The free piston linear engine system (FPLE) is considered as a promising powerplant, which has the advantages such as compact structure, short transfer path and variable compression ratio (CR) because the crank connecting rod is removed. However, the absence of crank-connecting rod inevitably produces uncertainty to the stable operation of the FPLE. A control system of the piston motion regulating for the FPLE is necessary. In this paper, the nonlinear dynamic model simulating the piston motion in a dual-piston FPLE is derived based on energy and force balance. The feasibility of the dynamic model is verified by experiment and simulation results. Based on instability mechanism analysis, a magnetoelectric load controller with motion stroke feedback is designed to maintain the piston position in a predefined CR by regulating the magnetoelectric force. The proposed magnetoelectric load controller is shown to have good control performance for the FPLE. The piston is always stabilized at the predefined position after a short adjustment time. The time of eliminating disturbance for the operation process is less than the start process. Furthermore, the increase in disturbance will result in the increase of time for adjustment.

中文翻译：

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自由活塞线性发动机系统保持稳定压缩比的磁电负载控制

自由活塞线性发动机系统（FPLE）被认为是一种很有前途的动力装置，由于取消了曲柄连杆，具有结构紧凑、传递路径短和可变压缩比（CR）等优点。然而，曲柄连杆的缺失不可避免地给FPLE的稳定运行带来了不确定性。FPLE 的活塞运动调节控制系统是必要的。在本文中，基于能量和力平衡推导了模拟双活塞FPLE中活塞运动的非线性动力学模型。通过实验和仿真结果验证了动态模型的可行性。基于不稳定机制分析，具有运动行程反馈的磁电负载控制器旨在通过调节磁电力将活塞位置保持在预定义的 CR 中。所提出的磁电负载控制器对 FPLE 具有良好的控制性能。经过短暂的调整时间后，活塞始终稳定在预定位置。运行过程消除干扰的时间小于启动过程的时间。此外，干扰的增加会导致调整时间的增加。