Characterization of two-axis equivalent circuit model of PM-BLDC motor by FEA

It was shown recently that the state-variables averaging method is applicable to permanent magnet brushless DC (PM-BLDC) motors and yields an equivalent circuit model analogous to that of the PM-BLAC motor. Calculation of the averaged reference frame voltages is difficult, but is crucial for the modeling accuracy. The identification of the averaged (dq) voltages must be carried out using detailed analysis. Here it is done using a dynamic finite element model of an inverter-driven motor. It is shown that these voltages can be modeled by quadratic functions of rotor speed. This lays down the basis for experiment to perform in order to identify these variations. The results obtained from the circuit model compare well with those obtained from the dynamic finite element analysis. Some results from physical model are given.