Abstract: In a controller, for use in an electric motor, which self-contains a current control system, a conducting portion of a feedback element from a current detector up to a summing point, and a conducting portion of a forward element from the summing point for the current control up to a gate terminal of each of switching devices are mounted in a power module to be hermetically encapsulated without being exposed to the external ambient atmosphere. The distributed processing is executed in the two portions, i.e., a current control loop, and a position control unit, a velocity control unit and an interface processing unit other than the current control loop. Therefore, the current control loop including the current feedback portion is constituted by another sub-microprocessor to be mounted together with the associated devices in a power module which is molded with resin such as epoxy resin.

Abstract: A power converter comprises a pulse generator capable of outputting two different levels of gate power. A thyristor (LTT) is turned on by the first gate power output from the pulse generator, and the second gate power is supplied to the thyristor (LTT) during the transient period from the time the thyristor valve current is cut off to the time the withstand voltage of the thyristor (LTT) recovers to the rated value. The second gate power is set at a low level by which the thyristor (LTT) will not be turned on when the second gate power with the normal level of voltage is applied to the thyristor.

Abstract: A single crystal material is filled in a crucible, and the whole of the single crystal material is melted to contain doping impurities. A solid layer coagulated upward from the bottom of the crucible is rendered to coexist with a melted layer over the solid layer. The solid layer is melted from the upper side thereof while pulling the single crystal from the melted layer. The ratio by weight between the solid layer and the single crystal material at the start of pulling is adjusted, together with the ratio by weight between the grown single crystal and the melting solid layer. The single crystal is thus grown while changing the volume of the melted layer.

Abstract: An apparatus for growing a single crystal having a crucible, two heaters arranged at the outside of the crucible and along the vertical direction, a heat shield placed at the outside of the heaters, a radiation shield for shielding the single crystal from the radiation heat, and an upper heat shield for preventing the upward heat, transfer of the heaters. In the apparatus, a melted layer and solid layer of raw material are formed in the upper and lower portions of the crucible, respectively. While melting the solid layer, the single crystal is pulled up. The lower portion of the heat shield is thinner than the upper portion. The ratio of the height to the diameter of the crucible is 0.85 or more. The melting amount of the solid layer is controlled in the pulling process according to the non-segregation condition in the variable-thickness melted layer method.

Abstract: A motor driving control apparatus having a function for performing an individual test operation of a servomotor driving control apparatus or an inverter apparatus by generating test operation command in the control apparatus in place of a command from an external controller, whereby both a function check and a performance check can be performed to attain an improvement in reliability and case of operation.

Abstract: Sine wave signals generated from a position detector are used as analog values to detect a fine position of a rotating or moving body, a rise or fall edge of the sine wave signal is used to detect a coarse position of the rotating or moving body, and the position or speed of the rotating or moving body is detected based on a signal indicative of the detected coarse position when the rotating or moving body is at high speed and based on a signal indicative of the detected fine position when the rotating or moving body is at low speed to thereby provide optimal control from high speed to low speed. Especially at extremely low driving, speed detection with superhigh resolution is effected using the analog value to decrease an uneven rotation of the rotating body.

Abstract: A thyristor valve circuit protected having an arrester to protect it from an overvoltage. The circuit includes a voltage detector for detecting a forward voltage level applied to the thyristor valve and generating a signal sVp when the detected voltage level exceeds a predetermined voltage which is set lower than the protection level of the arrester, and a circuit for generating a gate pulse applied to the thyristor valve in response to the signal sVp* from the voltage detector. The gate pulse generating circuit permits the gate pulse to be applied to the thyristor only when the condition of the presence of conduction command signal PHS and forward voltage signal FV, and the absence of output signal sVp* of the voltage detector, is satisfied.

Abstract: A signal whose frequency is proportional to a rotational speed of a rotor and whose rising and falling angles near points crossing zero becomes larger with the rotational speed of the rotor is used to produce a first signal of amplitude corresponding to the rising and falling angles and a second signal of amplitude corresponding to the frequency, a difference between the first and second signals is evaluated, and the first or second signals are corrected with the difference.

Abstract: A fixed slit plate and a rotary slit plate which is secured to a rotating shaft are provided between two photoconductive elements and a light emitting element, and the two photoconductive elements provide two outputs which have the phase difference .pi. therebetween. These two outputs thus provided are added to extract the dc component, thereafter exerting feedback control over the light emitting element such that this dc component is maintained at a constant level.

Abstract: An apparatus for detecting slag outflow when a molten metal covered by molten slag is poured from one vessel to another by receiving the thermal radiation energy at the microwave frequencies emitted from the pouring stream of the molten metal from said one vessel to another to measure a change in thermal radiation energy caused by the difference in the emissivity of the molten metal and of the molten slag is disclosed. The apparatus comprises; a microwave-focusing mechanism which has a focal point at the measuring target point; a waveguide means one end of which is connected to said microwave-focusing mechanism and which receives the thermal radiation energy from said microwave-focusing mechanism; and a radiometer connected to the other end of said waveguide means to measure the thermal radiation energy at microwave frequencies received through said waveguide means.

Abstract: An electromagnetic stirrer of linear induction motor type for a continuous casting machine, whose coils are arranged to differ a distance between poles of theeven function components of the travelling wave current distribution with respect to the center thereof from that of the odd function components so that a larger electromagnetic force is generated, thereby eliminating the internal defects, such as macro-segregation or center porosity, and improving quality of the ingot. Also, the electromagnetic stirrer, even when attached to a small-sized mold or a mold of small aspect ratio, demonstrates the sufficient effect.

Abstract: A method for detecting the surface level of a molten metal, particularly in a continuous casting process, utilizes the thermal radiations emanating from the surface of the metal. An antenna is directed so that its beam width encompasses a portion of the surface of the metal and the adjacent inner wall of the mold or container. The interference between radiations that propagate directly to the antenna from the surface of the metal and those that are reflected off the container wall is measured in terms of its electric power, i.e., the electromagnetic component of the radiations. Fluctuations in the measured electric power are indicative of changes in the level of the metal.

Abstract: Disclosed is a method of measuring the surface temperature of a metallic body. The method comprises: disposing a reflecting member such that the reflecting member constitutes a resonator in cooperation with a substantially flat surface of the metallic body; measuring the mean reflectivity of the resonator over a predetermined frequency band having a center frequency coinciding with the resonance frequency of the resonator, as well as the luminance temperature of the resonator; and computing the surface temperature of the metllic body from these measured values. Disclosed also is an apparatus for carrying out this measuring method. The method and apparatus are suited particularly to the measurement of the surface temperature of a steel sheet heated to a temperature ranging between 500.degree. and 800.degree. C.

Abstract: A control apparatus for an induction motor wherein an inverter is connected between a power source and the induction motor so as to energize the induction motor through the inverter, characterized in that when an input voltage of the inverter has lowered, a magnetizing current component command is decreased, while a torque current component command is increased.

Abstract: In a water-cooled high voltage device, a plurality of electrical modules are divided into a plurality of electrical units. The electrical modules are cooled by cooling water supplied from a pump through pipes which are disposed in the electrical units, respectively. The size of the pipe diameter is determined to be enough to allow cooling water to flow at a relatively low pressure and to properly cool the electrical modules.

Abstract: An arrester is provided including series connected first and second nonlinear resistance elements and a by-pass circuit. The by-pass circuit is connected in parallel with the second nonlinear resistance element and short-circuits the second nonlinear resistance element only when a voltage of a predetermined polarity is applied to the second nonlinear resistance element. An semiconductor circuit arrangement with a protection device is also provided, where the arrester is used for protecting a semiconductor device.

Abstract: A gate controlling circuit for a thyristor converter having a forward/reverse bias voltage detecting circuit connected between the anode and the cathode of one of a plurality of serially connected thyristors in a thyristor arm of the converter for determining whether the thyristor is forward or reverse biased. The output of the forward/reverse bias voltage detector is utilized to control the gate control signals supplied to the thyristors in the thyristor arm.

Abstract: In a gate control circuit for a thyristor converter, in which thyristor valves each having a plurality of series thyristors are connected to form a bridge, a detector for detecting a forward voltage applied across one of the thyristors and a circuit for supplying a gate signal to the gate of that thyristor valve are provided. The gate control circuit further comprises a circuit for supplying, when a bypass pair operation of the thyristor converter is switched over to a deblock operation, a signal to the gate of a continually conductive thyristor valve according to a control signal to a thyristor valve to be operated in deblock with the continually conductive thyristor valve and also a gate signal to the continually conductive thyristor valve.

Abstract: A gate controlling circuit for a thyristor converter having an inverse bias voltage detecting circuit which detects the inverse bias voltage across a thyristor and is connected between the anode and cathode of serially connected thyristors in a thyristor valve. A gate signal to all of the thyristors is supplied when the output of the inverse bias voltage detecting circuit drops or becomes zero after all of the thyristors are turned off.

Abstract: In an electric power converting apparatus comprising a plurality of branches each including a plurality of serially connected semiconductor switching elements, a non-linear resistor is connected in parallel with each semiconductor switching element, and a voltage division element including serially connected capacitor and a resistor is connected in parallel with each semiconductor switching element. A reactor is connected in series with each one of the branches and an arrestor is connected in parallel with a serially connected reactor and an associated branch.