Nonlinear Technique for Energy Exchange Optimization in Piezoelectric Actuators

Applications of piezoelectric actuators have increased dramatically during the past few decades. However, the capacitive nature of such devices makes their use delicate, especially in terms of power supply, as the instantaneous power may be much greater than the average effective power. This paper places particular focus on the description of a nonlinear technique for piezoelectric actuator control. This technique enables us to significantly increase the energy transfer efficiency of the device by reducing the reactive part of the power. Such an approach has the inverse effect of the well-known synchronized switch damping technique developed to reduce vibrations in smart structures. The proposed solution consists in disconnecting the driving voltage source from the piezoelectric element and switching the system to a passive electrical network at each occurrence of a voltage extremum. This switching strategy is designed to annihilate the reactive energy supplied by the voltage source and to decrease the active energy while ensuring a constant output power. Suppressing the reactive energy is particularly interesting for limiting the dimensions and energy requirements of power supplies. Compared to classical methods, the direct supply of both simulations and experimental validations has demonstrated the effectiveness of the proposed technique for eliminating all of the reactive energy and reducing the active power at frequencies close to the resonant one, while maintaining similar mechanical performances.