摘要
当前中国农田集群和能源短缺现状极大地促进了混合动力拖拉机的推广与使用,然而混动拖拉机动态变载荷工况加大了整机功率的耦合与分流难度。为此,该研究以发动机和双电机为动力源,利用图论原理设计出满足全功率范围作业需求的两种动力系统耦合分流构型。此外,为实现整机的高能效目的,提出了基于马尔科夫决策的能量管理策略:首先根据拖拉机的载荷谱对整机作业环境进行辨识,采集犁耕作业环境下的拖拉机工作参数将需求功率抽象为马尔科夫决策中的状态转移过程;然后将整机能耗作为最优控制的成本函数,通过价值迭代函数求解最优控制律下电机2的工作区间。最后,采用硬件在环试验对提出的能量管理策略进行了有效性和可行性验证。试验结果表明,相比于传统基于规则的能量管理,提出的能量管理试验策略降低了7.2%的油耗。所设计的耦合分流构型拓展了拖拉机动力系统能量流的路径,直接耦合分流构型拟替代传统动力换挡的技术难点。能量管理策略在能效特性方面有一定优势,所提出的耦合分流动力构型为突破大马力拖拉机动力换挡的卡脖子技术提供了参考。
A hybrid power system has been widely used in Hybrid Electric Tractors(HETs) under farmland clustering and energy shortage in China. However, a great design difficulty can be found in the dynamic and variable load conditions of a working tractor on an unstructured road. Particularly, the powertrain flow can be used to realize the coupling and decoupling between the output power of the driven axle and Power Take-Off(PTO). It is a high demand to develop flexible powertrain for tractors, in order to improve the operation performance of agricultural machinery. Thus, the coupled-split powertrain system has been proposed with the principle of graph theory towards the single engine, dual motors, and clutch. All power ranges demand has been satisfied with the variable combination mode between the clutch and power units. In addition, the energy allocation can be optimized between the engine and motors in the background of non-linear loads. In this study, a Markov Decision Process(MDP) based Energy Management Strategy(EMS) was proposed to allocate the power between the engine and motors along with the dynamic and variable load. Firstly, the spectrum of the working load was collected in the period to distinguish the working scenarios. Specifically, the sample of the working environment included plains, hills, and basins.Secondly, the demand power in plowing was abstracted as the state transition of the MDP in the premise of tractor parameters collected under the plow condition, with which the comprehensive dynamics of tractor loads were mathematically formulated.Thirdly, energy consumption was defined as the cost function in the optimal control process, which was solved by the value iteration function. The working range of motor-2 was determined under the guidance of optimal control. In the actual plowing condition, the torque of motor-2 was optimized and determined along with the demand power and state of charge(SOC),which was converted to a look-up table and download in the Vehicle Control Unit(VCU). Finally, the effectiv
作者
窦海石
张幽彤
艾强
赵心琦
Dou Haishi;Zhang Youtong;Ai Qiang;Zhao Xinqi(School of Mechanical Engineering,Beijing Institute of Technology,Beijing 100089,China)
出处
《农业工程学报》
EI
CAS
CSCD
北大核心
2022年第23期41-49,共9页
Transactions of the Chinese Society of Agricultural Engineering
基金
国家重点研发计划资助项目(2021YFB3101500),中国博士后基金资助项目(2022TQ0032,2022M710380)。
关键词
拖拉机
试验
能量管理策略
控制策略
耦合分流构型
马尔科夫决策
hybrid power tractors
experiment
energy management strategy
control strategy
coupled-split configuration
Markov decision
