HIGH VOLTAGE AC CONTROL OF SMA WIRES

Alternating voltage is available in many environments for actuators. Due to the fact that a lot of actuators cannot directly handle this type of supply voltage, such as shape memory alloy (SMA) actuators, the voltage is usually converted to direct current. In the case of SMA actuators, the supply voltage often even has to be adjusted to the electrical resistance of each particular actuator. Due to high energy potential in AC supplies, conventional activation for SMA actuators over several seconds is not possible. In this study a control procedure for SMA wire actuators with high AC voltage supply is presented, which allows very flexible and versatile control of SMA wires. In addition two different types of activation are distinguished in an experimental study: one-time activation and activation over a longer period of time. The objective of the one-time activation is to reach a given actuator displacement. The activation over time is intended to hold a given position. The results of this series of experiments are presented and the resulting energy saving potential in high voltage SMA activation is observed.