Lithium-ion battery state-of-charge estimation method based on a new state observer

Abstract

The invention discloses a method for estimating the charge state of a lithium ion battery of a novel state observer, thereby improving the accuracy of SOC estimation of a lithium ion battery. The method mainly comprises the following steps: step one, establishing a battery SOC-OCV model by using experimental data; step two, modifying the SOC-OCV relation model to include the SOH and temperature; step three, establishing a Thevenin lithium-ion battery model; step four, estimating initial parameters of the battery model in an offline state; step five, designing a novel state observer output error feedback matrix; step six, reading a current SOH, a current temperature T, a current current and a current terminal voltage of the battery; and step seven, observing the SOC value by using the stateobserver. The method has the following advantages: with the novel state observer, the observation error tends to be zero; the state observer has the clear structure and the parameters are designed simply; a problem that the traditional Kalman filter having the large computing load is difficult to apply to the practice is solved; and with the state observer, the high practicability, accuracy and precision of the lithium ion battery estimation method are ensured.

Description

technical field

[0001] The invention relates to the application field of new energy vehicle power batteries, in particular to a method for estimating the state of charge (SOC) of a lithium-ion battery. Background technique

[0002] Since battery SOC is not an electrical quantity that can be directly measured, it can only be estimated by certain methods. Only an accurate SOC value estimation can make a reasonable energy allocation to the whole vehicle, and can also correctly predict the remaining mileage of the vehicle; only an accurate estimation of the SOC value can fully utilize the potential of the battery and improve its use. The safety, but also can extend the service life of the battery. Since the battery is a complex nonlinear system, and the power of the battery is affected by many factors, such as temperature, coulombic efficiency, cycle life, self-discharge factors, etc. In addition, the randomness of the external environment and internal environmental parameters...

Examples

Embodiment Construction

[0028] The invention discloses a method for estimating the state of charge of a lithium-ion battery with a new state observer, aiming to improve the SOC estimation accuracy of the lithium-ion battery, which mainly includes the establishment of the SOC-OCV relationship, and the given unified expression includes SOH and The influence factor of temperature on SOC-OCV makes the SOC-OCV model more in line with the actual operation law; at the same time, a new type of state observer is designed to update and observe SOC, which can make the observation error tend to zero.

[0029] The algorithm of the present invention will be further described below in conjunction with the accompanying drawings.

[0030] combine figure 1 , to illustrate the detailed steps of SOC estimation.

[0031] Step 1: Use the experimental data to establish the model of battery state of charge SOC and open circuit voltage OCV.

[0032] The relationship between OCV-SOC is a key performance parameter of the bat...

technical field

[0001] The invention relates to the application field of new energy vehicle power batteries, in particular to a method for estimating the state of charge (SOC) of a lithium-ion battery. Background technique

[0002] Since battery SOC is not an electrical quantity that can be directly measured, it can only be estimated by certain methods. Only an accurate SOC value estimation can make a reasonable energy allocation to the whole vehicle, and can also correctly predict the remaining mileage of the vehicle; only an accurate estimation of the SOC value can fully utilize the potential of the battery and improve its use. The safety, but also can extend the service life of the battery. Since the battery is a complex nonlinear system, and the power of the battery is affected by many factors, such as temperature, coulombic efficiency, cycle life, self-discharge factors, etc. In addition, the randomness of the external environment and internal environmental parameters...

Examples

Embodiment Construction

[0028] The invention discloses a method for estimating the state of charge of a lithium-ion battery with a new state observer, aiming to improve the SOC estimation accuracy of the lithium-ion battery, which mainly includes the establishment of the SOC-OCV relationship, and the given unified expression includes SOH and The influence factor of temperature on SOC-OCV makes the SOC-OCV model more in line with the actual operation law; at the same time, a new type of state observer is designed to update and observe SOC, which can make the observation error tend to zero.

[0029] The algorithm of the present invention will be further described below in conjunction with the accompanying drawings.

[0030] combine figure 1 , to illustrate the detailed steps of SOC estimation.

[0031] Step 1: Use the experimental data to establish the model of battery state of charge SOC and open circuit voltage OCV.

[0032] The relationship between OCV-SOC is a key performance parameter of the bat...

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