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SOC estimation method for dynamically correcting ampere-hour integral method

An ampere-hour integration method and dynamic correction technology, which is applied in the direction of measuring devices, instruments, and measuring electronics, can solve the problems of inaccurate reflection, difficulty in initial SOC estimation of current sampling accuracy, and drastic changes in current, so as to achieve accurate and reliable estimation.

Pending Publication Date: 2022-03-18
FAW CAR CO LTD
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

At present, the commonly used estimation method is the ampere-hour integration method, which uses the ratio of the current integration to the current maximum capacity of the battery to obtain the SOC, but this method is limited by the accuracy of current sampling, difficulty in initial SOC estimation, battery self-discharge, drastic changes in current, and capacity decay. Influenced by factors, it cannot accurately reflect the real SOC

Method used

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  • SOC estimation method for dynamically correcting ampere-hour integral method
  • SOC estimation method for dynamically correcting ampere-hour integral method

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Embodiment 1

[0030] A method for estimating the SOC of a dynamically corrected ampere-hour integral method, comprising the following steps:

[0031] Step 1, OCV-SOC curve establishment:

[0032] Charge and discharge the lithium-ion battery at different temperatures (every 5 degrees Celsius) and at different SOCs, measure the open circuit voltage (OCV) data after standing for one hour, and establish OCV-SOC curves at different temperatures;

[0033] Step 2. Establishment of the second-order RC equivalent model of the battery:

[0034] Such as figure 1 As shown, the structure of the second-order RC model is: resistor R1, resistor R2 and resistor R3 are connected in series, and resistor R1 is connected to the positive pole of the power supply, resistor R3 is connected to the negative pole of the power supply, and capacitor C2 is connected in parallel with resistor R2, and capacitor C3 is connected in parallel with resistor R3;

[0035] The battery is equivalent to a second-order RC model, a...

Embodiment 2

[0047] The present invention provides a method for estimating SOC by dynamically correcting the ampere-hour integral method. The SOC is corrected by using the difference between the estimated and measured terminal voltages. The main steps are as follows:

[0048] Step 1. Acquisition of OCV-SOC curve: charge and discharge lithium-ion batteries at different temperatures and under different SOCs, and measure the open circuit voltage (OCV) after standing for one hour. The recorded data needs to use the three measured values ​​as the average value to establish OCV-SOC curves at different temperatures (-30°C, -25°C, -20°C, -15°C,,,, +50°C, +55°C, +60°C);

[0049] Step 2. Establishment of the second-order RC equivalent model of the battery: as figure 1 As shown, the battery is equivalent to a second-order RC model, and the open circuit voltage (U 开路 ) and terminal voltage (U 估算 ) relational formula: U 估算 =U 开路 -I t R 1 -U R2 -U R3 , where the sign of discharge current is +, a...

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Abstract

The invention belongs to the technical field of new energy automobiles, and particularly relates to an SOC estimation method of a dynamic correction ampere-hour integral method. Calculating the current battery SOC through an ampere-hour integral method, substituting the value into a battery second-order RC equivalent model to calculate the current battery end voltage (U estimation), carrying out difference calculation on the current battery end voltage (U real) and a real sampling end voltage value (U real), and if the difference is greater than a voltage sampling error (zeta u error), continuously correcting the sampling current value to correct the SOC value; otherwise, directly outputting the SOC value; compared with a traditional ampere-hour integral method for estimating the SOC, the method considers factors such as current sampling precision, battery internal resistance, temperature and aging, and SOC estimation is more accurate and reliable.

Description

technical field [0001] The invention belongs to the technical field of new energy vehicles, and in particular relates to an SOC estimation method of a dynamically corrected ampere-hour integral method. Background technique [0002] As the energy storage unit of new energy vehicles, the power battery’s state of charge (State Of Charge, SOC) reflects the remaining power of the battery, and is a key parameter to measure the battery’s discharge capacity, battery balance control, and cut-off conditions for charging and discharging. SOC cannot be directly measured. Measurement can only be estimated by collecting parameters such as voltage, current, and temperature through the battery management system (BMS). At present, the commonly used estimation method is the ampere-hour integration method, which uses the ratio of the current integration to the current maximum capacity of the battery to obtain the SOC, but this method is limited by the accuracy of current sampling, difficulty i...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/382
CPCG01R31/382
Inventor 刘松柏徐明栗顺姜大威王冬冬王禹张琦张清扬刘泓成曲美玥
Owner FAW CAR CO LTD
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