Lithium ion battery state-of-charge estimation method

A lithium-ion battery, state of charge technology, applied in the direction of measuring electricity, measuring electrical variables, instruments, etc., can solve the complex electrochemical reaction, cannot express the fractional order function relationship of the electrochemical reaction of the battery, and accurately estimate the battery is very difficult, etc. question

Inactive Publication Date: 2014-07-23
JILIN UNIV
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Problems solved by technology

During the use of lithium-ion power batteries for electric vehicles, the internal electrochemical reactions are complex, and its dynamic system is highly nonlinear, which makes it very difficult to accurately estimate the state of charge (SOC) of the battery.
[0003] Scholars at home and abroad have done a lot of research on battery state of charge (SOC) estimation algorithms. At present, the comm...

Method used

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  • Lithium ion battery state-of-charge estimation method
  • Lithium ion battery state-of-charge estimation method
  • Lithium ion battery state-of-charge estimation method

Examples

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Embodiment

[0158] The operation process of the present invention will be described below with a specific example.

[0159] In this example, the single battery 26650 produced by A123 Company is used as the target battery, with a capacity of 2.5AH and a rated voltage of 3.3V. The specific implementation process is as follows:

[0160] 1. Use an impedance analyzer to obtain the impedance spectrum curve of the target battery, such as figure 1 As shown, the state space model shown in formula (6) is obtained by analyzing the characteristics of different frequency bands of the impedance spectrum curve.

[0161] 2. Conduct static charging and discharging tests on lithium-ion batteries, and fit the relationship curve between open circuit voltage (OCV) and battery state of charge (SOC) to obtain the parameters in formula (5) and . The specific test steps are as follows:

[0162] 1) Discharge the selected power battery at 1C at room temperature (20°C) to reach the discharge cut-off voltage a...

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Abstract

The invention relates to a lithium ion battery state-of-charge estimation method, belongs to the field of battery charge testing and provides a lithium ion battery SOC estimation method based on a fractional order Kalman filtering method. The lithium ion battery state-of-charge estimation method comprises the specific steps of establishing a fractional order state space model of a lithium ion battery, obtaining a relation curve of open-circuit voltage and a charge state through fitting and using the fractional order Kalman filtering method to estimate the SOC of the lithium ion battery. The lithium ion battery state-of-charge estimation method simulates complicated electric chemical reaction inside the battery well, improves the modeling accuracy of the lithium ion battery and further improves the estimation accuracy of the SOC of the lithium ion battery.

Description

technical field [0001] The invention belongs to the field of testing battery state of charge. Background technique [0002] The battery state of charge (State of Charge, SOC) is used to represent the remaining capacity of the battery, which can only be estimated indirectly by measuring the external characteristic parameters (such as voltage, current, and temperature) of the battery pack. During the use of lithium-ion power batteries for electric vehicles, the internal electrochemical reactions are complex, and its dynamic system is highly nonlinear, which makes it very difficult to accurately estimate the state of charge (SOC) of the battery. [0003] Scholars at home and abroad have done a lot of research on battery state of charge (SOC) estimation algorithms. At present, the commonly used model-based estimation algorithms include state observer method, Kalman filter method, extended Kalman filter method, etc., but the above methods only It can express the integer-order fu...

Claims

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Application Information

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IPC IPC(8): G01R31/36
Inventor 马彦周秀文张吉星李炳思应振华赵海艳陈虹
Owner JILIN UNIV
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