	US 12,081,142 B2
	Modulator for flying-capacitor type multilevel converter, multilevel converter, and method for operating multilevel converter
Mario Schweizer, Rütihof (CH); Daniel Christen, Uster (CH); and Hemant Bishnoi, Aargau (CH)
Assigned to ABB Schweiz AG, Baden (CH)
Filed by ABB Schweiz AG, Baden (CH)
Filed on Aug. 16, 2022, as Appl. No. 17/889,113.
Claims priority of application No. 21191751 (EP), filed on Aug. 17, 2021.
Prior Publication US 2023/0060063 A1, Feb. 23, 2023
Int. Cl. H02M 7/483 (2007.01); H02M 1/00 (2006.01)

CPC H02M 7/4837 (2021.05) [H02M 1/0058 (2021.05)]

11 Claims

1. A modulator for a flying-capacitor type multilevel converter, the flying-capacitor type multilevel converter comprising one or more switching cells, the modulator comprising:

an input associated with the one or more switching cells, wherein the input is configured to receive a time-variant reference signal (Vref);

an output associated with the one or more switching cells, wherein a sequence of target levels (Vlev) is provided at the output; and

wherein the modulator is adapted to provide switching signals to the flying-capacitor type multilevel converter associated with the modulator, the flying-capacitor type multilevel converter operating to switch between discrete output levels according to a shape of the time-variant reference signal (Vref); and

wherein the modulator is further configured to:

a) determine a critical level as an intermediate output level of the flying-capacitor type multilevel converter that is closest to a level of the reference signal (Vref); and

b) output only target levels (Vlev) corresponding to output levels that are different from the critical level.