Hitachi, Ltd.

Hitachi Construction Machinery Co., Ltd.

Hitachi Industrial Products, Ltd.

Mitsuhiro Kadota

Takae Shimada

Mizuki Nakahara

Akihiko Kanouda

Yasuaki Norimatsu

Naoki Fukuda

Yuki Kawaguchi

Masatsugu Arai

Kimihisa Furukawa

Yuuichi Mabuchi

Atsushi Kitaguchi

Hiroyuki Shoji

Takayuki Satou

Takaaki Tanaka

Yuuichi Kunitomo

Akira Yonekawa

To provide an electric vehicle capable of reducing heat generation of the switching elements while achieving energy saving, the electric vehicle includes: an engine; a first generatordriven by the engine; a first rectifier circuitconnected to the output of the first generator; a first DC lineto receive the DC output of the first rectifier circuit; a driving motorconnected to the first DC line; a power converterconfigured to convert voltage of the first DC line; a second DC lineto receive the DC output subjected to voltage conversion by the power converter; an auxiliary deviceconnected to the second DC line; and a controllerconfigured to control the power converter. The controller is configured to, in response to the voltage Vof the first DC line becoming equal to or less than a first threshold V, control the output power Pof the power converter to a rated power P, and in response to the voltage becoming larger than the first threshold, control the output power Pto be smaller than the rated power.

Electric vehicle

When regeneration operation is being performed, electric power on a main-machine side is supplied to an auxiliary-machine side, a voltage on the auxiliary-machine side is controlled to become a first voltage value predetermined on the basis of operating voltage specifications of an auxiliary apparatus, a generator on the auxiliary-machine side is deactivated to stop supply of electric power to the auxiliary-machine side, and electric power on the auxiliary-machine side is supplied to a power storage apparatus. When the regeneration operation is ended, the supply of the electric power from the main-machine side to the auxiliary-machine side is stopped, the generator on the auxiliary-machine side is activated, the generator on the auxiliary-machine side is controlled such that a voltage on the auxiliary-machine side becomes the first voltage value, electric power of the power storage apparatus is supplied to the auxiliary-machine side, and the voltage on the auxiliary-machine side is controlled to become a second voltage value higher than the first voltage value. This enables reduction of fluctuations of a voltage supplied to auxiliary machines at a time of switching of regeneration operation by travel motors.

Regenerative braking system, and electrically driven work vehicle using the same

A power regeneration devicethat converts the power of a main engine DC lineconnected to a main engine power generatorthrough a rectification circuitto supply the converted power to an accessory DC lineconnected to an accessory power generatorthrough a rectification circuitincludes a plurality of power conversion modulestoN configured such that input sectionstoNa are connected in series. The main engine power generatorand a power consumption deviceare controlled such that a voltage input to the power regeneration devicedoes not exceed a voltage upper limit value Vm and a portion between a positive electrode terminal (+) and a negative electrode terminal (&#x2212;) of each of the input sections of the power conversion modules to be stopped is short-circuited by a bypass device and the voltage upper limit value Vm is decreased when some of the plurality of power conversion modulestoN are stopped. With this configuration, operational continuity can be improved while a device size increase is prevented.

Regenerative braking system and electrically-driven work vehicle using regenerative braking system

A power conversion device that suppresses voltage pulsation of a capacitor of a power converter with respect to a control target whose effective power is to be controlled is provided. The power conversion device includes a plurality of power conversion cells that are connected to each other, and convert a primary-side system voltage into a secondary-side system voltage, a capacitor that is connected to each of the plurality of power conversion cells, and a power conversion cell driver that drives the power conversion cells to add a 3N order higher-harmonic-wave voltage of each of alternating voltages of the plurality of power conversion cells to the each of alternating voltages, and output a voltage made by adding the each of alternating voltages and the 3N order higher-harmonic-wave voltage, when N is a natural number.

Power conversion device

Provided is a power conversion device which can be configured inexpensively and in which initial charging can be performed quickly. Accordingly, the power conversion device is provided with: a power conversion device cell having a first converter for converting a first AC voltage to a first DC voltage, a second converter for converting the first DC voltage to another voltage, and a first capacitor charged by the first DC voltage; and a control circuit for allowing charging of the first capacitor while changing the operational state of the first converter in accordance with the first DC voltage.

A power conversion device includes: power conversion cells; and a controller to control the cells. Each cell includes: a transformer; a primary conversion unit on a primary side of the transformer; a secondary conversion unit on a secondary side; a primary bypass device for short-circuiting between input terminals of the cell; and a secondary bypass device for short-circuiting between output terminals of the cell. The input terminals and/or the output terminals of the cells are connected in series. When the primary conversion unit(s) of a part of the cells is stopped, the controller turns on the primary bypass device and sets secondary DC link voltages to prescribed values; and when the secondary conversion unit(s) of a part of the cells is stopped, the controller turns on the secondary bypass device and controls the primary conversions units to set primary DC link voltages to prescribed values.

Power conversion device and three-phase power conversion device

A power conversion device includes three first power conversion cells each converting input power and outputting the converted power and having input terminals connected in parallel regarding a first power supply and three second power conversion cells each converting input power and outputting the converted power and having input terminals connected in parallel regarding a second power supply, wherein: the power output from the cell and the power output from the cell are combined to output a first phase power; the power output from the cell and the power output from the cell are combined to output a second phase power; and the power output from the cell and the power output from the cell are combined to output a third phase power. The first phase, second phase, and third phase powers are output as the phase powers or inter-line powers of a three-phase system.

Power conversion device and method for controlling power conversion device

In a power conversion device, a power conversion unit includes a single-phase inverter on a secondary side of a resonant type converter that has an input of a direct current. A power conversion unit group is configured by connecting outputs of the single-phase inverters of a plurality of power conversion units in series. Respective phases of three phase alternate current are formed with the three power conversion unit groups housed in a power conversion device housing. The plurality of power conversion units constituting the power conversion unit group are disposed along a longitudinal direction of the power conversion device housing. The respective three power conversion unit groups are disposed at an upper stage, a middle stage, and a lower stage in a height direction of the power conversion device housing. The power conversion device housing has one end side in the longitudinal direction as output terminals of the three power conversion unit groups. The power conversion device housing has the other end side in the longitudinal direction where terminals of the three power conversion unit groups are connected in common.

Power conversion device, cooling structure, power conversion system, and power supply device

In a power conversion device in a configuration in which a plurality of power converter cells has serially connected outputs and includes a converter and an inverter as components, when a load is light, the cells also operate with a light load, and efficiency is reduced. A power conversion device has a plurality of power converter cells. The outputs of the cells are connected in series. The device has a controller that controls the cells. The cells each have a converter that converts an externally inputted power supply voltage and generates a DC link voltage and an inverter that converts the DC link voltage into an alternating current voltage and outputs the current. The controller stops a converter in some of the cells depending on power supply electric power or load electric power. The inverter continues to operate using a link capacitor as a power supply.

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Tokyo, Japan

Mitsuhiro Kadota