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Constant Speed Control Strategy of Composite Braking System of Hybrid Electric Coach

J. H. Tang, K. Y. Wang, L. C. Zhang, & K. J. Jiang
Source: J. H. Tang, K. Y. Wang, L. C. Zhang, & K. J. Jiang, Constant Speed Control Strategy of Composite Braking System of  Hybrid Electric Coach, Journal of Mechanical Engineering Research and Developments, vol. 39, no. 4, pp. 800-814, 2016. 
 
Document Type: Research Article
 
Abstract: In order to improve the safety and economy performance of hybrid electric coach in the downhill braking process, a kind of combined braking mode with friction braking, regenerative braking and hydraulic retarder is put forward in this paper. In view of the downhill braking state with constant speed, a hierarchical control system architecture for active control is established. According to the difference between target speed and actual speed and its change rate, the fuzzy recognition method is used to obtain the target braking torque. Based on the optimal recovery ratio of braking energy, anti-thermal degradation performance and braking stability, the ideal braking force distribution strategy of the composite braking system is formulated in the process of downhill with constant speed. The mathematical models and simulation models on electric machinery, battery, hydraulic retarder, temperature rise of friction brake and braking force distribution strategy are established. The typical driving condition, when the road slope is 6%, the target speed is 70km/h, the adhesion coefficient of road is 0.7, is selected, and the simulation and analysis are carried out. The simulation results show that the constant speed control strategy and mathematical models proposed are correct and feasible, which provide a theoretical basis for the follow-up study.

Keywords: Hybrid electric vehicle; Composite braking system; Hydraulic retarder; Braking force distribution; Constant speed control.