Research On The Performance Of Hydrostatic Transmission Hybrid Vehicle's Drivingand Braking Control Systems

Global competition, energy shortages, environmental pollution problems have prompted people to consider fuel economy issues. Hybrid technology as an important branch, hydrostatic transmission hybrid vehicles have gradually led governments, research institutions and auto makers are highly valued.Hydrostatic transmission with secondary regulation is a new kind of transmission technology, which changes the swash angle of hydraulic pump/motor to adapt to the load change. Hydraulic accumulator has the advantage of higher power density and the ability to accept the high rates and high frequencies of charging and discharging, both of which are favorable for energy conversion and storage requirements during vehicle braking. In addition, hydrostatic transmission with secondary regulation has the advantages of continuously variable speed adjustment, easy to achieve positive inversion and prevent overload of engine and so on. Therefore hydraulic hybrid technology is well suited for luxury passenger cars, sport utility vehicles, light duty trucks and heavy-duty trucks. It is undoubtedly important to apply secondary regulation to developing and exploring new hybrid vehicles to save energy and protect environment. Based on the application of secondary regulation technology in hybrid vehicles, series hybrid vehicles of hydrostatic transmission with secondary regulation are studied and analyzed in depth and breadth in this article.After consulting a lot of related literatures and reference materials at home and abroad, this paper summarizes the development of hydrostatic transmission hybrid vehicles. Energy regeneration system and the engine in accordance with the different configurations, the hydraulic hybrid vehicles are divided into four forms, and the hydrostatic transmission characteristics of hybrid vehicles made related presentations.After studying the operation principle of hydrostatic transmission hybrid vehicles, and the typical work patterns. According to the control system requirements, are established electro-hydraulic servo valve, hydraulic pump / motors and hydraulic pump - energy storage combinations of dynamic performance of the mathematical model, and establish a hydraulic pump / motor loop control model.According to the characteristics of driving and braking system designed torque control mode and speed control mode, established the corresponding mathematical model and analyzed its stability. Under PID control and discrete characteristics of sliding mode control design the corresponding drive and brake system controller.Finally, research related to the contents of this simulation, and analysis of simulation results. The experimental results shown that torque control method is well suit for hydrostatic transmission hybrid system, discrete sliding mode robust controller is better than PID controller and hydraulic regenerative braking strategy and energy control strategy are quite effective.