Analysis, simulation and microprocessor implementation of a current profiling scheme for field-weakening applications and torque ripple control in brushless DC motors

A method of current profiling based on the instantaneous power theory is used as an alternative means of providing field weakening in brushless DC motors. The overall advantage of this method is the enhancement of field-weakening performance of the drive and a reduction in torque ripple compared with that obtained with rectangular current excitation. A closed loop PI torque controller is incorporated into the scheme to provide torque control, and this is also shown to keep torque ripple under control throughout the field-weakening range