1Efficient Charge Recovery Method for Driving Piezoelectric Actuators with Quasi-Square Waves

In this paper, an efficient charge recovery method for driving piezoelectric actuators with low fre-quency square waves in low power applications such as mobile microrobots is investigated. Efficiency issues related to periodic mechanical work of the actuators and the relationship among the driving elec-tronics efficiency, the piezoelectric coupling factor, and the actuator energy transmission coefficient are discussed. The proposed charge recovery method exploiting the energy transfer between an inductor and a general capacitive load is compared with existing techniques which lead to inherent inefficien-cies. A charge recovery method is then applied to piezoelectric actuators, especially to bimorph ones. Unitary efficiency can be theoretically obtained for purely capacitive loads while intrinsic losses such as hysteresis necessarily lower the efficiency. In order to show the validity of the method, a prototype driving electronics consisting of an extended H-bridge is constructed and tested by experiments and simulations. Preliminary results show that 75 % of charge (i.e. more than 56 % of energy) can be recovered for bending actuators such as bimorphs without any component optimization at low fields. Piezoelectric actuators are widely used in smart structure applications due to their high bandwidth