Parallel inverter having higher frequency at start-up

Claim 1

AN INVERTER DEVICE FOR CONNECTION ACROSS DC LEADS COMPRISING A TRANSFORMER HAVING A PRIMARY WINDING, A SECONDARY WINDING, AND A CORE STRUCTURE MAGNETICALLY LINKING SAID WINDINGS, THE MID-POINT OF SAID PRIMARY BEING CONNECTED TO A POSITIVE DC LEAD, A PARALLEL COMMUTATING CIRCUIT HAVING TWO LEGS AND BEING CONNECTED BETWEEN THE ENDS OF SAID PRIMARY WINDING AND A NEGATIVE DC LEAD AND INCLUDING IN EACH LEG THEREOF AND SCR, TRIGGER MEANS FOR ALTERNATELY APPLYING PULSES TO THE GATES OF SAID SCR''S FOR OPERATING SAID INVERTER AT A PREDETERMINED OPERATING FREQUENCY, AND MEANS FOR INCREASING THE FREQUENCY OF THE PULSES SUPPLIED BY SAID TRIGGER MEANS TO SAID GATES AT THE TIME OF START-UP, SAID TRANSFORMER BEING A LEAKAGE REACTANCE TRANSFORMER WHICH INCLUDES AN EXTENDED SECONDARY WINDING CONNECTED IN SERIES WITH SAID FIRST MENTIONED SECONDARY WINDING, A CONDENSER CONNECTED ACROSS BOTH OF SAID SECONDARY WINDINGS TO PROVIDE A CONDENSER CIRCUIT, THE CROSS SECTION OF SAID CORE BEING SUCH THAT THE SECONDARY PORTION THEREOF OPERATES IN THE SATURATION RANGE WHEN A RESISTIVE LOAD APPROACHING RATED CAPACITY IS CONNECTED ACROSS SAID FIRST MENTIONED SECONDARY, RESISTANCE MEANS CONNECTED IN SERIES IN SAID CONDENSER CIRCUIT, CONTACT MEANS SHUNTING OUT SAID RESISTANCE MEANS TO PROVIDE A HIGH Q CIRCUIT AT RATED OUTPUT FREQUENCY, AND A SLOW ACTING RELAY FOR ACTUATING SAID CONTACT MEANS INTO CLOSED POSITION AFTER THE FREQUENCY OF SAID TRIGGER MEANS IS STABILIZED AT SAID PREDETERMINED OPERATING FREQUENCY.