A high-rate shape memory alloy actuator for aerodynamic load control on wind turbines

A high-rate shape memory alloy actuator for aerodynamic load control on wind turbines

Lara-Quintanilla, A.
Hulskamp, A.W.
Bersee, H.E.N.

Aerospace Engineering

Structure Integrity and Composites

2013-03-04

This paper discusses the development of a high rate shape memory alloy (SMA) driven actuator. The concept of the actuator was developed to act as aerodynamic load control surface on wind turbines. It was designed as a plate or beam-like structure with prestrained SMA wires embedded off its neutral axis. Moreover, the SMA material was embedded in channels through which air was forced to actively cool the wires when the recovery load was to be released. Wires were implemented on both sides of the neutral axis to deflect the beam in both directions. Thermal analysis of the cooling channels showed that they increased the cooling up to tenfold in comparison to the same set-up without forced convection. Subsequently a fuzzy logic controller was designed to control the thermo-mechanical system. The inputs were the error between the deflection and the set point, the value of the set point and the time derivative of the set point. The output consisted of two signals to the valves that controlled the flow through the channels and a signal heating signal that was split to both sets of wires, depending on its sign. The controller was tested on an antagonistic set-up, through which a similar thermo-mechanic behaviour as with the actuator was obtained, but eliminating the beam dynamics. The results were satisfactory; an actuation bandwidth of 1Hz was attained. Subsequently, the controller was tested on the actuator. With increasing actuation frequency, until 0.6Hz a relatively small error between the set point and the actual deflection was observed. Above that frequency the error increased, but also the sinusoidal response was lost. This is believed to be due to snap-through behaviour around the neutral position of the actuator. This was substantiated by the apparent inability of the actuator to track the set point around the neutral position in tracking a composite sinusoidal set point.

Shape Memory Alloys
Fuzzy Logic Controller
Aerodynamic Load Control
Wind Turbines
Control

http://resolver.tudelft.nl/uuid:a7be07c6-81b2-4486-a993-72a2da24644f

https://doi.org/10.1177/1045389X13478271

Sage Publications

1530-8138

http://jim.sagepub.com/content/early/2013/03/03/1045389X13478271

Journal of Intelligent Material Systems and Structures, 2014; Authors version

Institutional Repository

journal article

(c) 2014 The Author(s)