Design and simulation of advanced charge recovery piezoactuator drivers

Abstract

The German Artificial Sphincter System project aims at the development of an implantable sphincter prosthesis driven by a piezoelectrically actuated micropump. The system has been designed to be fully implantable, i.e. the power supply is provided by a rechargeable lithium polymer battery. In order to provide sufficient battery duration and to limit battery dimensions, special effort has to be made to minimize power consumption of the whole system and, in particular, of the piezoactuator driver circuitry. Inductive charge recovery can be used to recover part of the charge stored within the actuator. We are going to present a simplified inductor-based circuit capable of voltage inversion across the actuator without the need of an additional negative voltage source. The dimension of the inductors required for such a concept is nevertheless significant. We therefore present a novel alternative concept, called direct switching, where the equivalent capacitance of the actuator is charged directly by a step-up converter and discharged by a step-down converter. We achieved superior performance compared to a simple inductor-based driver with the advantage of using small-size chip inductors. As a term of comparison, the performance of the aforementioned drivers is compared to a conventional driver that does not implement any charge recovery technique. With our design we have been able to achieve more than 50% reduction in power consumption compared to the simplest conventional driver. The new direct switching driver performs 15% better than an inductor-based driver. A novel, whole-system SPICE simulation is presented, where both the driving circuit and the piezoactuator are modeled making use of advanced nonlinear models. Such a simulation is a precious tool to design and optimize piezoactuator drivers.

Design and analysis of charge-recovery driving circuits for portable peristaltic micropumps with piezoelectric actuators

“…However, the practical implementation may be limited by the timing control and the operating voltage. The direct switching charge recovery circuit has lower power consumption than the inductance-based method [25]. According to the measured results in Ref.…”

“…According to the measured results in Ref. [25], the direct switching method had a 33.3% performance higher than the inductance-based method when offering the same energy. Furthermore, the effective cooperation of industry will make the technology of energy storage capacitor easier, cheaper, and smaller than a high quality factor inductor of the inductance-based method.…”

“…There are different kinds of charge recovery circuit, such as inductance-based [16,24] and direct switching [25]. In the inductance-based method, the key point is the LC resonance by an external inductor and the parasitic-capacitance of piezoelectricactuator.…”

A New Concept of a Drug Delivery System with Improved Precision and Patient Safety Features

“…This can be achieved with multilayer piezoactuators. The functionality of multilayer piezoelectrically driven micropumps is shown in [19,20]. With the reduction of the applied voltage almost the same performance can be expected.…”

Design and Experimental Analysis of Charge Recovery for Piezoelectric Fan

“…The charge recovery strategy can theoretically recover all the energy of the piezoelectric element and greatly improve the energy recovery efficiency of the circuit. Biancuzzi [32,33] proposed not only an inductor-based circuit capable of voltage inversion across the actuator without additional negative voltage sources, but also a direct switch alternative concept using small chip inductors. Xu et al [34] designed and implemented a miniaturized, lightweight circuit topology with an efficiency of 84.6%, indicating that the circuit can be applied to micro mobile robots driven by piezoelectric actuators.…”