A Control-Oriented Model for Trajectory-Based HCCI Combustion Control
A Control-Oriented Model for Trajectory-Based HCCI Combustion Control
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DOI：
10.1115/1.4039664
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发表时间：
2018-09
影响因子：
1.7
通讯作者：
Chen Zhang;Zongxuan Sun
中科院分区：
文献类型：
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作者：
Chen Zhang;Zongxuan Sun
此前，作者提出了基于活塞轨迹的自由活塞发动机(FPE)均质压燃(HCCI)燃烧控制的概念，并通过实现不同的活塞轨迹展示了其对发动机热效率和排放的好处。为了在实际应用中实现基于轨迹的均质压燃燃烧控制，必须建立一个具有足够化学动力学信息的面向控制的模型。本文提出了这样一个模型，并将其在计算速度和模型保真度方面与现有的三种模型进行了比较：采用一步全局反应的简化模型、采用Jones-Lindstedt机制的降阶模型和包含详细化学反应机理的基于复杂物理的模型。提出了一种独特的相分离方法，在保证预测精度的同时，大大减少了计算时间。此外，本文还表明，在不同的空燃比(AFR)、不同的压缩比(CR)和不同的活塞运动模式下，所提出的模型在多种工作条件下都能保持高保真度。最后给出了一个算例，展示了面向控制的模型如何通过改变轨迹来实现对均质压燃燃烧阶段的实时优化。仿真结果表明，燃烧相位可以根据需要快速调整，进一步验证了基于活塞轨迹的燃烧控制的有效性。
Previously, the authors have proposed the concept of piston trajectory-based homogeneous charge compression ignition (HCCI) combustion control enabled by a free piston engine (FPE) and shown its benefits on both engine thermal efficiency and emissions by implementing various piston trajectories. In order to realize the HCCI trajectory-based combustion control in practical applications, a control-oriented model with sufficient chemical kinetics information has to be developed. In this paper, such a model is proposed and its performance, in terms of computational speed and model fidelity, is compared to three existing models: a simplified model using a one-step global reaction, a reduced-order model using Jones–Lindstedt mechanism, and a complex physics-based model including detailed chemical reaction mechanisms. A unique phase separation method is proposed to significantly reduce the computational time and guarantee the prediction accuracy simultaneously. In addition, the paper also shows that the high fidelity of the proposed model is sustained at multiple working conditions, including different air-fuel ratios (AFR), various compression ratios (CR), and distinct piston motion patterns between the two end positions. Finally, an example is presented showing how the control-oriented model enables real-time optimization of the HCCI combustion phasing by varying the trajectories. The simulation results show that the combustion phasing can be adjusted quickly as desired, which further demonstrates the effectiveness of the piston trajectory-based combustion control.