基于遗传算法非线性PID的柴油机共轨压力控制

Diesel Common-Rail Pressure Control with Genetic Algorithm Nonlinear PID

摘要:

高压共轨柴油机共轨压力随不同工况的调节能力及其压力的稳定性,从根本上影响着柴油机系统的燃油经济性与排放性能;针对共轨压力的控制,给出了在起动、过渡、正常、停机以及故障等工况下的轨压控制策略,设计了带预控制的积分分离非线性PID控制器,采用遗传算法对PID参数进行了在线自适应整定,实现了在不同柴油机工况下对不同轨压变化的优化控制;台架实验结果表明,在不同工况下采取的控制策略是适用的,采用的积分分离技术能减少控制超调,预控制技术能缩短轨压稳定时间并减少轨压波动,遗传算法对非线性PID控制器参数的在线优化,平均可在柴油机起动后6.7 s内完成,所设计的非线性PID控制器可把轨压控制偏差稳定在1.4%以下。

Abstract:

The fuel economy and emissions performances of high pressure common rail diesel engine are influenced severely by the adjustment and stability of rail pressure following real-time operating condition. Different rail pressure control strategies are adopted in different model of start, transition, normal, shutdown and fault conditions. A nonlinear PID with technologies of integrator separateness and pre-control is designed using in normal condition. These Parameters of nonlinear PID are adjusted adaptively by online genetic algorithm. The optimal rail pressure controls under different conditions are realized. Bench test results showed that control strategies under different conditions were suitable; the control overshoot was effectively reduced by using integral separation technology, the rail pressure settling time was shortened and rail pressure fluctuation was lessened by adopting pre-control technology, it took about 6.7 seconds after the engine starting to optimize nonlinear PID parameters by genetic algorithm, the pressure in common rail was kept at an almost constant value which fluctuation range was no more than 1.4% by the recommended genetic algorithm nonlinear PID controller. 