ReFreeDrive - Deliverable 3.3: CR-IM Thermal Design Report for Inner and Outer Rotor Motor

The present report covers the thermal design analysis for Copper Rotor Induction Motors (CR-IM) with Inner Rotor (IR) for traction systems in Electric Drive Technologies (EDT). This is one of the technical solutions investigated by ReFreeDrive project. In Work Package 3, Inner Rotor (IR) and Outer Rotor (OR) induction motors configurations with cage built using diecasted or fabricated rotor technologies are proposed. When IR topology is used in combination with high rotational speed, i.e. 20000rpm, the torque density and the specific power are increased. Similarly, an OR topology can be used at lower rotational speed, i.e. 18000rpm, the increase in torque density and specific power is guaranteed due to the inherent higher diameter in the motor airgap. This report is divided in four main sections: Section 1 (Introduction). The optimisation and scalability principles are briefly discussed. Section 2 (Electromagnetic Design) describes the Key Performance Indicators (KPIs) and the boundary conditions. A comparison between the reference CR-IM inner rotor electromagnetic design and final optimised design is presented. The design analysis is based on a hybrid 2D Finite-Element Analysis (FEA) method and analytical magnetic equivalent circuit. Section 3 (Mechanical Design) contains the stress and modal analysis results, that demonstrate the feasibility of the CR-IM inner rotor topology. Section 4 (Thermal Design) describes the performance of the CR-IM inner rotor optimised design using two cooling systems using water-ethylene glycol mixture of automotive transmission fluid as heat extraction fluids