Important calculations: sinusoidal operation

Off-resonance, a piezoelectric actuator is mostly capacitive, so the supply current can be estimated using the simplified formula below.

With:

f: operating frequency

C: apparent piezo capacitance

Vp-p: peak to peak voltage

Note that the apparent capacitance increases with the amplitude of the input signal. At full amplitude, current draw can be 40% higher than calculated using small signal capacitance.

Around resonance, in the case of an actuator providing high coupling, the actuator deviates from the capacitive behaviour; therefore, the other parameters in the model have to be taken into account.

In dynamic mode, inertial forces due to the fast acceleration of a mass are dependent on frequency as seen in the formula below.

With:

f: operating frequency

meff: equivalent moving mass

Δ: peak to peak displacement

Calculations - stress limit

This equation can be used as a first approach to estimate the dynamic stress on the actuator due to the acceleration. In more complex cases, for example in the case of high damping, it is recommended to use a more detailed model for the estimation of the maximum stress.