Layout Optimization Of Pure Electric Bus Power Units For The Handling And Stability

In the field of pure electric vehicles,It’s very significant to develop pure electric city buses firstly.Because popularizing pure electric city buses will greatly reduce the environmental pollution in urban areas.Also,the pure electric vehicles have advantages than traditional fuel vehicles,such as starting and stopping quickly,that are consistent with the operating characteristics of city buses.They run along a fixed line, Therefore, It’s possible to construct charging facilities.At present, pure electric bus are produced from the original traditional fuel vehicles chassis.In the arrangement of the powertrains,engineers usually only roughly mounted parts on the chassis,without analyzing handling dynamics.These lead to poor handling and stability of the vehicle in running, and fail to meet requirements of using.The main content of this paper is researching powertrain layout to make the pure electric city buses have excellent handling and stability.The study is based on a bus whose length is12m.According to the vehicle design targets,matched and optimized the parameters of the batteries,motor,and the main reducer.Reference to main pure electric bus drivetrain layout schemes in the domestic market,and under the guidance of car layout design principles, designed three representive powertrains layout schemes.Established a system dynamics model of the city bus in the software Admas/Car. According to the schemes above,mounted each part,such as motor,batteries,on the body of the city bus model.Accordance with the provisions of the national standards,simulated and analyzed the handling and stability performance and evaluated scores for the bus for different powertrains layout schemes.found scheme1get the highest score,and scores were balanced in different simulation events.The score of scheme2was lower than schemel,but,in the simulation of steering wheel angle pulse input,score on the evaluation of the resonance peak level was failed. The score of scheme3was lowest.Therefore,chose scheme2as the best scheme.By random road ride simulation to examine ride performance of the EV bus when powertrains are placed as scheme1.Then,used multi-objective design optimization software Isight as an integrated platform,integrated Adams/Car software,MATLAB software and optimization algorithms together,formed a automated optimization process.First,DOE design was done.coordinates of batteries and motor were factors,handling and stability evaluation was response.used Optimal Latin hypercube design to calculate the sensitivity of each factor,identified main factors.Then the main factors were seen as design variables,the ranges of design variables were decided by the space of the bus and considering the collision security.Handling and stability evaluation was seen as objective function,riding evaluation,weighted RMS value of acceleration,was constraint.Selected Particle Swarm Optimization as the optimization algorithm.Done simulation of the bus in the scheme which was been optimized Contrasted simulation results of curve and evaluation scores between the bus in scheme1and in optimized scheme,found the handling and stability of the city bus had been improved.