Research on system identification based on hydraulic pump-motor of HMCVT

In order to study the speed ratio regulation and dynamic change of hydraulic mechanical continuously variable speed tractor, it is necessary to comprehend the dynamic characteristics of the hydraulic circuit. The identification method was adopted to study the pump-motor system of transmission. Firstly, the typical identification method of combination modeling was selected to establish the model, and then the corresponding experiments were designed to determine the transfer function parameters and models of the combined modeling. Based on these, through further simplification and indirect methods, with the help of MATLAB toolbox, a fast system identification method was established by calculating the transmission ratio of the pump motor system through the output speed of the gearbox, the engine speed and the drive ratio of the front gear of the pump, as well as the transmission ratio of the gearbox. Filter was used to remove the influence of noise during the experiment. Compared with the test data, the models established by the two identification methods have higher accuracy. The positive and negative fitting rates of the fast identification method are 91.85 and 91.13, respectively, which can meet the needs of subsequent research. This study can be used as a reference for the subsequent control design of transmission and the study on the quality of the transmission.