Kabushiki Kaisha Toshiba

Naoto Shinohara

Kazunobu Nagai

Motofumi Tanaka

Toshiki Osako

Hiroki Murayama

Hiroyuki Yasui

Satoshi Hanai

Haruhisa Wada

Kazuhisa Matsuge

Daisuke Yamagishi

Shigeo Maezawa

Yusuke Shibano

A creeping discharge element drive device of an embodiment includes a switching element, a current detector, a zero-cross detection circuit, a storage, and a controller. The current detector detects alternating currents flowing through the switching element. The zero-cross point detection circuit detects a zero-cross point of the alternating currents. The storage stores a first threshold value of a resonant period. The controller drives the switching element to apply a test voltage to the creeping discharge element, determines a resonant period of the alternating currents from the detected zero-cross points of the alternating currents, and restricts or stops the driving of the switching element in response to the resonant period exceeding the first threshold value.

Creeping discharge element drive device and creeping discharge element drive method

A power converter connected between a direct current power supply and a load, the power converter including a switching unit energizing the load based on inputted control signal, a voltage detector detecting a voltage of the direct current power supply, and a protection operation portion detecting a steep elevation of the voltage and performing protection operation to stop a switching operation by the switching unit, wherein the protection operation portion includes an addition circuit adding a predetermined voltage to the voltage detected by the voltage detector and a delay time generator connected to an output of the addition circuit, and wherein the protection operation is performed when a difference between the voltage detected by the voltage detector and an output voltage of the delay time generator reaches a certain value.

Power converter

A wind power generation system according to an embodiment includes a blade; a lightning protection device; an electric device; a voltage application mechanism; a first lightning arrester element; and a second lightning arrester element. The lightning protection device includes a receptor provided at the blade and guides a current of lightning to the ground from the receptor via a lightning conductor. The electric device is installed at the blade and includes a first electric conductor and a second electric conductor provided apart from each other. The voltage application mechanism applies a voltage between the first electric conductor and the second electric conductor. The first lightning arrester element has one end thereof electrically connected to the first electric conductor and has the other end thereof grounded. The second lightning arrester element has one end thereof electrically connected to the second electric conductor and has the other end thereof grounded.

Wind power generation system

In one embodiment, system for driving an electromagnetic appliance includes an electromagnetic appliance, a main-drive unit and a sub-drive unit. The electromagnetic appliance includes coils for n number of phases, the coils for each of the n phases being arranged in a pair and wound so as to be excited in a predetermined direction by being energized with opposite-phase currents. The main drive unit is connected to each of the coils and energizes the paired coils with opposite-phase currents. The sub-drive unit is provided parallel with the main-drive unit and is configured to suppress a short-circuit current occurring at the main-drive unit when switching energization of the coils.

System for driving electromagnetic appliance and motor driven vehicle

A switching control device controls a drive circuit including one or more series circuits each one of which includes an upper switching element and a lower switching element. The switching control device includes an upper side temperature detection unit detecting a temperature of the upper switching element (hereinafter, 'an upper side temperature'), a lower side temperature detection unit detecting a temperature of the lower switching element (hereinafter, 'a lower side temperature'), and a signal generation circuit adding an offset value to a command voltage of a PWM signal output to the upper and lower switching elements to generate and output a PWM signal to the switching elements so that the upper and lower side temperatures approximate to each other.

Switching control device

An inverter device includes a DC positive input line and a DC negative input line, a main bridge which includes a pair of series-connected switching elements with diodes being connected in reverse parallel with the switching elements respectively, an auxiliary bridge which includes a pair of series-connected switching elements with diodes being connected in reverse parallel with the switching elements respectively and a current-limiting reactor. A plurality of sets each one of which includes the main bridge and the auxiliary bridge is connected between the DC positive and negative input lines. Each set constitutes a phase. The current-limiting reactor is connected between a common connection point of both switching elements of the main bridge and a common connection point of both switching elements of the auxiliary bridge in each set.

Growing community of inventors

Kawasaki, Japan

Naoto Shinohara