Thermal Parametric Sensitivity Analysis of an IPMSM With Multi Three-Phase Sector Windings Topology Under Normal, Partial and Partial Overload Operating Conditions

Electrical machines designed with multiple three-phase winding sets are widely proposed for high current and high power applications. Moreover, they are considered the preferred choice for fault-tolerant applications due to their redundant structure enabling the machine to work under partial operating conditions. However, under partial operating conditions, when a single or multiple three-phase winding sets are disconnected, the normal operating behavior of the machine is degraded, enabling the machine to work with a reduced level of efficiency. Under this condition, the machine's healthy three-phase winding sets can be overloaded to keep the machine operating with the same torque level as under the healthy condition. It increases the risk of three-phase winding sets insulation failure, which may ultimately result in reducing the machine life span, reliability or even result in the machine's thermal failure. This paper presents the thermal analysis for a multi three-phase sector winding machine having a water-jacket cooling system. A coupled electromagnetic FEA and thermal analysis is presented by first investigating the machines electromagnetic performance and then coupling it to the thermal model (Lumped parameter thermal network) for accurate temperature prediction. Furthermore, a parametric sensitivity analysis is presented under three-phase winding sets normal, partial and partial overload conditions. The different thermal design variables for the parametric sensitivity analysis are carefully chosen, and the thermal behavior of the prototype machine is fully investigated. The detailed parametric sensitivity analysis leads to an optimized design model of the prototype machine with improved thermal behavior, particularly under partial overload operating conditions.