Abstract: Aiming at the problems of difficult power distribution and large power loss in the hybrid power system caused by the variable operating conditions and lagging response of the power generation system of the series hybrid tractor, a multipower point control strategy combined with the dynamic coordination of the power generation system is proposed to be suitable for practical application. Firstly, the engine and generator efficiencies are integrated to obtain the optimal working curve of the power generation system efficiency and multiple working points are selected based on the power demand of the tractor; secondly, the switching logic of the working points is formulated to adjust the target output power of the power generation system in real time; and finally, the fuzzy PID control method is adopted to optimize the actual response process of the power generation system. Simulation results show that the proposed strategy can greatly improve the utilisation of the power battery and stabilise the engine to work at high efficiency for a long time. Moreover, the response characteristics of the power generation system are optimised, the speed overshoot is reduced to within 20 r/min, and the target power response time is reduced by 12.5% on average. Meanwhile, compared with the powerfollowing strategy, the combined fuel consumption of this strategy was reduced by 6.67% and 5.69% under the typical working conditions of ploughing and transition respectively.

Key words: hybrid tractor, energy management, coordinated control, fuzzy PID control, multiple power point control

摘要： 针对串联式混合动力拖拉机作业工况多变、发电系统响应滞后所导致的混合动力系统功率分配难及功率损失大等问题，提出一种适宜实际应用的结合发电系统动态协调的多功率点控制策略。首先综合发动机及发电机效率求得发电系统效率最优工作曲线并基于拖拉机功率需求选定多个工作点；其次制定工作点切换逻辑以实时调整发电系统目标输出功率；最后采用模糊PID控制方法优化发电系统的实际响应过程。仿真结果表明，所提策略能够大幅提升动力电池的利用程度，稳定发动机长时间工作在高效率点；发电系统的响应特性得以优化，转速超调量减小至20 r/min以内，目标功率响应时间平均降低12.5%。同时，与功率跟随策略相比，在犁耕和转场2种典型工况下，该策略下综合燃油消耗分别降低6.67%、5.69%。

关键词: 混合动力拖拉机, 能量管理, 协调控制, 模糊PID控制, 多功率点控制