A charge controller for linear operation of a piezoelectric stack actuator

This paper examines the position control problem of piezoelectric stack actuators and presents a method for overcoming the hysteresis nonlinearity between the applied voltage and the actuator displacement. An inverting charge control circuit is implemented to linearize the stack actuator movement by taking advantage of the linear relationship between charge and displacement. The charge control feedback loop is analyzed in detail. It incorporates an operational amplifier to provide high loop gain, a high-voltage amplifier (HVA) to drive the stack actuator, and a lead compensator to ensure stability. Experiments were conducted to compare the responses of the stack actuator under voltage and charge control. The experimental data show that the charge control provides linear actuator operation from 1 Hz-10 Hz over approximately 35% of the actuator operating range, and from 1 Hz-20 Hz over approximately 19% of the operating range.