A Load Control Strategy for Stable Operation of Free-Piston Electromechanical Hybrid Power System

Abstract

The free-piston electromechanical hybrid power system affords the advantages of a simple construction and high thermal efficiency due to the removal of the crankshaft. However, the unrestricted trajectory of the piston linkage assembly also give rise to challenges for stable operation during the process of start-up or operation. In order to realize the stable operation of free-piston electromechanical hybrid power system, this paper proposed a load control strategy. Firstly, a dynamic model is established through thermodynamic and electromagnetic theory, and its effectiveness is verified by experiment and simulation. On this basis, a coupling load control model based on linear active disturbance rejection control is developed. The reliability of the proposed load control strategy is validated under different interference fluctuations. The simulation results demonstrate that no matter whether the interference occurs during the start-up process or the operation process, the proposed control strategy exerts effective limiting function over the piston linkage assembly and maintain its stable operation. Moreover, compared with the PID control strategy, the proposed strategy exhibits faster response times and a smoother start-up process. The compression ratio fluctuation range was reduced from 0.1 to 0.001, the control accuracy has been greatly improved.