Two-dimensional semi-analytical steady-state thermal model of permanent magnet machines with water-cooled structure

In this article, a thermal semi-analytical model (T-SAM) considering water-cooled structure is proposed for the first time, which is based on harmonic modeling (HM) technology and takes into account material inhomogeneities, that is, different thermal conductivities of the motor parts. Then, the calculation process of steady-state heat distribution of the water-cooled permanent magnet (PM) motor is proposed by combining with the electromagnetic finite element method (FEM) and computational fluid dynamic (CFD). The results obtained from thermal FEM serve as a reference for comparison with the outcomes of T-SAM. Remarkably, T-SAM exhibits a high concordance with thermal FEM and a noteworthy reduction in computational time—only a quarter of that required by thermal FEM. Validation of T-SAM is further demonstrated through experimental results obtained from a prototype with a surface-attached cooling structure (SACS). Notably, the T-SAM has potential application for other types of PM electrical motors, such as slotted surface-mounted, slotted surface–inset or slotted spoke-type PM motors.