Mechanical and energetic characteristics of an energy harvesting type piezoelectric ultrasonic actuator

Abstract Piezoelectric ultrasonic actuators (PUA) are fascinating and precision-controlled actuators in some mechatronics systems. This study proposed an energy harvesting type piezoelectric ultrasonic actuator (H-PUA) and investigated its mechanical and energetic characteristics. The proposed H-PUA has a sandwich-type stator composed of a metal body, an exciting piezoelectric (PZT) ring and a harvesting PZT ring. The exciting PZT ring bonded on the bottom surface of the stator was used to produce a traveling wave, and the harvesting PZT ring bonded on the top surface of the stator was used to harvest the vibration-induced energy of the stator and convert it into electric energy. Sensitivity analysis method was used to optimize the stator structure. Finite element analysis using ANSYS software was performed for both the mechanical and energetic characteristics of the new actuator. A prototype H-PUA was fabricated and subsequently used to test the mechanical and energetic characteristics. When the rotor torque is zero and the pre-pressure is 100 N, the prototype H-PUA has mechanical output characteristics of no-load speed 112 rpm and stalling torque 0.78 Nm when the exciting voltage amplitude is 152 V 0−p with frequency 36.0 kHz. The maximum harvesting output power of a sector area of the harvesting PZT ring reaches 54 mW when it is connected to an optimized load resistance 11 kΩ. Experiments have shown that the harvesting output energy can fully meet with the power supply demands of some low-power (i.e., mW/μW level) mechatronics systems, such as LED.