Design and Simulation of Hybrid Electric Vehicle Control Strategy Based on Capacity Difference

Abstract

Although hybrid electric vehicle can achieve zero pollution emission, it is difficult to popularize and apply due to the constraints of battery energy density, service life, price and so on. The quality of control strategy directly determines the performance of the whole vehicle. Therefore, the research on control strategy is also one of the technologies with the widest scope and the deepest degree in the field of hybrid electric vehicles. The research scope of hybrid electric vehicle control strategy is from static optimization for specific working conditions to on-line adjustment and dynamic optimization of control strategy under random road conditions by identifying and predicting the actual driving conditions. Due to slight differences in production process and materials, different production batches and other reasons, the difference in the electrical performance of single batteries is an inevitable result. These differences in the application of multiple batteries in series will not only reduce the capacity of the series battery pack, but also cause serious potential safety hazards such as overcharge and overdischarge. In case of serious imbalance, hot spots may appear in the single battery, which is very dangerous. In this paper, the control strategy of hybrid electric vehicle is analyzed, and it is found that there is a process of accelerated decay of battery pack capacity evolution before reaching stability, and the main reason that battery pack life decays faster than that of single battery pack is that the capacity loss of battery pack is the sum of the difference between the capacity loss of single battery pack and the negative active lithium ion loss between single batteries with the minimum remaining charge capacity.