Cell-balancing method and battery management system performing the same

Patent metadata

Field	Value
Publication number	US-2019280489-A1
Application number	US-201916293419-A
Country	US
Kind code	A1
Filing date	Mar 5, 2019
Priority date	Mar 6, 2018
Publication date	Sep 12, 2019
Grant date	—

Abstract

A battery management system may include a plurality of balancing resistors respectively forming balancing discharging paths of cells connected in series to each other, a plurality of balancing switches respectively connected between the cells and the balancing resistors, and configured to control cell-balancing of each of the cells, a voltage-detecting circuit for detecting respective cell voltages of the cells, and a battery controller for acquiring respective balancing capacities of the cells based on the cell voltages, for obtaining duty cycles of the balancing switches according to the balancing capacities, and for scaling the duty cycles of the balancing switches according to a sum of duty cycles of two adjacent cells from among the cells.

First claim

What is claimed is:

1 . A battery management system comprising:
a plurality of balancing resistors respectively forming balancing discharging paths of cells connected in series to each other; a plurality of balancing switches respectively connected between the cells and the balancing resistors, and configured to control cell-balancing of each of the cells; a voltage-detecting circuit for detecting respective cell voltages of the cells; and a battery controller for acquiring respective balancing capacities of the cells based on the cell voltages, for obtaining duty cycles of the balancing switches according to the balancing capacities, and for scaling the duty cycles of the balancing switches according to a sum of duty cycles of two adjacent cells from among the cells.

2 . The battery management system of claim 1 , wherein the two adjacent cells partly share a balancing discharging path for cell-balancing.

3 . The battery management system of claim 2 , wherein balancing switches of the two adjacent cells are alternately turned on.

4 . The battery management system of claim 1 , wherein the battery controller is configured to calculate a sum of duty cycles of combination of two adjacent cells, is configured to calculate a scale factor so that a maximum value of the sum of duty cycles is 100%, and is configured to scale the duty cycles of the balancing switches using the scale factor.

5 . The battery management system of claim 1 , wherein the battery controller is configured to set a ratio of respective duty cycles of the balancing switches based on a ratio of respective balancing capacities of the cells.

6 . The battery management system of claim 1 , further comprising a battery integrated circuit for controlling the balancing switches according to the duty cycles of the balancing switches.

7 . A battery management system comprising:
a plurality of balancing resistors respectively forming balancing discharging paths of cells connected in series to each other; a plurality of balancing switches respectively connected between the cells and the balancing resistors for controlling a cell-balancing of each of the cells; a voltage-detecting circuit for detecting cell voltages of the cells; and a battery controller for acquiring balancing capacities of the cells based on the cell voltages, for obtaining duty cycles of the plurality of balancing switches according to the balancing capacities, and for scaling the duty cycles of the plurality of balancing switches according to a power consumption upper limit corresponding to a balancing discharging of the cells.

8 . The battery management system of claim 7 , wherein the battery controller is configured to calculate a total power consumption by summing the balancing capacities of the cells, and is configured to scale the duty cycles of the balancing switches when the total power consumption is greater than the power consumption upper limit.

9 . The battery management system of claim 8 , wherein the battery controller sets a ratio of respective duty cycles of the balancing switches based on a ratio of respective balancing capacities of the cells.

10 . The battery management system of claim 7 , wherein the battery controller is configured to calculate a current scale factor based on a ratio of a current upper limit on a substrate on which the balancing resistors are mounted to a sum of average balancing currents flowing in each of the balancing discharging paths, and is configured to scale the duty cycles of the balancing switches by using the current scale factor.

11 . The battery management system of claim 7 , wherein the battery controller is configured to scale the duty cycles of the balancing switches according to a current upper limit allowable to a single balancing discharging path.

12 . The battery management system of claim 7 , wherein the battery controller is configured to calculate a current scale factor of each of the balancing switches based on a ratio of a current upper limit to an average balancing current flowing in each of the balancing discharging paths, and is configured to scale the duty cycles of the balancing switches by using the current scale factor.

13 . The battery management system of claim 7 , wherein the battery controller is configured to scale the duty cycles of the balancing switches according to a sum of duty cycles between two adjacent cells from among the cells.

14 . A battery management system comprising:
a plurality of balancing resistors respectively forming balancing discharging paths of cells connected in series to each other; a plurality of balancing switches respectively connected between the cells and the balancing resistors for controlling a cell-balancing of each of the cells; a voltage-detecting circuit for detecting cell voltages of the cells; a battery controller for acquiring balancing capacities of the cells based on the cell voltage, and for obtaining duty cycles of the balancing switches according to the balancing capacities; and a battery integrated circuit for controlling operation of the balancing switches by using a balancing task, which is repeatedly executed during an execution cycle that is shorter than a balancing cycle, and which corresponds to the duty cycles, to allow a turn-on state of the balancing switches only during a part of an execution period of the balancing task.

15 . The battery management system of claim 14 , wherein the battery integrated circuit is configured to count on-periods, in which the balancing switches are turned on by the balancing task within one balancing cycle, for each of the balancing switches, and is configured to maintain a state of a balancing switch in a turn-off state until the balancing cycle ends wherein a value obtained by counting on-periods corresponds to a duration of a corresponding duty cycle.

16 . The battery management system of claim 14 , wherein the battery controller sets a ratio of respective duty cycles of the balancing switches based on a ratio of respective balancing capacities of the cells.

17 . The battery management system of claim 16 , wherein the battery controller is configured to scale the duty cycles of the balancing switches according to a sum of duty cycles between two adjacent cells from among the cells.

18 . The battery management system of claim 16 , wherein the battery controller is configured to scale the duty cycles of the balancing switches according to a power consumption upper limit of the cells.

19 . The battery management system of claim 16 , wherein the battery controller is configured to scale duty cycles of the balancing switches according to a current upper limit of a single balancing discharging path.

20 . A cell-balancing method of a battery pack comprising a plurality of cells connected in series to each other, the method comprising:
detecting cell voltages of the cells; acquiring balancing capacities of the cells based on the cell voltages; acquiring duty cycles of a plurality of balancing switches for controlling a balancing discharging of the cells based on one or more respective ratios of the balancing capacities of the cells; and controlling the balancing switches based on the duty cycles.

21 . The cell-balancing method of claim 20 , further comprising scaling the duty cycles of the balancing switches according to a sum of duty cycles between two adjacent cells from among the cells.

22 . The cell-balancing method of claim 20 , further comprising

Assignees

• Samsung Sdi Co Ltd

Inventors

• Hidaka Takao
• Kim Hwa-Su

Classifications

• H02J7/585

  Sequential battery discharge in systems with a plurality of batteries · CPC title

• H02J7/575

  Parallel/serial switching of connection of batteries to charge or load circuit · CPC title

• H02J7/96

  in response to battery voltage · CPC title

• H02J7/82

  Control of state of charge [SOC] · CPC title

• H02J7/52

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