Fuji Electric Co., Ltd.

Fuji Electric Device Technology Co., Ltd.

Nippon Steel Corporation

Vallourec Oil and Gas France

Fuji Electric Systems Co. Ltd.

Kyushu University

Fuji Device Technology Co., Ltd.

Yukihiro Nishikawa

Masakazu Gekinozu

Yasuhito Tanaka

Masaki Sakuma

Masahiko Sakurai

Masaaki Sugino

Kunio Matsubara

Tatsuya Yamamoto

Kenji Fujita

Michiya Yamada

Takashi Iida

Masahito Shoyama

Kesanobu Kuwabara

Takeshi Nozawa

Koki Hebishima

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.

Power conversion device, control device for power conversion device, and power conversion control method

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.

Power conversion circuit including a first bridge circuit and a second bridge ciruit

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.

Threaded connection for steel pipe

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.

Isolated DC/DC converter, control unit for isolated DC/DC converter, and DC/AC converter

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.

Threaded joint for steel pipes

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.

Electronic equipment cooling device and power converter having electronic equipment cooling device

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.

Bidirectional DC/DC converter

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.

Magnetic component cooling structure and power converter having the same

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.

Cooling device and power converter having cooling device

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.

Resonant DC-DC converter control device

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.

Switching power supply system and control circuit of the switching power supply system

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.

Bi-directional DC/DC converter with frequency control change-over

A flyback type switching power supply includes between P and N of a direct current output a sudden load change detector circuit, which normally has no power consumption, that detects only a transient fluctuation of a direct current output voltage, and starts the switching of a primary side semiconductor switch when there is no load or a light load, even when the semiconductor switch is in an off state, thereby enabling the detection of the direct current output voltage in a tertiary winding, and suppressing a drop in the direct current output voltage.

Switching power supply

A switching power supply device and method for control thereof, including an input voltage generating unit, a transformer, an output voltage generating unit, a MOS transistor, an output voltage detecting unit, a switching control unit, and a power supply unit. The output voltage detecting unit detects a transformer tertiary winding voltage, compares it with a first reference value, compares the differentiated tertiary winding voltage with a second reference value, and determines the start and end of a detection period based on the two comparisons. The output voltage detecting unit also samples and holds the voltage with two sampling pulses within the detection period, selects one of the two sampled and held voltages, and outputs the selected voltage when the detection period ends.

Switching power supply device and method for control thereof

A current flowing through a switching element () of a power supply is detected by an AC current transformer (), and a capacitor () is charged by a voltage corresponding to the current. A reduction factor of the terminal voltage of the capacitor in an off period of the switching element () is calculated based on an amplification factor of the terminal voltage of the capacitor, an absolute value of an instantaneous value of an input power supply voltage, and an instantaneous value of a direct current output voltage, and the capacitor is discharged so that the terminal voltage of the capacitor decreases by the reduction factor in an off period of the switching element (). A current flowing through an inductor () is estimated from the terminal voltage of the capacitor.

Growing community of inventors

Hino, Japan

Yukihiro Nishikawa