Other

Hitachi, Ltd.

Hitachi Appliances, Inc

Hitachi Computer Peripherals Co., Ltd.

Takeshi Onaka

Kenichi Onda

Norikazu Tokunaga

Katsunori Hayashi

Ryouhei Saga

Satoru Masuyama

Hiroshi Kimura

Tatsumi Yamauchi

Noboru Akiyama

Yasuyuki Kojima

Koichi Taniguchi

Koichi Tokushige

Noriyuki Bunkou

Keiji Sato

Nobuyuki Aihara

Shigekazu Zemba

Akihiko Kanouda

Ryohei Saga

An air conditioning system is arranged to use a power line for communication. The air conditioning system includes one or more indoor units, one or more outdoor units, and a system controller for controlling the indoor units or outdoor units and executes communications between the indoor units and the outdoor units as overlapping a signal on the power line for supplying electric power. The outdoor units are connected with the system controller through a leased communication line. The indoor unit provides a power line communication device being connected with the power line. The outdoor unit provides a leased communication device being connected with the leased communication line. A bridge is also provided for connecting the leased communication line and the power line. The control information is exchanged mutually between the indoor units, the outdoor units and the system controller through the power line.

Indoor and outdoor unit communication via signal from a power line

A power supply provided with: an AC/DC converter which receives AC power, converts the AC power into DC power, and outputs the DC power; a DC/DC converter which receives the DC power from the AC/DC converter, and controls a level of an output voltage of the DC/DC converter to be equal to a level of a voltage to be used by a load while the DC/DC converter supplies the output voltage to the load; a DC converter which is connected to an input of the DC/DC converter; and a DC power storage means which supplies electric power to the DC/DC converter through the DC converter.

Power supply with uninterruptible function

A power supply provided with: an AC/DC converter which receives AC power, converts the AC power into DC power, and outputs the DC power; a DC/DC converter which receives the DC power from the AC/DC converter, and controls a level of an output voltage of the DC/DC converter to be equal to a level of a voltage to be used by a load while the DC/DC converter supplies the output voltage to the load; a DC converter which is connected to an input of the DC/DC converter; and a DC power storage device which supplies electric power to the DC/DC converter through the DC converter.

A DC power supply device comprises an AC/DC converter , a DC/DC converter , and a DC converter 3 converting DC power from a battery to DC voltage for connecting to output terminals of the AC/DC converter. The DC power supply device is provided with a controlling circuit which observes a charging control level and a load sharing level, impresses a charging command on a UPS controlling part controlling the DC converter, and simultaneously provides a PFC controlling part controlling the AC/DC converter with a current command when a voltage level is less than the charging control level, stops only the charging command when the voltage level is more than the charging level and less than the load sharing level, and provides the UPS controlling part and the PFC controlling part with current commands when the voltage level is more than the load sharing level. The AC/DC converter and the DC converter supply power in parallel when a load is more than a prescribed value, and the DC converter supplies power as a backup when a trouble is present in an AC power input.

DC power supply device

A DC-DC converter is provided with a calculation circuit which estimates current flowing through a reactor in a control circuit for controlling a switching element and a circulation use element, and the switching element and the circulation use element are controlled by making use of the calculated reactor current value. Thereby, a DC-DC converter which operates in a high efficiency and with low ripple even during a light load condition and realizes a high response performance during load variation is provided.

Synchronized rectifier voltage step down DC-DC converter and control circuit therefor

A DC power supply device comprises an AC/DC converter , a DC/DC converter , and a DC converter converting DC power from a battery to DC voltage for connecting to output terminals of the AC/DC converter. The DC power supply device is provided with a controlling circuit which observes a charging control level and a load sharing level, impresses a charging command on a UPS controlling part controlling the DC converter, and simultaneously provides a PFC controlling part controlling the AC/DC converter with a current command when a voltage level is less than the charging control level, stops only the charging command when the voltage level is more than the charging level and less than the load sharing level, and provides the UPS controlling part and the PFC controlling part with current commands when the voltage level is more than the load sharing level. The AC/DC converter and the DC converter supply power in parallel when a load is more than a prescribed value, and the DC converter supplies power as a backup when a trouble is present in an AC power input.

A direct-current power-supply apparatus provided by the present invention comprises a switching converter for converting an input direct-current power into another direct-current power, a control circuit and an isolation means. The switching converter has a main switch device for generating a pulse voltage from the direct-current input, a synchronous-rectification circuit on the output side of the switching converter and a reverse-current-blocking switch. On the other hand, the control circuit includes a PWM formation unit for driving the main switch device, a synchronous-rectification control unit for controlling an operation to drive the synchronous-rectification circuit and a driving control unit for controlling an operation to drive the reverse-current-blocking switch. The control circuit operates by using a common electric potential appearing on the output side of the switching converter as a reference electric potential. A driving signal is applied to the main switch device through the isolation means. Thus, the direct-current power-supply apparatus is controlled without need for exchanges of the signal for driving the main switch device and a signal isolated between control devices including a switch for synchronous rectification.

Direct-current power-supply apparatus, control circuit thereof and semiconductor integrated circuit device for power supply

A power supply apparatus includes a semiconductor switching device for outputting power and a control circuit for controlling the on/off operation of the semiconductor switching device. The control circuit includes a circuit for applying, when turning on the semiconductor switching device, a first control signal corresponding to the difference between the output voltage of the power supply apparatus and a first reference value to the semiconductor switching device in accordance with the increase in the output voltage from the power supply apparatus thereby to operate the semiconductor switching device in a non-saturated area, so that the semiconductor switching device is turned on gradually.

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Hitachi, Japan

Takeshi Onaka