Efficient and Reliable Electrical Connections for High-Power Applications With SMA-Actuated Zero Insertion Force Connectors

Abstract The electrification of mobility has been steadily increasing in recent decades. As a result, the demands on connector systems for fast-charging battery electric vehicles (EVs) are increasing. Zero insertion force (ZIF) connectors hold considerable promise due to their ability to facilitate minimal insertion and withdrawal forces during mating, while maintaining high contact normal forces (CNF) for a secure electrical connection during power transmission. The increasing charging currents for high-power charging of EVs requires the optimization of existing electrical connection systems and the development of innovative solutions. The increased charging currents are exacerbating thermal problems at the socket-pin interface, which are currently being addressed with liquid cooling systems. An energy-efficient strategy for reducing electrical contact resistance (ECR) involves increasing CNF, though this leads to greater mating forces and accelerated wear. To address this issue, this paper explores the use of shape memory alloy (SMA) actuated ZIF connectors to achieve optimal contact mechanics without compromising reliability and durability. A structured, multi-step development process creates a high-current application concept aligned with Combined Charging System Type 2 (CCS2) requirements. Finite Element (FE) simulations validate the design’s feasibility and mechanical performance, offering insights into stress distribution, deformation, and SMA actuation efficiency. Two functional prototypes are fabricated and experimentally tested on ECR and mating forces using a custom-built test bench. Results demonstrate that the SMA-driven ZIF connector reduces mating forces by up to 72% compared to commercial systems while maintaining stable electrical connections. A second model is developed for direct CCS2 integration, facilitating increased CNF without raising mating forces. This study underscores the potential of ZIF connectors in fast-charging infrastructure for electromobility, merging ZIF and SMA technologies to create a reliable, user-friendly high-current connector.