| The heavy commercial vehicle is of great significance for the development of modern society construction. The driving cycles of traditional heavy commercial vehicle are complex.The driving wheels may slip on the low adhesion bad road. The vehicle may be short of traction when climbing a large slope. Besides, when the vehicle brakes frequently or coasts on lasting downhill, the brake wears seriously, and the vehicle kinetic energy can’t be recycled, so there will be energy dissipation and poor fuel economy.Faced with the above problems, based on the national nature science fund issue and the cooperation with an enterprise, an hydraulic hub-motor auxiliary drive and regenerative brake system is proposed by adding a hydraulic pump, an accumulator, two hub-motors, a controller and so on. This system can improve the passing ability of vehicle on the low adhesion bad road, and enlarge the traction when climbing a large slope. Besides, the system can recycle the vehicle kinetic energy when it brakes frequently or coasts on lasting downhill, and reduce the wear of brake. Relative to the traditional vehicle, the modifications and increased costs of the hub-motor hydraulic driving heavy vehicle are small. The analysis of system configuration scheme and parameters match, design of control algorithm, establishment of the simulation platform, offline and hardware-in-the-loop simulation are the four key aspects to be researched in this paper.(1) The feasibility of the hydraulic hub-motor auxiliary drive and regenerative brake system scheme is verified through the theoretical calculation in this paper. Based on the requirements of auxiliary drive and energy recovery, the parameters of accumulator are calculated.(2) In the aspect of the two different assistant modes of hydraulic pump-motor auxiliary and accumulator-motor auxiliary, the control algorithms of the hydraulic pump displacementregulation and the control signal regulation of the accumulator discharge valve are mainly researched in this paper. To identify braking intention demand and to coordinate different working modes are proposed in this paper when the vehicle is braking. The braking force distribution strategy of regenerative braking is intensively researched.(3) From the perspective of the vehicle dynamics, the mathematical models of the whole vehicle power train are built. The model of hydraulic drive system is built on the platform of AMESim, the models of mechanical drive system and algorithms are built on the platform of MATLAB/Simulink, the communication is realized by using S-Function, then the off-line simulation platform of vehicle is built. Besides, with the help of d SPACE real time simulation system and TTC200 controller, the hardware-in-the-loop simulation platform is set up.(4) The feasibility of the control algorithm is verified by the off-line simulation analysis in this paper. The dynamic performances of pump-motor auxiliary and accumulator-motor auxiliary are obtained, and the different application conditions of the two are compared.Besides, the braking energy recovery rates are analyzed under different conditions. Lastly, the ratio of oil saving of the hydraulic hub-motor auxiliary drive and regenerative brake system is obtained on the platform of hardware-in-the-loop based on a certain driving cycle, the dynamic coordination capability of work mode switch is also tested. The above contents are the foundation of the following real vehicle algorithm research.Nowdays, the research and application of hydraulic hybrid technology in China are far behind foreign counterparts. The hydraulic hub-motor auxiliary drive and regenerative brake system in this paper is original in China. It has important theoretical value and practical significance to independently carry on hydraulic hybrid system development to our country. |
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