A Novel Resonant Controller Discretization and Design Procedure Based on Inverse Nyquist Diagrams

Resonant controllers, whether Resonant Proportional (PR) or Vectorial Proportional Integral (VPI), are increasingly used in power electronics converters. Since they are most often embedded in digital microcontrollers, the discretization effects of their mathematical models directly impact the dynamics of the final system. This paper proposes a new discretization for the PR and VPI resonant controllers. Allied to this proposition, a design algorithm focused on optimizing the closed-loop stability of the system via inverse Nyquist diagrams and harmonic current compensation is also proposed. Simulation results prove the validity of the proposed discretization as well as the design algorithm.