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Hydrautrans has patented a mechanical-hydraulic-electrical wind turbine drivetrain solution, which is unique in offering superior lower LCOE performance through multiple technology-related and other benefits for next-generation offshore turbines.


Hydrautrans was awarded a European patent for its mechanical-hydraulic drive system in 2012. An additional European patent (pending) covering different technology aspects was filed in recently.



Main design features:

Dedicated flexible drivetrain solutions


Hydrautrans innovative drivetrain solutions are capable of fully matching future demands for next generation onshore and offshore turbines. With a substantial lowering of LCOE being the leading principle, Hydrautrans drivetrains combine competitive system efficiency with an elongated service life, a compactness and favourable mass characteristics.



Mechanical-hydraulic drivetrain - torque split

 
Key elements of this high-speed mechanical-hydraulic drivetrain design are a main shaft semi-integrated with a distributed single-stage gearbox, sixteen pumps, four hydraulic motors and two generators.


The mechanical torque split principle allows lighter dimensioned gears, and the use of multiple smaller-size pumps. The low rotor speed, 8.5 – 12.5rpm depending upon size and application, is first stepped up in the gearbox and again by the hydraulic pump-motor system. The gearbox and the hydraulic pump-motor system is designed for minimal 25-year operating life. The entire system is developed to achieve maximum reliability with minimized operational costs.


The Hydrautrans Drive Train (HDT) consists of four modules, whereby each module has four pumps powering a high-speed hydraulic motor. Two of these motors are coupled to a  generator.





Hydraulic drive elements - peak loads dampening


Hydraulic drives are characterized by a high torque density, which enables compact systems with favourable mass characteristics. 

Another interlinked benefit is the near-elimination of gearbox drivetrain peak loads, offering enhanced reliability, lower operational costs and elongated drivetrain and turbine service life.



Floating Cup® - high efficiency and elongated service life


Hydraulic drive systems are often associated with low efficiency compared to mechanical equivalents. Hydrautrans has overcome this inherent disadvantage by choosing the INNAS Floating Cup® pump & motor technology, which offers 98.5% efficiency for individual pumps and motors, and a total HDT efficiency of 95%.


These patented and already at smaller scale fully validated and commercially available hydraulic devices, as a key feature operate without internal metal-to-metal contact between floating cups and pistons. This essential technology benefit translates into superior system efficiency and elongated service.



High-speed DFIG – cost-effective and more efficient


The Hydraulic Drive Train (HDT) incorporate two high-speed doubly fed induction generators (DFIG) as the standard fitting. Main characteristic is a partial converter rated at 20% of generator rated power. Such converters are less expensive and offer additional reliability enhancing and reduced power conversion loss benefits compared to full convertor equivalents.