Introduction to Fluid Power Technology

Electro-hydraulic variable-speed drives enables the possibility to substantially increase the efficiency of hydraulic systems, while their electric interface makes them especially suitable for electrified machinery and e-mobility applications.

Typically realized as standalone drives, however, these require installation of per actuator peak power resulting in high component material usage and associated costs. Electro-hydraulic variable-speed drive networks targets multiactuator systems, and allows to completely avoid throttle control, making these highly efficient. Such drive networks enable power sharing both hydraulically and electrically, realizing a highly flexible power distribution and consequently power installations may be substantially reduced compared to standalone electro-hydraulic variable-speed drives.

Major challenges in enabling this technology involves drive architecture design as the number of unique architectures increases exponentially with the number of actuators, and actuator control due to strong flow and pressure couplings. At this point, these challenges are at the center of research activities.

A fluid power transformer is an essential component when seeking an energy efficiency system using a single pump unit for multiple actuators and may such be an enabler for energy efficient fluid power system for e-Mobil machinery.

Ongoing activities aim at designing, implementing, and bringing a novel fluid power transformer technology to market.

Ongoing activities works on developing control strategies for digital fluid power system, especially discrete displacement cylinders.

Currently this technology is employed in the power take off system of wave energy converters harvesting energy of ocean waves.

A further application for the DDC technology is as actuator for an exoskeleton in which energy efficient control is the research focus.

Tribology in fluid power is a key focus in regard to efficiency and reliability of components. However, a significant challenge is the experimental techniques in tribology.

The current focus is on development of in-situ non-invasive techniques for tribodynamic state observation, which can aid designers to improve components, and provide a path for smart Tribomechatronic control and prognostic systems for fluid power technology.

Improving the reliability of, e.g., hydraulic pitch systems is one of the means to ensure larger production of offshore wind turbines and the green transition to a climate-neutral society.

In the HyRel project, we are exploiting the digital transformation and advances in sensor technology to accomplish this.

This is done by developing improved methods for assessing the reliability and expected lifetime already in the design phase; by advancing accelerated lifetime testing methods; and by developing advanced on-board diagnostic algorithms for condition monitoring and fault detection for fluid power systems and components.