Power storage system and power storage method

Patent metadata

Field	Value
Publication number	US-2016329737-A1
Application number	US-201415107750-A
Country	US
Kind code	A1
Filing date	Dec 26, 2014
Priority date	Dec 27, 2013
Publication date	Nov 10, 2016
Grant date	—

Abstract

A power storage system includes: a power generation element that performs environmental power generation; a storage battery that is supplied with power generated by the power generation element; a DC/DC converter that converts an output voltage from the power generation element into a predetermined voltage; a first switch unit that switches whether directly supply the output voltage from the power generation element to the storage battery or to supply thereto via the DC/DC converter; and a first changeover unit that compares a voltage of the storage battery with a first threshold voltage, and controls the first switch unit according to a comparison result, in a case where a voltage of the voltage or higher of the storage battery bringing the DC/DC converter into a main boost mode is the first threshold voltage.

First claim

1 . A power storage system comprising:
a power generation element that performs environmental power generation; a storage battery that is supplied with power generated by the power generation element; a DC/DC converter that converts an output voltage from the power generation element into a predetermined voltage; a first switch unit that switches whether to directly supply the output voltage from the power generation element to the storage battery or to supply thereto via the DC/DC converter; and a first changeover unit that compares a voltage of the storage battery with a first threshold voltage, and controls the first switch unit according to a comparison result, in a case where a voltage of the voltage or higher of the storage battery bringing the DC/DC converter into a main boost mode is the first threshold voltage, wherein the first changeover unit controls the first switch unit so that the output voltage is directly supplied from the power generation element to the storage battery, in a case where the voltage of the storage battery is equal to or lower than the first threshold voltage, and the first changeover unit controls the first switch unit so that the output voltage is supplied from the power generation element to the storage battery via the DC/DC converter, in a case where the voltage of the storage battery exceeds the first threshold voltage.

2 . The power storage system according to claim 1 , wherein
the storage battery is constituted of a first storage battery and a second storage battery having a capacity larger than a capacity of the first storage battery, and in a case where a second threshold voltage is higher than the first threshold voltage, the output voltage is supplied to only the first storage battery from the power generation element if the voltage of the storage battery is equal to or lower than the second threshold voltage.

3 . The power storage system according to claim 2 , further comprising:
a second switch unit that performs switching between an electrical connection state and disconnection state between the first storage battery and the second storage battery; and a second changeover unit that compares the voltage of the first storage battery with a second threshold voltage, and controls the second switch unit according to a comparison result, wherein each of the first storage battery and the second storage battery is configured to supply power to an external load apparatus, the second threshold voltage is equal to or higher than a voltage causing the external load apparatus to be operated, the second changeover unit controls the second switch unit so that the first storage battery is disconnected from the second storage battery, and thus power generated by the power generation element is supplied to only the first storage battery, in a case where the voltage of the first storage battery is equal to or lower than the second threshold voltage, and the second changeover unit controls the second switch unit so that the first storage battery is connected to the second storage battery, and thus power is supplied from the first storage battery to the second storage battery, in a case where the voltage of the first storage battery exceeds the second threshold voltage.

4 . The power storage system according to claim 3 , further comprising:
a third switch unit that performs switching between an electrical connection state and disconnection state between the first storage battery and the second storage battery, and the external load apparatus; and a third changeover unit that compares the voltage of the first storage battery with a third threshold voltage, and controls the third switch unit according to a comparison result, wherein the third changeover unit controls the third switch unit so that the first storage battery and the second storage battery are connected to the external load apparatus, in a case where the voltage of the first storage battery is higher than the third threshold voltage, and the third changeover unit controls the third switch unit so that the first storage battery and the second storage battery are disconnected from the external load apparatus, in a case where the voltage of the first storage battery is lower than the third threshold voltage.

5 . The power storage system according to claim 4 , wherein
the third threshold voltage is set to be a predetermined voltage higher than an operation voltage causing the external load apparatus to be operated, and to be lower than the second threshold voltage.

6 . The power storage system according to claim 1 , wherein
the second changeover unit has hysteresis characteristics, and compares the voltage of the first storage battery with the second threshold voltage using the hysteresis characteristics, in a case where the voltage of the first storage battery exceeds the second threshold voltage, the second changeover unit controls the second switch unit so that the first storage battery is connected to the second storage battery, and in a case where the first storage battery is connected to the second storage battery, and the voltage of the first storage battery is reduced to a fourth threshold voltage or lower, the fourth threshold voltage being a predetermined voltage lower than the second threshold voltage and being a predetermined voltage higher than the first threshold voltage, the second changeover unit controls the second switch unit so that the first storage battery is disconnected from the second storage battery.

7 . The power storage system according to claim 1 , wherein
the power generation element is constituted of power generation element cells which are connected in series to each other.

8 . The power storage system according to claim 1 , wherein
the power generation element is a low illuminance solar battery which can be used in an environment of a predetermined illuminance or lower.

9 . A power storage method comprising:
providing a power storage system including a storage battery that is supplied with power generated by a power generation element performing environmental power generation, a DC/DC converter that converts an output voltage from the power generation element into a predetermined voltage, a switch unit that switches whether to directly supply the output voltage from the power generation element to the storage battery or to supply thereto via the DC/DC converter, and a changeover unit that compares a voltage of the storage battery with a first threshold voltage, and controls the switch unit according to a comparison result, in a case where a voltage of the voltage or higher of the storage battery bringing the DC/DC converter into a main boost mode is the first threshold voltage; causing the changeover unit to control the switch unit so that the output voltage is directly supplied from the power generation element to the storage battery, in a case where the voltage of the storage battery is equal to or lower than the first threshold voltage; and causing the changeover unit to control the switch unit so that the output voltage is supplied from the power generation element to the storage battery via the DC/DC converter, in a case where the voltage of the storage battery exceeds the first threshold voltage.

Assignees

• Fujikura Ltd

Inventors

• Yamamoto Kazuhiro
• Yanagimoto Ryoji
• Yamada Yuji
• Yano Kenjiro
• Okada Kenichi

Classifications

• H01G9/20

  Light-sensitive devices · CPC title

• H02J9/061

  for DC powered loads · CPC title

• H02J7/35 Primary

  with light sensitive cells · CPC title

• H01M2220/10

  Batteries in stationary systems, e.g. emergency power source in plant · CPC title

• Y02E10/50

  Photovoltaic [PV] energy · CPC title