Probabilistic analysis of continuously variable transmission to improve reliability

Renewable energy has surfaced as an energy source of interest recently. Wind Energy has been the leading source of renewable energy development for the past 20 years. Wind energy still has room for development to become economically efficient enough to be the leading source of energy. The biggest issue that maintains the bulk of focus is wind turbine drivetrains. The gearbox fails after 5 years of operation when the expected lifetime of the wind turbine is 20 years. The application to the automotive industry inspired the use of continuously variable transmissions (CVT) in a wind turbine. The CVT that is applied in this study is the Nu-Vinci CVP. This one was selected because of its planetary gear set configuration and its ability to transmit larger amounts of torque, which is required for wind turbine applications. The goal of this research is to reduce the Cost of Energy (COE) by increasing the reliability of CVTs in wind turbines. A probabilistic analysis is conducted on these variable drive-train systems to determine the reliability of continuously variable transmissions. The research question, “Does probabilistic dynamic analysis help to improve reliability of continuously variable transmissions?” is the basis of this study. To aid in answering this question three specific aims were developed, namely, (1) develop a computational framework, and (2) perform probabilistic dynamic analysis, (3) perform probabilistic analysis on the COE. It was shown that 5.5% of the time the generator torque of a system using a CVT is less than the system using a standard gearbox. It was also shown that provided the same input speed and torque the CVT has a slightly higher power generation. It was shown that 54% of the time the CVT has a lower COE than the standard gearbox. The CVT produces a constant generator speed and lower torque on the output shaft while producing a slightly higher amount of power than the standard gearbox. Because the shaft has lower torque the stress on the output shaft is less when using a CVT. The higher power production is attained while decreasing the COE. The reliability of the drivetrain is improved using a CVT.