Automatic biasing circuit for driving piezoelectric bimorph actuators safely and efficiently

This paper proposes a simple circuit configuration for driving piezoelectric bimorph actuators in a high efficient way but not depolarizing the piezoceramics. Different from generating the bias voltages via some direct voltage converters, here two bias voltages are obtained from the driving voltage itself directly through a simple circuit. The values of the bias voltages can be adjusted from zero to the maximum value or minimum value of the driving voltage. A parallel bimorph can be actuated by applying the bias voltages to its top and bottom electrodes and the alternating voltage to the intermediate electrode. Experiments show that this method is effective when the actuating frequency should be high enough so that the bias voltages vary small.