Abstract: A power conversion device includes a controller configured to alternately turn on a second upper arm and a second lower arm of a first bridge circuit such that on-times thereof do not overlap each other to increase power stored in a resonance capacitor of the first bridge circuit in a state in which a first leg of the first bridge circuit is turned off when transmitting power from a second bridge circuit to the first bridge circuit and performing step-up operation.

Abstract: This power conversion device includes a control unit that controls a switching operation of a switching element of the inverter unit. The control unit is configured to switch between frequency modulation control and phase shift control, based on the output from the output converter unit, and execute. Then, the control unit is configured to, when switching between frequency modulation control and phase shift control, execute overlap control for executing the phase shift control while executing the frequency modulation control, in a predetermined switching operation range.

Abstract: A threaded connection for a steel pipe includes a box which is an opening end of a second pipe and a truncated cone shaped pin which is an end of a first pipe and is inserted into the box, wherein the pin includes a male thread portion which is a tapered thread and a seal portion which includes a tapered surface, the box includes a female thread portion which is a tapered thread and a seal portion which includes a tapered surface, and in a state before make-up between the pin and the box, a minimum diameter of the tapered surface of the pin is smaller than a maximum diameter of the tapered surface of the box.

Abstract: A method for assembling a threaded connection for a steel pipe, which connects a first pipe formed with a pin having a truncated cone shape at an end thereof, and a second pipe formed with a box having an opening end. The pin includes a male thread portion, which is a tapered thread, and a seal portion, which includes a tapered surface. The box includes a female thread portion, which is a tapered thread, and a seal portion, which includes a tapered surface. The tapered surface of the pin has a minimum diameter smaller than a maximum diameter of the tapered surface of the box. The method includes making-up the male thread portion and the female thread portion by screwing, whereby a root of the male thread portion and a crest of the female thread portion come into contact with each other after the seal portion of the pin and the seal portion of the box come into contact with each other.

Abstract: A power conversion device includes a controller configured to alternately turn on a second upper arm and a second lower arm of a first bridge circuit such that on-times thereof do not overlap each other to increase power stored in a resonance capacitor of the first bridge circuit in a state in which a first leg of the first bridge circuit is turned off when transmitting power from a second bridge circuit to the first bridge circuit and performing step-up operation.

Abstract: An isolated DC/DC converter includes: DC/AC converter; an isolation transformer; a rectifier circuit; and a control unit. The control unit includes a DC input power calculation unit that calculates a DC input power of the DC/AC converter; a first adjustment unit that calculates a DC input power command value such that a DC output voltage detection value follows a DC output voltage command value; an input power limit unit that limits an upper limit value of the DC input power command value to a predetermined value and output the DC input power command value; a second adjustment unit that calculates a DC output power command value such that a DC input power calculation value follows the DC input power command value; and a drive pulse generation unit that generates drive pulses for semiconductor switching device based on the DC output power command value.

Abstract: An isolated DC/DC converter includes: DC/AC converter; an isolation transformer; a rectifier circuit; and a control unit. The control unit includes a DC input power calculation unit that calculates a DC input power of the DC/AC converter; a first adjustment unit that calculates a DC input power command value such that a DC output voltage detection value follows a DC output voltage command value; an input power limit unit that limits an upper limit value of the DC input power command value to a predetermined value and output the DC input power command value; a second adjustment unit that calculates a DC output power command value such that a DC input power calculation value follows the DC input power command value; and a drive pulse generation unit that generates drive pulses for semiconductor switching device based on the DC output power command value.

Abstract: A threaded joint is constructed of a pin and a box, the box having an outside diameter less than 104% of an outside diameter of a tubular body having the pin. The box includes, in order from an end of the box toward the tubular body: a lip portion and a female threaded portion, the lip portion including a shoulder surface and a sealing surface. The pin includes a shoulder surface, a sealing surface, and a male threaded portion. The lip portion of the box has a nose portion disposed between the shoulder surface and the sealing surface and an annular portion disposed between the sealing surface and the female threaded portion. The nose portion and the annular portion are not in contact with the pin, and a length of the annular portion is longer than a thread pitch of the female threaded portion.

Abstract: An electronic equipment cooling device is provided, which has housing in which heat-generating components are housed, and which can cool surfaces of the housing. A blower fan blows air toward the surfaces via a chamber room. An inclined flat plate-like partition portion is provided inside the chamber room so as to distribute a desired amount of air corresponding to a heat generating ratio of the respective surfaces.

Abstract: A threaded joint is constructed of a pin and a box, the box having an outside diameter less than 104% of an outside diameter of a tubular body having the pin. The box includes, in order from an end of the box toward the tubular body: a lip portion and a female threaded portion, the lip portion including a shoulder surface and a sealing surface. The pin includes a shoulder surface, a sealing surface, and a male threaded portion. The lip portion of the box has a nose portion disposed between the shoulder surface and the sealing surface and an annular portion disposed between the sealing surface and the female threaded portion. The nose portion and the annular portion are not in contact with the pin, and a length of the annular portion is longer than a thread pitch of the female threaded portion.

Abstract: A bidirectional DC/DC converter includes first and second control circuits, and first and second bridge circuits respectively connected to first and second direct current voltage supplies. In one embodiment variant, when power is supplied from the first direct current voltage supply to the second direct current voltage supply, the first control circuit carries out PFM control of the first bridge circuit at a frequency equal to or lower than the resonance frequency of an LC resonant circuit in accordance with a control amount based on the voltage and current of the second direct current voltage supply. When power is supplied in the other direction, the second control circuit carries out fixed frequency control of the second bridge circuit, using phase shift control or the like, in accordance with a control amount based on the voltage and current of the first direct current voltage supply.

Abstract: Provided is a cool air flow space in which cool air, that is generated by an inner fan disposed inside a housing, flows in the housing. An attachment member mounts a magnetic component on a bottom portion of the housing at a position within the cool air flow space. The attachment member includes a top plate and a pair of legs that extends downward from the top plate and that is fixed to the bottom portion.

Abstract: A cooling device includes a plurality of side wall fins formed on an outer surface of a first side wall of a housing, and a plurality of bottom fins formed on a bottom surface of a bottom portion of the housing. A cover member covers the side wall fins and bottom fins from an outer side to form side wall and bottom cooling channels. A chamber is provided that forms a fluid introduction chamber in a direction facing a second side wall so as to communicate with the side wall cooling channel and the bottom cooling channel. A coolant supply device is externally attached to the chamber so as to supply a coolant to the fluid introduction chamber. The side wall fins and the bottom fins are formed in predetermined shapes to adjust an amount of the coolant in the side wall cooling channel and the bottom cooling channel.

Abstract: A threaded connection for a steel pipe includes a box which is an opening end of a second pipe and a truncated cone shaped pin which is an end of a first pipe and is inserted into the box, wherein the pin includes a male thread portion which is a tapered thread and a seal portion which includes a tapered surface, the box includes a female thread portion which is a tapered thread and a seal portion which includes a tapered surface, and in a state before make-up between the pin and the box, a minimum diameter of the tapered surface of the pin is smaller than a maximum diameter of the tapered surface of the box.

Abstract: A control device is configured to, when the direct current output voltage of a resonant DC-DC converter is of a value that exceeds the maximum value that can be output in a fixed frequency control region, there is a switch from fixed frequency control to frequency modulation control. Because of this, conduction loss and turn-off loss caused by backflow current among semiconductor switching elements of the resonant DC-DC converter are reduced, power conversion efficiency is improved, and the range of voltage that can be output by the resonant DC-DC converter is expanded.

Abstract: A switching power supply system includes a transformer having a primary winding, a secondary winding and a tertiary winding, a switching device inputted to the primary winding carrying out switching operation on the basis of a first control signal or a second control signal, an output voltage producing section rectifying and smoothing a voltage generated in the secondary winding to produce an output voltage, an output voltage detecting section producing an output voltage detection signal based on a voltage generated in the tertiary winding, a checking pulse generator generating pulses of the first control signal, and a switching controlling section producing the second control signal on the basis of the output voltage detection signal. The switching power supply system is capable of carrying out stable control of the output voltage on the secondary winding side of the transformer with a low power loss.

Abstract: Sound-absorbing material is provided which is more effective for the same volume. A sound-absorbing body is formed characteristically by hot-compression molding of a raw material (C) comprises a flexible polyurethane foam to a volume ratio ranging from 1/1.5 to 1/12. In the molding, metal molds (A·B) are heated in an electric furnace up to a set temperature of 180° C.; the flexible polyurethane foam of the cell number of 50 is held between the metal molds (A·B), and compressed and heated in the electric furnace in this state at 180° C. for 60 minutes; the fixing clamp is removed; and the hot-compressed urethane foam is taken out to obtain the intended sound-absorbing body.

Abstract: A bidirectional DC/DC converter includes first and second control circuits, and first and second bridge circuits respectively connected to first and second direct current voltage supplies. In one embodiment variant, when power is supplied from the first direct current voltage supply to the second direct current voltage supply, the first control circuit carries out PFM control of the first bridge circuit at a frequency equal to or lower than the resonance frequency of an LC resonant circuit in accordance with a control amount based on the voltage and current of the second direct current voltage supply. When power is supplied in the other direction, the second control circuit carries out fixed frequency control of the second bridge circuit, using phase shift control or the like, in accordance with a control amount based on the voltage and current of the first direct current voltage supply.

Abstract: A cooling structure for cooling a magnetic component, includes a housing adapted to house the magnetic component; a cold air flow path space arranged in the housing for a cold air to flow therethrough; an internal fan disposed inside the housing for flowing the cold air; and an attachment member adapted to fix the magnetic component mounted on a bottom portion of the housing at a position facing a suction side of the internal fan in the cold air flow path space, so that the cold air generated on the suction side of the internal fan passes inside the magnetic component. The bottom portion of the housing mounted with the magnetic component is a cooling body.

Abstract: A bi-directional DC/DC converter comprises bridge circuits connected to DC voltage sources, an isolation transformer, an LC resonance circuit, and detection circuits for detecting voltages and currents of the DC voltage sources. A control circuit in the power flow from a first DC voltage source to a second DC voltage source changes over between fixed frequency control and frequency modulation control according to the magnitude of a control variable, and a control circuit in the power flow from a second DC voltage source to the first DC voltage source changes over between fixed frequency control and frequency modulation control according to the magnitude of another control variable. Thus, the bi-directional DC/DC converter can be applied to devices with a wide range of input and output voltages.