A lightweight electromagnetic actuator for high voltage DC power grids

Abstract High voltage direct current (HVDC) is a highly efficient alternative for transmitting large amounts of electricity over long distances, and holds great potential to enable stronger, smarter and greener power grids based on renewable energy sources. However, efficient management of HVDC grids calls for robust switchgear technology, which is still under development. In particular, fast switching speed is paramount to limit peak fault current and energy loss in hybrid HVDC circuit breakers (HHBs). In such breakers, the switching speed depends on the mass of the moving parts. Therefore, lightweight is paramount. Here, a lightweight electromagnetic actuator for HHBs is conceived using Design for Additive Manufacturing (DfAM) tools, including topology optimization and free-shape design. A prototype is manufactured by selective laser melting (SLM) of alloy Ti-6Al-4V. The prototype weighs 25% less than the actuator designed and manufactured using traditional methods (i.e. CAD, milling) and materials (i.e. Al alloys). The performance of the actuator in service is simulated by transient modal mechanical analyses using finite element methods. The results show that the high strength of the material selected, combined with the bionic geometry designed and the resulting lightweight, allow the actuator to withstand the extreme accelerations of the HHB (3000 g) without yielding, enabling ultra-fast switching –namely, below 1 ms.