Method and device for measuring a battery cell current
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 (S 1 ) 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 (S 2 ), and a battery cell current is determined (S 3 ) on the basis of the time period determined.
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 .