QFT Approach to Robust Control of DC-DC Buck Converter

This work addresses the disturbance attenuation problem of DC-DC buck converter system with uncertainties using the well-known robust PID controller. Quantitative Feedback Theory (QFT) approach is used to synthesize the robust PID controller by means of loop-shaping technique. The advantages of proposed design are (i) explicit inclusion of disturbance dynamics by means of the o/p impedance transfer function and audio susceptibility transfer function in the design stage itself, (ii) easy and simple controller design method to accommodate the uncertainty in the converter system transfer function, (iii) point by point frequency design method facilitates the tradeoffs between different conflicting requirements. Extensive Simulation have been carried out on the buck converter subjected to a variation in the load resistance and in source voltage.