Loop Shaping Based Robust Controller Design for Boost Converter in DC Microgrid

Maintaining constant power at the load end leads to an increase in output voltage and a proportional decrease in output current and vice versa. Constant power loads (CPLs) introduce hunting instability. Negative impedance characteristics of CPLs can disrupt the balance between generation and load, potentially leading to voltage collapses. Control scheme of the boost converter needs to be designed to accommodate the unstable load characteristic as discussed above. Proportional-integral-derivative (PID) controller has been considered in the present work, because of its popularity in industrial applications. Furthermore, it needs tuning of only three parameters and gives satisfactory closed-loop performance. This paper proposes a novel quantitative feedback theory (QFT) based PID controller for boost converter in DC microgrid. QFT is a powerful design approach in the frequency domain that allows the user to design a controller to achieve the desired performance for any given uncertainty in plant parameters. Experimental results demonstrate that the closed-loop system achieves a significant enhancement compared to the most recently reported control strategies.