FIELD: conversion equipment. SUBSTANCE: converter has one main and two auxiliary single-phase inverters which outputs are coupled to primary windings correspondingly of main 13 and two auxiliary 14 and 15 transformers. Finishes of secondary winding 16, 17 of main inverter are coupled through A. C. keys 20, 21, 23, 24, 26, 27 to each of output leads A, B, C of converter and its intermediate tap is connected to specified leads through secondary windings 18 and 19 of auxiliary transformers and A.C. keys 22, 25, 28 placed in series. When keys 20-28 are switched on in compliance with definite algorithm quasi-sinusoidal voltage with number of steps in quarter of period equal to 22,5 is formed across output of converter. EFFECT: increased operational stability of converter. 4 dwg
