Design of a Dual-Stage Driving Circuit for Piezoelectric-Actuated Micropump With Bimorph Transducer

Abstract

Piezoelectric micropumps assembled with micro-electro-mechanical systems (MEMS) technology have been introduced in small-scale flow rate applications. The micropumps can be used in portable devices, where the power consumption of the whole driving system should be considered. Designing a driving circuit with compact size and high conversion efficiency for such a piezoelectric micropump is necessary to boost it for being used in portable devices. This article presents a dual-stage driving circuit for piezoelectric micropump with a bimorph transducer. An interleaved boost converter cascade with a modified half-bridge driving circuit is implemented. The interleaved boost converter working at 50% fixed duty mode can generate a high voltage, and the modified driving circuit can use a LC network to simultaneously drive the bimorph piezoelectric transducer (PZT) and recover the charge stored in the bimorph PZT. Compared with the traditional driving method, the proposed charge-recovery driving method has fewer electronic components and simple control scheme, the energy loss of the circuit is reduced by 49%, 50%, and 55% at 40 Hz, 80 Hz, and 120 Hz, respectively. The piezoelectric micropump obtains an extra flow rate and a maximum of 12% increase in mechanical power.