Research On Brake Energy Recovery Control Strategy Based On EHB Technology

Developing new energy vehicles is the only way out for the automotive industry facing environmental pollution and energy shortage problems.From the government's purchase subsidies for new energy vehicles to the release of the “Measures for the Parallel Management of the Average Fuel Consumption of Passenger Vehicle Enterprises and New Energy Vehicle Integration”,we can see that the government is determined to promote the development of C hina's new energy vehicle market.At the same time,this is also a rare opportunity for China,as the world's largest consumer market for new energy vehicles,to develop from a large automobile country to a powerful automobile country.To enhance the competitiveness of the new energy vehicle s,a direct and effective method is to increase the driving range of new energy vehicles.Although the battery industry has developed in r ecent years,there has been no breakthrough in battery performance.Brake energy recovery technology can improve the energy utilization efficiency and extend the driving range without increasing the hardware cost of the vehicle.It is of great significance studying of this technology.Based on the EHB technology-based brake energy recovery hydraulic braking platform,this article developed a brake energy recovery control strategy.Firstly,this paper designed a hardware-in-the-loop simulation system scheme for brakie energy recovery.A EHB technology-based hydraulic braking platform was built.Based on the mathematical model analysis and characteristic testing of the platform hardwares,a wheel cylinder pressure follow-up control algorithm was established and verified through semi-physical simulation.Thus,the control of the brake energy recovery hydraulic brake system was realized.Secondly,using field oriented control method,torque control simulation of of permanent magnet synchronous motor was carried out.The braking principle of permanent magnet synchronous motor was analyzed,and a method to optimize the braking torque of the motor by maximizing the braking power generated by the motor was proposed,the optimal braking torque curve of the motor was obtained.By analyzing the loss model of the permanent magnet synchronous motor,the influence of the rear axle distribution coefficient of the regenerative braking force on the braking energy recovery was studied.Through simulation calculations,it was concluded that the efficiency of the motor system is highest when the regenerative braking force is evenly distributed between the front and the rear axles.Finally,the secondary development of the electric vehicle model in the Advisor software was carried out to b uild a four-wheel independent drive electric vehicle model.Based on the previous research results,with the advantage that the braking force of the four wheels in EHB technology-based hydraulic braking system can be flexibly controlled,a braking energy recovery control strategy was designed and then verified by simulation test.Compared to the result of another simulation test,where regenerative braking torque of the motor was optimized with the goal of maximizing the motor efficiency,the braking energy recovery control strategy based on EHB technology designed in this paper can recover brake energy very well and maximize energy recovery.