Brushless synchronous motor control system and circuitry therefor

Claim 1

IN A BRUSHLESS SYNCHRONOUS MOTOR HAVING ROTATING FIELD WINDING MEANS, AN ALTERNATING CURRENT EXCITER ARMATURE ROTATABLE WITH THE FIELD WINDING MEANS AND RECTIFIER MEANS CONNECTED TO THE EXCITER ARMATURE TO SUPPLY DIRECT CURRENT EXCITATION TO THE FIELD WINDING MEANS, A CONTROL SYSTEM COMPRISING A DISCHARGE CIRCUIT CCONNECTED ACROSS SAID FIELD WINDING MEANS AND INCLUDING A RESISTOR FOR DISCHARGING CURRENT INDUCED IN THE FIELD WINDING MEANS AT SUBSYNCHRONOUS SPEEDS, A SEMICONDUCTOR EXCITER SWITCH CONNECTED IN AN EXCITATION CIRCUIT BETWEEN THE RECTIFIER MEANS AND THE FIELD WINDING MEANS TO CONTROL SAID DIRECT CURRENT EXCITATION, A FIRING CIRCUIT FOR TRANSMITTING A SHARP GATING PULSE TO SAID EXCITER SWITCH SO AS TO APPLY THE EXCITATION VOLTAGE TO SAID FIELD WINDING MEANS SUBSTANTIALLY AT A PREDETERMINED SLIP VOLTAGE FREQUENCY AND PHASE OF THE SLIP VOLTAGE CYCLE, SAID FIRING CIRCUIT INCLUDING VOLTAGE DROPPING MEANS CONNECTED ACROSS SAID FIELD WINDING MEANS AND ALSO INCLUDING A SILICON CONTROLLED RECTIFIER FREQUENCY SWITCH AND A UNIJUNCTION TRANSISTOR PHASE SWITCH CONNECTED IN A SERIES PULSE PATH, A TRANSFORMER CONNECTED IN SAID SERIES PULSE PATH AND COUPLED WITH SAID EXCITER SWITCH SO THAT THE LATTER SWITCH IS FIRED WHEN SAID SERIES PULSE PATH IS PULSED, RESPECTIVE ENERGY STORAGE CIRCUIT MEANS RESPONSIVE TO POSITIVE FIELD VOLTAGE DEVELOPED ACROSS SAID VOLTAGE DROPPING MEANS SO AS RESPECTIVELY TO FIRE SAID SILICON CONTROLLED RECTIFIER AND SAID UNIJUNCTION TRANSISTOR, THE ENERGY STORAGE MEANS ASSOCIATED WITH SAID SILICON CON-