Analog to digital to analog rate control circuit for traction motor control systems

Claim 2

In a motor control system wherein a motor control signal source supplies motor control input signals for application to a motor control signal utilization circuit which regulates performance of a motor, means for limiting the acceleration rate of said motor comprising: a. a clock source generating periodically recurring clock pulses; b. bidirectional counting means for algebraically adding said clock pulses to generate a digital count; c. conversion means for converting said digital count into a corresponding analog signal; d. coupling means to couple said analog signal as a control output signal, to said motor control signal utilization circuit. e. steering means connected to continuously cause said bidirectional counting means to selectively add or subtract clock pulses responsive to comparison of the magnitudes of said control input and of said control output signals; f. means for establishing the recurence frequency of said clock pulses to limit the maximum incremental change per unit time of the magnitude of the control output signal so that the magnitude of the motor control output signal varies proportionately but at a predetermined maximum rate of change, in respect to the control input signal.

Claim 3

The arrangement of claim 1 wherein said steering means comprises comparison means for comparing said control input signal and said control output signal and steering logic means for directing said bidirectional counter to add or subtract clock pulses responsive to which of said aforesaid signals has the greater magnitude.

Claim 4

The arrangement of claim 2 wherein said comparison means comprises a high gain difference amplifier having its input connected to receive said aforesaid signals and providing at its output a steering signal of a predetermined first or of a predetermined second state dependent upon which of said signals has the greater magnitude.

Claim 5

The arrangement of claim 3, wherein said steering logic means couples clock pulses to either up count or down count responsive to the state of said steering signal input lines of said bidirectional counter.

Claim 6

The arrangement of claim 4 wherein said clock pulse source continuously supplies clock pulses to said bidirectional counting means during operation of said propulsion control system, said control input signal being limited to variation intermediate a predetermined voltage magnitude, and the count capacity of said bidirectional counting means exceeding the number of counts required to generate a control output signal said predetermined voltage magnitude so as to prevent reset of said counting means during operation of said propulsion system.

Claim 7

The arrangement of claim 5 wherein said coupling means provides a control output signal to said comparison means which signal Is offset in respect to said analog output signal sufficiently to prevent undesired reset of said counting means.

Claim 8

The arrangement of claim 2 comprising frequency control means responsive to applied frequency control input signals to selectively modify the recurrence frequency of said clock pulses.

Claim 9

The arrangement of claim 7 wherein said clock source comprises resistance and capacitance means in an oscillatory circuit for establishing the recurrence frequency of said clock pulses, means for shunting said resistance means with serially connected impedance and semiconductor switching means, said switching means being actuated in response to an electrical signal to shunt said impedance means across said resistance means to modify the recurrence frequency of said clock pulses.

Claim 10

The arrangement of claim 1 wherein said bidirectional counting means comprises reset means adapted to be energized in connection with shut down of the motor control system.

Claim 11

In an electrical propulsion control system for a traction vehichle wherein a motor control signal source supplies a motor control input signal utilization circuit which regulates performance of the traction motors of the vehicle, means for limiting the maximum acceleration rate of the vehicle comprising: a. a clock pulse source generating recurring clock pulses; b. bidirectional counting means comprising a steering signal input, up count and down count inputs, and digital count outputs; c. up/down logic connected to supply said clock pulses to said up count input in response to a steering signal input in response to a steering signal input having a first state and to supply said clock pulses to said down count input in response to a steering signal input having a second state; d. digital to analog conversion means connected to convert the digital count output to a corresponding analog signal output; e. comparison on means having inputs, and a steering signal output coupled to the steering signal input of said up/down logic means; f. coupling means to couple said analog signal as a control output signal to said motor control signal utilization circuit and to an input of said comparison means; g. means for coupling said control input signal from said motor control signal source to input of said comparison means; h. said comparison means being constructed to compare the magnitudes of said applied control input and control output signals to supply at its steering signal output a signal having first or second states dependent on which of the compared signals has the greater magnitude; i. means for establishing the recurrence frequency of said clock pulses to limit the maximum incremental change per unit time of the magnitude of said control output signal so that the magnitude of the motor control output signal while varying proportionately to said control input signal has its rate of change limited such that the traction vehicle''s rate of acceleration is maintained within predetermined limits.

Claim 12

In an electrical propulsion control system for a traction vehichle wherein a motor control signal source supplies a motor control input signal utilization circuit which regulates performance of the traction motors of the vehicle, means for limiting the maximum acceleration rate of the vehicle comprising: a. a clock pulse source generating recurring clock pulses; b. bidirectional counting means comprising a steering signal input, up count and down count inputs, and digital count outputs; c. up/down logic connected to supply said clock pulses to said up count input in response to a steering signal input in response to a steering signal input having a first state and to supply said clock pulses to said down count input in response to a steering signal input having a second state; d. digital to analog conversion means connected to convert the digital count output to a corresponding analog signal output; e. comparison on means having inputs, and a steering signal output coupled to the steering signal input of said up/down logic means; f. coupling means to couple said analog signal as a control output signal to said motor control signal utilization circuit and to an input of said comparison means; g. means for coupling said control input signal from said motor control signal source to input of said comparison means; h. said comparison means being constructed to compare the magnitudes of said applied control input and control output signals to supply at its steering signal output a signal having first or second states dependent on which of the compared signals has the greater magnitude; i. means for establishing the recurrence frequency of said clock pulses to limit the maximum incremental change per unit time of the magnitude of said control output signal so that the magnitude of the motor control output signal while varying proportionately to said control input signal has its rate of change limited such that the traction vehicle''s rate of acceleration is maintained within predetermined limits.