Modeling and Load Emulation Experimental Verification of a Vehicle Powertrain System Test Bench Based on Rigid-Flexible Coupling Transmission Shaft

A long rigid-flexible coupling transmission shaft (RFCTS) is usually used to connect the dynamometer with the device under test (DUT) in semi-anechoic chamber. However, due to the parameter error and torsional vibration characteristic of RFCTS, load emulation loading accuracy of the test bench is lower. Therefore, the research focused on establishing a control-oriented vehicle powertrain system test bench (VPSTB) model based on RFCTS to further improve the load emulation loading accuracy. First, a 14-degrees of freedom (DOF) high-order lumped mass model of VPSTB is established, and the stiffness and moment of inertia equivalent parameters are obtained. Subsequently, a 7-DOF simplified control-oriented VPSTB model is established based on 14-DOF model, and the model parameters are identified by the recursive least squares estimation (RLSE) method with forgetting factor. Simultaneously, the natural frequency of 14-DOF high-order model and 7-DOF simplified model is calculated, then un-damped vibration response of the two models are compared and analyzed. Finally, simulation and experimental are carried out under open-loop and closed-loop conditions, which show that the effectiveness of 7-DOF simplified model parameters, and it also indicate that the 7-DOF simplified VPSTB model can achieve better loading accuracy of load emulation.