Current limiting inverter circuits and apparatus for operating electric discharge lamps and other loads

Claim 1

AN APPARATUS FOR OPERATING AN ELECTRIC DISCHARGE LAMP WITH AN ALTERNATING POTENTIAL COMPRISING: A PAIR OF INPUT LEADS FOR CONNECTION IN CIRCUIT WITH A D.C. SUPPLY MEANS, FIRST AND SECOND UNILATERAL SEMICONDUCTOR SWITCHING DEVICES OPERABLE BETWEEN A HIGH AND A LOW IMPEDNACE CONDITION, SAID FIRST SEMICONDUCTOR SWITCHING DEVICE BEING CONNECTED IN CIRCUIT WITH SAID FIRST INPUT LEAD, SAID SECOND SEMICONDUCTOR SWITCHING DEVICE BEING CONNECTED IN CIRCUIT WITH THE OTHER OF SAID INPUT LEADS, SAID FIRST AND SECOND SEMICONDUCTOR SWITCHING DEVICES BEING JOINED IN SERIES CIRCUIT RELATION, A SATURATING REACTOR HAVING A FIRST AND A SECOND SATURABLE CORE, A FIRST BIAS MEANS ASSOCIATED ONLY WITH SAID FIRST SATURABLE CORE, A SECOND BIAS MEANS ASSOCIATED ONLY WITH SAID SECOND SATURABLE CORE, A FIRST AUXILIARY WINDING WOUND ON BOTH OF SAID SATURABLE CORES AND COUPLED WITH SAID FIRST SEMICONDUCTOR DEVICE, A SECOND AUXILIARY WINDING WOUND ON BOTH OF SAID CORES AND COUPLED WITH SAID SECOND SEMICONDUCTOR SWITCHING DEVICE, SAID FIRST AUXILIARY WINDING CAUSING THE FIRST SEMICONDUCTOR SWITCHING DEVICE TO BE DRIVEN TO A HIGH AND LOW IMPEDANCE CONDITION IN RESPONSE TO THE CONDITION OF SATURATION OF SAID FIRST SATURABLE CORE AND SAID SECOND AUXILIARY WINDING CAUSING THE SECOND SEMICONDUCTOR SWITCHING DEVICE TO BE DRIVEN TO A HIGH AND LOW IMPEDANCE CONDITION IN RESPONSE TO THE CONDITION OF SATURATION OF SAID SECOND SATURABLE CORE, A MAIN WINDING WOUND ON BOTH OF SAID SATURABLE CORES AND HAVING ONE END CONNECTED IN CIRCUIT WITH SAID FIRST AND SECOND SWITCHING DEVICES, CIRCUIT MEANS FOR JOINING THE OTHER END OF SAID MAIN WINDING IN CIRCUIT WITH ONE END OF THE ELECTRIC DISCHARGE LAMP AND FOR CONNECTING THE OTHER END THEREOF IN CIRCUIT WITH THE D.C. SUPPLY MEANS THEREBY TO CAUSE CURRENT FLOW FROM THE SUPPLY MEANS IN ONE DIRECTION WHEN ONE OF SAID SEMICONDUCTOR SWITCHING DEVICES IS DRIVEN TO A LOW IMPEDANCE CONDITION AND TO CAUSE CURRENT TO FLOW THROUGH SAID MAIN WINDING IN THE OPPOSITE DIRECTION WHEN SAID OTHER SWITCHING DEVICE IS DRIVEN TO THE LOW IMPEDANCE CONDITION, A FIRST UNIDIRECTIONAL CONDUCTING DEVICE CONNECTED ACROSS SAID FIRST SEMICONDUCTOR SWITCHING DEVICE TO PROVIDE A PATH FOR REVERSE CURRENT FLOW THEREACROSS, A SECOND UNIDIRECTIONAL CONDUCTING DEVICE CONNECTED ACROSS SAID SECOND SEMICONDUCTING SWITCHING DEVICE TO PROVIDE A PATH FOR REVERSE CURRENT FLOW THEREACROSS, SAID FIRST SATURABLE CORE BEING RENDERED ACTIVE IN RESPONSE TO THE FLOW TO CURRENT THROUGH SAID MAIN WINDING IN ONE DIRECTION AND INACTIVE IN RESPONSE TO THE FLOW OF CURRENT IN THE REVERSE DIRECTION DURING A PORTION OF THE POSITIVE HALF CYCLE TO HOLD THE CURRENT AT A SUBSTANTIALLY CONSTANT LEVEL AND THE SECOND SATURABLE CORE BEING RENDERED ACTIVE IN RESPONSE TO THE FLOW OF CURRENT THROUGH SAID WINDING IN SAID REVERSE DIRECTION AND INACTIVE IN RESPONSE TO FLOW OF CURRENT IN SAID ONE DIRECTION DURING A PORTION OF THE NEGATIVE HALF CYCLE TO MAINTAIN THE CURRENT SUBSTANTIALLY CONSTANT.

Claim 2

AN APPARATUS FOR OPERATING AN ELECTRIC DISCHARGE LAMP WITH AN ALTERNATING POTENTIAL COMPRISING: A PAIR OF INPUT LEADS FOR CONNECTION IN CIRCUIT WITH A D.C. SUPPLY MEANS, FIRST AND SECOND UNILATERAL SEMICONDUCTOR SWITCHING DEVICES OPERABLE BETWEEN A HIGH AND A LOW IMPEDNACE CONDITION, SAID FIRST SEMICONDUCTOR SWITCHING DEVICE BEING CONNECTED IN CIRCUIT WITH SAID FIRST INPUT LEAD, SAID SECOND SEMICONDUCTOR SWITCHING DEVICE BEING CONNECTED IN CIRCUIT WITH THE OTHER OF SAID INPUT LEADS, SAID FIRST AND SECOND SEMICONDUCTOR SWITCHING DEVICES BEING JOINED IN SERIES CIRCUIT RELATION, A SATURATING REACTOR HAVING A FIRST AND A SECOND SATURABLE CORE, A FIRST BIAS MEANS ASSOCIATED ONLY WITH SAID FIRST SATURABLE CORE, A SECOND BIAS MEANS ASSOCIATED ONLY WITH SAID SECOND SATURABLE CORE, A FIRST AUXILIARY WINDING WOUND ON BOTH OF SAID SATURABLE CORES AND COUPLED WITH SAID FIRST SEMICONDUCTOR DEVICE, A SECOND AUXILIARY WINDING WOUND ON BOTH OF SAID CORES AND COUPLED WITH SAID SECOND SEMICONDUCTOR SWITCHING DEVICE, SAID FIRST AUXILIARY WINDING CAUSING THE FIRST SEMICONDUCTOR SWITCHING DEVICE TO BE DRIVEN TO A HIGH AND LOW IMPEDANCE CONDITION IN RESPONSE TO THE CONDITION OF SATURATION OF SAID FIRST SATURABLE CORE AND SAID SECOND AUXILIARY WINDING CAUSING THE SECOND SEMICONDUCTOR SWITCHING DEVICE TO BE DRIVEN TO A HIGH AND LOW IMPEDANCE CONDITION IN RESPONSE TO THE CONDITION OF SATURATION OF SAID SECOND SATURABLE CORE, A MAIN WINDING WOUND ON BOTH OF SAID SATURABLE CORES AND HAVING ONE END CONNECTED IN CIRCUIT WITH SAID FIRST AND SECOND SWITCHING DEVICES, CIRCUIT MEANS FOR JOINING THE OTHER END OF SAID MAIN WINDING IN CIRCUIT WITH ONE END OF THE ELECTRIC DISCHARGE LAMP AND FOR CONNECTING THE OTHER END THEREOF IN CIRCUIT WITH THE D.C. SUPPLY MEANS THEREBY TO CAUSE CURRENT FLOW FROM THE SUPPLY MEANS IN ONE DIRECTION WHEN ONE OF SAID SEMICONDUCTOR SWITCHING DEVICES IS DRIVEN TO A LOW IMPEDANCE CONDITION AND TO CAUSE CURRENT TO FLOW THROUGH SAID MAIN WINDING IN THE OPPOSITE DIRECTION WHEN SAID OTHER SWITCHING DEVICE IS DRIVEN TO THE LOW IMPEDANCE CONDITION, A FIRST UNIDIRECTIONAL CONDUCTING DEVICE CONNECTED ACROSS SAID FIRST SEMICONDUCTOR SWITCHING DEVICE TO PROVIDE A PATH FOR REVERSE CURRENT FLOW THEREACROSS, A SECOND UNIDIRECTIONAL CONDUCTING DEVICE CONNECTED ACROSS SAID SECOND SEMICONDUCTING SWITCHING DEVICE TO PROVIDE A PATH FOR REVERSE CURRENT FLOW THEREACROSS, SAID FIRST SATURABLE CORE BEING RENDERED ACTIVE IN RESPONSE TO THE FLOW TO CURRENT THROUGH SAID MAIN WINDING IN ONE DIRECTION AND INACTIVE IN RESPONSE TO THE FLOW OF CURRENT IN THE REVERSE DIRECTION DURING A PORTION OF THE POSITIVE HALF CYCLE TO HOLD THE CURRENT AT A SUBSTANTIALLY CONSTANT LEVEL AND THE SECOND SATURABLE CORE BEING RENDERED ACTIVE IN RESPONSE TO THE FLOW OF CURRENT THROUGH SAID WINDING IN SAID REVERSE DIRECTION AND INACTIVE IN RESPONSE TO FLOW OF CURRENT IN SAID ONE DIRECTION DURING A PORTION OF THE NEGATIVE HALF CYCLE TO MAINTAIN THE CURRENT SUBSTANTIALLY CONSTANT.