Control of Flying Capacitor Multilevel converter in fault state after grid disturbance

An effective HW reconfiguration of a FCM (Flying Capacitor Multilevel) converter and also of its control algorithm in case of a fault of one element in the converter phase is presented. A strategy starts from the theory of FCM converters with unequal distribution of voltages on converter capacitors. The use of additional switching elements and capacitors with higher rated voltage is a necessary condition for the presented approach. Because a number of redundant switching states in faulted phases is limited, joint-phase redundancies are recommended to be used to balance capacitor voltages. The case of a 4-level FCM converter is analyzed in detail as an example.