Current control of piezoelectric actuators with power loss compensation

This paper introduces a feedforward charge control method, which controls the displacement by the amount of current fed to the actuator. The method includes estimation and compensation of the power losses occurring in the actuator. Power losses are estimated with an experimentally created dynamic model, that does not include the load and self heating effects. Even though the method is based on feedforward control, the amount of current is controlled in closed loop, using a precise current measurement and a PID controller. Experiments with a piezo bender show promising results; the hysteresis was nearly reduced to one part in twenty and drift to one part in ten, in comparison to open-loop voltage control. The proposed method can predict the power losses quite accurately and can therefore be utilized not only for the control but also for power estimation in applications where power consumption is critical.