• Søren Valentin-Pedersen
  • Rasmus Aagaard Hertz
  • Peter Sloth-Odgaard
4. term, Electro-Mechanical System Design, Master (Master Programme)
The Speed-variable Switched Differential Pump (SvSDP) system is a direct hydraulic drive used for high-performance motion tracking of linear hydraulic actuators. The system shows improved energy efficiency at cylinder velocities different from zero compared to conventional valve controlled drives. To further increase efficiency of the SvSDP at zero cylinder velocity, it is proposed in this project through a topology optimisation, to employ two different concepts both capable of improving the energy efficiency related to load holding sequences.

The two concepts may be separated into two categories, one which utilises a valve design and one with a pump design, both seeking to minimise the shaft torque associated with load holding situations for improved motor efficiency. The valve-based concept uses two main-line valves to precisely control the cylinder position while retaining a return side pressure thus obtaining the best functionalities of the SvSDP concept and a valve controlled drive. The pump proposal also aim to reduce the shaft torque by balancing the available chamber pressures over oppositely mounted pumps.

Both proposals are modelled and linearised followed by a RGA number analysis. The RGA results indicate heavy input and output couplings for both systems throughout the frequency domain. A decoupling approach utilising both input- and output transformations is proposed in order to decouple the plant and allow for a linear control approach. Linear controllers are designed to give the system robustness towards disturbances.

The two topologies both shows improved energy efficiency but at a cost of added components and complexity.
Publication date2 Jun 2017
Number of pages166
ID: 258871525