Magnetic and Thermal Modelling of Hollow Conductors for Improved Cooling and Force Density of Coreless Linear Motors

The feasibility of using direct liquid cooled hollow conductors in coreless linear motors is evaluated in this paper. Hollow conductors with direct water cooling can significantly improve the heat dissipation inside electrical machines. Two different concepts for winding coils from hollow conductors are considered. A moving coil and moving magnet topology are analysed. The magnetic models, based on harmonic modelling or a surface charge model, and a 3D thermal equivalent circuit (TEC) model are used to model the coils. The model is validated via a FEM analysis. A coupled electromagnetic-thermal analysis is implemented. Further, the proposed motor with hollow conductors is compared to a state-of-the-art direct liquid cooled linear motor. The proposed topology with hollow conductors shows an improvement of the cooling performance, compared to the state-of-the-art motor. However, a much higher current is required to achieve a similar force profile.