US 12,249,929 B2
Method for operating an inverter assembly and inverter assembly for carrying out the method
Harald Kreuzer, Pettenbach (AT); Roland Pieler, Pettenbach (AT); Christoph Pernegger, Pettenbach (AT); and Richard Grasboeck, Pettenbach (AT)
Assigned to Fronius International GmbH, Pettenbach (AT)
Appl. No. 18/722,673
Filed by Fronius International GmbH, Pettenbach (AT)
PCT Filed Dec. 22, 2022, PCT No. PCT/EP2022/087441
§ 371(c)(1), (2) Date Jun. 21, 2024,
PCT Pub. No. WO2023/118417, PCT Pub. Date Jun. 29, 2023.
Claims priority of application No. 21217364 (EP), filed on Dec. 23, 2021.
Prior Publication US 2024/0421725 A1, Dec. 19, 2024
Int. Cl. H02M 7/5395 (2006.01); H02M 1/00 (2007.01); H02M 1/12 (2006.01)
CPC H02M 7/5395 (2013.01) [H02M 1/007 (2021.05); H02M 1/12 (2013.01)] 13 Claims
OG exemplary drawing
 
1. A method for operating an inverter assembly having at least one inverter for converting respectively a direct voltage into an alternating voltage with a mains frequency,
wherein in the at least one inverter, the direct voltage of a DC source connected to a DC input is transformed via a DC/DC-converter to an intermediate circuit voltage, and the intermediate circuit voltage is converted in a DC/AC-converter having two power units, each connected to an AC output, which are mutually modulated by a control device, into the alternating voltage, which alternating voltage corresponds to the total of the opposite voltages at the AC outputs of the power units opposite the negative pole of the intermediate circuit voltage, and the alternating voltage is fed into a supply network connected to the AC outputs,
wherein before feeding the alternating voltage into the supply network, a leakage capacitance to ground is determined at the DC input of the at least one inverter, and it is determined which AC output is connected to which line of the supply network,
wherein, taking into consideration the determined leakage capacitance and a defined maximum leakage current and the determined connection situation at the AC output, the power units of the at least one inverter are asymmetrically modulated by the control device in such a way that the amplitudes of the voltages at the AC outputs of the power units, which correspond to the alternating voltage to be fed in the supply network, differ in size, the modulation of the power unit of the DC/AC-converter connected to the phase connection of the supply network taking place in such a way that the voltage with the greater amplitude comes about at the AC output of this power unit, and the modulation of the power unit of the DC/AC-converter connected to the neutral conductor of the supply network takes place in such a way that the voltage with the lower amplitude comes about at the AC output of this power unit, as a result of which the leakage currents are minimized and the at least one inverter is connected without the risk of exceeding the defined maximum leakage current, and
wherein in an event that the maximum leakage current is reached, a predetermined period of time is waited and, before feeding the alternating voltage into the supply network, the leakage capacitance to ground at the DC input of the at least one inverter is determined again and it is checked again whether the defined maximum leakage current is exceeded.