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Piezo Engineering Tutorial
Figure C-10:
Maximum sinusoidal peak-peak voltage of a given amplifier with various piezo
Consider the following additional examples of voltage, power and current calculations for selecting a piezo
stage:
Example 1
A 100 μm pk-pk sinusoidal motion at 35 Hz is desired from a stage with a piezo capacitance of 5 μF. The
selected amplifier has a semi-bipolar supply of +150 V/-30V, a 300 mA peak current rating and a 130 mA
continuous current rating. Will this amplifier be able to supply enough current to perform this move?
Example 1 Calculations
Assume that to perform the 100 μm pk-pk motion, the full voltage range is used and at mid-travel, the voltage
is at the mean of the rail voltages (e.g., 60 V). Therefore:
Recalling that the capacitance can increase by as much as 60% for large signal conditions, the capacitance
used for this calculation is assumed to be 5 μF • 1.6 = 8 μF. The current is then calculated as:
Therefore, i
= 158 mA and i
pk
In this example, the peak and continuous currents are all less than the amplifier rating. Therefore, this
amplifier is capable of supplying the necessary current to perform the desired move profile.
58
stack capacitances
= 112 mA. The voltage and current waveforms are shown in
rms
Appendix C
QNP3 Hardware Manual
Figure
www.aerotech.com
C-11.
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