Nonlinear Dynamic Model of PMBLDC Motor Considering Core Losses

The phase variable model is used commonly when simulating a motor drive system with a three-phase permanent magnet brushless dc (PMBLDC) motor. The phase variable model neglects core losses and this affects its accuracy when modeling fractional-slot machines. The inaccuracy of phase variable model of fractional-slot machines can be attributed to considerable armature flux harmonics, which causes an increased core loss. This study proposes a nonlinear phase variable model of PMBLDC motor that considers the core losses induced in the stator and the rotor. The core-loss model is developed based on the detailed analysis of the flux path and the variation of flux in different components of the machine. A prototype of fractional slot axial flux PMBLDC in-wheel motor is used to assess the proposed nonlinear dynamic model.