Abstract: In this paper, the multivariable robust approach is used to obtain simple controllers for both single and current- sharing (paralleled) DC/DC converters. Linear time-invariant nominal model of the power stage is derived and asymptotic uncertainty bounds are constructed to cover the parametric uncertainty, nonlinear effects in control, CMC switching effects and random switching control. Robust model of the current-sharing converters is developed and joint framework for the frequency domain robust design is proposed for both single and current-sharing configurations. The feasibility of the approach is demonstrated by two design examples: random control of the single unit buck converter and deterministic control of the three paralleled buck units. Several robust controllers are designed and verified for robustness and performance in the closed-loop with the Matlab and pSpice models.
Keywords: DC/DC converter, current sharing, pulse width modulation, random switching, robust modeling, robust control, simple controllers.