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Variable speed digital hydraulic transformer–based servo drive

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Original languageEnglish
JournalProceedings of the Institution of Mechanical Engineers. Part I: Journal of Systems and Control Engineering
Publication statusE-pub ahead of print - 2019
Publication typeA1 Journal article-refereed


This article studies a digital hydraulic servo drive driven by a variable speed electric servomotor. Digital displacement control is implemented by using a two-port digital hydraulic power management system having six pistons and 18 on/off control valves. The first port of the digital hydraulic power management system controls the cylinder speed, while the second port is connected to a hydraulic accumulator. The peak power is taken from the accumulator, and the electric servomotor supplies only the average power into the system. An experimentally validated simulation model is used, and the results show a combination of adequate controllability and excellent energy efficiency. The estimated reduction in the size of the electric motor is 57%.


  • DHPMS, Digital hydraulics, variable speed drives

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