Stability Control And Energy Management Of Four-wheel-drive Hydrogen-electric Hybrid Power Vehicles

The rise of sustainable energy can alleviate the environmental pollutions and the shortage of oil resources caused by petrol.Compared with pure electric systems,hydrogen-electric hybrid power systems have the advantages of fast charge,long cruising range,and low-temperature resistance,which will become the future mainstream of energy systems.When a vehicle is accelerating,the yaw stability control based on the differential braking will cause the vehicle to decelerate,which cannot ensure the longitudinal response required by drivers.The independent driving torque control based on the four-wheel drive system can improve the driving and handling performance of vehicles.Therefore,four-wheel-drive hydrogen-electric hybrid electric vehicles will become the mainstream of the development of sustainable energy vehicles in the future.Besides,the rapid development of automation and information technologies has brought new opportunities to the stability control and energy management of hydrogen-electric hybrid power vehicles.The study of hydrogen-electric hybrid power vehicles has also become a key issue in academic and industrial circles.The stability control is designed to ensure the driving stability and handling performance of hydrogen-electric hybrid power vehicles by steering and driving control.The energy management strategy can improve the fuel economy and system durability of four-wheel-drive hydrogen-electric hybrid electric vehicles by velocity optimization,torque distribution and power distribution.However,at present,the stability control and energy management of four-wheeldrive hydrogen-electric hybrid electric vehicles are generally in a separate state.Therefore,how to integrate stability control with the energy management strategy is a worthy topic.In addition,how to organically integrate environment information,velocity optimization,power distribution,and vehicle dynamics control to establish an integration system framework of information flow and energy flow,and to improve the driving stability,fuel economy,and system durability of fourwheel-drive hydrogen-electric hybrid electric vehicles,finally achieves the stability control and energy optimization for practical applications,which is a very challenging and complex problem.This paper aims to meet the application requirements of real-time stability control and efficient energy optimization of four-wheel-drive hydrogen-electric hybrid electric vehicles.Based on highly real-time sliding mode control and passivity-based control strategies,and combines an efficient hierarchical control system framework,we propose an integrated control strategy to reduce the design complexity of holistic framework and nonlinear optimization,which can improve the real-time performance and achieve the multi-objective optimization of vehicle system.Firstly,considering the stability and energy consumption of vehicle lateral motions,a hierarchical framework is proposed to integrate the lateral stability and energy efficiency control.A reference model is introduced to transform the lateral stability control into a steady-state tracking control problem.Based on an integral terminal sliding mode control method,an upper controller is designed to track the desired vehicle states to ensure the lateral stability.Then,a penalty term considering the tire slip ratio is constructed in the cost function of lower torque distribution,so as to realize the optimal distribution of wheel torques and reduce the energy consumption derived from the tire slip.Secondly,a passivity-based control approach is designed to improve the robustness and lateral stability of path-tracking based on a port-Hamiltonian model.A path-tracking error system is established by the port-Hamiltonian model.The passivity-based control theory based on interconnection and damping assignment uses passive outputs to design feedback control inputs,which can make the closed-loop path-tracking system passive and improve the stability and robustness of control system.Meanwhile,direct yaw control is integrated into the path-tracking control strategy to ensure the lateral stability.In addition,an optimal torque distribution strategy considering tire wear and average utilization of tire forces is proposed to further ensure the driving stability.Then,an efficient coordinated control method considering velocity optimization is proposed for vehicle planar motions.A nonlinear vehicle model integrated with four wheel dynamics is presented for the planar motion control.An optimization problem considering mechanical and motor energy consumption is established,and an analytical form of optimal velocity is obtained by dynamic optimization theory to ensure the real-time performance of velocity optimization and reduce energy consumption.The error-tracking of desired vehicle states is described by a portHamilton model,and the passivity-based control is used to design the coordinated controller and track desired vehicle planar motions,the theoretical analysis for the stability and robustness of control system is given.At the same time,based on the energy consumption model of motors,an optimal torque distribution strategy is designed to reduce the motor energy consumption.In addition,a nonlinear observer is proposed to estimate the lateral velocity,which can reduce the cost of sensor measurement and improve the accuracy and reliability of velocity observation.Finally,an energy management strategy with longitudinal control is established to achieve the multi-objective optimization for the driving system and energy system of four-wheel-drive hydrogen-electric hybrid electric vehicles.Among them,a highly real-time hierarchical velocity optimization is designed to reduce the energy consumption,and the effectiveness of velocity optimization is verified by real human-driven data.Then,a multi-objective energy management strategy based on quadratic programming optimization and a speed-tracking controller based on sliding mode control are proposed to track the desired power and speed while ensuring the realtime performance of the algorithm,which improves the driving stability,fuel economy,and system durability of four-wheel-drive hydrogen-electric hybrid electric vehicles.Through the above-mentioned work,we have deeply explored the combination of stability control and energy management of four-wheel-drive hydrogen-electric hybrid electric vehicles,and the proposed strategy has been effectively verified.Finally,a brief summary of our work is given,the future work is planned at the same time.