Research On Optimal Control Technology Of Energy Recovery For Hybrid Electric Vehicles

When the HEV brakes or speeds down,the motor is in the regenerative braking state,so the motor can both achieve energy recovery and make the vehicle brake.The energy recycled is used to drive vehicles.Then it will extend the mileage of vehicles and improve vehicle utilization.Therefore,regenerative braking is a very important research direction of HEV.During the process of energy recovery,the vehicle's kinetic energy can not be completely converted into electrical energy stored in the storage device,energy loss is unavoidable during braking,such as loss of air resistance,rolling resistance loss,loss of electrical machinery,loss of braking control systems and so on.Only about 60% percent of the mechanical energy can be recovered.As the existing recycling technology is not perfect,the actual energy recovery is only a lot,how to achieve the maximum energy recovery is very critical.The braking energy on the drive wheel can be recovered by the energy recovery device and stored in the energy storage device to achieve recycling,and the braking energy on the driven wheel can only be consumed by the friction,so the vehicle braking process involves the front wheel and rear wheel braking force power distribution problem,that is,friction braking torque and regenerative braking torque distribution problem.Under the premise of ensuring the safety and stability of vehicle braking,energy recovery can be maximized by optimal control technology.In order to solve the electric vehicle braking energy recovery less problems,in this paper,the energy recovery strategy of hybrid electric vehicle based on the rear wheel hydraulic braking structure is put forward.On the basis of this algorithm,a double fuzzy control strategy is proposed to optimize the braking energy recovery.In this paper,the present situation of the braking energy recovery technology is analyzed,and the basic principle of the braking energy recovery technology is analyzed on the basis of the existing control strategy.The braking mode of different braking force is determined by the size of the braking force partition.Then,the vehicle energy recovery module is established,which mainly includes the vehicle dynamic module,the hydraulic brake mechanical module,the generator module,the motor module and the battery module.In addition,in the analysis process focused on the analysis of the composite power storage device,in the sudden increase or sudden load,the rational use of battery and super capacitor,both protect the battery,and extend the battery life,also make full use of the super capacitor charge and discharge,to achieve the best mixed energy storage effect and gives the vehicle model.Finally,a regenerative braking control algorithm is proposed,and the energy recovery is optimized by the double fuzzy control strategy.First,put forward the pedal stroke Fuzzy control strategy,by controlling the pedal stroke before and after the distribution of wheel power;and then put forward the fuzzy control strategy of front wheel braking torque distribution,a reasonable allocation of front wheel friction braking force and regenerative braking force to achieve the best braking energy recovery.Based on this strategy,the control model is established in Matlab / Simulink environment,and the model is inserted to the ADVISORD simulation software ADVISOR is embedded to simulate.The experimental results are compared with the single fuzzy control strategy in terms of torque output,SOC change,motor operating area map and simulation data.It is proved that the double energy control strategy proposed in this paper can recycle increase braking energy by 30% or more,to achieve the optimization of the braking energy recovery.