Direct current motor control systems

Claim 1

AN IMPROVED DRIVE SYSTEM FOR A DIRECT CURRENT MOTOR HAVING A FIELD CIRCUIT AND AN ARMATURE CIRCUIT, COMPRISING A SPEED CONTROL CIRCUIT PROVIDING A SPEED CONTROL SIGNAL CORRESPONDING TO THE DIFFERENCE BETWEEN A PRESELECTED SIGNAL AND A SIGNAL PROPORTIONAL TO THE SPEED OF THE DIRECT CURRENT MOTOR, A FIRST AMPLIFIER FOR CONTROLLING THE MAGNITUDE OF THE CURRENT IN SAID FIELD CIRCUIT, SAID FIRST AMPLIFIER PROVIDING FIELD CURRENT THAT VARIES INVERSELY WITH THE MAGNITUDE OF CONTROL SIGNAL APPLIED THERETO, A FIRST TRANSISTOR CONNECTED ACROSS SAID FIRST AMPLIFIER AT THE COLLECTORBASE ELECTORODES THEREOF, SAID FIRST TRANSISTOR BEING SELECTIVELY CONDUCTIVE AND NON-CONDUCTIVE AT THE COLLECTOR-BASE ELECTRODES AND DURING NON-CONDUCTION PRESENTING AN IMPEDANCE GREATER THAN THAT OF SAID FIRST AMPLIFIER, A SECOND AMPLIFIER FOR CONTROLLING THE MAGNITUDE OF THE VOLTAGE IN SAID ARMATURE CIRCUIT, SAID SECOND AMPLIFIER PROVIDING AN ARMATURE VOLTAGE THAT VARIES DIRECTLY WITH THE MAGNITUDE OF THE CONTROL SIGNAL APPLIED THERETO, A SECOND TRANSISTOR BEING CONNECTED ACROSS SAID SECOND AMPLIFIER AT THE COLLECTOR-BASE ELECTRODES THEREOF, SAID SECOND TRANSISTOR BEING SELECTIVELY CONDUCTIVE AND NON-CONDUCTIVE AT THE BASE ELECTRODES AND DURING NON-CONDUCTION PRESENTING AN IMPEDANCE GREATER THAN THAT OF SAID SECOND AMPLIFIER, SAID SPEED CONTROL CIRCUIT AND SAID COMBINATION OF FIRST AMPLIFIER AND FIRST TRANSISTOR AND SAID COMBINATION OF SECOND AMPLIFIER AND SECOND TRANSISTOR BEING CONNECTED IN A SERIES LOOP FOR APPLYING SAID SPEED CONTROL SIGNAL SELECTIVELY TO SAID FIRST AND SECOND AMPLIFIER IN ACCORDANCE WITH THE CONDUCTION AND NON-CONDUCTION STATE OF SAID FIRST AND SECOND TRANSISTORS, MEANS INCLUDING A THIRD TRANSISTOR OPERATIVE INTO A FIRST CONDITION RESPONSIVE TO AN ARMATURE CIRCUIT VOLTAGE BELOW A PREDETERMINED VOLTAGE FOR RENDERING SAID FIRST TRANSISTOR CONDUCTIVE AND SAID SECOND TRANSISTOR NONCONDUCTIVE IN THE COLLECTOR-BASE PATH AND OPERATIVE INTO A SECOND CONDITION RESPONSIVE TO AN ARMATURE CIRCUIT VOLTAGE ABOVE A PREDETERMINED VOLTAGE FOR RENDERING SAID FIRST TRANSISTOR NON-CONDUCTIVE AND SAID SECOND TRANSISTOR CONDUCTIVE IN THE COLLECTOR-BASE PATH, WHEREBY BELOW SAID PREDETERMINED ARMATURE VOLTAGE SAID ARMATURE CIRCUIT IS ENERGIZED TO INCREASE SAID ARMATURE VOLTAGE AND MOTOR SPEED AND ABOVE SAID PREDETERMINED ARMATURE VOLTAGE SAID FIELD CIRCUIT IS ENERGIZED TO DECREASE THE FIELD CURRENT AND INCREASE MOTOR SPEED.