Control of interconnected power electronic converters in dc distribution systems

This paper examines a typical structure of multi-stage converters present in direct current (dc) distribution systems. In such electric power distribution systems, point-of-load converters behave as a constant power load (CPL). Such loads may result in destabilizing nonlinear effects to their supply bus voltage. An analysis of the open loop dynamic behavior of the line regulating converter feeding CPLs is performed. This analysis gives the background to understand the proposed washout sliding mode controller to regulate the dc bus voltage under constant impedance load (CIL) and CPL changes. Also, the operating limits of the controlled system are determined in terms of the maximum power drained by CPL and CIL connected to the bus. The theoretical analysis is validated through simulation results.