PEBB (power electronics building block) systems are typical nonlinear systems. Under the conventional but still popular linear control design, the system stability margin varies from one operating point to another. This paper introduces a novel approach to monitoring the DC bus stability margin of a PEBB system online. At the steady state of the system, a small-signal perturbation current î p is injected into the DC bus, and the load-side response current î L is measured. By checking the validation |î L ( jw)| < |î p ( jw)|, the system stability margin can be examined. Experiments on a 48 V DC DPS demonstrate the proposed measurement approach. An implementation approach is also proposed for an 800 V DC PEBB-based testbed system.
