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A fault diagnosis method for series connection of power battery packs

A power battery pack and series connection technology, which is applied in the direction of measuring electricity, measuring electrical variables, instruments, etc., can solve the problems of low reliability of fault diagnosis, inability to distinguish contact resistance and increase in battery internal resistance, etc. The method is convenient and intuitive, and increases Reliability and the effect of reducing the operating load

Active Publication Date: 2020-01-03
UNIV OF SCI & TECH OF CHINA +1
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0005] The purpose of the present invention is to solve the problem of low reliability of fault diagnosis only from the threshold value and the inability to distinguish the increase of contact resistance and battery internal resistance. Fault diagnosis method for series connection of power battery packs with voltage detection abnormal coefficient and temperature rise rate threshold to improve diagnostic reliability

Method used

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  • A fault diagnosis method for series connection of power battery packs
  • A fault diagnosis method for series connection of power battery packs
  • A fault diagnosis method for series connection of power battery packs

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example

[0062] Example (1): The mean square error value of each battery cell is as follows Figure 4 As shown, the mean square error values ​​of the 3rd and 4th battery cells are always approximately zero, while the mean square error values ​​of the 1st and 2nd battery cells are greater than zero and there are obvious fluctuations, so it is preliminarily determined that there is an abnormal voltage. The voltage detection anomaly coefficient calculated by Z-score based on the mean square error is as follows: Figure 5 As shown, in addition to the shelving state, the abnormal voltage coefficients of the 3 and 4 battery cells are less than zero, and the voltage abnormal coefficients of the 1 and 2 battery cells are greater than zero. There is a connection failure, that is, a secondary failure has occurred. recombine Image 6 As shown, except battery cell 1 (directly connected to the cycler negative pole), the temperature rise rate of battery cell 2 is significantly greater than twice t...

example ( 2

[0063] Example (2): The mean square error value of each battery cell is as follows Figure 7 As shown, the mean square error values ​​of the 1 and 4 battery cells are always approximately zero, while the mean square error values ​​of the 2 and 3 battery cells are greater than zero and there are obvious fluctuations, so it is preliminarily determined that there is an abnormal voltage. The voltage detection anomaly coefficient calculated by Z-score based on the mean square error is as follows: Figure 8 As shown, in addition to the shelving state, the abnormal voltage coefficients of the 1 and 4 battery cells are less than zero, while the voltage abnormal coefficients of the 2 and 3 battery cells are greater than zero. There is a connection failure, that is, a secondary failure has occurred. recombine Figure 9 As shown, except battery cell 1 (directly connected to the negative electrode of the cycler), the temperature rise rate of battery cell 3 is significantly greater than ...

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Abstract

The invention puts forward a power battery pack series connection fault diagnosis method. A battery pack is formed via series connection of n battery single cells, and a crossover voltage test method.A battery management system is used for recording battery single cell voltage and battery single cell surface temperature. An MATLAB / simuink is used for simulating adopted power batteries and recording simulation voltage. A mean squared error between experimental and simulation output voltages is calculated to preliminarily determine if voltage exception occurs. If yes, a Z-score is calculated asa voltage detection exception coefficient based on the mean squared error. According to the voltage detection exception coefficient, whether a fault is connection failure or increased internal resistance of single cells; if yes, the fault is determined as a secondary fault, and the rise rate of battery surface temperature is calculated to determine whether the rise rate is greater than a preset threshold value; if yes, the fault is determined as a primary fault. Via the method disclosed in the invention, reliable diagnosis of connection failure of the power battery pack can be realized, increase of contact resistance and increase of internal resistance can be differentiated from each other, only a simple algorithm is needed, and an operating burden of a battery management system can be effectively lowered.

Description

technical field [0001] The invention relates to the technical field of power battery packs for vehicles, in particular to a fault diagnosis method for series connection of power battery packs. Background technique [0002] Usually, an electric vehicle battery pack consists of several large-capacity battery cells connected in series to meet the performance and power requirements of electric vehicles. However, equipment defects, as well as a series of factors such as road conditions and vehicle performance during the driving of electric vehicles, may cause loosening of the connections between batteries. Once the connector is loose, the contact resistance between the two battery cells will increase, which will directly affect the measurement of the battery cell voltage by the battery management system. At the same time, the Joule heat generated on the connector between the batteries will also increase, resulting in a decrease in the surface temperature of the battery. raised. ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/396
CPCG01R31/367G01R31/396
Inventor 王青松马迷娜罗志民段强领邵立勇孙金华刘彩秋李国辉曹克楠王玉坤
Owner UNIV OF SCI & TECH OF CHINA
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