Integral Control of Megawatt Power Electronic Systems as Generalized Hybrid Systems

This article proposes and discusses the integral control of megawatt power electronic (MPE) systems. First, we propose that MPE systems share the common features defined as generalized hybrid systems (GHSs), where large-timescale continuous dynamic embodies the discrete process, while the discrete process embodies the small-timescale continuous switching transient. Then, we propose that such a GHS calls for an integral control of the "continuous–discrete–continuous" process, which considers the multiple timescales simultaneously. The necessity of an integral and simultaneous control in MPE over a separate control or hardware integrity is discussed. Then, the state-of-the-art control methods for the large-timescale "continuous–discrete" dynamics and the small-timescale "discrete–continuous" transients are reviewed within the context of GHSs. Based on the investigations, in-depth discussions are provided on why and how to combine the above separate methods to simultaneously control the multiple timescales and form an integral control. The need of the integral control is summarized. Two examples of a switching loss reduction and an electromagnetic interference (EMI) performance improvement in MPE systems are provided to demonstrate why and how to consider and control the multitimescale behaviors tightly and simultaneously. Future trends in the study of integral control for MPE are briefly discussed.