CONCLUSION
This paper discusses the speed control of position
sensorless brushless DC motor in which the position of the
rotor at the start of the motor is determined based on the
motor-phase saturation inductance change and after sufficient
back-EMF is generated, the rotor position is determined by
the state of back-EMF. The circuit has been constructed and
simulated using Matlab-Simulink and desired results were
obtained. The plots showing the phase voltage, back-EMF
and the motor RPM were analysed. Compared to the
conventional speed controllers this is cost effective and can be
custom made for specific applications.