Structural Analysis of Slewing Bearings for Wind Turbines

Abstract

This study is a structural analysis of slewing bearings for wind turbines. The ball of a bearing delivers load while making contact with raceways of the inner and outer rings. To facilitate stress analysis of the slewing bearing, which has more balls than other types of bearing, the balls were converted into spring elements. Considering the shape of contact between balls and raceways, one, two, and three spring elements were introduced. Global finite element analysis of the bearing, with balls as spring elements, showed that the bearing experienced different degrees of deformation depending on the number of springs. Using the bearing deformation obtained from the global analysis, cut boundary constraint was applied for local contact analysis of balls and raceways. The contact stress between balls and raceways showed that more uniform stress could be achieved by increasing the number of springs.

Systemic optimal control of wind energy system regulating conjointly generator speed and battery recharging current

“…The nominal internal battery voltage can be maintained constant in this case, and the sizes of the wind turbine components can be determined systemically from inverse analytical program of the turbine having as inputs the maximal current in the battery. This method is used for sizing electric vehicles as shows in Shin et al (2013), Kim et al (2010), Buticchi et al (2012), Kang (2017), Tounsi (2015), Nhidi et al (2015), and Ben Amor et al(2015).…”

“…The equation of the motion of rotating parts is deduced from the fundamental relation of dynamic (Ben Amor et al, 2015; Buticchi et al, 2012; Kang, 2017; Kim et al, 2010; Nhidi et al, 2015; Tounsi, 2015):…”

“…The three induced electromotive forces e a , e b , and e c are expressed by the following three equations (Ben Amor et al, 2015; Buticchi et al, 2012; Kang, 2017; Kim et al, 2010; Nhidi et al, 2015; Tounsi, 2015) :…”

“…Each phase of the generator is equivalent to a resistor in series with an inductance and an induced electromotive force. The generator three phase’s model is described by the following equations (Ben Amor et al, 2015; Buticchi et al, 2012; Kang, 2017; Kim et al, 2010; Nhidi et al, 2015; Shin et al, 2013; Tounsi, 2015):…”