Thermal Analysis of a Multi-Three-Phase PM Motor in Nominal, Overload and Post-Fault Operations

Electric motors designed with double and triple three-phase winding are solutions to improve the fault tolerance of the electric motor drives requiring to continue to operate even under partial fault conditions. The stator winding is split into two winding subsets, each of them connected to standard three-phase inverter. In the event of a fault, one of the two subsets is simply disconnected and the machine can continue to operate at a reduced power or with some overload of the remaining winding subset. This paper deals with a thermal analysis of a surface-mounted permanent magnet (SPM) motor under various operating conditions, designed for the rotors of a helicopter tail. The behaviour of motor is investigated when all the coils are supplied (healthy condition) and when only a portion of the machine winding is supplied, so as to verify which is the thermal limit for such operating conditions.