| 摘要 |
A method and a device balance a three-phase system (18) that is produced by means of an invertor (12) from a d.c. voltage source (10), such that the output (R',S',T') of this invertor (12) is equipped with a filter (14) to which a neutral grounding transformer (16) has been added. In keeping with the invention, absolute values (ûR*, ûS*, ûT*), each of which is fed into a regulator device (34, 42; 36, 44; 38, 46) are formed from measured phase-to-phase voltages (uRL, uSL, uTL). Each absolute value produces a phase-to-phase voltage manipulated variable (UStR, UStS, UStT) such that by means of a transformer device (54), these phase-to-phase voltage manipulated variables (UStR, UStS, UStT) are transformed into phase-to-neutral manipulated variables (UStr, USts, UStt) and are fed into angularly symmetrical control units (96, 98, 100). In this way, using a simple mono-phase control of absolute values, a three-phase system (18) with an asymmetrical load can remain symmetrical and, while retaining the symmetry of angle, the absolute values of the invertor (12) are controlled in an asymmetrical fashion.
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