Current-controlled shape memory alloy actuators for automotive tumble flap

Mechatronics devices are becoming a mandatory option in the automotive framework, as high integration and low weight are common requirements for most applications. To this aim non-electric drives are being investigated. An attractive option is the use of Shape Memory Alloy (SMA) actuation technology that allows achieving a very high power/weight ratio for light and small actuators. Feasibility studies were made to show the potential of SMA as actuators. This paper proposes the application of a SMA actuator for automotive tumble flaps. A critical comparison between traditional and SMA actuators is presented, and the attention is focused on the power converter used to "drive" the SMA. Experiments were made on a prototype realized for angular control of tumble flaps of an air intake manifold for internal combustion engines that allows achieving better gas combustion and higher performances. The proposed control scheme includes a current feedback that allows a sensorless control position for the tumble shaft.