Thermal Analysis of the Solid-Rotor Permanent Magnet Synchronous Motors with Air-cooled Hybrid Ventilation Systems

The rotor temperature rise of high voltage line start solid rotor permanent magnet synchronous motors (HVLSSR-PMSMs) may be too high while operating, which properly cause thermal demagnetization for permanent magnets. Therefore, it is necessary to perform the thermal investigation on HVLSSR-PMSM. In this paper, a 315kW, 6kV HVLSSR-PMSM with the air-cooled hybrid ventilation system is studied in the view of thermal phase. The losses, obtained from the electromagnetic analyses, are applied to the thermal investigation as the distributed heat sources. Whilst, both the mathematical and the geometrical models are proposed for the three-dimensional (3-D) fluid- thermal coupled investigation, from which the fluid velocity and the temperature in motor different components are determined. While with the hybrid ventilation system, temperatures in motor different components reduce obviously comparing with those in motor with the original cooling system. The experimental investigations are performed on prototypes in both cases, which verify the calculation results, and approve the effectiveness of the proposed hybrid air cooling system as well.