Dynamic performance coordination control of hydraulic electrical energy-regenerative suspension based on road excitation self-adaptation

Abstract: Compared with the passive suspension, the hydraulic electrical energy-regenerative suspension can not only recycle the energy dissipated by the suspension, but also improve the dynamic performance of vehicle, which has attracted extensive attention of scholars at domestic and abroad. However, the most of research focuses on the analysis of energy-feedback characteristics，without considering how to improve the dynamic performance of vehicles adaptively according to complex road conditions while restoring energy considered. In addition, the ride comfort and handling stability of vehicle are mutually constrained, and the contradiction between them is still prominent under the passive mode. In order to meet the optimal performance of hydraulic electrical energy-regenerative suspension during the global operating condition, a hydraulic electrical energy-regenerative suspension with 3 working modes focusing on comfort, sport and comprehensiveness modes was designed to regenerate vibration energy while improving the ride comfort and handling stability of the vehicle in this paper. The road excitation frequency was chosen as the suspension mode switching threshold. The hydraulic electrical energy-regenerative shock absorber was composed of a hydraulic cylinder, a hydraulic rectifier bridge, a hydraulic motor, 2 accumulators, the hydraulic pipeline, a rotary motor, etc., wherein the hydraulic rectifier bridge consisted of 4 one-way valves. The DC-DC converter was introduced into the suspension energy-regenerative circuit. Based on this, the damping force formula of the shock absorber was derived. The double loop semi-active control scheme consisting of skyhook-groundhook control and fuzzy PID control was designed. The semi-active control of the hydraulic electrical energy-regenerative suspension was achieved based on the energy-regenerative circuit. The DC-DC converter could work in both boost and buck modes. The duty cycle of the MOS tube switching signal in the DC-DC converter was adjusted real time to change the damping force of the damper. Moreover, the Kalman Filter algorithm was introduced to accurately obtain the suspension state variables to track the ideal damping force. The first-order zero-crossing detection method was introduced to identify the main frequency of the road input, which was used as the switching threshold of each suspension working mode. The simulation results showed that the hydraulic electrical energy-regenerative semi-active suspension could switch the working mode adaptively according to the road frequency, and improve the vehicle dynamic performance effectively than the single mode control of semi-active suspension while regenerating energy. The proposed hydraulic electrical energy-regenerative suspension combined with road frequency self-adaption could coordinate suspension dynamic performance with energy-regenerative characteristics. The vehicle body acceleration in the comfort mode was reduced by 13.75% compared with that of the single mode control suspension, and the tire dynamic load was reduced by 17.76% in the sport mode. To verify the effectiveness of the simulation, a bench test was performed. The deviations of the PTP(peak-to-peak) value of test and simulation data of vehicle body acceleration were 1.36%, 15.72%, 4.86%, and 13.6%, respectively, and the ones of the tire dynamic load were 9.34%, 13.62%, 7.82%, and 15.47%, respectively. The errors between the test and simulation results was within 16%, which verified the correctness of the simulation results and the feasibility of the semi-active suspension system. The study provides an important reference for the performance upgrade of the hydraulic electrical energy-regenerative suspension.