Mitsubishi Electric Corporation

Akiko Tabuchi

Hidetoshi Kitanaka

Keita Hatanaka

Kikuo Izumi

Shoji Yoshioka

Yoshinori Kanda

Kazuyoshi Watabu

Toshiyuki Fujii

Daigo Takemura

Tetsuya Okuda

Takahiro Kato

Shinichi Furutani

Ryoji Miyatake

Kazuhiko Tsutsui

Yoji Tsutsumishita

Jun Hattori

Shinya Noguchi

Manabu Ohashi

Ryota Onishi

Naohisa Kawahara

The power conversion device includes common DC buses, AC buses, DC connection terminals, AC connection terminals, N pairs of distributed power supply connection terminals, N DC/DC converters for transferring power between the common DC buses and the distributed power supply connection terminals, M DC/AC converters for transferring power between the AC buses and the common DC buses, and a control unit for controlling each converter on the basis of a high-order control command. The DC connection terminals are connected to the common DC buses and connected to an external DC power distribution grid, the AC connection terminals are connected to the AC buses and connected to an external AC power distribution grid, and the distributed power supply connection terminals are connected to the DC/DC converters and connected to external DC distributed power supplies.

Power conversion device

A controller of each power conversion device in a power conversion system controls a switching element unit, based on a detected value of reactor current flowing through a filter reactor, a detected value of output voltage output between the terminals of a filter capacitor, and a detected value of output current flowing through an output reactor. The controller generates a voltage command based on the output current and the output voltage and generates a correction amount of the voltage command based on the output current in which a reference frequency component is removed. The controller generates a current command based on the addition value of the voltage command and the correction amount and controls the switching element unit such that the reactor current matches the current command.

Power conversion device and power conversion system

A power generation system is provided in which, when a static frequency converter (SFC) is connected to synchronous generator's armature windings, an AC exciter performs AC excitation by allowing a d-axis winding and a q-axis winding of the AC exciter to configure d-q orthogonal axes; and, at the time of steady-state operation of the synchronous generator, an alternating current(s) supplied from an electric power source is rectified by a thyristor excitation device, and also the AC exciter thereby performs DC excitation by connecting the d-axis winding and the q-axis winding in series with each other.

Power generation system

An AC motor drive motor system includes a charge and discharge controller controlling a charging and discharging circuit based on a DC voltage value on the output side of a converter and a charging and discharging current value of a power storage device. The charge and discharge controller, when regenerative power via an inverter from an AC motor exceeds a power threshold, charges the power storage device such that the DC voltage value becomes a voltage threshold corresponding to the power threshold. When regenerative power is the power threshold or less, the converter performs regeneration when the DC voltage value reaches a regeneration start voltage threshold or higher, and ends regeneration when the DC voltage value reaches a regeneration end voltage threshold or lower. The DC-voltage-value time averaged value during regeneration is set lower than that at no-load time when the converter does not perform power supply and regeneration.

AC motor drive system

When regenerative power from an AC motor via an inverter exceeds a predetermined power threshold, a charging/discharging control unit, which outputs a control signal for controlling the inverter on the basis of a DC bus voltage value and a charging/discharging current value, causes a power storage device to be charged such that the DC bus voltage value becomes a voltage threshold corresponding to the power threshold and causes a charging current at a start time of charging to the power storage device to start from a charging current value that is based on a DC bus voltage value.

A state-of-charge estimation apparatus connected to a power storage device having cell batteries, and estimating a state of charge of the power storage device, the apparatus including a first SOC computation unit computing a current integration value based on a total current from a current detector detecting the total current flowing to the storage device from a power conversion device using a previous SOC value as an initial value, and outputting the integration value as a first state-of-charge estimated value, and a second SOC computation unit estimating, after discharge suspension in the storage device, an open-circuit voltage based on a total voltage on a connection point between the conversion device and the storage device, a previous value of the total voltage, and a gain with time passage after discharge suspension in the storage device, and outputting the open-circuit voltage as a second state-of-charge estimated value.

State-of-charge estimation apparatus

A state-of-charge estimating apparatus includes at least a first arithmetic unit configured to calculate, as a first estimation value, the present estimation value calculated based on a battery capacity, the last estimation value, and an electric current flowing in and out between a current control apparatus, which controls charge and discharge amounts of a power storage apparatus, and the power storage apparatus, and a second arithmetic unit configured to calculate, during constant current control, as the present value of a second estimation value, an estimation value calculated based on an equivalent circuit model of a battery and a voltage of the battery and, on the other hand, calculate, during constant voltage control, as the second estimation value, the present estimation value calculated taking into account a resistance change of the battery based on the equivalent circuit model of the battery and the voltage of the battery.

State-of-charge estimating apparatus

In the case where DC power from a DC power supply is converted to AC power by an inverter and supplied to an AC motor, a power compensator is connected in parallel with a DC power input portion of the inverter, and a control device of the power compensator charges/discharges a power storage device to perform a power compensation process A when power demand for the AC motor exceeds a predetermined value, and takes into account power allowance which can be inputted and outputted from the DC power supply to the power storage device and performs a power storage adjustment process B of performing auxiliary charge of the power storage device within the range of the power allowance when the power compensation process A is unnecessary.

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Tokyo, Japan

Akiko Tabuchi