US 12,424,944 B2
Method for fixing an output power limit of a frequency converter and a method for diagnosing conditions of DC-link capacitors
Piotr Krysztofiak, Rawa Mazowiecka (PL); and Artur Falkowski, Cracow (PL)
Assigned to ABB Schweiz AG, Baden (CH)
Filed by ABB Schweiz AG, Baden (CH)
Filed on May 31, 2023, as Appl. No. 18/326,315.
Claims priority of application No. 22176628 (EP), filed on Jun. 1, 2022.
Prior Publication US 2023/0396149 A1, Dec. 7, 2023
Int. Cl. H02M 5/458 (2006.01); G01R 31/00 (2006.01); H02M 1/15 (2006.01); H02M 1/32 (2007.01); H02M 7/539 (2006.01)
CPC H02M 5/458 (2013.01) [H02M 1/32 (2013.01); G01R 31/00 (2013.01); H02M 1/15 (2013.01); H02M 7/539 (2013.01)] 11 Claims
OG exemplary drawing
 
1. A computer-implemented method for fixing an output power limit of a frequency converter, comprising:
determining voltage differences ΔUi between at least two DC-link circuit capacitors or at least two blocks of DC-link circuit capacitors for each of at least two different values of an output power Pout(i) of a frequency converter, thus providing at least two sets of the voltage differences ΔUi, where i=(1, 2 . . . , n), wherein the voltage differences ΔUi are determined during stable thermal conditions of the frequency converter;
determining a percentile value for each set of the voltage differences ΔUi in order to eliminate the highest errors occurring during determination of voltage differences ΔUi, wherein the elimination is done through rejection of values higher than the determined percentile, where i=(1, 2 . . . , n);
determining characteristic ΔU=f(Pout) from the values of the percentile,
determining a maximum allowable voltage difference ΔUmaxallow, where
ΔUmaxallow=⅓·Udc
where Udc represents a voltage of a DC-link circuit;
fixing a value of an output power limit Poutlimit of the frequency converter for the determined maximum allowable voltage difference ΔUmaxallow.