电动复合增压系统模式切换过程研究

Mode Switch Process of Electric Compound Supercharging System

电动复合增压技术可有效解决涡轮增压柴油机低速性能恶化的问题,使柴油机低速段的稳态、瞬态性能得到良好提升。应用GT-Power仿真软件建立了某型废气涡轮增压柴油机的电动复合增压模型,然后在Simulink软件中建立了电机、旁通阀模型和对应的控制模型。通过GT-Power与Simulink联合仿真,分析了在电动复合增压系统模式切换过程中旁通阀与电机转速之间的耦合关系,研究了旁通阀开闭时刻与开闭速率对柴油机进气系统的影响,并提出了在模式切换过程中避免产生进气压力、流量波动的方法。研究表明:对于电动增压器切入工作过程,当旁通阀流量近似等于0时,快速关闭旁通阀对发动机进气流量、压力波动影响最小;对于电动增压器切出工作过程,当旁通阀进出口压力近似相等时,开启旁通阀对发动机进气流量、压力波动影响最小。

The electric compound supercharging technology can effectively solve the deterioration problem of low-speed performance of turbocharged diesel engine and hence improve the steady and transient performance of engine at low speed.For a certain exhaust-turbocharged diesel engine,the electric compound supercharging model was established by using GT-Power simulation software,and the motor and bypass valve model and corresponding control model were established in Simulink software.Through the co-simulation of GT-Power and Simulink,the coupling relationship between the bypass valve and the motor speed during the mode switch process was analyzed for the electric compound supercharging system,the influence of the timing and velocity of bypass valve opening and closing on the intake system of engine were studied,and the method of avoiding the intake pressure and flow fluctuation during the mode switch process was put forward.The results show that the intake flow and pressure fluctuation are affected least when the electric booster is introduced by quick closing the bypass valve at the moment that the mass flow of bypass valve is approximately equal to zero,as well as when the electric booster is not applied by opening the bypass valve at the moment that the inlet and out pressure of bypass valve are approximately equal.