On the positive and negative damping effect of piezoelectric structure using switched-mode bidirectional energy conversion circuit

The introduction of a switched-mode bidirectional energy conversion circuit (BECC) facilitates the development of piezoelectric devices toward integrated and energy-efficient multi-functional designs. These new designs realize the organic combinations of two or more functions among energy harvesting (EH), vibration excitation (VE), and dynamic sensing. Yet, the structural effect after applying the BECC was not comprehensively investigated and strictly quantified. This letter analyzes the electromechanical joint dynamics of a piezoelectric structure using the BECC, which was developed after the synchronized triple bias-flip (S3BF) technique, under different EH and VE operation modes. It shows that the EH modes electrically induce an extra positive damping effect, while the VE modes induce a negative one. A lumped model and impedance analysis are used to evaluate the electrically induced damping and the energy conversion efficiency by the BECC. The closed-form expression of the vibration displacement under different operation modes is derived. Experiments are carried out under different operation modes and frequencies. The theoretical and experimental results show good agreement. They validate the damping tuning capability of BECC in either positive or negative damping directions. This switched-mode interface circuit offers a promising solution for building an adaptive dynamic control of piezoelectric structures with high energy efficiency.