µ-Based Controller Design for Switching Regulators with Input Filters

M.S. Elmore and V.A. Skormin (USA)


Robust Control, Optimal Control, Power Systems, Modeling and Simulation, Stability


A switching power supply (SPS) requires an input filter to reduce the high frequency current harmonics generated by switch action that are returned to the source. The interaction between the input filter and control loop of the SPS can adversely affect loop stability, audiosusceptibility and output impedance. To guarantee system stability 1+is ZZ must satisfy the Nyquist stability criterion, where sZ is the input filter output impedance and iZ is the SPS closed-loop input impedance. Parametric uncertainty in the SPS can cause a nominally stable system to become unstable. Component uncertainties in the SPS are isolated from the nominal structure M and the structured singular value is used to analyze robustness of SPS stability with a conventionally designed 2-stage, phase-lead controller with an integrator. It is shown that stability robustness can be improved with a controller designed with a -synthesis technique known as D-K iteration. The -optimal controller lessens input filter and SPS interactions and improves system stability.

Important Links:

Go Back