An innovative natural air-cooling system technique for temperature-rise suppression on the permanent magnet synchronous machines

[Display omitted] •An innovative speed-variable FE model of PMSM with radial and circumferential airflow ducts is analyzed.•An in-core circular natural cooling system is proposed for broad types of external sources.•The model is verified through the heat transfer calculation at each heat flux sensor, along with experimental investigation.•The Computational fluid dynamics analysis evaluated the heat transfer at a number of specific positions of heat flux sensors on the cores.•Finally, the temperature-rise is suppressed by 11°C without failing in the efficiency. This paper investigates a three-dimensional finite-element (3D-FEA) thermal analysis based on an embedded cooling system with various number of ducts for the outer-rotor permanent magnet synchronous machines (PMSMs). The segmented stator core due to closed-slot topology is the reason of a high temperature-rise at this core. The application-oriented study is aimed to reduce temperature-rise of the conventional model at the stator core via radial and circumferential airflow ducts. A temperature distribution, and heat transfer comparison among all FE models such as conventional, two and four ducts in-core natural cooling systems will be comprehensively presented through freezing the electromagnetic performance. The alternative models using FEA, and computational fluid dynamic (CFD) are experimentally verified the innovative technique, in which the generator is operated by a vertical axis twisted savonius type wind turbine (VAWT).