Hydrostatic Drive for a Wind Turbine

Abstract

One of the main issues with conventional wind turbines is their reliability and expensive maintenance. To address this issue, the Innovative Engineers student group and the Center for Compact Efficient Fluid Power at the University of Minnesota came together to form a research team to develop and test a relatively new wind turbine technology in the field: a hydrostatic transmission for wind turbines. A hydrostatic transmission is a pump and motor fluidly coupled using hydraulic lines. This has several advantages including increasing the reliability of the wind turbine, making its maintenance easier and improving the efficiency of mid-sized wind turbines by allowing the turbine to set the rotor rpm independently of the generator rpm. Research at the University of Minnesota has indicated that the energy output of a conventional mid-sized wind turbine can be increased on average up to 4% by adding a hydrostatic transmission (Thul, 2011, p. 40). To test this, a small (~1kW) wind turbine will be constructed and will be fitted with sensors including hall sensors, a pressure transducer, and a wind speed anemometer. An Arduino microcontroller was used to read all the sensors, store the data and control the wind turbine by controlling the current through the generator and the displacement of the hydraulic motor. The rotor RPM and pressure measurements for the pump were compared to the RPM and current outputs of the generator to determine the efficiency of the hydrostatic wind turbine. While the efficiency results are not conclusive yet, the turbine shows promise to be an efficient and reliable solution. Leakage, high efficiency loss at low wind speeds and weather all pose challenges for the design of this sort of a turbine, but these issues can be overcome.