An Approach for Buck Converter PI Controller Design Using Stability Boundary Locus

In this paper, a proportional-integral (PI) controller is designed for the DC-DC Buck converter to regulate its output voltage in presence of load current and line voltage disturbances. The parameter of PI controller is tuned based on the stability boundary locus approach. A step-wise procedure is discussed for tuning the PI parameters to satisfy the minimum phase margin requirements. For precise control, the nonidealities of the Buck converter have been included in its mathematical model. State-space averaging technique is used to obtain the duty cycle to output voltage transfer function of the non-ideal Buck converter. Finally, the performance of the proposed controller is validated on an experimental prototype.