Liquid cooling of stacked piezoelectric actuators for high-power operation

Abstract

In this article, we propose a liquid cooling solution to reduce the temperature rise and expand the working range of stacked piezoelectric actuators (PEAs) for high-frequency and large-stroke operation. Based on an analysis and preliminary testing of the power dissipation and temperature rise, a specific liquid cooling solution for a single PEA is designed and its effectiveness is verified through experiments. To incorporate liquid cooling into a high-bandwidth fast steering mirror (FSM) system driven by PEAs, a compact and self-contained cooling unit is proposed and evaluated. Subsequent experimental results validate its effectiveness, but also show some deficiencies for this cooling solution. To further improve the cooling efficiency, two new coolants are adopted based on an analysis of the heat transfer coefficient, and a suitable direct liquid cooling solution is established. Experimental results show that the cooled PEA can operate continuously over 8 kHz with a peak-to-peak voltage of 100 V whilst its maximum temperature is restricted to around 40 ○C using this cooling solution. The reliability and coolant insulation properties have been verified by a 3-month long continuously operational test.