Method for balancing states of charge of an electrical energy store

Patent metadata

Field	Value
Publication number	US-2021091423-A1
Application number	US-202017027260-A
Country	US
Kind code	A1
Filing date	Sep 21, 2020
Priority date	Sep 20, 2019
Publication date	Mar 25, 2021
Grant date	—

Abstract

Method for balancing states of charge of an electrical energy store with a plurality of battery cells.

First claim

1 . A method for balancing states of charge of an electrical energy store with a plurality of battery cells, the method comprising:
a) acquiring a voltage magnitude U mess,i that represents an electric voltage of a battery cell; b) determining a maximum positive electric charge Q i,Pos of the battery cell with respect to an electric reference voltage level U BalLevel of all the battery cells of the electrical energy store with balanced states of charge according to
Q i,Pos =OCV PosErr ( U mess,i +U PosErr )− OCV PosErr ( U BalLevel ),

wherein OCV PosErr represents a no-load voltage curve with a positive capacity estimation error and U PosErr represents a sensor tolerance of the acquired voltage magnitude U mess,i and a modeled positive battery cell voltage error; c) determining a maximum negative electric charge Q i,Neg of the battery cell with respect to the electric reference voltage level U BalLevel of all the battery cells of the electrical energy store with balanced states of charge according to
Q i,Neg =OCV NegErr ( U mess,i −U NegErr )− OCV NegErr ( U BalLevel ),

wherein OCV NegErr represents a no-load voltage curve with a negative capacity estimation error and U NegErr represents a sensor tolerance of the acquired voltage magnitude U mess,i and a modeled negative battery cell voltage error; d) determining an electric charge ΔQ i to be balanced of the battery cell according to
Δ Q i =Q i −Q min ,

wherein Q i represents an electric charge of the battery cell with respect to the reference voltage level U BalLevel and Q min represents a minimum electric charge of all the battery cells located in a series circuit with respect to the reference voltage level U BalLevel ; e) determining a charge error ΔQ i,Err of the electric charge ΔQ i to be balanced according to
Δ Q i,Err =Q i,Pos −Q min,Neg ,

wherein Q min,Neg represents an electric charge Q i,Neg of the battery cell with the minimum electric charge Q min ; f) determining an electric charge ΔQ i,use to be balanced of the battery cell according to
Δ Q i,use =ΔQ i −W*ΔQ i,err ,

wherein W represents a predefinable weighting factor; g) calculating a duration t i,bal for balancing the state of charge of the battery cell on the basis of the electric charge ΔQ i,use that is to be balanced when the electric charge ΔQ i,use to be balanced exceeds a predefined threshold value, according to

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wherein R Bal represents an ohmic resistance assigned to the battery cell; and
h) balancing the state of charge of the battery cell for the duration t i,bal .

2 . The method according to claim 1 , wherein the full charge error ΔQ i,err is subtracted from the electric charge ΔQ i that is to be balanced if the weighting factor W adopts the value 1, and the charge error ΔQ i,err is not taken into consideration if the weighting factor W adopts the value 0.

3 . The method according to claim 1 , wherein the no-load voltage curve, the sensor tolerance, and/or the capacity estimation errors are determined statically and/or dynamically in order to determine the maximum positive charge Q i,Pos and/or the maximum negative charge Q i,Neg .

4 . The method according to claim 1 , wherein the electric reference voltage level U BalLevel of the battery cells of the electrical energy store with balanced states of charge of all the battery cells is 3.7 V.

5 . The method according to claim 1 , wherein the capacity estimation error of the no-load voltage curve OCV is a maximum of ±4%.

6 . An electrical energy store comprising:
a plurality of battery cells; at least one voltage sensor; and at least one electronic battery control device, the at least one electronic battery control device configured to carry out the steps of the method according to claim 1 .

7 . The electrical energy store according to claim 6 , further comprising:
discharge resistors for the selective discharge of individual battery cells.

8 . A computer program comprising commands whose effect is that the electrical energy store according to claim 6 .

9 . A machine-readable storage medium on which the computer program according to claim 8 is stored.

10 . A use of an electrical energy store according to claim 6 for electric vehicles, hybrid vehicles, plug-in hybrid vehicles, aircraft, pedelecs or e-bikes, for portable devices for telecommunications or data-processing, for electric hand tools or kitchen appliances, as well as in stationary stores for storing electrical energy that has been obtained regeneratively.

Assignees

• Bosch Gmbh Robert

Inventors

• Becker Jens
• Kroener Christoph
• Zafiridis Triantafyllos

Classifications

• H02J7/965

  obtained with the battery disconnected from the charge or discharge circuit · CPC title

• H02J2105/37

  exchanging power with electric vehicles [EV] or with hybrid electric vehicles [HEV] · CPC title

• H02J7/52

  for charge balancing, e.g. equalisation of charge between batteries · CPC title

• Y02E60/10

  Energy storage using batteries · CPC title

• Y02T10/70

  Energy storage systems for electromobility, e.g. batteries · CPC title