Research On Energy Management Strategy Optimization For Hybrid Electric Bus Based On Load Reconfiguration

Hybrid bus technology is an important way to realize the "energy saving and emission reduction" in city.To further excavate the fuel economy of hybrid buses,the energy management strategy of hybrid bus combining the bus characteristics in Jinan City was optimized:1.Typical Driving Cycle Construction of BusThe typical driving cycle is the research basis of the energy management strategy in the hybrid system.There is no such a driving cycle applied to all regions and all models in theory.In order to solve the problem that the existing research can not fully reflect the transient characteristics when generativing intraclass representative cycle with fragment extraction method,the way using markov state transition probability to generate intraclass representative cycle was proposed,which can highlight the transient characteristics of driving cycle as well as optimize the driving construction results.The comparison shows that the method is 13.4%,49.3%and 28.0%higher than the traditional method in velocity,acceleration and velocity-acceleration probability density distributions.2.Load Reconstruction of BusVehicle load is the basis of the control parameters of the vehicle as well as the input condition of the energy management strategy of the hybrid system.Because the current research on the energy management strategy of hybrid buses is mainly based on the fixed-known load,which can not reflect the actual characteristics of the vehicle load changes drastically during the actual operation of the bus,a load reconfiguration method based on dual-expansion Kalman Filtering Algorithm with changing parameter structure about space model of vehicle longitudinal dynamics was studied to achieve the vehicle load reconstruction of bus.Comparation with the sample data with measured load data shows,the average convergence rate of the algorithm is about 7?12s,and the average estimation error after convergence is less than 3%which can realize the precision requirement of load reconstruction.3.Simulation Study on Energy Management Strategy of Hybrid Electric Bus.Energy management strategy is the core of improving the economics and emissions of hybrid systems.Because the adaptive equipment consumption minimization strategy can make the system to achieve instantaneous suboptimal and maintain the balance of SOC,it was optimized in order to further enhance its fuel-saving potential in this paper.Study of Equipment Consumption Minimization Strategy based on variable SOCIn order to solve the problem that the system can not obtain the instantaneous optimal in order to maintain the balance of electricity using adaptive equipment consumption minimization strategy,an adaptive equipment consumption minimization strategy based on variable SOC reference which can get by recycle energy was proposed after analyzing the defect of the fixed SOC reference in this paper.The simulation result shows that on the basis of maintaining the balance of electricity,the economics of this method has 4.61%improvement over the traditional method.Optimization of Equipment Consumption Minimization Strategy based on Optimization TheoryIn order to solve the problem that a complex penalty function need to design for the power maintenance ability in the above strategy,a way to abtain the optimal equivalent factor which can maintain the balance of electricity was proposed.By analyzing the relationship between the optimal equivalent factor and the optimal control result,the method of obtaining the instantaneous optimal equivalent factor based on the dynamic programming algorithm and the equipment consumption minimization strategy was put forward.As a result,an adaptive equipment consumption minimization strategy was then designed with the rule between mean instantaneous optimal equivalent factor and electricity maintenance level.The simulation result shows that the proposed method can maintain the balance of SOC,and the economics of this method has 4.2%improvement over the the previous strategy,which achiveing further optimization of the energy management strategy4,Test Berification of Hybrid Bus Energy Management StrategyIn order to solve the problem that simulation can not realize the real-time and reliability evaluation of the energy management strategy,the experimental verification of the energy management strategy was done by using a virtual vehicle test system based on the powertrain hardware in the loop,By analyzing the physical structure and working flow of the target vehicle,the virtual vehicle test system is realized.Energy management strategy was designed SIMULINK and it was embed in the control system.The result shows that the developed single-shaft parallel hybrid virtual vehicle test bed can realize the related functions.The two strategies can achieve power maintenance,which has 3.18%,7.78%improvement than the traditional strategy.