Topology Optimisation of Hydraulic Cylinder Direct Drive Targeting Energy Effciency and Control Performance
Authors
Valentin-Pedersen, Søren ; Hertz, Rasmus Aagaard ; Sloth-Odgaard, Peter
Term
4. term
Education
Publication year
2017
Submitted on
2017-06-02
Pages
166
Abstract
Speed-variable Switched Differential Pump (SvSDP) er et direkte hydraulisk drivsystem til præcis, højtydende styring af lineære hydrauliske cylindre. Systemet bruger allerede mindre energi end traditionelle ventilstyrede drev, når cylinderen er i bevægelse. Dette projekt adresserer den resterende ineffektivitet ved nul cylinderhastighed, dvs. når systemet skal fastholde en last i ro. Gennem topologioptimering undersøges to designkoncepter, der skal sænke akselmomentet under last-holdning og dermed forbedre motoreffektiviteten: et ventilbaseret og et pumpebaseret koncept. I det ventilbaserede koncept anvendes to hovedlinjeventiler til præcist at fastholde cylinderens position, mens der opretholdes et retursidetryk. Det kombinerer nyttige funktioner fra både SvSDP-tilgangen og et ventilstyret drev. I det pumpebaserede koncept udlignes de tilgængelige kammertryk over to modsat monterede pumper for at reducere akselmomentet. Begge koncepter modelleres og lineariseres (forenkles til en lineær model) og analyseres derefter med Relative Gain Array (RGA) for at vurdere, hvordan input og output påvirker hinanden på tværs af frekvenser. RGA-resultaterne viser stærk kobling i begge systemer. For at muliggøre en enkel lineær reguleringsudformning foreslås en afkoblingsstrategi med input- og outputtransformationer, og der udformes lineære regulatorer for robusthed over for forstyrrelser. Samlet set øger begge topologier energieffektiviteten, men kræver flere komponenter og giver højere kompleksitet.
The Speed-variable Switched Differential Pump (SvSDP) is a direct hydraulic drive designed for precise, high-performance control of linear hydraulic cylinders. It already uses less energy than conventional valve-controlled drives when the cylinder is moving. This project targets the remaining inefficiency at zero cylinder velocity, that is, when the system must hold a load still. Through topology optimisation, two design concepts are explored to lower shaft torque during load holding and thereby improve motor efficiency: a valve-based concept and a pump-based concept. In the valve-based concept, two main-line valves hold the cylinder position accurately while maintaining pressure on the return side. This combines useful features of the SvSDP approach with those of a valve-controlled drive. In the pump-based concept, the available pressures in the cylinder chambers are balanced across two oppositely mounted pumps to reduce shaft torque. Both concepts are modelled and then simplified to linear form, followed by Relative Gain Array (RGA) analysis to assess how inputs and outputs interact across frequencies. The RGA results show strong coupling in both systems. To enable a straightforward linear control design, a decoupling strategy using input and output transformations is proposed, and linear controllers are designed to provide robustness to disturbances. Overall, both topologies improve energy efficiency, at the cost of additional components and greater system complexity.
[This abstract was generated with the help of AI]
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