Charge Drive Used For High-speed Piezoelectric Drive Stages

Piezoelectric actuators have been extensively applied in various micro-drive stages due to their compact size,high stiffness and fast response.With the development of science and technology,the requirement for the bandwidth of the drive platform is higher and higher.During the process of designing high-speed drive stages,there always exists a problem that the whole structural resonance of the platform usually occurs at a lower frequency compared to the resonance of the actuator itself.To remove the effect of the low frequency mode of the supporting structure on the performance of the actuator,the inertial force transmitted to the base needs to be counterbalanced in the course of actuation.For the novel asymmetric drive configuration,due to the existence of the dynamic hysteresis in piezoelectric materials,the effect of counterbalancing the inertial force can be undesirable if the voltage drive is used to solve the above problem.In this paper,instead of the traditional voltage drive,the charge drive is introduced.The main contents of the paper are as follows:1)The hysteresis of the piezostack under different excitation frequencies was measured,and the results show that the higher the frequency was,the larger the hysteresis exhibited.2)The residual inertial force caused by the hysteresis of the piezoelectric material in the asymmetric structure was analyzed theoretically.Through modeling the hysteresis curve of the piezostacks,the residual inertial force of the asymmetric actuator during the driving process was calculated,and the results show that it was proportional to the square of the frequency,which demonstrates the necessity of using linear driving methods at high frequency theoretically.3)Comparison experiments were conducted on the asymmetric structure of the cantilever.The asymmetric actuator comprised of two identical piezostacks was installed on the free end of the cantilever.The piezostacks were actuated by the voltage drive and the charge drive respectively,and the vibration amplitude of the free end of the cantilever was detected,which indicated the magnitude of the residual inertial force transmitted to the cantilever.The experimental results show that the vibration amplitude of the cantilever by using the charge drive was much smaller than that obtained by the voltage drive,which demonstrated that the charge drive is more significant than the voltage drive.4)The charge drive was applied in a dual-stage piezostack.It was proven through the experiment that the bandwidth of the high-speed stage would be restricted by the low frequency mode of the entire big piezostack without counterbalancing the inertial force transmitted to the low-speed stage.The comparison experiments of using the voltage drive and the charge drive were conducted on the high-speed stage,which demonstrated the superiority of the charge drive in suppressing the inertial force of the high-speed stage to the voltage drive.A second-order low-pass filter and a subtraction circuit were designed to realize the connection of the high-speed stage with the low-speed stage.The frequency response of the dual-stage piezostack in the frequency range from 1 kHz to 60 kHz was measured.The experimental result shows that the frequency response curve of the dual-stage piezostack was relatively flat in the measurement interval,and the large resonance peak of the low-speed stage was well suppressed by the low-pass filter.