Smooth control of polyphase induction motors

Claim 1

A CONTROL SYSTEM FOR OPERATING FROM A THREE TERMINAL SOURCE OF A THREE PHASE POWER SUPPLY, A TWO PHASE ALTERNATING CURRENT MOTOR HAVING A MAIN PHASE WINDING AND TWO OPPOSED CONTROL PHASE WINDINGS WITH MEANS FOR DERIVING FROM THE SUPPLY A MAIN PHASE VOLTAGE AND A CONTROL PHASE VOLTAGE IN RELATIVE PHASE QUADRATURE, SAID MOTOR WINDINGS EACH BEING FED FROM THE POWER SUPPLY THROUGH A RESPECTIVE PAIR OF GATABLE RECTIFIERS, EACH SAID PAIR OF RECTIFIERS BEING CONNECTED IN ANTI-PARALLEL RELATION TO PROVIDE A FULL WAVE A.C. VOLTAGE, SAID SYSTEM COMPRISING A PAIR OF RESETTABLE MAGNETIC AMPLIFIERS FOR EACH PAIR OF GATABLE RECTIFIERS, MEANS CONNECTING THE INPUT OF EACH PAIR OF MAGNETIC AMPLIFIERS TO THE PHASE OF THE VOLTAGE SOURCE FOR ITS RESPECTIVE MOTOR WINDING TO GOVERN EACH AMPLIFIER OF ITS RESPECTIVE PAIR TO CONDUCT AND RESET IN MUTUAL PHASE OPPOSITION WITH RESPECT TO EACH OTHER, MEANS CONNECTING THE OUTPUT OF EACH PAIR OF MAGNETIC AMPLIFIERS TO ITS RESPECTIVE PAIR OF GATABLE RECTIFIERS TO GOVERN THE CONDUCTION OF EACH ONE OF THE PAIR IN ADJACENT HALF CYCLES DURING THE CONDUCTING HALF CYCLES OF ITS RESPECTIVE AMPLIFIER, SAID MAGNETIC AMPLIFIERS EACH HAVING A RESET VOLTAGE OF SUFFICIENT MAGNITUDE TO PRODUCE NO OUTPUT DURING CONDUCTION HALF CYCLES, MEANS TO APPLY AN A.C. VOLTAGE IN PHASE WITH ONE OF THE CONTROL WINDINGS AND IN PHASE QUADRATURE WITH THE MAIN PHASE WINDING TO SUBTRACT FROM THE NORMAL MAGNITUDE OF THE RESET VOLTAGE OF THE MAGNETIC AMPLIFIERS FOR THE MAIN PHASE WINDING DURING A PORTION OF EACH RESET CYCLE AND TO SUBTRACT FROM THE RESET VOLTAGE OF THE MAGNETIC AMPLIFIERS FOR ONE CONTROL WINDING DURING EACH COMPLETE RESET CYCLE AND TO ADD TO THE RESET VOLTAGE OF THE MAGNETIC AMPLIFIERS FOR THE OTHER CONTROL WINDING DURING EACH COMPLETE RESET CYCLE TO PRODUCE AN OUTPUT TO GATE THE RECTIFIERS DURING EACH CONDUCTION CYCLE FOR THE MAIN PHASE WINDING AND MAGNITUDE OF THE CONTROL VOLTAGE TO GOVERN THE TIME FOR GATING THE RESPECTIVE RECTIFIERS DURING EACH CONDUCTION CYCLE TO CONTROL THE AVERAGE CURRENT TO THE MOTOR WINDINGS.