| By using the power coupling mechanism to reasonably combine the engine,motor,and power transmission mechanism,optimizing the size of each component,and reasonably distributing the output power of different power sources,the hybrid electric powertrain improves the energy utilization efficiency.Therefore,hybrid electric vehicles have good energy-saving and emission-reduction performance,and have become one of the most important options for reducing greenhouse gas emissions and solving the fossil energy shortage problem.Among the different types of hybrid electric powertrains,the single motor hybrid powertrain has the advantages of high production inheritance and low manufacturing cost,and has broad market application prospects,making it one of the current research hotspots in the field of hybrid electric vehicles.Since the powertrain configuration determines the power coupling form and power transfer path of the power source,and the component size and energy management strategy seriously affect the distribution of power source operating points,the fuel economy and drivability performance of hybrid electric powertrain are affected by the powertrain configuration,component size,and energy management strategy.In addition,the optimization of component size is directly related to the choice of powertrain configuration,and the design of energy management strategy is closely related to the system configuration and component size,which makes the optimization design of the above three factors affect and restricts each other.However,there are few studies on the comprehensive optimization of hybrid electric powertrain system configuration,component size,and energy management strategies.Therefore,relying on The National Key Research and Development Program of China "Study on the System Configuration and Dynamic Control Method of Plug-in/Extended Range Hybrid Electric Powertrain",this paper takes the single motor hybrid electric powertrain as the research object and carries out researches on hybrid electric powertrain performance analysis and evaluation method,system configuration synthesis and screening method,and high-efficiency comprehensive optimization method for system configuration,component size,and energy management strategy.The main research work is as follows:(1)Considering the influence of system configuration selection,component parameter matching and energy management strategy design on the performance of the hybrid electric powertrain,the evaluation indexes used to evaluate the drivability performance,fuel economy,product economy,and operation efficiency of the system working mode of the single motor hybrid electric powertrain are determined.An integrated optimization method of powertrain component size and energy management strategy based on dynamic programming algorithm and multi-objective particle swarm algorithm is established to obtain the optimal value of performance evaluation indexes for different powertrain design schemes.On this basis,taking the powertrain design scheme as the candidate layer,the optimal value of the performance index of the design scheme as the evaluation layer,and the overall score of the design scheme as the decision-making layer,a design scheme evaluation model considering the product economy and system working mode operating efficiency is established.Finally,a performance analysis and evaluation method of the single motor hybrid electric powertrain is formed,which provides a quantitative basis for the optimization of single motor hybrid electric powertrain design.(2)By analyzing the common characteristics of different types of single motor hybrid electric powertrain in power coupling form and power transmission characteristics,a new fundamental matrix equation,and two new adjacency matrices are established to describe the working state of the actuator and the connection relationship between system components in the powertrain.Thus,an improved adjacency matrix method that can describe the topological structure information of the single motor hybrid electric powertrain is proposed,and the mapping relationship between the system configuration and the matrix variables is established.Considering the differences of working characteristics of different dynamic coupling/transmission mechanisms,a system configuration characteristic analysis method based on the improved adjacency matrices and matrix transformation theory is proposed,so that the dynamic equations of system working modes can be solved automatically by computer.On this basis,a synthesis and search method for the single motor hybrid electric powertrain configuration is formed based on the improved adjacency matrix,which solves the problems of configuration expression,generation,search,and working characteristics analysis of the single motor hybrid electric powertrain.(3)Based on the synthesis results and grouping method of the single motor hybrid electric powertrain configuration,and by analyzing the topological structure characteristics of powertrain configurations in different system configuration groups,a system working mode set of the single motor hybrid electric powertrain is established to describe the relationship between system topology,system power coupling form,system dynamic equation and improved adjacency matrices.By analyzing the working characteristics of the single motor hybrid electric powertrain,the mechanical structure feasibility constraints and system functional constraints of the single motor hybrid electric powertrain are proposed.Besides,a system configuration feasibility screening and isomorphism detection method based on the system working mode set is established,which can provide a large number of system configuration alternatives for the design scheme optimization of the single motor hybrid powertrain.(4)Based on the numerical expression model of the single motor hybrid powertrain configuration,the multi-objective particle swarm algorithm is used to simultaneously search the system configuration and component size.By analyzing the position of the particles satisfying the non-dominated constraints in the search space,the search space composed of the system configuration alternatives and the component size optimization range is adaptively segmented.Then,by adjusting the search ability of the particles with weak convergence in the sub blank search space,the global search ability of the population in the search space is enhanced.In addition,combined with the working mode set of the single motor hybrid electric powertrain,a hybrid electric powertrain performance analysis method that can reduce the amount of simulation calculation is proposed,which improves the efficiency of solving the fitness value of the population.Finally,a high-efficiency comprehensive optimization method for the system configuration,component size,and energy management strategy of the single motor hybrid electric powertrain is proposed,which solves the problems of large calculation amount and long optimization time in the joint optimization of the three.By comparing with the nested optimization method,the global search ability,convergence,and efficiency of the proposed method are verified. |
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