Hitachi Computer Peripherals Co., Ltd.

Hitachi Information & Telecommunication Engineering, Ltd.

Hitachi, Ltd.

Hitachi Maxell, Limited

Hitachi Maxwell, Ltd.

Hitachi Information & Telecommunication Eng., Ltd.

Fumikazu Takahashi

Masahiro Hamaogi

Akihiko Kanouda

Yoshihide Takahashi

Minehiro Nemoto

Kimiaki Taniguchi

Takae Shimada

Masato Isogai

Isao Nemoto, Legal Representative

Toshikatsu Miyata

Takao Gotou

Takashi Tanabe

Kosuke Abe

Yusuke Katsuyama

Akinori Uchida

Susumu Nagafuchi

Tatsumi Yamauchi

Fumio Murabayashi

Hiroyuki Shoji

Akira Kikuchi

Kazuhisa Miyamoto

Kazuharu Kuchimachi

Nobuyuki Aihara

Kuniyoshi Watanabe

Wataru Mochizuki

Yen-Shin Lai

Hirofumi Oyamada

Daisuke Ishida

A power converter includes a plurality of converters which are connected in parallel to a DC power supply in which an operating point is changed in accordance with an output current or an output voltage. The plurality of converters include maximum power point tracking units for performing maximum power point tracking calculations of the DC power supply. Results of the maximum power point tracking calculations of the plurality of converters are unified between the plurality of converters and the plurality of converters are controlled based on the unified calculation result.

Power converter

A power conversion system is capable of distinguishing easily and clearly between being interconnected to the power system and being in an isolated operation. The power conversion system converts DC power to AC power to interconnect with a power system and injects reactive power into a grid node for determining an isolated operation, including: a voltage detector that detects an output voltage at the grid node; a current detector that detects an output current at the grid node; a frequency measurement unit that measures a frequency of the output voltage at the grid node; a reactive-power measurement unit that measures reactive power at the grid node; and an isolated-operation determination unit that determines whether or not the power conversion system is in an isolated operation as disconnected from the power system. The isolated-operation determination unit includes a reactive-power-fluctuation determination unit that performs a first isolated-operation determination from the reactive power.

Power conversion system and method for detecting isolated operation of the same

A power storage system is provided with charge switches, discharge switches, a bidirectional DC/DC converter and a power storage system controller connecting all the battery packs to an external circuit to achieve parallel charge and discharge, and the power storage system starts the charge by setting a rated charge current value per one battery pack to Iset and setting the rated charge current value Iset as an initial value of a charge current command value Iref(1), thereafter monitor the charge current of each of the battery packs after elapse of a predetermined time so as to subtract its maximum value Ibmax(1) from the charge current command value Iref(1), and add the rated charge current value Iset to result of subtraction Ierr (Iref(1)&#x2212;Ibmax(1)) so as to set as a new charge current command value Iref(2) and carry out pre-charge in such a manner as to carry on the charge.

Power storage system and power source system

In a step-up step-down converter device, a diode is connected in parallel to a switch connecting a positive pole side and a negative pole side for stepping up and stepping down an input voltage, a diode is connected in parallel to a switch in a positive pole side of a closed circuit constructed between an input direct voltage and an output side load, and a control circuit detecting an output voltage generates 1Phase PWM and 2Phase PWM obtained by logically adding and multiplying two difference values having phase difference in comparison with a triangle waveform signal which is 180 degrees different in phase from an error signal based on a difference value between the output voltage and a target reference voltage, and alternately turns on and off switches respectively by using 1Phase PWM or 2Phase PWM at the step-down or step-down operation time.

Step-up step-down converter device

A power supply device of the invention includes a first switching leg including first and second switching elements between DC terminals; a second switching leg including third and fourth switching elements between the DC terminals; a first capacitor leg including first and second capacitors between the DC terminals; a second capacitor leg including third and fourth capacitors between AC terminals; a first inductor between a connection of the first and second switching elements and one of the AC terminals; a second inductor between a connection of the third and fourth switching elements and another of the AC terminals; a controller; an AC power supply connected to the AC terminals and the connection of the third and fourth capacitors; and a DC power supply between the DC terminals, wherein the controller charges the first and second capacitors to a voltage higher than a voltage crest of the AC power supply.

Power supply device operating switching elements of first and second switching legs to charge first and second capacitors to a voltage higher than a voltage crest value of an AC power supply and method of operating the power supply device

A power storage system is provided with a battery and a battery charger which charges a battery pack having a battery voltage and current detection circuit. A charge circuit is structured such as to acquire terminal voltage information of the battery from a battery voltage detection circuit of the battery pack in a charging process, carry out a constant current charge control in a state in which the terminal voltage of the battery is equal to or lower than a previously determined reference voltage value of the battery, and switch to a constant voltage charge control maintaining the output voltage of the charge circuit in the case that the terminal voltage of the battery goes beyond the reference voltage value, thereby carrying on the charge until the battery is fully charged. Therefore, the power storage system can accurately charge the battery to a prescribed amount safely.

Power storage system with constant current charge control or constant voltage charge control depending on battery terminal voltage in a charging process

Proposed are a power factor correction device and its control method capable of obtaining a stable output as the output of a power supply unit while simplifying and miniaturizing the configuration. In the power factor correction device and the control method thereof including a coil and a switching element, and a control unit for controlling ON/OFF of the switching element, provided are an input voltage detection unit for detecting an input voltage of the power factor correction device, an output voltage detection unit for detecting an output voltage, and a coil current detection unit for detecting a coil current that is generated in the coil pursuant to the ON/OFF operation of the switching element. The control unit predicts an OFF time of the switching element of each switching cycle for controlling the switching element in a critical mode based on a voltage value of the input voltage detected with the input voltage detection unit, a voltage value of the output voltage detected with the output voltage detection unit, and a current value of the coil current detected with the coil current detection unit, and controls the ON/OFF of the switching element based on the prediction result.

Power factor correction device and method with off time prediction for critical mode operation

In a digital controlled power supply including a digital controller for generating a PWM signal which is used to turn on and off a switching element to obtain an output voltage for a load based on an input voltage, the digital controller includes an AD converter for receiving an analog output current from the power supply and converting the current into a digital value to produce a digital output current value, an arithmetic processing unit for conducting an arithmetic operation of a pulse width for each period of a sampling frequency of the AD converter or a frequency of carrier wave as a criterion to obtain the PWM signal, and a frequency controller for variably controlling the frequency of carrier wave and the sampling frequency on the basis of the digital output current value from the AD converter.

Digital controlled power supply

To provide a smaller and more efficient switching power supply, the switching power supply includes: a high frequency transformer; a primary side switching circuit adapted to switch a current flowing through a primary winding of the high frequency transformer to thereby generate predetermined voltages in a secondary winding and an auxiliary winding of the high frequency transformer; a secondary side rectifier adapted to rectify a voltage generated in the secondary winding to supply the rectified voltage to a load; a charging circuit adapted to rectify a current flowing through the auxiliary winding and to switch the rectified current to thereby charge a secondary battery at a constant current; and a switch, provided between the secondary battery and the load, which supplies, when the voltage supplied to the load is interrupted, the voltage of the secondary battery to the load without going through the high frequency transformer.

Switching power supply

A DC backup power supply system having a plurality of loads to which AC from a commercial power source is supplied, and DC power storage means for supplying DC power to the plurality of the loads at the time of a power outage of the commercial power source, said DC backup power supply system including: a control circuit having a first DC backup output for supplying a power from the DC power storage means to the plurality of the loads, including a specific load, only during the power outage of the commercial power source, and a second DC backup output for continuously supplying a power from the DC power storage means to the specific load regardless of the power outage of the commercial power source or sound operation thereof, the control circuit supplying the respective powers from the same DC power storage means to the first and second DC backup outputs.

DC backup power supply system, a disk array and a DC backup power supply

An object of the invention is to provide a small and low-cost switching power supply unit with a backup function in which a proper circuit construction can be selected by simple method when it is necessary to compensate for the instantaneous drop or power failure and a disk array system having the switching power supply unit. To accomplish the object, a backup unit which can insert and pull out its hot line into a switching power supply unit casing and has a secondary battery and its state monitoring/control unit is built in the unit, and proper charge/discharge management of the secondary battery can be made. When the backup unit is unnecessary, a backup unit formed by a plurality of capacitors whose hot lines can be similarly inserted and pulled out can be built in an enclosing space of the backup unit.

Switching power supply unit and disk array system

To provide a power supply apparatus having high control resolution of an output power. A PWM signal generating circuit includes: a non-inverting element, and an inverting element; and further includes a counterfor performing count operation in response to rising of a clock signal, a counterfor performing count operation in response to falling of the clock signal, comparison circuits, and a multiplexer. These circuit elements are controlled by PWM control means. As another circuit element, the PWM signal generating circuit includes a logical sum element. The PWM signal generating circuit serves to arbitrarily change both period and logic 'H' time of a PWM signal to be outputted at a time interval which is one half of the clock period. Thus, there is provided a power supply apparatus in which resolution of a PWM signal has been improved within a broad duty range, and fine control of an output power has been performed within a broad output power range.

PWM signal generating circuit and power supply apparatus comprising such PWM signal generating circuit

A backup power supply is so constructed that it is provided with multiple DC backup power suppliestoN, each containing nickel-metal hydride battery, stored upright on the bottom of the disk array unit; cooled by cooling air through the ventsfor ventilation from the bottom to the top; and connected with the output of the AC/DC converterswith the backboard Very compact disk array unit with an uninterruptible power supplying function can be realized.

Data processing unit and DC backup power supply

A DC backup power supply system having a battery a charge-discharge circuit for charging and discharging a power between the battery and a DC line and a control circuit for controlling the charge-discharge circuit, wherein the battery has a number of battery cells and cylindrical portions of the battery cells are laid on an approximately horizontal plane.

DC backup power supply system

An uninterruptible power system for inputting an AC power, converting the AC power into a desired power, supplying the desired power to a load, and upon occurrence of an AC failure, converting a DC power from energy accumulation means into the desired power and supplying the desired power to the load, wherein the DC power from said energy accumulation means is passed through two serially connected boost means, and thereafter the power is converted into the desired power to be supplied to the load, wherein first boost means of the two serially connected boost means, which is nearer to the energy accumulation means, raises the DC electric power from said energy accumulation means to supply second boost means of the two serially connected boost means when supply of electric power is interrupted, and lowers inputted electric power for charging the electric accumulation means during an ordinary operation.

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Hitachi, Japan

Fumikazu Takahashi