Apparatus for limiting the rate of rise of current in a multi-loop motor control system

Claim 2

In a motor control system of the type in which a controller responsive to a reference signal is utilized to control the current supplied to a motor, and wherein the output of the controller is limited between upper and lower maximum values; the improvement of means for limiting the rate of rise of current at the output of the controller comprising: a ramp function generator connected to the output of said controller and adapted to produce a gradually increasing output in response to a step input, and circuit means coupled to the output of said ramp function generator and adapted to gradually vary the upper and lower limits of said controller whereby the output of the controller will at first move to its limiting value followed by a gradual increase in that limiting value while the motor current increases as the output of said ramp function generator increases.

Claim 3

The motor control system of claim 1 wherein said controller is of the proportional plus integral type.

Claim 4

The motor control system of claim 1 wherein said controller is a speed controller.

Claim 5

The motor control system of claim 1 wherein said controller is provided with a transfer impedance feedback path between its input and output terminals, at least one conduction control means in shunt with said feedback path, and means coupled to said ramp function generator for controlling said conduction control means to provide limiting action.

Claim 6

The motor control system of claim 4 which includes first and second conduction control means, each connected between the input and output terminals of said amplifier, and including means responsive to the output of said ramp function generator to cause one of said conduction control means to conduct to provide controlled limiting of negative polarity output when the ramp output of said generator is negative-going and for causing the other of said conduction control means to conduct to provide controlled limiting of positive polarity output when the output of said ramp function generator is positive-going.

Claim 7

The motor control system of claim 5 wherein each of said conduction control means is a limiter for a different polarity output.

Claim 8

The motor controller of claim 1 wherein said controller comprises an operational amplifier having its output connected through a resistor to the output line of the controller, a transfer impedance feedback path connecting the output line of the controller to the input of said amplifier, said ramp function generator comprising a second operational amplifier having its input connected to a source of fixed potential, a circuit path comprising a capacitor connecting said output line to said input of the second operational amplifier, and a diode connecting the output of said second operational amplifier to said output line whereby said diode will clamp the output of said first operational amplifier at a level established by said fixed potential source, the clamping level increasing along a ramp in response to a step input applied to said controller.

Claim 9

The motor controller of claim 1 wherein said controller comprises an operational amplifier having its output connected to the base side of emitter-follower transistor means, a transfer impedance feedback path including a capacitor and a resistor in series connecting the emitter side of said emitter-follower transistor means to the input of said amplifier, said ramp function generator comprising a second operational amplifier having its input connected to a source of fixed potential, a circuit path including a capacitor connecting said input of the second operational amplifier to the emitter side of said emitter-follower transistor means, and a diode connecting the output of said second operational amplifier to the basE of said emitter-follower transistor means whereby said diode will clamp the output of said first operational amplifier at a level established by said fixed voltage source, the clamping level increasing along a ramp in response to a step input applied to said controller.

Claim 10

The motor controller of claim 8 wherein said ramp function further comprises a third operational amplifier having its input connected to a source of fixed potential, and a second circuit path including a capacitor connecting said input of the third operational amplifier to the emitter side of said emitter-follower transistor means, and wherein a second diode connected between the output of the third operational amplifier and the base side of said emitter-follower transistor means and adapted to conduct current in one direction, and wherein said diode connecting the base side of said emitter-follower transistor means to the output of said second operational amplifier is adapted to conduct current in the opposite direction.

Claim 11

The motor controller of claim 9 wherein said emitter-follower means comprises a PNP transistor and an NPN transistor having their bases and emitters interconnected, means connecting said bases to the output of said first-mentioned operational amplifier, and means connecting said emitters to the second and third operational amplifiers.

Claim 12

A controllable power supply means connected to the motor for supplying current to the motor comprising: A. a motor; B. first controller means responsive to a first reference signal and a first condition of said motor for regulating said condition; C. second controller means responsive to the output of the first controller means and a second condition of said motor for regulating the second condition; D. ramp function generating means coupled to the output of the first controller means for producing a ramp function output in response to a step input into the controller; and E. adjustable means coupled to the first controller for limiting the output of the first controller, said adjustable means being adjustable in response to the ramp function generating means to change said limit value as a function of the changing values of said ramp function, whereby a limit is imposed on the rate of change of said second condition.

Claim 13

A controllable power supply means connected to the motor for supplying current to the motor comprising: A. a motor; B. first controller means responsive to a first reference signal and a first condition of said motor for regulating said condition; C. second controller means responsive to the output of the first controller means and a second condition of said motor for regulating the second condition; D. ramp function generating means coupled to the output of the first controller means for producing a ramp function output in response to a step input into the controller; and E. adjustable means coupled to the first controller for limiting the output of the first controller, said adjustable means being adjustable in response to the ramp function generating means to change said limit value as a function of the changing values of said ramp function, whereby a limit is imposed on the rate of change of said second condition.

Claim 14

The combination as in claim 11 wherein the second condition is motor current.

Claim 15

The combination as in claim 12 wherein the first condition is motor speed.

Claim 16

The combination as in claim 11 wherein said ramp function generating means produces a ramp function sloping in one direction in response to positive-going step input into the first controller means, and produces a ramp function sloping in the opposite direction in response to negative-going step input into the first controller means, and wherein said adjustable means responds (a) to said one direction slope ramp function to limit the rate of change of said second condition in one direction, and (b) to said opposite direction slope ramp function to limit the rate of change of said second condition in the opposite direction.

Claim 17

The combination as in claim 11 wherein: G. said adjustable limiting means comprises an operational amplifier, a fixed voltage source connected to the amplifier input, and a diode connecting the output of the first controller means and the output of the amplifier, and H. said ramp generating means comprises said amplifier and feedback path including a capacitor connecting the output of the first controller to the input of the amplifier.