Method for accurately estimating SOC (State of Charge)

Abstract

The invention provides a method for accurately estimating an SOC (State of Charge). The charge curves of a battery at different temperatures and different multiplying powers are utilized, the SOC is corrected according to monomer voltage when the battery is charged, and the estimate accuracy of the SOC is improved. The method comprises the two steps of low end correction and high end correction. The method provided by the invention has the advantages that the correcting opportunity of the SOC is increased, the estimate accuracy of the SOC is increased, and the method is simple and easy to realize, popularize and use. According to the invention, the low ends and the high ends of the charge curves are fully utilized to correct the SOC on the basis of an open-circuit voltage process and an ampere-hour integration process. As the low-end correction of the SOC is increased in the charge process, the estimate accuracy of the SOC under charge interruption conditions can be improved.

Description

technical field [0001] The invention relates to the field of battery management, in particular to a method capable of accurately estimating SOC. Background technique [0002] The remaining power of the battery, also known as the State of Charge (SOC) of the battery, is one of the important parameters of the battery state and provides a basis for the control strategy of the electric vehicle. Accurately estimate the remaining power of the current battery, ensure that the SOC is maintained within a reasonable range, prevent overcharge or overdischarge from damage to the battery, and provide a technical direction for us to use the battery reasonably, improve the service life of the battery, and reduce maintenance costs. How to obtain the battery SOC value accurately and reliably is the most basic and important task of the battery management system. [0003] At present, a lot of research has been done on the accurate estimation of battery SOC at home and abroad. Due to the limit...

AI Technical Summary

Problems solved by technology

The ampere-hour integration method has high requirements for current sampling accuracy, otherwise a large cumulative error may occur after long-term operation. In fact, there is a certain error in the current ampere-hour integration method.

In addition, the Kalman filter method and the fuzzy neural network method are common. Due to the hardware limitation of the battery management system and the maturity of the algorithm itself, it has not been verified by a large number of practical applications.

[0005] Since the lithium iron phosphate battery has a very flat charge and discharge platform, and the SOC of the battery management system requires high accuracy and real-time online estimation, the open circuit voltage method is not suitable for lithium iron phosphate batteries.

However, there is a cumulative error in the ampere-hour integration method. The current national standard requires that the error should not exceed 8%, and the ampere-hour integration method is not easy to meet this requirement.

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