A method for estimating the electric charge of a power battery

Abstract

The invention provides a power battery electric charge quantity estimation method. The method includes the following steps of firstly, obtaining the function relationship between the SOC and an open-circuit voltage through an open-circuit voltage method; secondly, measuring the initial value of the SOC; thirdly, sampling and obtaining the SOC estimated initial value of an unscented Kalman filter; fourthly, conducting Sigma point sampling of UT conversion of the unscented Kalman filter according to a battery state equation and an observation equation, obtaining an estimated value of the observation quantity, and estimating an SOC estimated value and a covariance of a power battery at the next moment. According to the method, the open-circuit voltage method and the unscented Kalman filter are used in cooperation for conducting SOC estimation, the estimation accuracy is high, the SOC initial value is obtained through the open-circuit voltage method, SOC estimation modification is conducted, the estimation accuracy is improved, and in the unscented Kalman filter non-linearization approximation process, errors are reduced, the calculation speed is high, and the SOC estimation efficiency is improved.

Description

technical field [0001] The invention relates to the technical field of electric vehicle battery management, in particular to a method for estimating the electric charge of a power battery. Background technique [0002] The battery management system is a key component to realize the energy distribution of electric vehicles, and estimating the battery state of charge (SOC) in the battery management system is one of its key technologies. At present, the cruising range of electric vehicles is limited. During the driving process of electric vehicles, it is necessary to remind the driver of the current cruising range according to the remaining power of the battery in real time. In actual use, since the electric vehicle is in the process of starting, accelerating, constant speed, decelerating and parking, the current corresponding to the power battery is different, and the working characteristics of the power battery itself are highly nonlinear. The working environment of the uppe...

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Problems solved by technology

However, this method has the following problems: First, the complex Jacobian matrix needs to be calculated in the extended Kalman filter, which will increase the estimation time due to the complexity of the calculation process; secondly, the nonlinear function must be linearized, and the linearization process It affects the accuracy of the estimation process and also increases the estimation error; finally, when the difference between the given initial value and the actual value is too large, the SOC estimation error will increase and be relatively large, and it will take a long time to approach the real process

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