A novel strategy using H infinity theory with optimum weight selection for the robust control of sensorless brushless DC motor

A direct implementation of H infinity theory for the robust control of a sensorless brushless direct current motor is proposed in this paper. This provides a better dynamic performance compared to conventional Proportional Integral controller and simulation results of the comparison are presented. For the proper weight selection of H infinity controller, particle swarm optimization technique is employed which results in small sensitivity function in low frequency region and small complementary sensitivity function in high frequency region which is the trade off required for good reference tracking, disturbance rejection, being insensitive to modelling errors and noise. The reduced torque ripples along with improved rise time and steady state error by 0.6% and 25% respectively results in low noise, less vibration and better robust performance irrespective of external disturbances compared to PI controller.