Hitachi Information & Telecommunication Engineering, Ltd.

Yusuke Katsuyama

Fumikazu Takahashi

Yoshihide Takahashi

Kimiaki Taniguchi

Susumu Nagafuchi

Akinori Uchida

Masahiro Hamaogi

Daisuke Ishida

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

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

Growing community of inventors

Yokohama, Japan

Yusuke Katsuyama