Design Considerations for Fast Mechanical Switches Using Piezoelectric Actuators

Hybrid circuit breakers (HCB) have been proposed as protection devices for multi-terminal DC power systems. The HCB consists of a fast mechanical switch (FMS), which carries the nominal current, in parallel with a semiconductor switch, which breaks the fault current. While most of the proposed FMS prototypes are based on Thomson coil actuators, FMS based on piezoelectric actuators have a faster response time and better stroke control. However, the contact separation and contact forces in piezoelectric FMS are an order of magnitude lower than Thomson coil-based FMS. This paper investigates the design considerations for FMS using piezoelectric actuators, i.e. the trade-offs between the blocked force, stroke, response time, and dimensions of the actuator using finite element model and spring mass damper models. The results are expected to guide the development of future versions of piezoelectrically actuated FMS.