Pre-Curve Braking Planning of Battery Electric Vehicle Based on Vehicle Infrastructure Cooperative System (SAE Paper 2020-01-1643)

Braking energy recovery is an important method for Battery Electric Vehicle (BEV) to save energy and increase driving range. The vehicle braking system performs regenerative braking control based on driver operations. Different braking operations have a significant impact on energy recovery efficiency. This paper proposes a method for planning the braking process of a BEV based on the Intelligent Vehicle Infrastructure Cooperative System (IVICS). By actively planning the braking process, the braking energy recovery efficiency is improved. Vehicles need to decelerate and brake before entering a curve. The IVICS is used to obtain information about the curve section ahead of the vehicle's driving route. Then calculating the reference speed of the curve, and obtaining the vehicle's braking target in advance, so as to actively plan the vehicle braking process. First, this paper builds a vehicle dynamics model and analyzes the vehicle's dynamic characteristics when cornering to build a curve safe vehicle speed model. A safety factor is introduced to the safe speed model to calculate the reference speed in the curve, that is, the vehicle braking target. After that, the regenerative braking process is analyzed to study the influencing factors of braking energy recovery efficiency. With the goal of improving the efficiency of braking energy recovery, combined with the demand for driving speed efficiency, a method of pre-curve braking process planning is determined. The planning method was simulated 8 times under 4 typical cornering conditions, and the results showed that the average braking energy recovery rate reached 0.7198.