Method and apparatus for determining a constant current limit value

• US 10,067,193 B2
• Filed: 07/26/2016
• Issued: 09/04/2018
• Est. Priority Date: 07/27/2015
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Cois, Olivier, Zafiridis, Triantafyllos
• Primary Examiner(s): Breene, John
• Assistant Examiner(s): Islam, Mohammad
• Application Number:
  US15/219,996
• Publication Number:
  US 20170030973A1
• Time in Patent Office: 770 Days
• CPC Class Codes: G01R 19/16542 for batteries charge condition monitoring in G01R31/36
• CPC Class Codes: G01R 31/367 Software therefor, e.g. for battery testing using modelling or look-up tables
• CPC Class Codes: G01R 31/3842 combining voltage and current measurements
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: G01R 31/389 Measuring internal impedance, internal conductance or related variables
• CPC Class Codes: H01M 10/42 Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells H01M10/60 takes precedence
• CPC Class Codes: H01M 10/44 Methods for charging or discharging circuits for charging H02J7/00
• CPC Class Codes: H01M 10/48 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 Class Codes: Y02E 60/10 Energy storage using batteries

Abstract

A method for determining a constant current limit value by means of which a first current which flows through a battery cell is limited, wherein the constant current limit value is determined on the basis of a first function which specifies a first profile of the first current, which first profile is dependent on a plurality of parameters. The plurality of parameters include a first voltage which is applied between two terminals of the battery cell, a second voltage which specifies a no-load voltage of the battery cell, and a time variable.

Claims

1. A method for determining a constant current limit value (GIB) by means of which a first current (IB0) which flows through a battery cell is limited, wherein the constant current limit value (GIB) is determined on the basis of a first function which specifies a first profile of the first current (IB0), which first profile is calculated depending on a plurality of parameters, wherein the plurality of parameters include a first voltage (UB1) which is applied between two terminals (3, 4) of the battery cell, a second voltage (UB2) which specifies a no-load voltage (UB2) of the battery cell, and a time variable which specifies a variable prediction period, the method comprising:

measuring, with a current sensor, a current value (IB01) of the first current (IB0),

measuring, with a voltage sensor, a voltage value of the first voltage (UB1),

determining, with a controller that receives the current value (IB01) from the sensor, an actual correction voltage value depending on the measured current value (IB01) of the first current (IB0) and on the measured voltage value of the first voltage (UB1),

determining, with the controller, the constant current limit value (GIB) by means of a predefined function (IB) which is given by replacing the second voltage (UB2) with a correction voltage, which is dependent on the second voltage (UB2) and the actual correction voltage value, in the first function,

limiting, by the controller, the first current (IB0) according to the constant current limit value (GIB)

determining a changed preliminary correction voltage value (KUB21), and

setting, with the controller, the actual correction voltage value equal to the changed preliminary correction voltage value (KUB21).

2. The method according to claim 1, further comprising:

determining, with the controller, the correction voltage, which occurs in the predefined function (IB), as a linear combination between the second voltage (UB2) and the actual correction voltage value.

3. The method according to claim 1, further comprising:

determining, with the controller, the constant current limit value (GIB) as a constant current limit value function (GIB) which corresponds to the predefined function (TB) when the first voltage (UB1) has a predefined voltage value (GUB1) and the time variable has a predefined value, wherein the predefined value of the time variable specifies a duration of a maximum prediction period for which the constant current limit value is valid.

4. The method according to claim 1, wherein the parameters also include further parameters.

5. The method according to claim 4, wherein:

defining the constant current limit value function (GIB) in accordance with a first equation which is specified below and in which GIB indicates the constant current limit value function (GIB), GUB1 indicates the predefined voltage value (GUB1) of the first voltage (UB1), UB2 indicates the second voltage (UB2), KUB22 indicates the actual correction voltage value, i indicates a natural number which lies between 1 and a natural number n, TP indicates the predefined value of the time variable, and U0i, R0, Ri and τ

i indicate the further parameters;

6. The method according to claim 1, wherein determining the changed preliminary correction includes:

calculating, with the controller, a current value (IB02) of the first current (IB0) on the basis of the measured voltage value of the first voltage (UB1) and a resistance value of the internal resistor of the battery cell,

calculating, with the controller, an actual function value (IB21) of the second function, and

changing, with the controller, the preliminary correction voltage (KUB21) until the actual function value (IB21) of the second function corresponds to the measured current value (IB01) of the first current (IB0).

7. The method according to claim 6, further comprising:

determining, with the controller, the correction voltage, which occurs in the second function, as a linear combination between the second voltage (UB2) and the preliminary correction voltage value (KUB21).

8. An apparatus for determining a constant current limit value (GIB) by means of which a first current (IB0) which flows through a battery cell is limited, wherein the apparatus comprises a voltage sensor, a current sensor and a controller, wherein the voltage sensor is designed to measure a voltage value of a first voltage (UB1) which is applied between two terminals (3, 4) of a battery cell and to supply the said voltage value to the determination unit, the current sensor is designed to measure a current value (IB01) of the first current (IB0) and to supply the said current value to the controller, the controller designed to

measure, via the current sensor, a current value (IB01) of the first current (IB0),

measure, via the voltage sensor, a voltage value of the first voltage (UB1),

determine an actual correction voltage value depending on the measured current value (IB01) of the first current (IB0) and on the measured voltage value of the first voltage (UB1),

determine the constant current limit value (GIB) by means of a predefined function (IB) which is given by replacing the second voltage (UB2) with a correction voltage, which is dependent on the second voltage (UB2) and the actual correction voltage value, in the first function,

limit, the first current according to the constant current limit value,

determining a changed preliminary correction voltage value (KUB21), and

setting, with the controller, an actual correction voltage value equal to the changed preliminary correction voltage value (KUB21).