Normally, the BLDC motor drives a sensitive load which is severely influenced by such disturbances. The main aim of this work is to investigate the performance of BLDC motors when they are tied to weak grids. Thus, this paper presents a study on the performance of the BLDC motor under disturbed utility conditions and implements an efficient solution in order to guarantee a soft operation in the case that a BLDC drives a sensitive load. A buck-boost DC converter is merged with the BLDC drive inverter in order to be able to mitigate voltage dips as well as voltage swells. A short interruption of one or two phases of the grid voltage can also be mitigated.
The BLDC motor is controlled via cascade PI-controller layout that has an outer loop for the speed control and inner loop for the DC voltage control. The PI controllers' gains are optimized by using the ant-colony optimization technique and then implemented in a simulation model using MATLAB/SIMULINK. Six cases of disturbances have been simulated including balanced and unbalanced dips, swells and short interruption of one or two phases of the grid. Simulation results with various disturbances show the ability of the proposed controller to mitigate the grid disturbances with good transient and steady-state responses.