液压挖掘机并联混合节能动力系统多目标优化控制策略

A Multi-Object Optimal Control Strategy for a Parallel Hybrid Power System in Hydraulic Excavators

针对采用电容蓄能进行能量回收的并联式液压挖掘机混合动力系统提高能量效率和降低转矩变化幅度的问题,提出了一种基于实时优化力矩分配的新型多目标优化控制策略。根据负载特性将由电动机/发电机与柴油机构成的混合动力装置的工况分为高负载和低负载两个采用不同目标转速的工作区,通过曲线拟合对定转速下转矩与能量效率特性关系进行建模,构建以转矩为变量的目标函数,并通过惩罚函数对转矩变化幅度进行限制,提高系统的能量效率并降低转矩变化对系统机械结构的损害。采用仿真程序和模拟实验平台分别进行了实验,以验证该策略的效果。实验结果表明:与固定比例转矩策略相比,系统的最大转矩变化幅度降低了37.9%,总体能量损耗和燃油损耗分别降低了8.74%和8.9%。采用该控制策略后,系统在提供相近的功率输出特性的情况下,其总体的能量消耗、燃油消耗和转矩特性均得到了改善。

A novel optimal torque control allocation strategy for the control of the power system that consists of the DC motor/generator and the diesel engine is proposed to improve the energy efficiency and to decrease the torque amplitude of variation for a parallel hybrid power system with an energy regenerator by capacitor for hydraulic excavator.Two work areas with different rotate speeds are built based on load forces.Curve fitting is used to model the character between the torque and the energy efficiency,and a penalty function is built to decrease torque range,then multi-object optimal cost functions are put forward.Experiments are performed by simulation program on a simulated experiment platform.The results and a comparison with the constant torque strategy show that the proposed strategy decreases the torque amplitude of variation by37.9%,the whole energy by 8.74%,and the fuel consumption by 8.9%.It can be concluded that the new strategy improves the energy consumption,the fuel consumption and the impact on mechanics system caused by torque range.