Hitachi, Ltd.

Hitachi Automotive Systems, Ltd.

Katsuhiro Higuchi

Ryuichi Saito

Atsushi Saito

Akihiko Kanouda

Toshiaki Morita

Kenji Kubo

Hiroyuki Shoji

Hidenori Shinohara

Seigou Yukutake

Akira Ishii

Yoshimasa Takahashi

Osamu Otsuka

Toshiya Sato

Hiroshi Houzouji

Toshio Hiraishi

Hidekazu Nishidai

A power supply device that converts inputted direct-current power to direct-current power with a predetermined voltage to supply the power to the outside includes a voltage conversion circuit that converts the voltage of the inputted direct-current power, a voltage measurement circuit that measures a voltage value indicating a voltage potential difference between a ground voltage potential in the power supply device and a ground point provided outside the power supply device and connected to the ground voltage potential via a ground strap cable, a current measurement circuit that measures a current value of a load current flowing when de direct-current power is supplied from the power supply device, and an arithmetic circuit that calculates a resistance value corresponding ground connection of the power supply device, based on the voltage value measured by the voltage measurement circuit and the current value measured by the current measurement circuit.

Power supply device

A power converter includes an inverter in an inverter case, and a DC/DC converter in a converter case detachably fixed to the inverter case. The inverter includes power semiconductor modules, and the DC/DC converter includes a down-converter circuit and/or a boost converter circuit. The inverter case includes first and second path-forming members thermally contacting the converter case. In the first path-forming member, the power semiconductor module is inserted into a first coolant path. In the second path-forming member, the power semiconductor module inserted into the second coolant path, which is parallel to the first coolant path. The DC/DC converter includes an inductance device, and a switching device board on which a switching device con rolling electric current in the inductance device is mounted. The inductance and switching devices are in an area of the converter case thermally contacting first and second path forming members.

Power converter

The DC-DC converter connects a first and a second switching circuit for converting power mutually between direct current and alternating current respectively to a first DC power source and a second DC power source and has a transformer between the AC terminals thereof. Here, between the AC terminals of the second switching circuit and the negative pole terminal of the DC power source, a voltage clamp circuit composed of a series unit of switching devices with a reverse parallel diode and a clamp condenser is connected. An isolated bidirectional DC-DC converter which prevents a reduction in a circulating current at time of buck and an occurrence of a surge voltage at time of voltage boost and realizes highly efficiency, low noise, and miniaturization is provided.

Isolated bidirectional DC-DC converter

A semiconductor device in which the lifetime of mounted components can be prolonged. A cooling system for controlling the temperature of a refrigerant through a heating section and a radiator is provided. The semiconductor device is connected to the cooling system and is cooled. A variation width (&#x394;T) of temperature controlled by the cooling system through the heating section and the radiator is smaller than a temperature variation (&#x394;T) of the refrigerant caused by variations in operating conditions of the semiconductor device (&#x394;T&#x2266;&#x394;T).

Semiconductor device

Growing community of inventors

Hitachinaka, Japan

Katsuhiro Higuchi