Hitachi, Ltd.

Hitachi Construction Machinery Co., Ltd.

Kazuhiro Imaie

Motoo Futami

Masaya Ichinose

Shinya Oohara

Mamoru Kimura

Kazumasa Ide

Mitsugu Matsutake

Yasuhiro Kiyofuji

Keizo Shimada

Naoshi Sugawara

Takashi Hotta

Kotaro Shimamura

Akira Bando

Yuichiro Morita

Shigeta Ueda

Takashi Yagyu

Yoshitaka Takahashi

Mitsuyasu Kido

Takeshi Takehara

Tomohiko Yasuda

Akira Kikuchi

Hiromitsu Sakai

Michio Fushiki

Tadashi Sodeyama

Takashi Yagyuu

Hajimu Kozawa

Tetsuhiro Fujimoto

Shintarou Oku

A wind power generation system includes an excessive current consumption device, an AC input of which is connected between a generator rotor and an excitation converter on a system failure to detect a DC voltage ascent of the excitation converter and operate a shunt circuit on the system failure.

Wind power generation system

An electrically-driven dump truckuses resistors to convert electric power generated during retarder braking operation into heat energy. A body framehas front and rear wheels, a support baseA, a cabmounted on an upper left surface of the support base, and a control cabinetmounted on an upper surface of the support base. A plurality of resistor boxesare mounted on an upper base plateB and are arranged in a stacked manner such that the plurality of resistor boxesare located to the right of the control cabinetin order to secure right side visibility from the cab. Each resistor box has a casing with plural resistors connected in parallel, an inlet port and an outlet port. A fan for cooling the resistors is housed in the casing.

Electrically-driven dump truck

An electric motor control system including a generator, an AC motor, a power converter for driving the AC motor using a DC output voltage of the generator, and an electric motor controller for controlling the power converter. The electric motor controller controls the power converter by predicting a change in the DC voltage.

Electric motor control system, series hybrid vehicle, electric motor control apparatus, and electric motor control method

In an electric drive system for a vehicle, an alternator is driven by an engine to generate electric power which is used to drive a motor to generate a driving force. During a retardation of the vehicle, the motor is operated as an alternator to convert kinetic energy to electric energy which is used to retard the vehicle. A retard resistor is provided for absorbing electric energy generated during the retardation state. The retard resistor is cooled down by an AC blower.

Electric drive system for vehicle, electric control system for vehicle, electric drive method for vehicle

A power generation apparatus and method includes an AC energization synchronous generator, a switching device which connects to a network disposed on a stator side of the AC energization synchronous generator, an energizing device which applies a variable frequency AC to a secondary winding of the AC energization synchronous generator, and a first voltage detection unit which detects a voltage of the switching device on the stator side. A rotational frequency of the AC energization synchronous generator is estimated or calculated based on a frequency of a stator side voltage of the switching device, while the switching device is open.

Power generation apparatus using AC energization synchronous generator and method of controlling the same

A variable speed wind power generation system including a wind turbine, a generation power command unit for generating a generation power command value based on a state quantity of the wind turbine and a generator control unit for controlling the power converter for controlling electric power of the generator, wherein the generator control unit operates to regulate the generation power of the generator in order to change the generation power amount according to the generation power command value.

Variable speed wind power generation system

A power generation apparatus and method includes an AC energization synchronous generator, a switching device for connecting to a network disposed on a stator side of the AC energization synchronous generator, an energizing device for applying a variable frequency AC to a secondary winding of the AC energization synchronous generator, and a first voltage detection unit for detecting a voltage of the switching device on the stator side. A rotational frequency of the AC energization synchronous generator is estimated or calculated based on a frequency of a stator side voltage of the switching device, while the switching device is open.

In a power generation apparatus equipped with an AC energization synchronous generator, when energization of a secondary winding starts to conduct connecting to the network of the AC energization synchronous generator to a network voltage, energization of the secondary winding starts at a fixed frequency and a slip frequency is calculated from a difference between a frequency of the network voltage and a resultant stator voltage frequency. Thereafter, energization starts at the calculated slip frequency and a voltage having a frequency generally coincident with the network frequency is output to the stator to incorporate the generator to the network. A phase is adjusted to make zero a phase difference when the rotation speed changes or the phases become different.

A motor is driven with variable frequency AC power converted from DC power, and an AC output power from the motor is converted to DC. In the conversion, an electromotive force regenerated by the motor is consumed by a plurality of resistors. When the consumption of the electromotive force is impeded in any of systems including any of the plurality of resistors, the electromotive force is consumed by the systems including the remaining resistors. Even if a system including any of the plurality of resistors fails, the electromotive force can by consumed by the other systems including the remaining resistors, thus providing a reliable rheostatic brake.

AC drive apparatus, vehicle control apparatus, and power conversion method and vehicle control method

Because of the necessity of resolver for detecting a rotating position, which is very expensive, and noise suppression of the rotating position signal line on a doubly-fed machine, cost increase of the generator and reduced reliability due to possible failures are inevitable. In order to solve such problem, a generation system in the present invention is equipped with an exciter that estimates the slip frequency of the doubly-fed machine from each primary current Iand voltage Vand secondary current Iand voltage Vof the doubly-fed machine and excites the secondary of the doubly-fed machine at the estimated slip frequency.

Electrical rotating machine control unit and power generation system

In a synchronization system adopted in a synchronous-multisystem control apparatus comprising a plurality of systems operating synchronously with each other at a fixed control period, the synchronous-multisystem control apparatus can be operated in a single-system mode in the event of failures occurring simultaneously in some of the systems. The synchronous-multisystem control apparatus employs a plurality of control circuits each provided for one of the systems. Any particular one of the control circuits comprises:

Synchronization system and synchronization method of multisystem control apparatus

In a synchronization system adopted in a synchronous-multisystem control apparatus including a plurality of systems operating synchronously with each other at a fixed control period, the synchronous-multisystem control apparatus can be operated in a single-system mode in the event of failures occurring simultaneously in some of the systems. The synchronous-multisystem control apparatus employs a plurality of control circuits each provided for one of the systems. Any particular one of the control circuits includes: a period-signal generating circuit for generating a period signal indicating a start point of a control period; a synchronization-reference selecting circuit for outputting a synchronization-reference signal by referring to period signals generated by the systems; and a control-period correcting circuit for correcting a control period of the particular system by forming a judgment on a synchronization shift of the period signal generated by the particular system from the synchronization-reference signal and keeping the control period as it is in case the synchronization-reference signal is not generated.

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Hitachi, Japan

Kazuhiro Imaie