Battery state monitoring circuit and battery device

Patent metadata

Field	Value
Publication number	US-9812743-B2
Application number	US-201514753722-A
Country	US
Kind code	B2
Filing date	Jun 29, 2015
Priority date	Jun 30, 2014
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Provided is a battery state monitoring circuit and a battery device capable of predicting a state of charge of a secondary battery with high accuracy. The battery state monitoring circuit includes a pseudo-equivalent circuit of the secondary battery, and causes a current flowing through a sense resistor to flow to the pseudo-equivalent circuit of the secondary battery, to thereby measure a pseudo-open circuit voltage of the secondary battery.

First claim

What is claimed is:

1. A battery state monitoring circuit for monitoring charge and discharge of a secondary battery, to thereby detect a state of charge of the secondary battery, the battery state monitoring circuit comprising:
a first terminal and a second terminal to which the secondary battery is connected;
an equivalent circuit of the secondary battery, the equivalent circuit comprising a first capacitor, a first resistor and a second resistor connected in series, and a second capacitor connected in parallel with the second resistor;
a sense resistor for detecting a charge and discharge current of the secondary battery;
a voltage-current converter including input terminals respectively connected to both ends of the sense resistor and an output terminal connected to the equivalent circuit, for measuring a voltage between the both ends of the sense resistor, to thereby cause a current depending on the charge and discharge current to flow to the equivalent circuit;
a first A/D converter for monitoring a voltage of the first terminal;
a second A/D converter for monitoring an open circuit voltage of the equivalent circuit; and
an arithmetic circuit for detecting the state of charge of the secondary battery based on an output signal of the first A/D converter and an output signal of the second A/D converter.

2. The battery state monitoring circuit according to claim 1 , wherein the first capacitor includes one terminal connected to the second terminal and the first resistor and the second resistor are connected in series between another terminal of the first capacitor and the output terminal of the voltage-current converter and the second capacitor is connected in parallel with the second resistor, and
wherein the second A/D converter measures a voltage of the another terminal of the first capacitor.

3. The battery state monitoring circuit according to claim 1 , further comprising:
a first constant current circuit connected between the first terminal and another terminal of the first capacitor; and
a second constant current circuit connected between the another terminal of the first capacitor and the second terminal.

4. The battery state monitoring circuit according to claim 2 , further comprising:
a first constant current circuit connected between the first terminal and another terminal of the first capacitor; and
a second constant current circuit connected between the another terminal of the first capacitor and the second terminal.

5. The battery state monitoring circuit according to claim 1 , further comprising a switching circuit connected between the first terminal and another terminal of the first capacitor.

6. A battery device, comprising:
a secondary battery; and
the battery state monitoring circuit according to claim 1 .

Assignees

• Seiko Instr Inc
• Sii Semiconductor Corp

Inventors

• Koike Toshiyuki
• Sano Kazuaki
• Sakurai Atsushi
• Mukainakano Hiroshi

Classifications

• H01M10/48 Primary

  Accumulators combined with arrangements for measuring, testing or indicating the condition of cells, e.g. the level or density of the electrolyte (constructional details of current conducting connections for detecting conditions inside cells or batteries, e.g. details of voltage sensing terminals, H01M50/569) · CPC title

• G01R31/3606

  Physics · mapped topic

• G01R31/3662

  Physics · mapped topic

• H01M10/44

  Methods for charging or discharging (circuits for charging H02J7/00) · CPC title

• G01R31/3842

  combining voltage and current measurements · CPC title