Motor speed modifier control

Claim 2

A motor control system for a D.C. motor having a field and armature and exhibiting available torque over a motor speed range within a desired speed-torque relationship and comprising: means for providing a motor speed signal representative of actual motor speed, means for providing a speed reference signal representative of a desired motor speed, motor speed control means for controlling energization of said motor to operate at a motor speed dependent upon a given relationship of said motor speed signal and said reference speed signal, and speed modifier control means including means for providing a torque signal representative of the available motor torque, and means for effectively varying said reference speed signal to reduce said motor speed only when said motor operates in a field weakened speed range and the available torque is less than that required for the motor speed to be within said desired speed-torque relationship.

Claim 3

A motor control system for a D.C. motor having a field and armature and exhibiting available torque over a motor speed range within a desired speed-torque relationship and comprising: means for providing a motor speed signal representative of actual motor speed, means for providing a speed reference signal representative of a desired motor speed, motor speed control means for controlling energization of said motor to operate at a motor speed dependent upon a given relationship of said motor speed signal and said reference speed signal, and speed modifier control means including means for providing a torque signal representative of the available motor torque, and means for effectively varying said reference speed signal to reduce said motor speed only when said motor operates in a field weakened speed range and the available torque is less than that required for the motor speed to be within said desired speed-torque relationship.

Claim 4

A motor control system for a D.C. motor having a field and armature and exhibiting available torque over a motor speed range within a desired speed-torque relationship and comprising: means for providing a motor speed signal representative of actual motor speed, means for providing a speed reference signal representative of a desired motor speed, motor speed control means for controlling energization of said motor to operate at a motor speed dependent upon a given relationship of said motor speed signal and said reference speed signal, and speed modifier control means including means for providing a torque signal representative of the available motor torque, and means for effectively varying said reference speed signal to reduce said motor speed only when said motor operates in a field weakened speed range and the available torque is less than that required for the motor speed to be within said desired speed-torque relationship.

Claim 5

A motor control system as set forth in claim 1 wherein said speed control means includes means for providing a control signal having a value dependent upon motor speed, and means for providing a modifying signal dependent upon the values of said motor torque signal and said control signal.

Claim 6

A motor control system as set forth in claim 2 including circuit means for receiving said speed reference signal and said modifying signal for deriving a modified speed reference signal for application to said motor speed control means to decrease said motor speed.

Claim 7

A motor control system as set forth in claim 2 wherein said torque signal providing means including means for measuring the actual available motor torque developed by said motor as said motor speed is varied.

Claim 8

A motor control system as set forth in claim 4 wherein said torque measuring means includes circuit means for developing a first signal having a magnitude dependent upon the value of the energizing field current for said motor and for developing a second signal having a value dependent on the magnitude of the motor armature current and developing therefrom a said torque signal having a value proportional to the product of said first and second signals and, hence, to the available motor torque.

Claim 9

A motor control system as set forth in claim 5 wherein said circuit means includes current sensing means for respectively sensing the motor field current and the motor armature current and signal converting means for providing said first and second signals in dependence upon the value of said field current and said armature current, and signal multiplying means for receiving said first and second signals to develop said torque signal having a magnitude which is proportional to the product of the magnitudes of said sensed field current and said sensed armature current.

Claim 10

A motor control system as set forth in claim 2 including circuit means for developing said control signal such that it varies inversely with speed only when the motor speed exceeds a predetermined amount.

Claim 11

A motor control system as set forth in claim 7 wherein said control signal developing means includes operational amplifier means, multiplying circuit means defining a feedback path between the output circuit and the inverting input circuit of said operational amplifier means, said multiplying means including circuit means for receiving said motor speed signal for multiplying the output of said operational amplifier means thereby, summing circuit means for developing a difference signal dependent upon the difference between said multiplied output signal from said multiplying means and a reference signal and supplying said difference signal to the inverting input circuit of said operational amplifier means.

Claim 12

A motor control system as set forth in claim 2 including circuit means for receiving said torque signal and said control signal and supplying a signal representative of a given relationship therebetween to said comparing means, said comparing means having an output circuit for carying a said modifying signal having a value dependent upon said given relationship.

Claim 13

A motor control system For controlling the motor speed of a D.C. motor having a load thereon and wherein said motor operates within a desired speed-torque relationship over an operating speed range and comprising: means for providing a motor speed signal representative of actual motor speed, means for providing a speed reference signal representative of desired motor speed, motor speed control means for controlling energization of said motor to operate at a motor speed dependent upon a given relationship of said motor speed signal and said reference speed signal, and speed modifier control means operative only during regenerative motor conditions for maintaining said motor speed within the desired speed-torque relationship of said motor and including circuit means for effectively measuring the load and means for modifying said reference speed signal in dependence on said measured load to reduce said motor speed when the motor speed exceeds that required for the available torque as determined by the measured load.

Claim 14

A motor control system For controlling the motor speed of a D.C. motor having a load thereon and wherein said motor operates within a desired speed-torque relationship over an operating speed range and comprising: means for providing a motor speed signal representative of actual motor speed, means for providing a speed reference signal representative of desired motor speed, motor speed control means for controlling energization of said motor to operate at a motor speed dependent upon a given relationship of said motor speed signal and said reference speed signal, and speed modifier control means operative only during regenerative motor conditions for maintaining said motor speed within the desired speed-torque relationship of said motor and including circuit means for effectively measuring the load and means for modifying said reference speed signal in dependence on said measured load to reduce said motor speed when the motor speed exceeds that required for the available torque as determined by the measured load.

Claim 15

A motor control system as set forth in claim 10 wherein said means for effectively measuring the load includes circuit means for developing a torque signal in dependence upon the magnitude of the actual motor torque developed, function generator means for developing a control signal having a value dependent upon actual motor speed and means for varying said reference signal in dependence upon the relative magnitudes of said torque signal and said reference signal to maintain said motor speed within the desired speed-torque relationship.

Claim 16

A motor control system as set forth in claim 10 wherein said load is a weight and is interconnected with said motor, said motor being a reversible drive D.C. motor to provide lifting torque over a given speed range for lifting said weight and restraining torque over a given speed range for lowering said weight, said means for providing a speed reference signal includes means for providing a signal exhibiting a first polarity representative of commanded motor lifting operation and a second polarity representative of commanded motor lowering operation and said motor speed control means includes circuit means for responding to the polarity and the magnitude of said speed reference signal for operating said motor in a motoring mode or in a regenerative mode for respectively raising or lowering said load at a speed in dependence upon the magnitude of said reference signal.