DPF热再生过程温度控制与试验

柴油机颗粒物捕集器(DPF)热再生发生时,其内部温度受DPF碳载量、排气温度和排气流量等影响,在特殊运行工况下具有较强非受控特性.为避免非受控再生引起的DPF失效风险,确保安全和可靠再生,通过降怠速(DTI)再生方式探讨了一种确定DPF安全再生温度的试验方法,得到安全再生温度曲线.针对DPF热再生过程中温度控制的大滞后特性,研究了一种采用发动机排气温度和排气流量作为增益补偿的优化热再生温度控制结构,并进行了控制算法的仿真分析和整车道路试验验证.结果表明:再生过程中对实际排气温度控制的超调量小于3%,稳态控制误差小于20℃,为促进DPF的安全和高效率再生提供了参考.

Experiment of DPF Temperature Control During Thermal Regeneration

During the thermal regeneration of a diesel particulate filter(DPF),temperatures inside the DPF may increase rapidly above critical thresholds in an uncontrolled way,especially under driving conditions when the engine speed is suddenly dropped to idle(DTI).The combination of excess DPF soot loading,high exhaust temperature and low exhaust flow rate at idle speed may create a temperature spike and lead to DPF failure.To ensure safety and reliable thermal regenerations,an alternate experimental approach based on DTI tests was investigated in this paper.Measurement records of the experimental results were systematically analyzed.The target regeneration temperature curve,which is critical for safety regenerations,was derived.An optimized closed-loop control of the target regeneration temperature was also investigated to account for reducing the uncertainties and risks caused by time-delays and disturbances.The exhaust gas flow and gas temperature in both of the feedforward design and the feedback algorithm were taken into account for dealing with disturbances and lags.The presented control strategy was validated in both simulation and vehicle road tests.Results show that the overshoot is less than 3%and the steady-state temperature control errors remain mostly less than 20℃even under aggressive disturbances during transient vehicle operation,which contributes to real DPF applications.