On the Design of a Fast Mechanical Switch-Based Amplified Piezoelectric Actuator

Fast mechanical switches (FMSs) play a significant role in the control and protection of dc power systems. The need for fast response, rapid actuating, and compact size actuators is the key enabler for the development of future dc grids. Regardless of their stroke limitation, piezoelectric actuators are fast, very controllable, and highly reliable. They can fit in FMSs or disconnectors designed for hybrid circuit breakers (HCBs). In this study, a fast-mechanical switch driven by an amplified piezoelectric actuator (APA) is proposed, analyzed, fabricated, and tested. The coupling dynamics of the piezo-based switch are formulated based on the electrodynamic model. The influence of key structural parameters on the switch characteristics was calculated, and the static and dynamic performances were obtained. According to the calculation, a prototype was constructed, and the travel of the proposed switch was experimentally validated. Furthermore, operational factors that influence the switch were investigated. Finally, the switch was insulated in a vacuum chamber and integrated as a fast-mechanical switch in a constructed HCB platform. The proposed switch achieved an accumulated gap of 0.95 mm in 1 ms and interrupted a dc power of 220 V/100 A and 500 V/20 A within 1.2 ± 0.2 ms.