for the fluid to be treated, the other end thereof as an outlet for the fluid to be treated, and the branch tube of each module as an outlet for the filtered fluid.

Abstract: A biospecific adsorbent comprising pyroglutamyl-lysyl-leucyl-argininal combined with a water-insoluble support is provided. This biospecific adsorbent is useful as an adsorbent for use in affinity chromatography and can be utilized for the purification of proteases such as urokinase.

Abstract: L-Argininal derivatives of the general formula: ##STR1## are disclosed. A method of manufacturing any such derivative is also disclosed. The L-argininal derivative of this invention has a strong inhibitory activity on proteases, such as serine and thiol proteases, and is expected to provide useful medicines, including those which are effective for diseases caused by abnormal elevation of protease activity.