Modeling and simulation on hydraulic system of hydraulic hybrid vehicles

To analyze the dynamic performance of hydraulic hybrid vehicles and to optimize the main design parameters of the hydraulic system, the mathematical models of the hydraulic system are established, which includes bidirectional variable-displacement motor, hydraulic accumulator and other components. The relation between polytropic exponent of bladder accumulator and variation rate of gas volume is defined. The hydraulic system is simulated. BCS-GEAR algorithm and switch states are applied to solve the unsteady phenomenon of the simulation process. The simulation results are analyzed. In the same initial conditions and controlling algorithm, experimental verification is performed on the self-developed test bed. The speed response of load and pressure of the hydraulic system are compared. The simulation results accords with the experimental data well. The accuracy of systematic models and simulation algorithm is proven.