Cell-wise monitoring of Lithium-ion batteries for automotive traction applications by using power line communication: battery modeling and channel characterization

In Lithium-ion battery systems used for automotive traction applications a communication network is required for monitoring and control functions. We consider the power line communication (PLC) as a good alternative to data transmission buses used up to date in Lithium-ion battery systems, with the main scope consisting in reducing the cable harness and achieving substantial cost savings. We propose a novel battery management concept based on a cell-wise monitoring of the battery. For this, each cell comprises a communication interface for data transmission over the existing power line. In this paper, the properties of Lithium-ion battery systems are investigated with focus on the power line channel transfer characteristics in the frequency band 1 MHz to 100 MHz. We propose a circuit based model of a single cell, which has been fitted to measurement data. The cell model is used as basic block for the modeling of (cascaded) large battery systems and is validated by impedance analysis of typical Lithium-ion batteries. As the channel capacity is strongly affected by noise, measurements were conducted in electric vehicles in order to obtain the noise characteristics of power electronic devices connected to the electric power train.