Abstract

Due to the characteristics of high-power density, the high-frequency electro-hydraulic acceleration control system (HFEHACS) has been an important component of vibration simulation equipment such as load simulators, and fatigue testing machines. However, the performance of the HFEHACS is strongly restricted by the inherent low bandwidth and low damping ratio of the electro-hydraulic subsystem. In general, these two shortcomings must be traded off to achieve the desired compromise performance. To expand the bandwidth and increase the damping ratio of the electro-hydraulic subsystem simultaneously, an improved control method that combines the three-variable control (TVC) method with dynamic pressure feedback was proposed in this work. First, the dynamic model of the high-frequency electro-hydraulic subsystem with an elastic base considered was established, and the influence of the elastic base on the HFEHACS was analyzed by simulation. Second, the basic TVC was designed to expand the bandwidth and suppress the resonance of the electro-hydraulic subsystem previously, after that, the dynamic pressure was estimated and added into the control method for increasing the damping ratio of the system and further suppressing the resonance of the system. Third, simulations and experiments were conducted to verify the effectiveness of the improved control method. Simulation results showed that the resonance of the HFEHACS caused by both the electro-hydraulic system and the elastic base could be suppressed well by the improved TVC. Experiments results showed that the bandwidth of the electro-hydraulic subsystem with the proportional controller could be expend to about 190Hz, and the bandwidth of the system with the traditional TVC method could be expanded to nearly 250Hz with relatively apparent resonance, while the bandwidth of the system with the proposed method was expanded to 250Hz with smaller resonance. Thus, the effectiveness of the proposed method in expanding the system bandwidth and reducing the system resonance simultaneously was demonstrated.

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