基于LS-SVM逆系统的汽油机瞬态空燃比复合控制研究

为实现瞬态空燃比有效控制,提出基于逆模型前馈控制附加无模型自适应反馈控制的复合控制策略。利用最小二乘支持向量机(LS-SVM)建立空燃比系统逆模型,对瞬态空燃比模型中的进气量进行动态前馈补偿,并结合无模型自适应(MFAC)通过修正喷油量对空燃比进行反馈控制,对系统扰动、误差等实现修正。利用瞬态工况试验数据进行仿真,并与台架试验实际数据进行了对比。结果表明,LS-SVM逆模能高精度地逼近空燃比瞬态过程,结合MFAC反馈控制提高了系统的鲁棒性和抗干扰能力。因此该复合控制策略可行,可用于发动机瞬态工况空燃比的精确控制。

Composite Control of Transient Air Fuel Ratio for Gasoline Engine Based on LS-SVM Inversion

To achieve effective control of transient air-fuel ratio for gasoline engines, a composite control method is proposed, which consists of inverse model feedforward based on least squares support vector machine(LS-SVM)and feedback control with model-free adaptive control(MFAC).The inverse model of transient air-fuel ratio system was set up with LS-SVM, which is able to dynamic compensate intake flow with feedforward control. And a MFAC feedback controller was used to as a compensation both internal and external disturbance in real time. Then the inverse model and the composite control method are used to simulate transient operating conditions which are compared with the actual acquisition of the air-fuel ratio. The results show that the inverse model based on LS-SVM can accurately approximate the air fuel ratio transient process, and this method has stronger robustness and anti interference combine the MFAC feedback control. Therefore, the composite control strategy has good control performances and can improve the control precision of air-fuel ratio in transient conditions.