Three phase inverter system with voltage and phase control

Claim 1

A THREE-PHASE STATIC INVERTER COMPRISING: AN OSCILLATOR CIRCUIT; FIRST SWITCH MEANS COUPLED TO AND CONTROLLED BY THE OUTPUT SIGNALS FROM SAID OSCILLATOR CIRCUIT FOR CONVERTING DIRECT CURRENT TO ALTERNATING CURRENT, SAID FIRST SWITCH MEANS PROVIDING A FIRST A.C. OUTPUT VOLTAGE AND BEING ADAPTED TO HAVE ITS INPUT TERMINALS CONNECTED TO A SOURCE OF DIRECT CURRENT; A FIRST PHASE CONTROL CIRCUIT COUPLED TO THE OUTPUT OF SAID OSCILLATOR CIRCUIT FOR GENERATING A SIGNAL HAVING THE SAME FREQUENCY BUT SHIFTED IN PHASE WITH RELATION TO THE OSCILLATOR OUTPUT SIGNAL; SECOND SWITCH MEANS CONNECTED TO SAID FIRST PHASE CONTROL CIRCUIT AND CONTROLLED BY THE SIGNAL GENERATED THEREBY FOR CONVERTING DIRECT CURRENT TO ALTERNATING CURRENT, SAID SECOND SWITCH MEANS PROVIDING A SECOND A.C. OUTPUT VOLTAGE DIFFERING IN PHASE FROM SAID FIRST A.C. VOLTAGE AND BEING ADAPTED TO HAVE ITS INPUT TERMINALS CONNECTED TO A SOURCE OF DIRECT CURRENT; A SECOND PHASE CONTROL CIRCUIT COUPLED TO THE OUTPUT OF SAID OSCILLATOR CIRCUIT FOR GENERATING A SIGNAL HAVING THE SAME FREQUENCY BUT SHIFTED IN PHASE WITH RELATION TO THE OUTPUT SIGNALS OF SAID OSCILLATOR AND SAID FIRST PHAE CONTROL CIRCUIT; THIRD SWITCH MEANS CONNECTED TO SAID SECOND PHASE CONTROL CIRCUIT AND CONTROLLED BY THE SIGNAL GENERATED THEREBY FOR CONVERTING DIRECT CURRENT TO ALTERNATING CURRENT, SAID THIRD SWITCH MEANS PROVIDING A THIRD A.C. OUTPUT VOLTAGE DIFFERING IN PHASE FROM SAID FIRST AND SECOND A.C. VOLTAGES AND BEING ADAPTED TO HAVE ITS INPUT TERMINALS CONNECTED TO A SOURCE OF DIRECT CURRENT; A THREE-LEG TRANSFORMER HAVING A PRIMARY AND A SECONDARY WINDING ON EACH LEG THEREOF; MEANS APPLYING THE A.C. OUTPUT VOLTAGES PROVIDED BY SAID FIRST, SECOND AND THIRD SWITCH MEANS RESPECTIVELY TO FIRST, SECOND AND THIRD PRIMARY WINDINGS ON SAID THREE-LEG TRANSFORMER; MEANS FOR CONNECTING A THREE-PHASE LOAD ACROSS THE THREE SECONDARY WINDINGS ON SAID THREE-LEG TRANSFORMER; MEANS FOR SENSING THE MAGNITUDES OF THE VOLTAGES ACROSS THE SECONDARY WINDINGS ON THE FIRST, SECOND AND THIRD LEGS OF SAID THREE-LEG TRANSFORMER AND FOR GENERATING SIGNALS COMMENSURATE THEREWITH;