Helmut Kogler, Rudolf Scheidl, Martin Lauber, Bernd Winkler,
"Hydraulic Efficient and Robust Converter Unit for Linear Motion under Energy Saving"
: Proceedings of the 11th Workshop on Digital Fluid Power, DFP22, September 19-20, 2022, Edinburgh, Scotland, 9-2022
Original Titel:
Hydraulic Efficient and Robust Converter Unit for Linear Motion under Energy Saving
Sprache des Titels:
Englisch
Original Buchtitel:
Proceedings of the 11th Workshop on Digital Fluid Power, DFP22, September 19-20, 2022, Edinburgh, Scotland
Original Kurzfassung:
Hydraulic cylinders are common and robust actuators for linear motion applications in harsh environments, like for instance on excavators. A hydraulic buck converter respresents a digital switching concept transfered from power electronics to hydraulics, which is used for the control of hydraulic actuators at low energy consumption. Basically, in a hydraulic buck converter the flow is controlled by the switching of digital hydraulic valves, which are operated in pulse width mode at a constant switching frequency. Actually, a single converter suffers from large pressure fluctuations due the digital valve switching. The pressure ripples are commonly reduced by additional pressure attenuation devices, like gas-loaded accumulators, which in turn result in a soft drive configuration. This drawback can be eliminated by a parallel arrangement of several smaller converters operated in a phase shifted mode. Since in this case no components for pressure attenuation are necessary anymore, a highly compact design of the converter is possible, which can be directly integrated into the actuator. In this paper an efficient and robust converter axis is presented, where several hydraulic buck converters are unified with a hydraulic differential cylinder. The resulting converter axis enables a linear motion at high energy efficiency. Since the digital valves are directly integrated in the actuator, the resulting converter unit must be supplied by a high pressure line and a tank line. Thus, in case of muliple hydraulic actuators, like on the boom of an excavator, one single common rail supply circuit is sufficient for all actuators and no interconnection piping is necessary. Furthermore, due to its highly integrated and compact design the converter unit can be operated in combination with a load sensing system, which even lowers the overall energy consumption of the multi-actuator system. The energy performance of the presented converter axis for certain load conditions is investigated by simulations, problems and limitations are discussed elaborately.
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