Advanced Energy Industries, Inc.
VIRTUAL RESISTIVE LOAD IN FEEDBACK LOOP DRIVING A PIEZOELECTRIC ACTUATOR

Abstract:

A virtual resistive load feedback circuit for driving a piezoelectric actuator is provided that accounts for a hysteresis error and drift within the movement of the actuator. The circuit may include a voltage divider and charge divider. A voltage monitor signal corresponding to a voltage of a driver signal and a current monitor signal corresponding to a current provided to the amplifier are combined by an operational amplifier and include electrical characteristics of the actuator such that the circuit approximates a virtual load across the actuator. A feedback portion of the operational amplifier may include a resistor and capacitor connected in parallel to provide the voltage and charge divide functions. The use of the virtual resistive circuit allows for the piezoelectric actuator to be ground referenced, with no external components connected directly to the actuator while gaining the feedback effect to counter the hysteresis and drifts errors of the actuator.