Bifurcation in PWM converter-based systems with wireless communication-based current controller

Mehdi Karbalaye Zadeh, Reza Parseh, Marta Molinas, Kimmo Kansanen

Abstract: This paper discusses the stability of current control for pulse-width modulated (PWM) voltage source converters (VSCs) subject to communication delay. The converters can be used properly as interface of controllable distributed energy resources (DERs) or for the active integration of converter-interfaced loads (CILs). The stability analysis is based on the identification of oscillatory modes by the bifurcation analysis. The bifurcation map indicates the non-linear impact of the communication delay on the output current of a three phase PWM inverter. The aim of the paper is to find limit delay for which the stability criteria of the controller are still satisfied. This limit delay allows for maximal flexibility for the communication system designer and leads to better resource allocation in case of channel distortion, limited bandwidth, etc in the wireless communication system.