Response and Control of Individual Stacks of a Multi-Stack Piezoelectric Actuator for DC Fast Disconnect Switches

Hybrid circuit breakers (HCBs) are a potential protection solution for medium-voltage direct current (MVDC) power systems. These HCBs require fast mechanical switches (FMS) with efficient actuators. Using piezoelectric actuators in an FMS has been a topic of discussion in previous research works in this area. Piezoelectric actuators can enable fast, reliable, and controllable actuation for HCB applications. Achieving a short actuation time and reduced overshoot in the displacement curve is necessary to ensure that the circuit breaker does not need to dissipate a large amount of energy, to minimize the peak fault current, and to reduce the probability of restriking. Traditionally, each stack of a multi-stack actuator is manufactured to receive the exact same input voltage signal. This work aims to explore the concept of controlling individual stacks of a piezoelectric actuator to achieve an optimal response. The hypothesis and theory behind controlling individual stacks is highlighted. A circuit to implement individual control is discussed and experimental results showing the need for individual stack control are analysed.