基于改进模糊PID算法的空燃比控制策略研究

对发动机瞬态工况空燃比进行控制时,由于单缸汽油机本身固有的非线性和时滞环节,传统PID控制很难取得满意的效果,本文构造了一种带动态补偿的模糊PID控制器.首先搭建了单缸机仿真模型,并将模糊PID控制算法应用于空燃比控制中,以适应系统的非线性;然后针对单缸机系统中固有的时滞环节提出一种动态时滞补偿器,以降低时滞环节对系统的影响;再将该时滞补偿器耦合于模糊PID控制器中,应用于单缸机瞬态工况下的空燃比控制.仿真结果表明,改进的模糊PID控制器不仅能补偿系统中时滞环节带来的非最小相位影响,而且能很好地适应发动机系统的非线性特征,从而使控制系统的稳定性、准确性、快速性均得到了很大的改善.

Research on Single Cylinder Engine A/F Control Based on a Modified Fuzzy-PID Strategy

For the accurate control of the air-fuel (A/F) ratio at transient condition, the traditional PID controller cannot achieve satisfactory results due to the inherent nonlinear characteristic and time delay of single cylinder engine. So, this paper constructed an improved fuzzy PID controller with dynamic time delay compensation. First, a model for single cylinder model was set up and a common fuzzy PID controller was applied to solve the non-linear problem. Then, a modified dynamic compensator was proposed to improve the time delay behavior inherited in single cylinder gasoline engine. And then, the compensator was coupled to the fuzzy PID controller and applied to the A/F ratio control of the engine under transient condition. The simulation results show that the improved fuzzy PID controller can not only compensate the non-minimum phase characteristic of the engine system caused by the time delay, but also adapt well to the nonlinear characteristics, and in return, the stability, accuracy and response speed of the control system are greatly improved.