Amplified piezo actuator

Fig. 6.19. Mechanical displacement amplification, a Implementation with elastic hinges, b moonie transducer, c amplified piezo actuator, APA (derived from [5])...

Several concepts of quasistatic motors exists as well. One of them is using at least one pair of amplified piezo actuators. The basic working principle of the Cedrat stepping piezomotor concept is illustrated through a simplified linear model based on a pair of APAs (Fig. 6.23). The displacements and forces produced by the APAs are transferred to the slider or the rotor by... 

Provided the self heating and the tensile forces are prevented, the amplified piezo actuators do not show any fatigue effect. For example, a test of an amplified piezo actuator imder full scale pulse (0... 150 V) with a driving frequency of 600 Hz, had a continuous duration of 6 months. It shows the ability of the actuator to operate for 10 ° cycles. 

The thermo-mechanics may be an issue in the case of a fine positioning application over a large range of temperature the PZT in the multilayer technique display various coefficient of thermal expansion, CTE (as a function of some construction details). Standard amplified piezo actuators displays fairly large CTE due to some thermal mismatch between the piezo component and the shell material. There are some possibilities to cancel this CTE in the application ... 

One also checks that the amplified piezo actuator is able to counteract acceleration perturbations in the order of 20 to 40 m under these levels which are largely representative of spacecraft microvibrations, the studied system remains linear. 

Increasing the amplifier output power naturally raises the question regarding the degree of efficiency of energy transfer between the controller and the converter. The example of the harmonically operated piezo actuator leads us to the following universal approach for improving the degree of efficiency. 

Fig. 6.146. Class C amplifier with piezo actuator as a load, a FuU charging and...

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