Analysis of multi-loop control strategies for power conversion applications

Multi-loop control strategies have commonly been used to control power converters of both the voltage-source and current-source topologies for power conversion applications including uninterruptible power supplies and utility interfaces for distributed power generation. However, these control strategies tend to be developed and comparatively evaluated for a particular application, with strategies for other applications presented as independent new developments. This paper presents a generalized analysis of different multi-loop control approaches using alternative feedback control variables for several system configurations, highlighting similarities and identifying a generalized optimal control variable selection criterion that is applicable across most multi-loop controlled power conversion systems. The principles presented have been verified by both detailed MATLAB simulation and experimental investigations.