The switched inertance hydraulic system (SIHS) is a novel high-bandwidth and energy-efficient device which can adjust or control flow and pressure by a means that does not rely on throttling the flow and dissipation of power. The three-port SIHS usually consists of a high-speed switching valve, an inertance tube and an accumulator. The device can provide an efficient step-up or stepdown of pressure or flow rate by using a digital control technique. The existing analytical models of an SIHS can effectively predict the flow response, pressure loss, system characteristics and efficiency. The optimal switching frequency and ratio of an SIHS can also be accurately estimated by using the analytical models. However, there is no study related to the ‘optimal inertance tube’, which considers the optimal tube diameter and length corresponding to different system operating frequencies and ratios. In other words, there is inertia and resistance balance of the system. This paper investigates the global optimisation of an SIHS based on genetic algorithm. The energy cost function is proposed, and the optimal solutions are presented. Numerical simulation models are used to validate the results. It provides a general guidance of the SIHS design and its parameter optimisation.
Keywords: Switched inertance hydraulic systems; System optimisation; Cost function; Genetic algorithm