A multilayer TWILA ultrasonic motor

A fully operational ultrasonic motor using bulk piezoelectric longitudinal actuators has been already introduced in our previous works. But despite of its interesting characteristics and its easily implementation, its high supply voltage (from 200 Vrms) could be a technological lock-in by imposing supplementary constraints in order to satisfy the electrical safety standards.To overcome this drawback, we have developed a new stator version which integrated multilayer longitudinal actuators, based on the bulk TWILA ultrasonic motor.If the global motor structure stays relatively closed to the bulk one, the new longitudinal actuator topology has been optimised with the help of a Finite Element Modeling.The higher capacitance value of the multilayer actuators requires the use of inductance compensation to optimise the motor drive.Finally, The mechanical performances are not only preserved but are now obtained under a main supply voltage (12 Vrms) 17 times lower than the previous bulk version. Moreover, the global efficiency is largely improved by reaching 20%.