Selection of optimal closed-loop controllers for DC-DC voltage regulators based on nominal and tolerance design

This paper discusses a tolerance design approach for the feedback compensation networks of DC/DC switching regulators, identifying the most reliable solutions among different feasible alternatives that fulfil closed-loop design constraints. A voltagemode-regulated DC/DC buck converter is considered as a case study. Given the performance and stability constraints, as tolerance ranges for crossover frequency and phase margin, feasible design solutions are sought by means of Monte Carlo and interval arithmetic computations. The search space is a set of available commercial values of RC parameters and related tolerances. Best design is identified by a weighted fitness function, exploring the set of solutions provided by different design approaches. The results presented in the paper highlight that the tolerance design approach allows one to find compensation networks that fit the given performance/robustness priorities better than those ones found by means of the classical nominal design approach.