Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells
Reexamination Certificate
2000-09-15
2001-08-21
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
C320S134000, C324S426000
Reexamination Certificate
active
06278257
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for detecting an abnormal electric-cell, and more particularly to a method for detecting an abnormal electric-cell in a battery system including a plurality of blocks serially connected together, wherein each of the plurality of blocks includes a plurality of cells serially connected together.
2. Description of the Related Art
A hybrid electric vehicle uses a battery system including a plurality of blocks serially connected together, wherein each of the plurality of blocks includes a plurality of cells serially connected together.
The following abnormal cell detecting methods are known in the art for use with the battery system as described above: a method for detecting a block which includes an abnormal cell by calculating an internal resistance for each block based on the relationship between the block voltage and the current for each block; and a method for detecting a block which includes an abnormal cell based on the difference in voltage between blocks.
However, in the former conventional method in which the internal resistance is calculated for each block based on the relationship between the block voltage and the current for each block, the influence of current hysteresis is considerable. Thus, there is a problem that it is difficult to calculate the internal resistance accurately.
The latter conventional method has a problem as follows. There may be a difference in temperature among a plurality of cells. Therefore, if a battery system is used for a long period of time, unevenness in capacitance among the cells occurs. Accordingly, a difference in voltage among blocks occurs. Thus, in the method for detecting a block which includes an abnormal cell based on the difference in voltage between blocks, there is a problem that it is difficult to distinguish a difference in voltage between the blocks because of the presence of the abnormal cell from a difference in voltage between the blocks because of the unevenness in capacitance.
If the discharge electric power and the charge electric power are calculated for each block in a method for detecting an abnormal cell, a cell in which a drop in electromotive force, a minor short, a short, etc., has occurred may be detected as an abnormal cell as well as a cell in which the internal resistance has increased.
SUMMARY OF THE INVENTION
According to one aspect of the invention, there is provided a method for detecting an abnormal cell in a battery system, wherein: the battery system includes a plurality of blocks serially connected together; each of the plurality of blocks includes a plurality of cells serially connected together; and the method includes: a first step of detecting a block voltage for each of the plurality of blocks and detecting a current of the battery system; a second step of calculating a charge/discharge electric power for each of the plurality of blocks based on the block voltage and the current; a third step of determining whether or not a value of the current is equal to or greater than a first predetermined value; a fourth step of determining whether or not a difference of the charge/discharge electric power between at least any two of the plurality of blocks is equal to or greater than a second predetermined value; and a fifth step of detecting a block including an abnormal cell based on determination results from the third step and the fourth step.
According to one embodiment of the invention, there is provided a method for detecting an abnormal cell, wherein: the plurality of blocks is grouped into at least a first group and a second group; and the fourth step includes a stop of determining: whether or not a difference of the charge/discharge electric power between at least any two of several blocks of the first group is equal to or greater than a second predetermined value; and whether or not a difference of the charge/discharge electric power between at least any two of the several blocks of the second group is equal to or greater than the second predetermined value.
According to another embodiment of the invention, there is provided a method for detecting an abnormal cell, wherein: a temperature difference of any one of the blocks of the first group is smaller than the temperature difference between any one of the blocks of the first group and any one of the blocks of the second group; and a temperature difference of any one of the blocks of the second group is smaller than the temperature difference between any one of the blocks of the second group and any one of the blocks of the first group.
According to still another embodiment of the invention, there is provided a method for detecting an abnormal cell, wherein the fourth step includes a step of determining that an abnormal cell in which an internal resistance has increased exists in the block in the case that the block satisfies the following conditions (1) and (2): (1) a charge power difference is greater than the average value of a charge power difference between at least any two of the plurality of blocks by an amount equal to or greater than a third predetermined value; and (2) a discharge power difference is smaller than the average value of a discharge power difference between at least any two of the plurality of blocks by an amount equal to or greater than a fourth predetermined value.
According to still another embodiment of the invention, there is provided a method for detecting an abnormal cell, wherein the fourth step includes a step of determining that an abnormal cell in which an internal resistance has increased exists in the block in the case that the block satisfies the following conditions (1) and (2): (1) a charge power difference is greater than the average value of the charge power difference between at least any two of several blocks of the first group by an amount equal to or greater than the third predetermined value; and (2) a discharge power difference of the block is smaller than the average value of the discharge power difference between at least any two of several blocks of the first group by an amount equal to or greater than the fourth predetermined value.
According to one aspect of the invention, there is provided a method for detecting an abnormal cell in a battery system, wherein: the battery system includes a plurality of blocks serially connected together; each of the plurality of blocks includes a plurality of cells serially connected together; and the method includes: a first stop of detecting a block voltage for each of the plurality of blocks and a current of the battery system; a second step of calculating a charge/discharge power for each of the plurality of blocks based on the block voltage and the current; a third step of obtaining a charge/discharge power accumulated value for each of the plurality of blocks based on a time accumulated value for each of predetermined periods of time of the charge/discharge power; a fourth step of determining whether or not a difference of the charge/discharge power accumulated value between at least any two of the plurality of blocks is equal to or greater than a first predetermined value; and a fifth step of detecting a block including an abnormal cell based on a determination result of the fourth step.
According to one embodiment of the invention, there is provided a method for detecting an abnormal cell, wherein: the plurality of blocks is grouped into at least a first group and a second group; and the fourth step includes steps of determining: whether or not a difference of the charge/discharge power accumulated value between at least any two of several blocks of the first group is equal to or greater than a first predetermined value; and whether or not a difference of the charge/discharge power accumulated value between at least any two of several blocks of the second group is equal to or greater than a first predetermined value.
According to another embodiment of the invention, there is provided a method for detecting an abnormal cell, wherein: a temperature difference
Ishihara Hirotaka
Nakanishi Toshiaki
Takada Masahiro
Kelly Michael K.
Matsushita Electric - Industrial Co., Ltd.
Snell & Wilmer LLP
Tso Edward H.
LandOfFree
Method for detecting abnormal cell does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method for detecting abnormal cell, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method for detecting abnormal cell will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2539978