Lithium-battery variable fractional order and equivalent circuit model and identification method thereof

Abstract

The invention discloses a lithium-battery variable fractional order and equivalent circuit model and an identification method thereof. The lithium-battery variable fractional order and equivalent circuit comprises a run time circuit and a battery I-V characteristic circuit, wherein a capacitor in the battery I-V characteristic circuit is a variable fractional order capacitor. A second order RC circuit model is generalized to a non-integer order, and the model parameters and the number of fractional order of different SOC are identified based on a least square method, so that the fractional order and equivalent circuit varying order according to the SOC is obtained. The instruction of fractional order realizes the continuous change of the order number of the model, so that the model is relatively stable, good in dynamic property and high in precision. The variation of fractional order realizes more freedom and more flexibility and innovation of the model. As the number of RC networks is not increased, the fractional order model effectively solves the contradiction between the accuracy and practicality of the model, is suitable for various working conditions of batteries, and has high practical value. The invention provides a precise battery model easy to realize for precise estimation of SOC.

Description

technical field [0001] The invention relates to a fractional-order variable-order equivalent circuit model of a lithium battery and an identification method thereof. Background technique [0002] In order to deal with the energy crisis and environmental pollution, electric vehicles have emerged as the times require and have become the focus of attention all over the world. As a key component of electric vehicles, vehicle-mounted power batteries are crucial to the power, economy and safety of the vehicle, and are a key factor restricting the scale development of electric vehicles. Lithium batteries have the advantages of high energy density, long service life, good cost performance and high single voltage, and gradually become one of the power sources of hybrid electric vehicles or pure electric vehicles. Accurate battery models are of great significance to the rational design and safe operation of vehicle-mounted power lithium batteries, and are the basis of battery SOC (st...

AI Technical Summary

Problems solved by technology

However, this model is an integer-order battery model, and the switching of the model can only be an integer-order change, so the model order fluctuates greatly, which does not conform to the gradual development law in nature, so the accuracy of the model is greatly limited

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