A phase variable model of brushless dc motors based on finite element analysis and its coupling with external circuits

This paper presents a fast and accurate brushless dc motor (BLDC) phase variable model for drive system simulations. The developed model was built based on nonlinear transient finite-element analysis to obtain the inductances, back electromotive force as well as the cogging torque. The model was implemented in a Simulink environment through the creation of an adjustable inductance component to account for the dependence of inductances on rotor position. Since no dq model for BLDC actually exists, the significance of this work is that it provides an accurate equivalent circuit model of BLDC motors for utilization in simulation environments. Using the developed model, the sensorless control and the torque ripple control issues were investigated and the simulation results show its practical effectiveness.