Stability analysis of closed loop pump control motor hydraulic system under non-stationary condition

ZHANG De, GU Li-chen, GENG Bao-long, CHENG Dong-hong, LIU Jia-min
(School of Mechatronic Engineering, Xi'an University of Architecture and Technology, Xi'an 710055, China)

Abstract: Aiming at the problem of the obvious nonlinear characteristic of hydraulic system and the poor operation stability under the extreme working condition, AMESim multi-disciplinary simulation software was used to model the multi-energy domain coupling closed loop hydraulic system, a typical closed pump control motor hydraulic system was simulated and analyzed. The influence of oil viscosity and effective bulk modulus on the stability of closed pump-controlled motor hydraulic system was studied under different oil gas content and temperature conditions. At the same time, the mechatronics test platform was further designed, the stability characteristics of the system were verified under different gas and temperature conditions when the load step up and the speed step down. The results indicate that the influence of oil gas content and oil temperature on the output stability of the closed pump control motor hydraulic system is quite obvious. With the increase of gas content, the overshoot of hydraulic motor speed increases by 0.12% and 0.18% with the increase of load step and the decrease of motor speed step respectively, and the system stability is weakened. With the increase of temperature, it decreases by 0.09% and 4.68% respectively, and the stability is enhanced.
Key words: closed loop hydraulic system; AMESim; bulk modulus; overshoot; system stability