Method and device for measuring a battery cell current

• US 10,018,678 B2
• Filed: 01/30/2015
• Issued: 07/10/2018
• Est. Priority Date: 02/13/2014
• Status: Active Grant

• Current Assignee: Robert Bosch GmbH
• Original Assignee: Robert Bosch GmbH
• Inventors: Hillenbrand, Philipp, Springer, Bernhard
• Primary Examiner(s): Hollington, Jermele M
• Assistant Examiner(s): Nasir, Taqi
• Application Number:
  US15/116,538
• Publication Number:
  US 20160377683A1
• Time in Patent Office: 1,257 Days
• Field of Search: 324416, 324 725, 324131, 324 295, 324425-437, 324141, 324142, 32420715, 324654, 324 7675, 324382, 324409, 324678, 429158, 429210, 429 10, 429105, 429447, 429204, 429 53, 429 61, 429 64, 320122, 320118, 320136, 320426, 320120, 320160
• CPC Class Codes: G01R 31/382 Arrangements for monitoring battery or accumulator variables, e.g. SoC
• CPC Class Codes: G01R 31/385 Arrangements for measuring battery or accumulator variables for monitoring G01R31/382
• CPC Class Codes: G01R 31/392 Determining battery ageing or deterioration, e.g. state of health
• CPC Class Codes: G01R 31/396 Acquisition or processing of data for testing or for monitoring individual cells or groups of cells within a battery
• 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: H02J 7/0013 acting upon several batteries simultaneously or sequentially H02J7/1423 takes precedence
• CPC Class Codes: H02J 7/0048 Detection of remaining charge capacity or state of charge [SOC]
• CPC Class Codes: H02J 7/005 Detection of state of health [SOH]

Abstract

The invention relates to a method and to a device for measuring a battery cell current through a battery cell unit. After the battery cell unit has been switched off, inductively stored energy from the battery cell unit is discharged (S1) by means of a discharging unit, wherein the inductively stored energy from the battery cell unit is energy stored by means of an inductive behavior of the battery cell unit, a time period in which the inductively stored energy from the battery cell unit has fallen to a predefined threshold value is determined (S2), and a battery cell current is determined (S3) on the basis of the time period determined.

Claims

1. A method for measuring a battery cell current (I_B) of a battery cell unit (20), the method comprising:

discharging an inductively stored energy from the battery cell unit (2) by means of a discharging unit (10) after the battery cell unit (2) has been switched off, wherein the inductively stored energy from the battery cell unit (20) is an energy stored by means of an inductive behavior of the battery cell unit (20),

determining a time period (t_M) in which the inductively stored energy from the battery cell (20) unit drops to a predefined threshold value, and

determining a battery cell current (I_B) on the basis of the time period (t_M) determined.

2. A method according to claim 1, characterized in that the battery cell unit (20) is switched off by the discharging unit (10).

3. The method according to claim 1, characterized in that the inductively stored energy from the battery cell unit (20) is detected using a measurement voltage (U_DS) induced by the battery cell unit (20) after said battery cell unit (20) has been switched off.

4. The method according to claim 1, characterized in that the inductively stored energy from the battery cell unit (20) is discharged, the battery cell unit (20) is switched off via a transistor, or both.

5. The method according to claim 4, characterized in that the inductively stored energy from the battery cell unit (20) is discharged via a parasitic diode of a MOSFET (14), which goes into breakdown due to a voltage induced by the inductively stored energy from the battery cell unit (20).

6. The method according to claim 4, characterized in that the inductively stored energy from the battery cell unit (20) is used to switch the transistor in order to discharge the inductively stored energy from the battery cell unit (20) across the switched transistor.

7. The method according to claim 6, characterized in that the discharge of the inductively stored energy from the battery cell unit (20) is triggered by means of a diode, which goes into breakdown due to a voltage induced by the inductively stored energy from the battery cell unit (20) and thus provides a voltage for switching the transistor.

8. A device for measuring a battery cell current (I_B) of a battery cell unit (20), the device comprising:

a discharging unit (10), which discharges an inductively stored energy from the battery cell unit (20) after said battery cell unit (20) has been switched off, wherein the inductively stored energy from said battery cell unit (20) is an energy stored by means of an inductive behavior of said battery cell unit (20),

a measuring unit (30), which determines a time period (t_M) in which the inductively stored energy from the battery cell unit (20) has fallen to a predefined threshold value (S), and

an evaluation unit (40), which determines a battery cell current (I_B) on the basis of the time period (t_M) determined.

9. A battery cell control unit (50) comprising:

a battery cell unit (20),

a discharging unit (10), which discharges an inductively stored energy from the battery cell unit (20) after said battery cell unit (20) has been switched off, wherein the inductively stored energy from said battery cell unit (20) is an energy stored by means of an inductive behavior of said battery cell unit (20),

a measuring unit (30), which determines a time period (t_M) in which the inductively stored energy from the battery cell unit (20) has fallen to a predefined threshold value (S), and

an evaluation unit (40), which determines a battery cell current (I_B) on the basis of the time period (t_M) determined.

10. A battery, characterized in that the battery comprises at least one battery cell control unit (40) according to claim 9.