Design and Experimental Validation of a High-Performance Electromagnetic Contactor for Harsh Environments

This paper presents the design and validation of a compact high-performance electromagnetic contactor for high-current direct current (DC) applications in harsh environments, with particular focus on cold cranking of heavy-duty vehicles. Cold cranking imposes stringent requirements due to elevated current demand, reduced battery capability, and tight actuation timing constraints. To address these challenges, a systematic design methodology is used, combining analytical magnetic circuit modelling, finite element analysis (FEA), and experimental validation. The study investigates key design aspects, including magnetic core selection, coil sizing, and contact geometry, under strict dimensional and thermal constraints. An analytical model is first used to predict electromagnetic force and current dynamics, and is subsequently validated using FEA. A prototype contactor is then constructed and experimentally tested to verify the predicted performance. Results show strong agreement between analytical, numerical, and experimental approaches, with force prediction errors below 10% across the operating range. The findings confirm the suitability of simplified analytical models for initial design stages and highlight the impact of material selection and inductance on actuation speed. The proposed workflow provides practical design guidelines for developing compact, efficient, and reliable contactors for high-current automotive applications operating under extreme conditions.