基于Simulink在不同排气背压下VGT增压系统控制策略

Control Strategy of VGT Turbocharging System Under Different Exhaust Back Pressure Based on Simulink

为了改善柴油机在高背压环境条件下进排气流速降低、涡前排温、缸内最高燃烧压力和油耗升高等问题,采用Simulink软件,基于柴油机数学模型建立某型号柴油机零维仿真模型和可变截面涡轮(variable geometry turbine,VGT)增压系统仿真模型,并根据试验结果对模型进行校核。利用所建立的仿真模型模拟在不同排气背压工况下的试验条件,匹配出最佳VGT喉口开度。以排气背压、增压压力为控制目标,利用比例、积分、微分(proportional-integral-derivative,PID)闭环控制方法设计VGT增压系统控制策略。仿真试验结果表明,所设计的控制策略能够满足在不同排气背压工况下VGT增压系统的自动调节,瞬态响应时间及超调量满足使用需求,可用于船用柴油机VGT增压控制系统。

In order to improve the problems of low inlet and exhaust flow rate,increasing exhaust temperature before turbocharger,maximum combustion pressure in cylinder and fuel consumption of diesel engine under high back pressure environment,the zero dimensional simulation model and variable geometry turbine(VGT)turbocharging system simulation model of a diesel engine were established based on the mathematical model of diesel engine by Simulink software,and the model was checked according to the test results・The established simulation model was used to simulate the test conditions under different exhaust back pressure conditions,in order to match the optimal throat opening of VGT.Taking the exhaust back pressure and boost pressure as the control target,the control strategy of VGT turbocharging system was designed using the proportional-integral-derivative(PID)closed-loop control method.The simulation results show that the designed control strategy can meet the automatic adjustment of VGT turbocharging system under different exhaust back pressure conditions,and the transient response time and overshoot meet the use requirements.It can be used in the VGT turbocharging control system of marine diesel engines.