Study On Economy-oriented Adaptive Cruise Control Of Pure Electric Vehicle

As a typical type of advanced driver assistance systems,the adaptive cruise control(ACC)systems is also an excellent carrier for economic driving strategy.The development of economy-oriented ACC system for pure electric vehicle can promote the intelligence level of electric vehicles,reduce energy consumption,and improve transportation efficiency.There are rare researches on economy-oriented ACC system for pure electric vehicles at present.Most of the only studies inherited the economic driving strategy for fuel vehicles.These strategies only focus only on the partial function,and the energy consumption optimization method is single and the energy saving effect is poor.In order to solve the above problem,this paper establishes ACC system architecture based on two-level energy consumption optimization for dual-axis independent drive electric vehicle.And several key technologies in the system are discussed in detail.In the upper-level controller,energy consumption optimization in ACC full scenarios is achieved by establishing a multi-objective optimization problem.For cruise mode,a predictive cruise speed optimization algorithm is developed based on discrete dynamic programming.The speed is selected as the state variable,road slope and vehicle state information are used to construct various performance indicators during the cruise.The economic speed is obtained by constructing and solving the objective function.The simulation shows that the predictive cruise speed optimization algorithm can save energy by 2.79%,and time cost has not increased excessively.For following mode,a multiobjective following control algorithm is proposed based on model predictive control(MPC).Targets of the system are analyzed,and the tracking performance,comfort performance,and economic performance of the vehicle are accurately quantified.The prediction optimization problem is established under the MPC framework,algorithm for solving nonlinear optimization problems are developed.According to the simulation results,multi-target following control algorithm does not cause degradation of tracking performance.Compared with MO-ACC(Multi-Objective Adaptive Cruise Control),the multi-objective following control algorithm of economy-oriented ACC saves energy by0.53%～3.33%.In the lower-level controller,the drive optimal torque distribution strategy based on the key component efficiency MAP is developed.This strategy uses a global optimization method.The braking is divided into three modes,considering the characteristics of the braking system: hydraulic braking,pure motor regenerative braking,and parallel regenerative braking.The braking torque distribution strategy in each mode has been developed.The distribution coefficient of the drive/brake torque is obtained by offline optimization.The simulation results prove that the optimal torque distribution strategy consumes 9.71%～13.7% less energy than the average distribution strategy.In order to avoid vehicle instability caused by torque distribution,a anti-slip regulation based on sliding mode control theory is designed.A coordinated control strategy of torque distribution and anti-slip regulation is proposed,which takes into account vehicle economy,stability and power performance.The simulation results show that the strategy can effectively limit the wheel slip rate,and does not cause the loss of vehicle dynamic performance.