Battery fuel gauge circuit

Patent metadata

Field	Value
Publication number	US-10365330-B2
Application number	US-201514944624-A
Country	US
Kind code	B2
Filing date	Nov 18, 2015
Priority date	Jul 1, 2015
Publication date	Jul 30, 2019
Grant date	Jul 30, 2019

Abstract

A battery fuel gauge circuit for determining the state of charge of a rechargeable battery is presented. The circuit comprises:
a coulomb counter for providing values that are indicative of a charging current or discharge current provided to/by the battery; a voltage sensor; a first pre-processing unit to provide a current change estimate based on the values provided by the coulomb counter; an event filter unit to confirm whether the current change estimate exceeds a certain threshold; an electromotive force unit to determine an electromotive force value of the battery; a state of charge estimator unit to determine the state of charge of the battery based on the electromotive force value.

First claim

What is claimed is:

1. Battery fuel gauge circuit for determining the state of charge of a rechargeable battery, the circuit comprising:
a coulomb counter for providing values that are indicative of a charging current or discharge current provided to/by the battery;
a voltage sensor for providing voltage samples of a voltage provided by the battery;
a first pre-processing unit being adapted to provide a current change estimate based on the values provided by the coulomb counter, said current change estimate indicating an unforced drop of charging/discharge current being detected at point of time t 0 ;
an event filter unit adapted to confirm whether the current change estimate exceeds a certain threshold;
an electromotive force unit adapted to determine an electromotive force value of the battery based on voltage and current information before and after a confirmed current change estimate indicating a drop of charging/discharge current at point of time t 0 ;
a state of charge estimator unit being adapted to determine the state of charge of the battery based on the electromotive force value provided by the electromotive force unit.

2. Battery fuel gauge circuit according to claim 1 , wherein the event filter unit further comprises a correlator, said correlator receiving information derived from the charging/discharge current and a prototype function, wherein the correlator is adapted to determine whether the information derived from the charging/discharge current and the prototype function comprise a similar shape.

3. Battery fuel gauge circuit according to claim 1 , wherein the event filter unit is further adapted to determine whether a charge or discharge rate of the battery is above a given charge/discharge rate threshold.

4. Battery fuel gauge circuit according to claim 1 , wherein the electromotive force unit comprises an enabling port, said enabling port being coupled with the output of the event filter unit in order to trigger the electromotive force unit by the event filter unit.

5. Battery fuel gauge circuit according to claim 1 , wherein the first pre-processing unit is adapted to provide said current change estimate based on a certain observation window.

6. Battery fuel gauge circuit according to claim 1 , wherein the first pre-processing unit is adapted to provide a first average current value, said first average current value being established based on values from the coulomb counter for a first half of the observation window, and a second average current value, said second average current value being established based on values from the coulomb counter for a second half of the observation window.

7. Battery fuel gauge circuit according to claim 1 , comprising a second pre-processing unit, the second pre-processing unit receiving voltage samples from the voltage sensor and being coupled with the electromotive force unit for providing a first average voltage value and a second average voltage value to the electromotive force unit, said first average voltage value being established based on voltage samples within a first half of the observation window and said second average voltage value being established based on voltage samples within a second half of the observation window.

8. Battery fuel gauge circuit according to claim 1 , wherein the first and/or second pre-processing unit is adapted to filter the values from the coulomb counter, current samples derived thereof and/or voltage samples by means of a low-pass filter.

9. Battery fuel gauge circuit according to claim 1 , wherein the electromotive force unit is adapted to calculate the electromotive force (EMF) of the battery based on the following formula:

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Assignees

• Dialog Semiconductor Uk Ltd

Inventors

• Mayr Michael

Classifications

• G01R31/367 Primary

  Software therefor, e.g. for battery testing using modelling or look-up tables · CPC title

• G01R31/3828

  using current integration · CPC title

• G01R31/3835

  involving only voltage measurements · CPC title

• G01R31/392

  Determining battery ageing or deterioration, e.g. state of health · CPC title

• G01R31/389

  Measuring internal impedance, internal conductance or related variables · CPC title