Direct AC/AC converter system

In a direct AC to AC converter system connected to an output load and including nine bilateral switches grouped by groups of three, each switch in one group being associated with a corresponding common output phase line and the switches of each group being associated with the respective input line phases;

• rectifier existence function means being provided for operating for conduction one switch of one group according to one of two polarities applicable to the associated ouput phase line, and for operating for conduction one pair of respective switches in the two other groups having a common input phase line and according to the other polarity, to derive between said associated output phase line and the two other output phase lines a voltage source defined by the line-to-line input voltage between said common input phase line and the input phase line related to said one switch of one group;
• and
• means operative with said rectifier existence function means for controlling said bilateral switches in accordance with an inverter function with regard to said output phase lines and under said voltage source;
• the combination of:
• means operative upon said rectifier existence function means for switching at a high frequency and alternatively from one pair of said respective switches relative to one common input phase line to another pair of said respective switches relative to the other common input phase line, and for establishing an average voltage source vs according to the formula:
• ##EQU15## where v is the peak voltage of said AC input and where .phi. is a function of the electrical angle .theta. of the AC input as follows:
• ##EQU16## whereby a sinusoidal input current is derived from said AC input.