Hitachi, Ltd.

The Kansai Electric Power Co., Inc.

Hitachi Appliances, Inc

Other

Hitachi Powdered Metals Co., Ltd.

Chikara Tanaka

Akio Takahashi

Yoshitaka Iwaji

Yuichi Satsu

Tsunehiro Endo

Hiroaki Miyata

Akira Bando

Noboru Baba

Chio Ishihara

Hiroto Nakagawa

Yasuo Notohara

Hideaki Katayama

Yuzo Ito

Kazuo Asaka

Yasuhiro Kiyofuji

Kazuhiro Satou

Tatsuo Ando

Tadao Kawai

Takahiro Suzuki

Eizo Kita

Yoshiaki Kurita

Yasuteru Oono

Kenta Watanabe

Keiji Saito

Akira Kikuchi

Keiichi Mitsuhashi

Yasuteru Ohno

A converter includes a converter circuithaving a plurality of bridge-connected semiconductor switching devices for converting AC power into DC power, a smoothing condenser connected in parallel to the DC side of the converter circuit and a current detector provided in a condenser circuit to control a condenser current flowing through the smoothing condenser to be a set value. The condenser current is controlled to be the set value (e.g. zero) to thereby reduce the capacity of the smoothing condenser and make the converter small.

Converter and power converter that becomes it with the converter

The present invention provides a soft magnetic powder composite core for an electric apparatus produced with soft magnetic particles having electric insulating layers on the surfaces thereof, wherein said electric insulating layers are formed by mixing said soft magnetic particles with an insulating layer-forming solution which comprises a phosphating solution and a rust inhibitor, which is an organic compound containing at least one of nitrogen or sulfur having a lone pair of electrons suppressing the formation of iron oxide and surfactant, and drying the treated soft magnetic particles at a predetermined temperature. The soft magnetic powder composite core is excellent in iron loss and magnetic flux density.

Treatment solution for forming insulating layers on magnetic particles process for forming the insulating layers, and electric device with a soft magnetic powder composite core

Process for forming insulating layers on soft magnetic powder composite

A semiconductor power conversion system comprising a multiphase bridge circuit which includes semiconductor devices having a controllable firing function and a reverse blocking characteristic, a gate control circuit which gives firing commands to the semiconductor devices, a short circuiting switch in which switching devices having a controllable firing function and a reverse blocking characteristic are connected in parallel with a DC output side of the multiphase bridge circuit, and a protection control device for performing a control for protecting the multiphase bridge circuit. The protection control device includes a device for detecting a commutation failure of the multiphase bridge circuit, and a device in response to the detection of the commutation failure for producing a blocking command for blocking the firing of the semiconductor devices of the multiphase bridge circuit and producing a short-circuiting command for firing the switching device which is short-circuited which bypasses current of the commutation failure. The protection control device further includes a device for detecting ending of a short-circuit based on the ceasing of current conduction of the short circuiting switch and for halting the blocking of the firing of the semiconductor devices of the multiphase bridge circuit.

Fault protection for a multiphase bridge power converter

An improved electric power conversion system comprising a multi-phase bridge circuit composed of semiconductors such as thyristors and an associated firing circuit. It is so constructed that: if the AC input current Iac flowing in the bridge circuit is equal to or larger in value that the DC output current Idc flowing out of the bridge circuit, it will be decided than an inner defect or fault is caused, and possible expansion of inner defect will be prevented by disabling the firing circuit to extinguish the thyristors in the bridge circuit, and if the AC input current Iac is smaller than the DC output current Idc in value, the bridge is permitted to continue the operation of power conversion, thus eliminating unnecessary interruption which otherwise would be caused by exterior disturbances. Also, an improved electric power conversion system may be equipped with a device to prevent an adverse effect from being caused by abnormal rise of thyristors' temperature.

Semiconductor electric power conversion system enabling fault and/or

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Hitachi, Japan

Chikara Tanaka