Research On The Control Strategy Of Two-Engine Electric Car Based On Chain Drive Coupler

This dissertation was completed with the support of the National Natural Science Foundation of China project "Mutation Mechanism and Key Design Technology of the Silent Chain(51775222)".The worsening global energy crisis has prompted a growing concern for energy conservation and environmental protection in recent years.As a result,major automobile enterprises have shown a strong preference towards electric vehicles due to their benefits of zero emissions,low noise,and high energy efficiency.These vehicles are now considered a crucial aspect of the future of the automobile industry.Compared with single engine,two-engine vehicles have higher working efficiency,lower energy consumption,better power and economic performance.However,the working environment of two engines is more complex than that of single engine,so more complex control strategies need to be matched.In the dual-engine dynamic coupling system,when compared to traditional gear drive systems,chain drive systems offer several advantages such as lightweight design,strong structural flexibility,and low transmission noise.Therefore,the control strategy of the two-engine electric car based on the chain drive coupler is studied.The specific research work is as follows:First,we determine the structure of the chain drive power coupler used in the twoengine electric vehicle.Based on the actual working conditions and the working principle of two driving modes,single engine drive and dual engine coupling drive,taking an actual electric vehicle as the main research object,combined with the vehicle parameters,respectively calculate the power required by three power indicators corresponding to the maximum speed,maximum climb and acceleration time,and determine the total power required by the three indicators by coupling the power.Selecting the appropriate engine provides the calculation basis for its control strategy,vehicle simulation and dynamics analysis.Secondly,a control strategy model for a two-engine coupled drive system based on the power coupler of a chain drive is developed using the Simulink module in Matlab.Eighteen main input signals and three main output signals are defined to convert the physical signals such as the driver’s intention,the actual running condition of the vehicle and the real-time driving ability of the engine into electronic signals,so as to realize the control and allocation of the vehicle.In order to simplify model control,Bus Creator module is used to summarize all input signals,and Double module is used for signal check and type conversion to realize matching with subsequent modules.The torque calculation modules under two working states of vehicle braking and normal running are set up respectively.By setting up a mode switching module,the working state of the vehicle can be switched.Thirdly,verify the superiority of the control strategy for two-engine electric cars based on a chain-driven coupling.The first method is to simulate and analyze the performance of an electric vehicle equipped with the control strategy.An overall vehicle model of the electric vehicle is established in AVL Cruise,and the established control strategy is added to the model of the electric vehicle in Cruise to simulate the operation of the vehicle under real-world conditions.Power and economy tasks are established to analyze whether the three power indicators of the electric vehicle meet the requirements,and to determine whether the overall vehicle’s fuel economy is improved.The time required for the electric vehicle to accelerate 100 km/h,the maximum slope the electric vehicle can reach,and the maximum speed the vehicle can reach are selected as power tasks in this dissertation.The energy consumption of the vehicle equipped with the control strategy and the vehicle without the control strategy are compared under the NEDC and CLTC conditions to evaluate the vehicle’s electric economy.The results show that under the control strategy,the acceleration time for the electric vehicle to reach 100 km/h is 5.55 seconds,the maximum slope the electric vehicle can reach is 37.8%,and the maximum speed the vehicle can reach is 177.66 km/h,which proves that the control strategy can meet the power requirements.At the same time,with this control strategy,the electric vehicle can save more than 20% of energy consumption,significantly improving its fuel economy.The second method is based on Recur Dyn software for multi-body dynamic analysis of a silent chain system under two-engine control strategy.Taking the active chain wheel speed as the main variable,simulations were established for four gradient operating conditions with speeds of 500 r/min,1000 r/min,2000 r/min,and 3000 r/min.The dynamic characteristics of the silent chain system under the two-engine control strategy were analyzed separately.The results showed that the chain plate motion trajectory of the silent chain system was stable,the peak contact force between the working chain plate and the active chain wheel was 1300 N,the peak tension between the chain links was 4376 N,and the peak tensioner tension was 880 N,all of which were within the corresponding safety thresholds.This indicates that the chain system operates smoothly and has good motion performance based on the control strategy in this dissertation.The above research results further verify the feasibility and superiority of the control strategy,and provide a certain theoretical reference value for the study of electric vehicle powertrain control strategy.