Speed regulating and control system for plural-phase-wound-rotor induction motors

Claim 2

A motor control system for controlling the speed of a pluralphase induction motor having a plurality of stator and rotor windings comprising: a plurality of silicon controlled rectifiers individually coupled to different ones of the rotor windings for controlling current flow therein; a plurality of trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such silicon controlled rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; phase shift circuit means responsive to at least one of the rotor winding voltages for supplying alternating-current signals to the input terminals of the trigger circuits for triggering each trigger circuit at some point during each cycle of the voltage of the rotor winding for the corresponding silicon controlled rectifier; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and adjustable bias circuit means for supplying adjustable direct-current bias to the input terminals of the trigger circuits for establishing the nominal operating speed of the motor.

Claim 3

A motor control system for controlling the speed of a plural-phase induction motor having a plurality of stator and rotor windings comprising: a plurality of silicon controlled rectifiers individually coupled to different ones of the rotor windings for controlling current flow therein; a plurality of trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such silicon controlled rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; phase shift circuit means responsive to at least one of the rotor winding voltages for supplying alternating-current signals to the input terminals of the trigger circuits for triggering each trigger circuit at some point during each cycle of the voltage of the rotor winding for the corresponding silicon controlled rectifier; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and second rectifier circuit means responsive to at least one of the rotor winding currents for supplying to the iNput terminals of the trigger circuits further direct-current signals of opposite polarity relative to the direct-current control signals for preventing excessive acceleration of the motor.

Claim 4

A motor control system for controlling the speed of a plural-phase induction motor having a plurality of stator and rotor windings comprising: a plurality of silicon controlled rectifiers individually coupled to different ones of the rotor windings for controlling current flow therein; a plurality of trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such silicon controlled rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; phase shift circuit means responsive to at least one of the rotor winding voltages for supplying alternating-current signals to the input terminals of the trigger circuits for triggering each trigger circuit at some point during each cycle of the voltage of the rotor winding for the corresponding silicon controlled rectifier; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and second rectifier circuit means responsive to at least one of the rotor winding currents for supplying to the iNput terminals of the trigger circuits further direct-current signals of opposite polarity relative to the direct-current control signals for preventing excessive acceleration of the motor.

Claim 5

A motor control system for controlling the speed of a three-phase induction motor having three stator windings and three rotor windings comprising: at least three silicon controlled rectifiers individually coupled to different ones of the rotor windings for controlling current flow therein; at least three trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; at least three phase shift circuit means responsive to the voltages of different ones of the rotor windings for supplying alternating-current signals to the input terminals of corresponding ones of the trigger circuits for triggering such trigger circuits at some point during each cycle of the corresponding rotor winding voltage; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and adjustable bias circuit means for supplying adjustable direct-current bias to the input terminals of the trigger circuits for establishing the nominal operating speed of the motor.

Claim 6

A motor control system for controlling the speed of a three-phase induction motor having three stator windings and three rotor windings comprising: at least three silicon controlled rectifiers individually coupled to different ones of the rotor windings for controlling current flow therein; at least three trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; at least three phase shift circuit means responsive to the voltages of different ones of the rotor windings for supplying alternating-current signals to the input terminals of corresponding ones of the trigger circuits for triggering such trigger circuits at some point during each cycle of the corresponding rotor winding voltage; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and adjustable bias circuit means for supplying adjustable direct-current bias to the input terminals of the trigger circuits for establishing the nominal operating speed of the motor.

Claim 7

A motor control system for controlling the speed of a three-phase induction motor having three stator windings and three rotor windings comprising: three pairs of silicon controlled rectifiers, each pair being coupled to a different one of the rotor windings for controlling current flow therein, one silicon controlled rectifier of each pair being poled for current flow in one direction and the other being poled for current flow in the other direction in the rotor winding; six trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; three pairs of phase shift circuit means, each pair being responsive to the voltage of a different one of the rotor windings for supplying alternating-current signals to the input terminals of the trigger circuits for the silicon controlled rectifiers coupled to the same rotor winding for triggering such trigger circuits at different points during each cycle of the rotor winding voltage; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and adjustable bias circuit means for supplying adjustable direct-current bias to the input terminals of the trigger circuits for establishing the nominal operating speed of the motor.

Claim 8

A motor control system for controlling the speed of a three-phase induction motor having three stator windings and three rotor windings comprising: three pairs of silicon controlled rectifiers, each pair being coupled to a different one of the rotor windings for controlling current flow therein, one silicon controlled rectifier of each pair being poled for current flow in one direction and the other being poled for current flow in the other direction in the rotor winding; six trigger circuits individually coupled to different ones of the silicon controlled rectifiers for firing such rectifiers when the signal level at an input terminal of the corresponding one of the trigger circuits exceeds a predetermined threshold level; three pairs of phase shift circuit means, each pair being responsive to the voltage of a different one of the rotor windings for supplying alternating-current signals to the input terminals of the trigger circuits for the silicon controlled rectifiers coupled to the same rotor winding for triggering such trigger circuits at different points during each cycle of the rotor winding voltage; rectifier circuit means responsive to at least one of the rotor winding voltages for supplying direct-current control signals to the input terminals of the trigger circuits for determining the phase angles at which the alternating-current signals trigger such trigger circuits and thereby regulating the speed of the motor; and adjustable bias circuit means for supplying adjustable direct-current bias to the input terminals of the trigger circuits for establishing the nominal operating speed of the motor.

Claim 9

A motor control system for controlling the speed of a plurality of induction motors each having stator and rotor windings comprising: a plurality of individual control systems each having a current control means coupled to the rotor winding of a different one of the motors for controlling current flow therein and control circuit means responsive to the rotor winding voltages of the same motor for controlling the operation of the current control means for controlling the speed of such motor; and circuit means for supplying a common periodic reference signal to the control circuit means of each of the control systems for causing all of the motors to run at the same speed.

Claim 10

A motor control system for controlling the speed of a plurality of induction motors each having stator and rotor windings comprising: a plurality of individual control systems each having a current control means coupled to the rotor winding of a different one of the motors for controlling current flow therein and control circuit means responsive to the rotor winding voltages of the same motor for controlling the operation of the current control means for controlling the speed of such motor; and circuit means for supplying a common periodic reference signal to the control circuit means of each of the control systems for causing all of the motors to run at the same speed.

Claim 11

A motor control system in accordance with claim 5 wherein the reference signal circuit means includes means for varying the frequency or repetition rate of the periodic reference signal and thereby varying the operating speed of the motors.