Control system for lithium ion battery of electric car

Abstract

The invention discloses a control system for a lithium ion battery of an electric car. The system achieves the safety control of the battery through precise estimation and feedback of the residual electric quantity of the battery, collects a discharging current, an output voltage and the temperature of the battery, carries out the filtering and noise reduction through a filter, and builds a mathematic relation between the residual capacity of the battery and the output current of the battery based on an ampere-hour method and a Proctor empirical formula. The system gives consideration to the temperature factor and a nonlinear change factor of the initial capacity of the battery, carries out the correction and compensation of the Kalman method, and reduces the estimation error of the residual capacity of the battery. The system employs an open-circuit voltage method and the Kalman filtering method for prediction and comparison, carries out the compensation of a gain matrix, obtains the nearly real initial capacity of the battery, and enables the prediction and estimation error to be smaller. Meanwhile, the system gives consideration to the impact on the residual capacity of the battery from the temperature, corrects the mathematic model of the ampere-hour method through the corrected parameters K and n, and further reduces the estimation error.

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