Abstract
The dynamic characteristics of power batteries directly affect the performance of electric vehicles, and the mathematical model is the basis for the design of a battery management system (BMS).Based on the electrode-averaged model of a lithium-ion battery, in view of the solid phase lithium-ion diffusion equation, the electrochemical model is simplified through the finite difference method. By analyzing the characteristics of the model and the type of parameters, the solid state diffusion kinetics are separated, and then the cascade parameter identifications are implemented with Particle Swarm Optimization. Eventually, the validity of the electrochemical model and the accuracy of model parameters are verified through 0.2–2 C multi-rates battery discharge tests of cell and road simulation tests of a micro pure electric vehicle under New European Driving Cycle (NEDC) conditions. The results show that the estimated parameters can guarantee the output accuracy. In the test of cell, the voltage deviation of discharge is generally less than 0.1 V except the end; in road simulation test, the output is close to the actual value at low speed with the error around ±0.03 V, and at high speed around ±0.08 V.
Highlights
Due to advantages of high energy density, high output power, long life, zero pollution, and wide operating temperature range, lithium-ion batteries have been attached great importance to new energy automotive industry with being the preferred choice
The electrochemical model can reflect the electrochemical process inside the battery, and the model involves a large number of actual parameters shown in Table 2 [13], which are too difficult to be measured directly
The electrode dynamics of Li ion battery is analyzed, and the electrochemical model is established by relevant theories
Summary
Due to advantages of high energy density, high output power, long life, zero pollution, and wide operating temperature range, lithium-ion batteries have been attached great importance to new energy automotive industry with being the preferred choice. Energies 2017, 10, 1811 battery system with real-time fault diagnosis capability for electric vehicles to ensure battery safety and performance [4] They put forward an integrated equivalent circuit and thermal model of a temperature-dependent LiFePO4 battery in an actual embedded application, which applied a cell balancing strategy to balance the SOC of each cell to increase the lifespan of the battery [5]. The average-electrode model, studied by Di Domenico et al [14,15], replaces the specific distribution of Li-ion concentration in electrode with the average concentration, greatly pushing the complexity into smaller Both of them have high accuracy at low to moderate operating rate, but the latter has higher order with the important diffusion kinetic characteristics in the solid particles retained. The research on the electrochemical model of lithium ion and its model reduction method can help to promote the application of electrochemical theory in the development of battery management technology.
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