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1. (WO2018060414) METHOD FOR OPERATING AN INVERTER, AND INVERTER

Pub. No.:    WO/2018/060414    International Application No.:    PCT/EP2017/074760
Publication Date: Fri Apr 06 01:59:59 CEST 2018 International Filing Date: Sat Sep 30 01:59:59 CEST 2017
IPC: H02M 7/49
H02M 7/493
H02M 7/5387
H02M 7/5395
Applicants: FRONIUS INTERNATIONAL GMBH
Inventors: STARZINGER, Johannes
NAGELMÜLLER, Martin
Title: METHOD FOR OPERATING AN INVERTER, AND INVERTER
Abstract:
The invention relates to a method for operating an inverter (1) and to an inverter (1) for converting a direct voltage (U DC ) into an alternating voltage (U AC ) with a specified grid frequency (f AC ) for supplying loads (12) and/or feeding into a supply grid (13), comprising a direct voltage input (2) and multiple AC power units (6) which are connected in parallel and comprise semiconductor switches (7) in a bridge circuit and freewheeling diodes (8) arranged parallel thereto. The outputs of the AC power units (6) are connected to an alternating voltage output (10) via a respective inductor (9). A common controller (11) is provided for synchronously controlling the semiconductor switches (7) of the AC power units (6) connected in parallel with a switching frequency (f S ) in order to prevent asymmetries between the parallel AC power units (6), said controller (11) being designed to block the semiconductor switches (7) of the AC power units (6) during individual zero crossings of the output alternating current (I AC ) over a specified duration (t F ) such that the inductors (9) can be discharged via the freewheeling diodes (8) of the semiconductor switches (7) and the sub-output currents (I Ai ) of the parallel AC power units (6) can thus be made symmetrical.