  This paper presents an algebraic technique to compute the maximum time-delay
that can be accepted in the control loop of a Brushless DC Motor (BLDCM) speed
controller before the closed loop response becomes unstable. Using a recently
proposed time-delay stability analysis methodology, we derive accurate
stability conditions for the BLDCM speed controller. The results of applying
the new method show that tuning the PI controller for very fast response in the
order of magnitude of the BLDCM mechanical time constant cause the time-delay
to significantly affect the system stability.
