The hydraulic buck converter exploiting the load capacitance

The hydraulic buck converter requires a pressure attenuation device at its output to smoothen the pressure ripples excited by the switching process. For this purpose often gas filled accumulators are used. Such accumulators’ installation with low hydraulic impedance is challenging and maintenance causes and extra effort. Furthermore, the nonlinear behavior of the gas spring is often unwanted. A number of applications, especially high force hydraulics, use huge cylinders with a correspondingly high fluid volume which may have sufficient capacitance for pressure attenuation. Additionally, a phase shifted operation of several parallel hydraulic buck converters reduces the pressure pulsations by increasing the effective switching frequency at the load. This paper investigates such a multi hydraulic buck converter arrangement with a phase shifted operation and with just the cylinder capacitance for pressure attenuation.