Dynamic characteristic analysis of replenishing/leaking parallel valve control systems

To improve the dynamic response of traditional pump control systems, this paper proposes two new control schemes: replenishing parallel valve control (RPVC) and leaking parallel valve control (LPVC). A parallel valve control system using the two control schemes is designed, and its system parameters, control performances and efficiency are analysed and verified by simulation and experiments. Compared to the pump control system, the proposed system has larger damping ratios which vary widely with operating points, and has lower velocity stiffness due to the increase of total leakage coefficients. Both the LPVC and RPVC could contribute to the dynamic response improvement. RPVC is preferred over LPVC because of more stable damping ratios and higher speed stiffness, and these advantages could be further improved by increasing the supply pressure of the control valve, but the LPVC scheme costs lower due to the unnecessary oil supply for the control valve. During the control process, the valve works at a low flow rate, but the pump provides the majority of the system flow, so two parallel valve control systems still have relatively high energy efficiency with rapid response. Therefore, the RPVC and LPVC will enrich the control mode of hydraulic systems