Abstract:
This paper presents an improved phase variable model and field-circuit coupling method to
evaluate the comprehensive performance of brushless DC (BLDC) motors in both steady and
dynamic conditions. In the proposed model, major motor parameters such as inductances, back
electromotive force and cogging torque are obtained based on time-stepping nonlinear finite
element analyses. The phase variable model is built and implemented in the
MATLAB/Simulink through look-up tables to decide the rotor position dependence of the
parameters. Furthermore, a mathematical method is proposed for determining the central point
voltage of the Y-connected three phase windings, so that the model can obtain the input voltages
of both energized and non-energized phase windings, and can be directly applied to BLDC
motors. By using the developed model, the comprehensive performance of a high-speed surface
mounted permanent magnet BLDC motor prototype is investigated.
