Modeling and simulation of permanent magnet brushless DC motor allowing for damping windings

The permanent magnet brushless DC motor (PMBDCM) has a non-sinusoidal back electromotive force (EMF) and requires rectangular stator currents to produce constant and more powerful electromagnetic torque. Sometimes, to smooth the commutation of power electronics, damping windings has to be mounted on the rotor, all these features make the PMBDCM analysis much more complicated. To solve this problem, a detailed mathematical model of PMBDCM allowing for damping windings were presented in this paper, during which phase parameters were adopted and flux density distribution was taken as a basic element As expected, it was difficult to disclose influence of damping windings in detailed model. Thereby, a simplified model was then developed to surmount the limitation. Further investigation showed that the relations of state variables could be clarified, and the discount of phase parameters was similar to that of d-q parameters, when resistance of the damping windings could be neglected. Finally, comparative analysis of the two models was carried out under Matlab/Simulink platform, and the results indicated that there was no essential difference between detailed model and simplified model, and the simplified model was more convenience to describe the performance of PMBDCM under proper condition. The analysis of this paper would give reference to the design and control of PMBDCM.