	US 12,107,488 B2
	Electrical converter and method for operating an electrical converter
Maxime Delzenne, Erfurt (DE); and Guenter Ebner, Henfenfeld (DE)
Assigned to Siemens Energy Global GmbH & Co. KG, Munich (DE)
Appl. No. 17/616,801
Filed by Siemens Energy Global GmbH & Co. KG, Munich (DE)
PCT Filed Jun. 6, 2019, PCT No. PCT/EP2019/064860 § 371(c)(1), (2) Date Dec. 6, 2021, PCT Pub. No. WO2020/244768, PCT Pub. Date Dec. 10, 2020.
Prior Publication US 2022/0311352 A1, Sep. 29, 2022
Int. Cl. H02M 1/32 (2007.01); H02M 1/00 (2007.01); H02M 7/483 (2007.01)

CPC H02M 1/327 (2021.05) [H02M 1/0009 (2021.05); H02M 7/4835 (2021.05)]

13 Claims

1. A method for operating an electrical converter which has an AC voltage side with at least two phases and a DC voltage side, the method comprising:

providing the electrical converter with at least two AC voltage connections on the AC voltage side and at least two parallel-connected series circuits, with each of the series circuits forming a respective converter arm of the converter and being assigned to one of the AC voltage connections on the AC voltage side of the converter;

wherein one or more circuit currents are able to flow between the at least two parallel-connected series circuits;

calculating a loading value describing a thermal loading of the converter on a basis of at least three current values, namely:

an active power current value that indicates an active power current component of a phase current flowing through one of the AC voltage connections;

a reactive power current value that indicates a reactive power current component of the phase current flowing through the one AC voltage connection; and

a circuit current value that indicates a magnitude of the one or more circuit currents flowing between the series circuits; and

controlling the converter while taking into consideration the loading value; and

calculating the series circuit-related circuit currents in accordance with

Iki(t)=(Ipi(t)+Igi(t))/2+Idc(t)/n−Iai(t)

where:

Iki(t) denotes a series circuit-related circuit current, as a function of time t, in an ith series circuit or an ith converter arm;

Ipi(t) denotes the active power current, as a function of time t, flowing through the AC voltage connection connected to the ith series circuit or to the ith converter arm;

Iqi(t) denotes the reactive power current, as a function of time t, flowing through the AC voltage connection connected to the ith series circuit or to the ith converter arm;

Idc(t) denotes the DC current, as a function of time t, flowing on the DC voltage side;

lai(t) denotes an arm current, as a function of time t, flowing between a positive DC voltage connection of the DC voltage side and the AC voltage connection connected to the ith converter arm; and

n denotes a number of series circuits or converter arms.