Abstract
Energy expressions for a piezoelectric actuator coupled to a resonant mechanical load are analyzed for the purpose of determining the energy requirements of controlled structures. The analysis illustrates that the energy dissipated within the linear amplifier is a function of four parameters: the driving frequency, the piezoelectric coupling coefficient, the relative stiffness of the actuator and load, and the amplifier supply voltage. The piezoelectric actuator and the mechanical load are assumed to be lossless to highlight the relationship between energy dissipated within the amplifier and the energy stored in the actuator. For a specific frequency, the minimum energy dissipation within the amplifier is equal to twice the stored electrical energy in the piezoelectric when the amplifier voltage is equal to the driving voltage of the actuator. Additional energy is dissipated within the amplifier when the supply voltage is greater than the driving voltage. In the case when the actuator displacement is constant as a function of frequency, the energy dissipation in the amplifier decreases near the resonance of the coupled electromechanical system and reaches a minimum when the piezoelectric charge due to the applied voltage is equal and opposite to the charge induced by the load. The steadystate amplitude of the charge, and hence the actuator current, is equal to zero at this frequency. The results illustrate that energy dissipation is minimized when the actuator is operated at near the resonance or antiresonance of the coupled electromechanical system.
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