A Bidirectional Energy Conversion Circuit Toward Multifunctional Piezoelectric Energy Harvesting and Vibration Excitation Purposes

Piezoelectric transducers provide a bidirectional channel for converting energy from mechanical form to electrical or in the opposite direction. Various applications were developed with either of these two energy-flow processes. For example, energy harvesters take advantage of the energy flow from mechanical to electrical domains, while vibration exciters utilize that from electrical to mechanical domains. However, few designs have integrated the bidirectional energy-flow processes in a single device in the past. Such an integration is beneficial to some multifunctional applications. The key obstacle of integrated bidirectional design results from the interface circuit design, rather than the transducer. This article makes a breakthrough by proposing a bidirectional energy conversion circuit (BECC) solution for the time-sharing energy harvesting and vibration exciting purpose. It is realized by developing a new control strategy on the synchronized triple bias-flip (S3BF) piezoelectric interface circuit, which was formerly used for energy harvesting enhancement. The control logic for energy harvesting and vibration exciting modes are discussed in detail. The time-sharing multi-functional ability is validated in experiments. It is the first time to realize a compact and integrated self-excitable energy harvester by using a single interface circuit. Experiments are carried out for validating the feasibility of the BECC toward future versatile engineering designs.