Control system for regulating the speed of an electric motor including static frequency detector for speed detection and regulation

Claim 2

Means for ascertaining the instantaneous rotor speed of an alternating current induction motor having a rotor and a stator and energizable from a source of alternating current electric power comprising: first means for detecting the instantaneous waveform of the current flow in said motor rotor; second means for extracting the fundamental frequency from said waveform and for providing a square wave signal related thereto; and third means for receiving and converting said square wave signal into an analog voltage signal proportional to speed.

Claim 3

A combination according to claim 1 wherein said first and second means comprise a fourth order active filter, an automatic gain control, and a Schmitt trigger circuit providing a square wave, and wherein said third means comprises at least one monostable multi-vibrator for converting said square wave to a constant time duration direct current output pulse.

Claim 4

In a control system for regulating the speed of an induction motor energizable from an alternating current source through a controlled rectifier bank, in combination: an operator's control movable to selected positions to effect motor operation and for providing a reference signal related to a selected position; means for sensing the instantaneous frequency of the current in said rotor and for providing a speed signal related to instantaneous rotor speed; means for providing a feedback signal related to said speed signal; and means for comparing said feedback signal and said reference signal and for providing an error signal for regulating said controlled rectifier bank to thereby regulate speed for a selected position of said operator's control.

Claim 5

In a control system for regulating the speed of an induction motor energizable from an alternating current source through a controlled rectifier bank, in combination: an operator's control movable to selected positions to effect motor operation and for providing a reference signal related to a selected position; means for sensing the instantaneous frequency of the current in said rotor and for providing a speed signal related to instantaneous rotor speed; means for providing a feedback signal related to said speed signal; and means for comparing said feedback signal and said reference signal and for providing an error signal for regulating said controlled rectifier bank to thereby regulate speed for a selected position of said operator's control.

Claim 6

A control system according to claim 3 wherein the means for sensing the instantaneous frequency and for providing a speed signal related to the instantaneous rotor speed comprises: first means for detecting the instantaneous waveform of the current flow in said motor rotor; second means for extracting the fundamentals frequency from said waveform and for providing a square wave signal related thereto; and third means for receiving and converting said square wave signal into an analog voltage signal proportional to speed.

Claim 7

A control system according to claim 4 wherein said first and second means comprise a fourth order active filter, an automatic gain control, and a Schmitt trigger circuit providing a square wave, and wherein said third means comprises at least one monostable multivibrator for converting said square wave to a constant time duration direct current output pulse.

Claim 8

In combination: an alternating current induction motor energizable from an alternating current source through a controlled rectifier bank and a control system for regulating the speed of said motor, said control system comprising: an operator's control having an operating member movable between a neutral position and any one of a plurality of operating positions, said control providing a reference signal related to handle movement and position; means for providing a speed signal related to instantaneous rotor speed, said means for providing said speed signal comprising means for deriving a signal related to the frequency of the current in said motor rotor. means for providing a feedback signal related to said speed signal; and means for comparing said feedback signal and said reference signal and for providing an error signal for operating said controlled rectifier bank to control motor speed.

Claim 9

In combination: an alternating current induction motor energizable from an alternating current source through a controlled rectifier bank and a control system for regulating the speed of said motor, said control system comprising: an operator's control having an operating member movable between a neutral position and any one of a plurality of operating positions, said control providing a reference signal related to handle movement and position; means for providing a speed signal related to instantaneous rotor speed, said means for providing said speed signal comprising means for deriving a signal related to the frequency of the current in said motor rotor. means for providing a feedback signal related to said speed signal; and means for comparing said feedback signal and said reference signal and for providing an error signal for operating said controlled rectifier bank to control motor speed.

Claim 10

A control system according to claim 6 wherein the means for providing a speed signal related to the instantaneous rotor speed comprises: first means for detecting the instantaneous waveform of the current flow in said motor rotor; second means for extracting the fundamental frequency from said waveform and for providing a square wave signal related thereto; and third means for receiving and converting said square wave signal into an analog voltage signal proportional to speed.

Claim 11

A control system according to claim 7 wherein said first and second means comprise a fourth order active filter, an automatic gain control, and a Schmitt trigger circuit providing a square wave, and wherein said third means comprises at least one monostable multivibrator for converting said square wave to a constant time duration direct current output pulse.

Claim 12

A control system for regulating the speed and torque of a reversible alternating current motor having stator windings energizable from an alternating current source through a controlled rectifier bank, comprising: an operator's control having a member selectively movable in opposite directions from a neutral position to effect forward and reverse operation of said motor, said control providing a reference signal related to member position; means for providing a speed signal related to instantaneous rotor speed, said means for providing said speed signal comprising means for deriving a signal related to the frequency of the current in said motor rotor; means for providing a feedback signal related to said speed signal; means including a summing circuit for comparing said feedback signal and said reference signal and for providing an error signal; means including a regulator circuit for processing said error signal and providing a control signal output proportional to said error signal; and firing pulse generator means for receiving said control signal and for providing firing pulses for operating said controlled rectifier bank to control motor speed.

Claim 13

A control system for regulating the speed and torque of a reversible alternating current motor having stator windings energizable from an alternating current source through a controlled rectifier bank, comprising: an operator's control having a member selectively movable in opposite directions from a neutral position to effect forward and reverse operation of said motor, said control providing a reference signal related to member position; means for providing a speed signal related to instantaneous rotor speed, said means for providing said speed signal comprising means for deriving a signal related to the frequency of the current in said motor rotor; means for providing a feedback signal related to said speed signal; means including a summing circuit for comparing said feedback signal and said reference signal and for providing an error signal; means including a regulator circuit for processing said error signal and providing a control signal output proportional to said error signal; and firing pulse generator means for receiving said control signal and for providing firing pulses for operating said controlled rectifier bank to control motor speed.

Claim 14

A control system according to claim 9 wherein the means for providing a speed signal related to the instantaneous rotor speed comprises: first means for detecting the instantaneous waveform of the current flow in said motor rotor; second means for extracting the fundamental frequency from said waveform and for providing a square wave signal related thereto; and third means for receiving and converting said square wave signal into an analog voltage signal proportional to speed.

Claim 15

A control system according to claim 10 wherein said first and second means comprise a fourth order active filter, an automatic gain control, and a Schmitt trigger circuit providing a square wave, and wherein said third means comprises at least one monostable multivibrator for converting said square wave to a constant time duration direct current output pulse.